United States Office of Water EPA-822-R-03-023
Environmental Protection 4304 October, 2003
Agency
AMBIENT AQUATIC LIFE WATER QUALITY CRITERIA FOR ATRAZINE -
REVISED DRAFT
SF
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AMBIENT AQUATIC LIFE WATER QUALITY CRITERIA FOR
ATRAZINE - REVISED DRAFT
CAS Registry No. 1912-24-9
SF
October 2003
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF WATER
OFFICE OF SCIENCE AND TECHNOLOGY
HEALTH AND ECOLOGICAL CRITERIA DIVISION
WASHINGTON D.C.
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NOTICES
This document has been reviewed by the Health and Ecological Criteria Division, Office of Science and
Technology, U.S. Environmental Protection Agency, and is approved for publication.
Mention of trade names or commercial products does not constitute endorsement or recommendation for
use.
This document is available to the public through the National Technical Information Service (NTIS),
5285 Port Royal Road, Springfield, VA 22161. It is also available on EPA's web site:
http://www.epa.gov/waterscience/criteria/atrazine.
DRAF
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FOREWORD
Section 304(a)(l) of the Clean Water Act of 1977 (P.L. 95-217) requires the Administrator of
the Environmental Protection Agency to publish water quality criteria that accurately reflect the latest
scientific knowledge on the kind and extent of all identifiable effects on health and welfare that might
be expected from the presence of pollutants in any body of water, including ground water. This
document is a revision of draft criteria published in 2001 based upon consideration of scientific input
received from the public and new information. Criteria contained in this document replace any
previously published EPA aquatic life criteria for the same pollutant.
The term "water quality criteria" is used in two sections of the Clean Water Act, section
304(a)(l) and section 303(c)(2). The term has a different program impact in each section. In section
304, the term represents a non-regulatory, scientific assessment of ecological effects. Criteria presented
in this document are such scientific assessments. If water quality criteria associated with specific
stream uses are adopted by a state as water quality standards under section 303, they become
enforceable maximum acceptable pollutant concentrations in ambient waters within that state. Water
quality criteria adopted in state water quality standards could have the same numerical values or
method resulting in a numerical value as criteria developed under section 304. However, in many
situations states might want to adjust water quality criteria developed under section 304 to reflect local
environmental conditions and human exposure patterns. Alternatively, states may use different data
and assumptions than EPA in deriving numeric criteria that are scientifically defensible and protective
of designated uses. It is not until their adoption as part of state water quality standards that criteria
become regulatory. Guidelines to assist the states and Indian tribes in modifying the criteria presented
in this document are contained in the Water Quality Standards Handbook (U.S. EPA, 1994). This
handbook and additional guidance on the development of water quality standards and other water-
related programs of this Agency have been developed by the Office of Water.
This draft document is guidance only. It does not establish or affect legal rights or obligations.
It does not establish a binding norm and cannot be finally determinative of the issues addressed.
Agency decisions in any particular situation will be made by applying the Clean Water Act and EPA
regulations on the basis of specific facts presented and scientific information then available.
Geoffrey H. Grubbs
Director
Office of Science and Technology
in
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ACKNOWLEDGMENTS
Daniel J. Call
University of Wisconsin-Superior
Superior, Wisconsin
Larry Brooke
University of Wisconsin-Superior
Superior, Wisconsin
Tyler K. Linton
Great Lakes Environmental Center
Columbus, OH
Gregory J. Smith
Great Lakes Environmental
Columbus, Ohio
Douglas J. Urban
U.S. EPA
Environmental Fate and Effects Division
Office of Pesticide Programs
Washington, D.C.
Stephanie R. Irene
U.S. EPA
Environmental Fate and Effects Division
Office of Pesticide Programs
Washington, D.C.
Frank Gostomski
(document coordinator)
U.S. EPA
Health and Ecological Criteria Division
Office of Water
Washington, D.C.
tal Center
IV
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CONTENTS
NOTICES ii
FOREWORD iii
ACKNOWLEDGMENTS iv
TABLES vi
FIGURES vii
Executive Summary 1
Introduction 3
Acute Toxicity to Freshwater Animals
Acute Toxicity to Saltwater Animals
Chronic Toxicity to Freshwater Animals M .... 10
Chronic Toxicity to Saltwater Animals 13
Toxicity to Aquatic Plants 14
Ecosystem Effects Data 18
Impacts to Plant Communicty Structure and Function 24
Endocrine Disruption Effects Data 39
Bioaccumulation 40
Other Data 41
Unused Data 52
Summary 55
National Criteria 58
Implementation 58
References 129
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TABLES
A. Selected Freshwater Acute and Chronic Plant Data Taken From Table 4 16
B. Selected Saltwater Acute and Chronic Plant Data Taken From Table 4 18
C. Summary of Endocrine Disruption Effects of Atrazine to Freshwater Organisms 25
1. Acute Toxicity of Atrazine to Aquatic Animals 66
2a. Chronic Toxicity of Atrazine to Aquatic Animals ^H .|. f. . . . ^H. . . .\ . 69
2b. Acute-Chronic Ratios . ^f^^^- /• -^^ ^l*^ ^1 70
3. Ranked Genus Mean Acute Values with Species Mean Acute-Chronic Ratios 71
4. Toxicity of Atrazine to Aquatic Plants 74
5. Bioaccumulation of Atrazine by Aquatic Organisms 80
6. Other Data on Effects of Atrazine on Aquatic Organisms 81
VI
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FIGURES
Page
A. Mesocosm/Microcosm Effects Scores 27
B. Plant Species Sensitivity Distribution 29
C. Example Matrix 31
D. Correlation Between Similarity Index and Brock 2000 34
E. Micro- and Mesocosm Study Effect Concentration 35
1. Ranked Summary of Atrazine GMAVs - Freshwater 60
2. Ranked Summary of Atrazine GMAVs - Saltwater 61
3. Chronic Toxicity of Atrazine to Aquatic Animals 62
4. Ranked Summary of Test Values for Freshwater Plants 63
5. Ranked Summary of Test Values for Saltwater Plants 64
6. Range of Reported Atrazine Lowest Observed Effect Concentrations (LOECs)
and No Observed Effect Concentrations (NOECs) Excluding Those LOECs
Where Recovery Was Reported to Occur 65
vn
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EXECUTIVE SUMMARY
Background:
Atrazine is the most extensively used herbicide in the United Sates for control of weeds in
agricultural crops and is toxic to aquatic organisms. EPA has developed ambient water quality criteria
for atrazine for the protection of aquatic life through its authority under section 304(a) of the Clean
Water Act (CWA). These water quality criteria are guidance for Sates and Tribes and in themselves
have no binding legal effect. The criteria may for the basis for State and Tribal water quality standards
and in turn become enforceable through National Pollutant Discharge Elimination System (NPDES)
permits or other environmental programs.
Freshwater Criteria:
For atrazine the criterion to protect freshwater aquatic life freshwater aquatic life and their uses
is an Average Primary Producer Steinhaus Similarity deviation for a site less than 5% (as determined
using CASM or other appropriate model and index) not exceeded more than once every three years on
the average (or other appropriate return frequency sufficient to allow system recovery) and a one-hour
average concentration that does not exceed 1,500 ug/L more than once every three years on the
average. The 5% index for the protection of aquatic plant community should also be protective of most
freshwater animals.
Saltwater Criteria:
For atrazine, the criterion to protect saltwater aquatic life from chronic toxic effects is 17 ug/L.
This criterion is implemented as a thirty-day average, not to be exceeded more than once every three
years on the average. The criterion to protect saltwater aquatic life from acute toxic effects is 760 ug/L.
This criterion is implemented as a one-hour average, not to be exceeded more than once every three
years on the average.
The criteria for atrazine were developed by the EPA Office of water (OW) using a large aquatic
toxicity data base and extensive mesocosm and mesocosm data. Adverse effect of atrazine on survival,
growth, and reproduction of aquatic organisms and on plant community structure were demonstrated in
numerous laboratory and field studies.
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This document provides guidance to States and Tribes authorized to establish water quality
standards under the Clean Water Act (CWA) to protect aquatic life from acute and chronic effects of
atrazine. Under the CWA, States and Tribes are to establish water quality criteria to protect designated
uses. While this document constitutes U.S. EPA's scientific recommendations regarding ambient
concentrations of atrazine, this document does not substitute for the CWA or U.S. EPA's regulations;
nor is it a regulation itself. Thus, it cannot impose legally binding requirements on U.S. EPA, States,
Tribes, or the regulated community, and it might not apply to a particular situation based upon the
circumstances. State and Tribal decision-makers retain the discretion to adopt approaches on a case-
by-case basis that differ from this guidance when appropriate. U.S. EPA may change this guidance in
the future.
DRAFT
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INTRODUCTION1
Atrazine is a herbicide with the empirical formula C8H14C15N5 and a molecular weight of 215.7.
It is a white, crystalline solid with a melting point of 173-175°C, a boiling point of 279°C, and
solubility in water of 33 mg/L at 25°C (Farm Chemicals Handbook 2000; Hunter et al. 1985). Atrazine
has an n-octanol-water partition coefficient (log P) of 2.82, a vapor pressure of 7.34 x 10"4 mm Hg, a
Henry's Constant of 8.32 x 10"6 atmmVM, and a hydrolysis half-life in excess of 1,000 days (Hunter et
al. 1985). These physico-chemical properties contribute to its environmental partitioning and degree of
persistence in the aquatic environment.
Atrazine is used extensively in the United States, Canada and other countries for the control of
weeds in agricultural crops, especially in crops such as corn, sorghum, wheat and soybeans. It is one of
the most heavily used pesticides in North America, generally being among the top few in terms of total
pounds of herbicide used (Braden et al. 1989; Burridge and Haya 1988; Ciba-Geigy 1994; Council on
Environmental Quality 1984; Moxley 1989; Pike 1985; Richards and Baker 1993). Annual domestic
usage during the past two decades has been in the general range of 30 to 40 million kilograms applied
to approximately 70 million acres of farm land in the U.S. (U.S. EPA 2000). It is also commonly used
in other countries (Bester and Huhnerfuss 1993; Bester et al. 1995; Caux and Kent 1995; Galassi et al.
1992, 1993; Lode et al. 1994). Atrazine is also used in combination with other herbicides including
alachlor, ametryne, linuron, paraquat, propachlor, amitrole, and cyanazine (Farm Chemicals Handbook
2000).
With this magnitude of application, atrazine has commonly been detected in surface waters of
agricultural watersheds where it has been used. Due to its relative mobility from soil, atrazine surface
water concentrations are highest in field runoff, with concentration peaks generally following early
major storm events that occur within a few weeks of application (Glotfelty et al. 1984; Muir et al. 1978;
Triplett et al. 1978; Wauchope 1978; Wauchope and Leonard 1980). Concentrations in the low mg/L
range may be encountered in edge-of-field run-off (Hall et al. 1972; Kadoum and Mock 1978; Klaine et
al. 1988; Roberts et al. 1979). Field run-off is diluted upon entering a stream or lake, resulting in
atrazine concentrations that are generally much lower (e.g., 1-10 (ig/L range) in such waters (Frank and
Sirons 1979; Frank et al. 1979; Richards and Baker 1993; Richard et al. 1975; Roberts et al. 1979; Wu
1981). Only trace levels (i.e., <1.0-33 ng/L) were reported in a pesticide monitoring study in California
XA comprehension of the "Guidelines for Deriving Numerical National Water Quality Criteria for the
Protection of Aquatic Organisms and Their Uses" (Stephen et al. 1985), hereafter referred to as the Guidelines, is
necessary to understand the following text, tables and calculations.
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(Pereira et al. 1996). However, individual maximum concentrations may be considerably higher.
Elevated levels of atrazine • £ (ig/L have been documented by Frenzel et al. (1998) in the Platte River
of Nebraska for greater than 60 days, and • 5 (ig/L for greater than 30 days. When considered over
several years, maximum concentrations reported in some creeks and rivers from midwestern
agricultural areas have ranged from 5 to 70 (ig/L (Ciba-Geigy 1992a,b,c,d, 1994; Frank and Sirons
1979; Frank et al. 1979, 1982; Illinois State Water Survey 1990; Muir et al. 1978; Richards and Baker
1993; Roberts et al. 1979). Factors that strongly and positively correlate with the release of atrazine
from soil include sediment organic carbon, landscape position, and tillage (Novak 1999).
Surface waters surrounded by agricultural lands may receive several pulsed doses over the
growing season corresponding to rainfall events (Herman et al. 1986). Annual patterns of atrazine
concentrations in Ohio streams show peak time-weighted mean concentrations of about 6 (ig/L in early
June, with a rapid increase from April to June, followed by a rapid decrease from June to August
(Richards and Baker 1993). Time-weighted mean concentrations between August and December are
considerably lower, most frequently being less than 1.0 (ig/L. Atrazine concentrations are the lowest,
and uniformly so, between January and April. Also, smaller streams were shown to have higher peak
concentrations, but of shorter duration, than larger streams (Richards and Baker 1993). The annual
cycle is similar in southwestern Ontario, but with the annual peak concentrations occurring at lower
levels and several weeks later than in Ohio (Bodo 1991). Nonetheless, atrazine concentrations in
Ontario have regularly exceeded 2 (ig/L, which is the Canadian water quality guideline for aquatic life
protection (Trotter et al. 1990). Exceedances have similarly been reported in surface waters of Quebec
(Caux and Kent 1995).
Among the highest surface water concentrations of atrazine are those in small reservoirs in
southern Illinois. These are currently being intensively monitored (Tierney et al. 1994a). Maximum
concentrations as high as 55 (ig/L have been reported from these reservoirs.
Similar seasonal trends in concentrations of atrazine to those in Ohio streams have been
observed in streams in Illinois (Ciba-Geigy 1992a; Illinois State Water Survey 1990), in Iowa (Ciba-
Geigy 1994), and in other midwestern states (Ciba-Geigy 1992c). In large rivers such as the
Mississippi, Missouri and Ohio Rivers, peak concentrations have most commonly occurred in June,
with mean levels of less than 5.0 (ig/L during the spring period (Ciba-Geigy 1992b). The maximum
concentrations were generally between 2 and 8 (ig/L, with a single maximum as high as 17.25 (ig/L
(Ciba-Geigy 1992b,c). Atrazine concentrations in the Mississippi River between Minneapolis,
Minnesota and New Orleans, Louisiana from July to August, 1991 ranged from 0.054 (ig/L to 4.7 (ig/L
(Pereira and Hostetler 1993).
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Atrazine residues in Illinois lakes tended to be lower than those in the streams (with less
pronounced peak values), however, the lower concentrations were sustained for longer durations (Ciba-
Geigy 1992a). It should be noted that the maximum observed atrazine concentration was less than 3.0
(ig/L at 61 percent of 42 sites monitored over 6 years between 1975 and 1988 (Ciba-Geigy 1992a).
Atrazine concentrations were considerably lower in Chesapeake Bay and its tributaries (Ciba-
Geigy 1992e). Here, the maximum observed concentration in a tributary was 14.6 (ig/L, and only three
out of 600 samples analyzed between 1976 and 1991 exceeded 3.0 (ig/L. The highest observed
maxima in the Upper and Lower Chesapeake Bay were 1.7 and 0.38 (ig/L, respectively. Models for the
Great Lakes suggest that concentrations should be quite low, not likely to exceed 0.13 (ig/L (Tierney et
al. 1994b). Individual measurements from Lake Erie taken at Toledo, Ohio, have not exceeded 0.35
(ig/L, while concentrations measured from samples collected in Lake Michigan at Michigan City,
Indiana, have been below 0.20 (ig/L (Ciba-Geigy 1992c).
In addition to field run-off, atrazine residues are also transported by volatilization into the
atmosphere and subsequent deposition. Atrazine has been measured in fog (Glotfelty et al. 1987), and
trace amounts have been shown to be transported by the wind (Elling et al. 1987). Atrazine was present
year-round in rainwater samples in Maryland, with the highest concentration of 2.2 (ig/L occurring in
May(Wu 1981).
Atrazine has been shown to be enriched at the microsurface layer of water (Wu 1981; Wu et al.
1980). This may be due to the presence of microsurface films which tend to concentrate certain
chemicals. Wu (1981) suggested that atrazine enrichment in the microsurface layer was more likely a
source of direct input rather than a result of atmospheric wet deposition, and that the main source of
atrazine at the site studied in Maryland was agricultural runoff.
Studies of atrazine persistence in water have produced varying results. Huckins et al. (1986)
reported the loss of atrazine from water within 4 days in a simulated prairie pond microcosm. In
shallow artificial streams, a 50 percent loss of atrazine occurred in 3.2 days (Kosinski 1984; Moorhead
and Kosinski 1986). Lay et al. (1984) reported an 82 percent loss in 5 days and a 95 percent loss in 55
days. The half-life of atrazine in wetland mesocosms was from 8 to 14 days (Detenbeck et al. 1996).
The half-life of 14C-labeled atrazine has been measured in estuarine water as 3 to 12 days, compared to
15 to 30 days in estuarine sediment and 330 to 385 days in agricultural soils (Jones et al. 1982; Kemp et
al. 1982a).
These rapid losses in small artificial systems and in an estuarine environment are contrasted
with reports of a 300-day half-life in a larger lake system (Yoo and Solomon 1981), surface water
losses of only 33 percent in 120 days and 0 percent in 85 days in two separate 0.49 hectare pond
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applications (Klaassen and Kadoum 1979), and a loss of only 40-50 percent in pond water over a
period of more than 5 months (Gunkel 1983). In two months time, approximately 25-30 percent of
individual 20 and 500 (ig/L atrazine applications to a 0.045 hectare Kansas pond had disappeared from
the water (deNoyelles et al. 1982). Approximately 25 percent of the initial applications remained after
12 months. The half-life of atrazine was approximately 3 months in Tasmanian streams (Davies et al.
1994a).
The above information indicates that the persistence of atrazine in water is highly variable,
dependent perhaps upon both the nature of the aquatic system into which it is introduced as well as the
climatic conditions at the exposure site. For example, Comber (1999) determined that significant
hydrolysis of atrazine occurs only at pH values of 4 or less, while photolysis was initiated only by
wavelengths below 300 nm at higher pH (pH 6 to 8). Based on this author's experiments, the aquatic
half-life of atrazine in sunny upland waters was predicted to be 6 days, but in low land rivers with
higher pH (7 to 8.5), the half-life would be in the order of months rather than days. The opposite is true
for groundwater where the half-life would be in the order of years due to exceedingly slow rates of
Biodegradation is considered to be one of the most important processes governing the
environmental fate of atrazine (Radosevich et al. 1996). Microbes isolated from aquatic ecosystems
that are capable of degrading atrazine have been reported. Mirgain et al. (1993) isolated a
Pseudomonas putida/Xanthomonas maltophilia pair with atrazine-degrading ability. Certain soil
bacteria have also been shown to be capable of degrading atrazine both aerobically and anaerobically
(Behki et al. 1993; Radosevich et al. 1995, 1996). Some soil fungi also can degrade atrazine (Donnelly
et al. 1993). In a salt marsh environment, the incorporation of atrazine into the sediment appeared to be
a prerequisite for its degradation (Meakins et al. 1995). Very little degradation occurred in the water
column.
Seybold et al. (1999) recently examined the fate of atrazine (14C-labeled) from two undisturbed
sediments over a 2-year period. The atrazine was released from the sediment into the water column
primarily through diffusion from the pore water. The amount of atrazine released was affected by
sediment type and temperature. More atrazine residue was released into the water column at 5°C than
at 24°C. However, degradation of the atrazine in sediment was high; less than 2 percent of extractable
atrazine and metabolites remained after 2 years. The authors concluded that the accumulation and later
release of atrazine is greatest at cold water temperatures and in sediments with low adsorption capacity.
Kruger et al. (1996) found that the mobilities of atrazine and its degradates were negatively correlated
with soil organic matter content and positively correlated with sand content of Iowa soils.
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The major atrazine degradate in aquatic systems is hydroxyatrazine (U.S. EPA 2000). Others
include deethylatrazine, deisopropylatrazine, and diaminoatrazine. The degradation products of
atrazine were found to be less toxic to algae (Stratton 1984) and submerged aquatic plants (Jones and
Winchell 1984) then the parent compound. Equivalent studies of atrazine degradate toxicity to aquatic
animals is sparse. Results from mammalian studies indicate that some atrazine degradates may be more
toxic than parent compound (U.S. EPA 2000).
The mode of atrazine's toxic action toward plants is blockage of electron transport within the
Hill reaction of photosystem II, thereby inhibiting photosynthesis (Moreland 1980). Vascular plants
and algae are both affected by this mode of action. In this way, atrazine has the demonstrated capacity
to reduce primary productivity in aquatic ecosystems (deNoyelles et al. 1982; Dewey 1986; Herman et
al. 1986; Kosinski and Merkle 1984; Pratt et al. 1988). On the other hand, the mode of toxic action
toward aquatic animals has not been documented, probably because atrazine is not considered acutely
toxic to these species. Recent evidence implicates atrazine as an indirect endocrine disrupter (Dodson
et al. 1999; Petit et al. 1997) that may act by stimulating the activity of the aromatase enzyme that
converts testosterone to estrogen (Sanderson et al. 2000). The occurrence of abnormal gonadal
development (including feminization and hermaphroditism) and reduced laryngeal muscle size in
exposed Xenopus laevis males has been reported at levels ranging from 1 (ig/L atrazine (Hayes et al.
2002) to approximately 20-21 (ig/L atrazine (Carr et al. 2003; Carr and Solomon 2003; Renner 2002).
Other investigators have demonstrated that atrazine causes induction of xenobiotic metabolizing
systems (Miota et al. 1999), and enhances the toxicity of organophosphorous insecticides to aquatic
invertebrates (Belden and Lydy 2000; Pape-Lindstrom and Lydy 1997).
Several reviews exist on atrazine and its environmental impact (CCREM 1989; deNoyelles et
al. 1994; Eisler 1989; Huber 1993, 1994; Solomon et al. 1996). These reviews indicated that a few
species of aquatic plants have been shown to be slightly affected by atrazine at concentrations below 10
(ig/L. The review by deNoyelles et al. (1994) stated that herbicides have little direct effects upon
animals, and that they tend to produce ecosystem effects from the bottom of the food chain upward, in
contrast to insecticides which act in the opposite direction. Huber (1993) and Solomon et al. (1996)
stated that plants readily recovered from the inhibitory effects of atrazine once the exposure was
reduced or eliminated.
A comprehension of the "Guidelines for Deriving Numerical National Water Quality Criteria
for the Protection of Aquatic Organisms and Their Uses" (Stephan et al. 1985), hereafter referred to as
the Guidelines, and the response to public comment concerning that document (U.S. EPA 1985) are
necessary to understand the following text, tables, and calculations. Results of intermediate
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calculations such as recalculated LC50 values and Species Mean Acute Values are given to four
significant figures to prevent roundoff error in subsequent calculations, not to reflect the precision of
values. The criteria presented herein are the Agency's best estimate of maximum concentrations of the
chemical of concern to protect most aquatic organisms or their uses from any unacceptable short- or
long-term effects. Whenever adequately justified, a national criterion may be replaced by a site-
specific criterion (U.S. EPA 1983a), which may include not only site-specific criterion concentrations
(U.S. EPA 1983b), but also site-specific durations of averaging periods and site-specific frequencies of
allowed excursions (U.S. EPA 1991). The latest comprehensive literature search for this document was
conducted in November, 1999. Data in the files of the U.S. EPA's Office of Pesticide Programs
concerning the effects of atrazine on aquatic organisms and their uses have been evaluated for use in
the derivation of aquatic life criteria. Some more recent information received through the submission
of public scientific views on the 2001 document and additional toxicity testing conducted since 2001
was also included.
ACUTE TOXICITY TO FRESHWATER ANIMALS
The data that meet the requirements of the Guidelines concerning the acute toxicity of atrazine
to freshwater organisms are available for 17 species (Table 1). Acute toxicity data for eight freshwater
invertebrate species ranged from 3,000 (ig/L for the hydroid coelenterate, Hydra sp. (Brooke 1990) to
49,000 (ig/L for the cladoceran, Daphnia magna (Putt 1991). A stonefly (Acroneuria sp.) was the
second most sensitive invertebrate tested, with an EC50 of 6,700 (ig/L (Brooke 1990). A cladoceran
(Ceriodaphnia dubia) had a Species Mean Acute Value (SMAV) of > 12,120 (ig/L (Jop 199la; Oris et
al. 1991), and the amphipod, Hyalella azteca, had an LC50 of 14,700 (ig/L (Brooke 1990). The
remaining invertebrate species tested, the snails (Physa acuta and Physa sp.) and an annelid
(Lumbriculus variegatus), had LC50 values in excess of 20,000, 34,100 and 37,100 (ig/L, respectively
(Roses etal. 1999; Brooke 1990).
The rainbow trout (Oncorhynchus mykiss) was the most sensitive freshwater vertebrate species
tested, with an LC50 of 5,300 (ig/L (Beliles and Scott 1965). The goldfish, Carassius auratus, was the
most tolerant fish species and is 11.32 times less sensitive to atrazine than rainbow trout (Table 1). The
fathead minnow (Pimephalespromelas) had a SMAV of 20,000 (ig/L (Dionne 1992), while the LC50
for the brown trout (Salmo trutta) was 27,000 (ig/L (Grande et al. 1994). The SMAVs for the
remaining vertebrate species, all fishes, were 6,300, >10,000, >10,000, >13,856 and >18,000 (ig/L for
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the brook trout, Salvelinus fontinalis (Macek et al. 1976); largemouth bass, Micropterus salmoides
(Jones 1962); channel catfish, Ictaluruspunctatus (Jones 1962); bluegill, Lepomis macrochirus (Beliles
and Scott 1965; Macek et al. 1976); and coho salmon, Oncorhynchus kisutch (Lorz et al. 1979),
respectively. The SMAV was based upon a flow-through test in the case of the fathead minnow, where
other test results were also available.
Three species of amphibians were tested with atrazine (Table 1). The leopard frog (Rana
pipiens), wood frog (Rana sylvatica) and American toad (Bufo americanus) each has a LC50 value of
>20,000 (ig/L atrazine. Based on these values, the amphibians evaluated are relatively acutely
insensitive to atrazine.
Freshwater Genus Mean Acute Values (GMAVs) were identical to the SMAVs in all cases with
the exception ofPhysa and Oncorhynchus, where the two species tested had different SMAVs (Table
3). Two of the four most sensitive freshwater genera to atrazine are invertebrates. The freshwater Final
Acute Value (FAV) for atrazine was calculated to be 3,021 (ig/L using the procedure described in the
Guidelines and the GMAVs for invertebrates, fish and amphibians in Table 3. The freshwater FAV is
lower than all available freshwater SMAVs except that for the Hydra, which it is less than one percent
higher (Figure 1).
ACUTE TOXICITY TO SALTWATER ANIMALS
The acute toxicity of atrazine to resident North American saltwater animals has been determined
with eight species of invertebrates and two species offish (Table 1). Although only two fish species
were tested, fish appear to have a similar sensitivity to atrazine as invertebrates. The saltwater SMAVs
range from 2,324 (ig/L for mysids, Americamysis bahia (formerly Mysidopsis bahia), to >30,000 (ig/L
for the eastern oyster, Crassostrea virginica. The copepod, Acartia tonsa, had similar LC50 values
resulting from a static unmeasured test (Ward and Ballantine 1985) and two renewal tests (Thursby et al.
1990) with measured values of 94, 91.73 and 210.1 (ig/L, respectively. An additional flow-through
measured test (McNamara 1991a) with the same species yielded an LC50 of 4,300 (ig/L. It is unclear
why there is such a large difference between the flow-through measured value and the other measured
results. There was nothing unusual about the variability of the chemistry data from the flow-through
tests to indicate a problem (coefficient of variations ranged from 2 to 15 percent). A possible
explanation is that the measured values from the static renewal tests were conducted with 70 percent
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technical grade atrazine, while the flow-through test used 97.1 percent atrazine. The other 30 percent
may have contributed to the higher toxicity. Because there is no obvious problem with the flow-through
data set for A. tonsa, the Guidelines state that the flow-through measured value must be used. Therefore,
the SMAV for this species is 4,300 (ig/L. LC50 values for the copepod, Eurytemora qffinis, were 500,
2,600 and 13,200 (ig/L at salinities of 5, 15 and 25 g/kg, respectively (Hall et al. 1994a,b). The resultant
SMAV was 2,579 (ig/L. The opposite trend was observed for the sheepshead minnow; the LC50 values
were 16,200, 2,300 and 2,000 (ig/L at salinities of 5, 15 and 25 g/kg, respectively, for larval fish (Hall et
al. 1994a,b). Two other LC50 values of 13,000 and >16,000 (ig/L for sheepshead minnow was derived
from the flow-through concentration measured test by Machado (1994b) and Ward and Ballantine
(1985). However, because the former LC50 values were from a more sensitive life-stage, an SMAV of
4,208 (ig/L has been calculated for this species.
Saltwater GMAVs (Table 3) were identical to the SMAVs in all cases with the exception of
Acartia where the two species tested had different SMAVs. Three of the four most sensitive saltwater
genera to atrazine are crustaceans. The saltwater FAV for atrazine, 1,519 (ig/L, was calculated using the
procedure described in the Guidelines and the GMAVs in Table 3. This saltwater FAV is lower than all
available saltwater SMAVs (Figure 2).
CHRONIC TOXICITY TO FRESHWATER ANIMALS
The data concerning the chronic toxicity of atrazine that are usable according to the Guidelines
are available for 6 freshwater species (Table 2a). Eight freshwater tests have been completed with two
invertebrate and four fish species.
The cladoceran, Ceriodaphnia dubia, was exposed to atrazine over its entire life cycle in two 7-
day tests (Oris et al. 1991). The end result was identical in both tests, with chronic limits of 2,500 and
5,000 (ig/L, and a calculated chronic value (geometric mean) of 3,536 (ig/L. An accompanying acute
toxicity test resulted in an LC50 of >30,000 (ig/L (Oris et al. 1991). The resultant acute-chronic ratio
was >8.484 (Table 2b).
In another 7-day life cycle exposure with C. dubia (Jop 1991b), atrazine did not affect survival at
any of the test concentrations (i.e., 290, 600, 1,200, 2,500 or 4,900 (ig/L). However, reproduction was
significantly reduced at the two highest treatment levels. An average of 10 young per female were
produced at these two treatments compared to a mean of 23 for the pooled controls. The chronic limits
in this study were 1,200 and 2,500 (ig/L, and the chronic value was 1,732 (ig/L. An accompanying
10
-------
acute value of >4,900 (ig/L (Jop 1991a) resulted in an acute-chronic ratio of >2.829. Therefore, the
species mean acute-chronic ratio is >4.899 (Table 3).
The midge, Chironomus tentans, was continuously exposed to atrazine for two generations in a
life-cycle test (Macek et al. 1976). The test was initiated by exposing first generation eggs through the
various larval instar stages, pupation and emergence. Eggs from first generation adults were then
continuously exposed in a similar fashion. Mean measured concentrations were 110, 230, 420, 780 and
1,330 (ig/L. No significant differences between controls and the lowest exposure (110 (ig/L) were noted
in hatchability, survival, pupation or emergence in first generation animals. Significant reductions in the
number of adults emerging in the first generation exposure occurred at atrazine concentrations of 230
and 420 (ig/L. First generation larvae exposed to higher concentrations experienced high mortality at
the early instar stages. In the second generation, hatchability was reduced at 420 (ig/L, while pupation
and emergence were reduced at 230 and 420 (ig/L of atrazine. Exposure to 110 (ig/L had no effect on
growth or development of the chironomid larvae. Based on these observations, the chronic limits were
110 and 230 (ig/L, and the resultant chronic value (geometric mean) was 159.1 (ig/L. A corresponding
acute value of 720 (ig/L for a test that was fed (Macek et al. 1976) yielded an acute-chronic ratio of
4.525 for C. tentans.
Rainbow trout (Oncorhynchus mykiss) were exposed to atrazine in an early-life stage test (ELS)
conducted in reconstituted water with a hardness of 50 mg/L as calcium carbonate (Whale et al. 1994).
The ELS test was divided into 3 main stages: (I) immediately post-fertilization to hatching (30-day
duration), (II) post-hatch to swim up (28-day duration), (III) post-swim up to 3 months old (28-day
duration), for a total exposure of 86 days. Mean measured concentrations (mean ± SD) were <10 (water
control), <10 (solvent control), 36 ± 12, 130 ± 50, 410 ± 170, 1,100 ± 660, and 3,800 ± 2,200 (ig/L,
respectively. Significant mortalities (58.8 percent) occurred in the highest atrazine exposure during
stage I and II of the test although no other dose response relationships could be defined. Significant
decrease in fish wet weight was observed in concentrations of 1,100 and 3,800 (ig/L compared to the
solvent control, although fry exposed to 1,100 (ig/L did show signs of a recovery in wet weight toward
the end of the stage III exposure. Statistical analysis of the dry weights of these same fish samples
showed that a significant decrease in weight occurred only in fish exposed to 3,800 (ig/L atrazine.
Because of the recovery in growth at the 1,100 (ig/L atrazine concentration, the chronic limits in this
study were set at 1,100 and 3,800 (ig/L, resulting in a chronic value of 2,045 (ig/L. An accompanying
acute value is not available for this species, therefore, an acute-chronic ratio cannot be calculated.
Yearling brook trout (Salvelinus fontinalis) and their offspring were continuously exposed to
atrazine for 306 days at mean measured concentrations of 65, 120, 240, 450 and 720 (ig/L (Macek et al.
11
-------
1976). At 90 days, significant reductions in weight and total length of first generation fish occurred at
concentrations of 240 (ig/L and above. At 306 days, weight and total length of first generation fish were
significantly less than controls at atrazine exposures of 120 (ig/L and above. Fish at these exposures
also appeared lethargic in comparison to the controls and fish at 65 (ig/L. Spawning activity and
hatchability of second generation fry did not appear to be affected, although considerable variability
between replicates in the observed characteristics of total number of eggs spawned, number of eggs per
female, percent fertilization and hatchability precluded statistical interpretation. High replicate
variability was also observed in morphological development of the embryos. At 30 days of exposure,
fry survival was similar for all treatments, but was significantly reduced at concentrations of 240 (ig/L
and above after both 60 and 90 days. As in first generation fry, length and weight of second generation
fry at 90 days were significantly less than controls at atrazine exposures of 240 (ig/L and above. Based
on the most sensitive measure, i.e., growth of first generation fish at 306 days, the chronic limits were 65
and 120 (ig/L, with a resultant chronic value of 88.32 (ig/L. A corresponding acute value of 6,300 (ig/L
(Macek et al. 1976) yielded an acute-chronic ratio of 71.33 for brook trout (Table 2b).
A fathead minnow full life-cycle chronic test that extended for 274 days was performed, with
mean measured atrazine concentrations of 0, 150, 250, 460, 990 and 2,000 (ig/L (Dionne 1992). At 30
days, first generation larval length was significantly reduced by concentrations • 990 (ig/L, whereas, at
60 days, length was reduced at concentrations • 460 (ig/L. At 274 days, survival was significantly
reduced at 990 and 2,000 (ig/L of atrazine. There was no effect upon the reproductive characteristics of
number of eggs per spawn, total number of eggs produced, number of spawns per female, or number of
eggs per female at any treatment level. Hatching success was slightly, but significantly, reduced at
concentrations of 250 (ig/L and above. Second generation larval growth (length and weight) was
significantly reduced at • 460 (ig/L of atrazine. The chronic limits were reported to be 250 and 460
(ig/L, based upon first and second generation larval hatching and growth. This resulted in a chronic
value of 339.1 (ig/L. An accompanying acute value of 20,000 (ig/L (Dionne 1992) yielded an acute-
chronic ratio of 58.98.
Bluegills (Lepomis macrochirus) were continuously exposed to atrazine for 18 months starting
with 7-10 cm long fish, continuing through spawning, and into a second generation for 60 days (Macek
et al. 1976). Mean measured exposure concentrations were 8, 14, 25, 49 and 95 (ig/L. Survival and
growth of first generation fish exposed to atrazine for 6 and 18 months were similar to the controls.
Spawning activity was too sporadic to indicate any adverse effects. Percent hatchability of eggs was
similar to controls at concentrations between 14 and 95 (ig/L. Low fry survival in the second generation
controls for the first 30 days precluded observations on survival effects due to atrazine in this time
12
-------
interval. However, between 30 and 90 days, survival was near 100 percent in the controls and all
atrazine treatments. Total length of second generation fish through 90 days was considered to be
unaffected by any of the atrazine exposures. From a lack of any adverse effect at concentrations as high
as 95 (ig/L, the chronic limits were set at 95 and >95 (ig/L. The resultant chronic value was >95 (ig/L.
A corresponding acute value of >8,000 (ig/L (Macek et al. 1976) yielded an acute-chronic ratio of
>84.21.
The acute values for C. tentans, S. fontinalis and L. macrochirus in tests reported by Macek et al.
(1976) were used in calculating acute-chronic ratios even though the acute test concentrations were not
measured. This was because of close agreement between nominal and measured concentrations in the
chronic tests. For six chronic tests, the overall agreement between measured and nominal concentrations
was 94.4 percent. Therefore, it appeared likely that the nominal concentrations presented for acute tests
were also in good agreement with actual concentrations.
CHRONIC TOXICITY TO SALTWATER ANIMAL
1
The chronic toxicity of atrazine to saltwater species has been determined in three 8-day life
cycle tests with the copepod, Eurytemora affinis, a 28-day life cycle test with the mysid, Americamysis
bahia, and an early life-stage test (28-day) with the sheepshead minnow, Cyprinodon variegatus (Table
2a). Survival was the most sensitive endpoint in the 8-day chronic tests with E. affinis. Tests were
performed at salinity levels of 5, 15 and 25 g/kg. At a salinity of 5 g/kg, survival was significantly
reduced to 37 percent at the 17,500 (ig/L concentration, while at the next lower concentration of 12,250
(ig/L it was similar to controls at 71 percent (Hall et al. 1995). The chronic value was 14,640 (ig/L. At
a salinity of 15 g/kg, the chronic limits were 17,500 and 25,000 (ig/L, and the chronic value was 20,920
(ig/L. Sensitivity appeared greater at a salinity of 25 g/kg, with chronic limits of 4,200 and 6,000 (ig/L,
and a chronic value of 5,020 (ig/L. Only at this highest salinity level was the acute value greater than
the chronic value. The resultant Acute-Chronic Ratio of 2.629, determined at a salinity of 25 g/kg
(13,200 (ig/L -^ 5,020 (ig/L), was considered to be the correct ratio for this species, and was used in
subsequent calculations involving the Species Mean Acute-Chronic Ratio.
Survival was the most sensitive endpoint in the mysid test (Ward and Ballantine 1985). Survival
was 60, 30, and 20 percent at 190, 290 and 470 (ig/L, respectively. No statistically significant effect was
observed for survival at concentrations • 80 (ig/L. Reproduction did not occur at 470 (ig/L, but no
adverse effects on reproduction were observed at all lower concentrations. The chronic value for
mysids, is 123.3 (ig/L based upon no survival effects at 80 (ig/L and a 40 percent reduction in survival at
13
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190 (ig/L. The acute value, as determined by the same authors, is 1,000 (ig/L and the resulting acute-
chronic ratio is 8.110 (Table 2b).
In the sheepshead minnow test (Ward and Ballantine 1985), juvenile survival was significantly
reduced at 3,400 (ig/L, but not at • *,900 (ig/L. All fish exposed to 5,700 (ig/L died. There was no
effect on either hatching success or growth in any of the concentrations with surviving fish (• 5,700
(ig/L). The chronic value for sheepshead minnows, based on mortality of juveniles, is 2,542 (ig/L. The
acute value for the sheepshead minnow, as determined by the same authors, is a "greater than" value
(>16,000 (ig/L). Therefore, the resulting acute-chronic value is >6.294.
The range of definitive species mean acute-chronic ratios (ACRs) for both freshwater and
saltwater differ by more than a factor of 10 (Table 2b - Acute-Chronic Ratios with greater than values
were not used for these calculations), and are not related to rank order of acute sensitivity (Table 3).
Since the available species mean ACRs do not meet Guideline requirements (Stephan et al. 1985), a
Final Acute-Chronic Ration (FACR) cannot be calculated, nor can a freshwater or saltwater Final
Chronic Value (FCV) based on the available aquatic animal data.
TOXICITY TO AQUATIC PLANTS
For inclusion in Table 4, according to the Guidelines, exposures with algae must have been for a
minimum of 4 days. With vascular plants, chronic exposures must have been conducted. In both cases,
it is a requirement that the concentrations of atrazine were measured during the tests. A Final Plant
Value can be obtained by selecting the lowest result from a test with an important aquatic species in
which the concentrations of test material were measured and the endpoint was biologically important.
Two species of freshwater green algae were exposed to atrazine in studies in which the exposure
duration was 4 days or longer and the atrazine concentrations were measured (Table 4).
Chlamydomonas reinhardtii cell numbers were reduced 50 percent after 4 days of exposure to 51 (ig/L
(Girling et al. 2000; Schafer et al. 1993), after 7 days of exposure to 21 (ig/L, and after 10 days of
exposure to 10.2 (ig/L (Schafer et al. 1993).
Selenastrum capricornutum had a 4-day EC50 of 4 (ig/L, based upon cell numbers (University of
Mississippi 1990). The EC50 values for pheophytin-a and chlorophyll-a content were 20 and 150 (ig/L,
respectively. The 4-day No-Observed-Effect-Concentration (NOEC) and Lowest-Observed-Effect-
Concentration (LOEC) values based on cell numbers were 0.5 and 1.0 (ig/L, respectively (University of
Mississippi 1990). Using the same species and cell number as an endpoint, Gala and Giesy (1990)
reported a 4-day EC50 of 128.2 (ig/L, and Hoberg (1991a) reported a 4-day EC50 of 130 (ig/L. Hoberg
14
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(1993a) calculated a 5-day EC50 of 55 (ig/L. EC10 values at 4 and 5 days were 90 and 26 (ig/L,
respectively, whereas, EC90 values at 4 and 5 days were 190 and 120 (ig/L, respectively (Hoberg 1991a,
1993a). The 4-day S. capricornutum NOEC and LOEC determined by Hoberg (1991a) were 76 and 130
(ig/L atrazine, respectively.
A 7-day exposure of the duckweed, Lemna gibba, to atrazine resulted in an EC50 of 180 (ig/L,
based upon frond production (Hoberg 1991b). Two 14-day studies were also conducted with L. gibba
(Hoberg 1993b,c). A major difference in these two studies was that, in the latter study, the effect
concentrations were calculated based upon the atrazine concentrations that were measured on the last
day only. This may have resulted in effect levels that appeared to be lower than in the first study, where
concentrations were measured more often during the test. In the first study (Hoberg 1993b), using frond
number as an endpoint, the EC10, EC50 and EC90 values were 6.2, 37, and 220 (ig/L, respectively, after
14 days of exposure. Using frond biomass, the EC 10, EC50 and EC90 values were 12, 45 and 170
(ig/L, respectively. The NOEC and LOEC for frond number were <3.4 and 3.4 (ig/L atrazine,
respectively. In the second study (Hoberg 1993c), the EC10, EC50 and EC90 values were 2.2, 50, and
98 (ig/L, respectively, using the frond number endpoint, while the respective values for frond biomass
were 4.2, 22, and 110 (ig/L. The authors determined a NOEC of 8.3 (ig/L and a LOEC of 18 (ig/L based
on frond number (Hoberg 1993c).
Exposure of a different species of duckweed, Lemna minor, to atrazine for 14 days resulted in a
NOEC of 10 (ig/L based upon a biomass endpoint (University of Mississippi 1990). In this study, a
LOEC of 100 (ig/L was obtained for the biomass endpoint. The EC50, based on biomass, was 8,700
(ig/L. Girling et al. (2000) reported aZ. minor 28-day growth NOEC of 38 (ig/L atrazine, and the LOEC
was 120 (ig/L atrazine. In another study using L. minor (Kirby and Sheahan 1994), 10-day exposures to
atrazine yielded EC50 values that were comparable to those found for L. gibba by Hoberg (1993b,c).
EC50 values of 56, 60 and 62 (ig/L were obtained based upon frond number, fresh weight and
chlorophyll content, respectively.
Elodea (Elodea canadensis) was exposed to atrazine for 20 days by Girling et al. (2000), and the
NOEC and LOEC values based on length were 20 and 30 (ig/L atrazine, respectively. In a study
conducted by the University of Mississippi (1990), the effects of atrazine were evaluated both in the
absence and presence of sediment. In the absence of sediment, LOEC values of 10 and 100 (ig/L were
observed, based upon mature frond production and biomass, respectively. With sediment present, the
biomass LOEC was also 100 (ig/L. Biomass EC50 values were 1,200 and 25,400 (ig/L when sediment
was absent and present, respectively, in the test systems.
15
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As stated in the Guidelines (Stephan et al. 1985), the Final Plant Value (FPV) is the
lowest result from a test with an important aquatic plant species in which the concentrations of
test material were measured, and the endpoint was biologically important. In this case, the
freshwater FPV would be the geometric mean of the two duckweed species (Lemna gibba and
Lemna minor) species mean chronic values (SMCVs) of 6.44 |ig/L (Hoberg 1993b,c) and 46.19
|ig/L (University of Mississippi 1990; Girling et al. 2000), or 17.25 |ig/L atrazine (Text Table A).
Using the geometric mean of the two SMCVs for Lemna is consistent with the Guidelines, and is
how all the SMAVs and GMAVs are calculated in the WQC documents.
Text Table A. Selected Freshwater Acute and Chronic Plant Data Taken From Table 4.
Species
Green alga,
Chlamyaomonas
reinhardtii
Green alga,
Chlamyaomonas
reinhardtii
Green alga
Selenastmm
capricornutum
Green alga
Selenastmm
capricornutum
Green alga
Selenastmm
canricornutum
Duckweed,
Lemna gibba
Duckweed,
J^emna vibba
Duckweed,
Lemna minor
Duckweed,
Lemna minor
Elodea,
Elodea
canadensis
Elodea,
Elodea
canadensis
Acute
Value
(EC50)
51
(4 days)
51
(4 days)
4
(4 days)
130
(4 days)
128.2
(4 days)
180
(7 days)
50
ri4 davst
56
(10 days)
-
—
1,200
(10 days)
SMAV
(Hg/L)
*
51
40.55
94.89
56
-
—
1,200
GMAV
(Hg/L)
J
^K
51
40.55
72.89
—
1,200
NOEC - LOEC
(Hg/L)
—
0.5- 1.0
(4 days - cell #)
76 - 130
(4 days - cell #)
—
<3.4-3.4
(14 days- frond #)
8.3 - 18
n 4 davs- frond #1
10 - 100
(14 days -biomass)
38 - 120
C28 davs - erowtli)
20-30
(20 days - length)
10 - 100
(10 days -biomass)
Chroni
c Value
(Mg'L)
1
0.7071
99.398
—
3.4
12.2
31.62
67.5
24.49
31.62
SMCV
(Mg'L)
—
—
8.384
—
6.440
46.19
27.83
Reference
Girling et al.
2000
Schafer et
al.1993
Univ. of
Mississippi
1990
Hoberg
1991a
Gala and
Giesy 1990
Hoberg
1991b, 1993b
Hoberg
1993c
Univ. of
Mississippi
1990
Girling et al.
2000
Girling et al.
2000
Univ. of
Mississippi
1990
16
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Information on the sensitivities of saltwater plants to atrazine is available for five phytoplankton
species and five vascular plant species, representing nine genera (Table 4). Although the phytoplankton
test results do not meet the minimum requirement of a four-day exposure, they are included here to show
that their sensitivity to atrazine is similar to vascular plants. All of the plant effect concentrations were
less than the acute values for aquatic animals. Short-term (two and three day) growth tests with
phytoplankton resulted in EC50 values ranging from 79 to 265 (ig/L (Mayer 1987; Walsh 1983); a factor
of only 3.4. Two species of estuarine submerged vascular plants, Potamogeton perfoliatus and
Myriophyllum spicatum, exposed for 28-35 days to various concentrations of atrazine, had IC50 values
for final biomass and photosynthesis between 25 and 117 (ig/L, with the biomass endpoint being more
sensitive in both species (Kemp et al. 1982b, 1983, 1985). The sago pondweed, Potamogeton
pectinatus, was tested (Hall et al. 1997) for atrazine toxicity for 28 days at three salinities (1, 6, and 12
g/kg). Dry weight was the most sensitive endpoint with chronic values (calculated as the geometric
mean of the respective NOEC and LOEC values) of 21.2, 21.2 and 10.6 (ig/L at salinities of 1, 6, and 12
g/kg salinity, respectively. The wild celery, Vallisneria americana exposed to atrazine for 42 days had
chronic values of 6.19 (ig/L for leaf area (Correll and Wu 1982) and 178.9 (ig/L for dry weight (Forney
^^^H^^^^P ^^^^1 ^^^^H ^^^^^^^^^^M ^^^1 ^^^^H ^^^^I^^^^M
and Davis 1981). Four separate 21-day exposures of the seagrass, Zostera marina, resulted in LC50
values ranging from 100 to 540 (ig/L (Delistraty and Hershner 1984).
For saltwater, the FPV would be the geometric mean of the three Potamogeton pectinatus
(Sago pondweed) measured chronic studies conducted by Hall et al. (1997) at different salinities,
or 16.83 |ig/L atrazine (Text Table B). Using the geometric mean of the SMCVs for the three P.
pectinatus tests is consistent with the Guidelines, and is how all the SMAVs and GMAVs are
calculated in the WQC documents.
17
-------
Text Table B. Selected Saltwater Acute and Chronic Plant Data Taken From Table 4.
Species
Redheadgrass pondweed,
Potamoseton nerfoliatus
Sago pondweed,
Potamogeton pectinatus
Sago pondweed,
Potamogeton pectinatus
Sago pondweed,
Potamoveton nectinatus
Eurasian water milfoil,
Mvrionhvllum snicatum
Wild celery,
Vallisneria americana
Wild celery,
Vallisneria americana
Eelgrass,
Zostera marina
Eelgrass,
Zostera marina
Eelgrass,
Zostera marina
Eelgrass,
Zostera marina
Salinity
(g/kg)
9
1
6
12
9
5
3,6
22
20
20
19
NOEC - LOEC
(Mg/L)
IC50
(35 davs - biomass^
15-30
(28 days - dry wt.)
15-30
(28 days - dry wt.)
7.5 - 15
C28 davs - drv wt.t
IC50
3.2- 12
(42 days - leaf area)
100 - 320
(42 davs - drv wt~)
LC50
(21 days)
LC50
(21 days)
LC50
(21 days)
LC50
(21 days)
Chronic
Value
(Mg/L)
30
21.2
21.2
10.6
2?1
6.19
k 178.9
540
100
365
367
SMCV
(Mg/L)
30
16.83
25 •
33.28
291.6
Reference
Kemp at al. 1982b,
1983 1985
Halletal. 1997
Halletal. 1997
Halletal. 1997
Kemp at al. 1982b,
1983. 1985
Cornell and Wu
1982
Forney and Davis
1981
Delistraty and
Hershner 1984
Delistraty and
Hershner 1984
Delistraty and
Hershner 1984
Delistraty and
Hershner 1984
ECOSYSTEM EFFECTS DATA
Several aquatic ecosystem studies, either artificial laboratory microcosms or field mesocosms,
have provided valuable insight into ecosystem structural and functional responses to atrazine (see Other
Data, Table 6). A mixed assemblage of algal species exposed to 10 (ig/L of atrazine for periods of time
ranging from 1 day to 3 weeks exhibited reductions in gross productivity between 39 and 78 percent
(Kosinski and Merkle 1984; Kosinski et al. 1985). Exposure of an experimental stream periphyton
community to 1,000 (ig/L for 14 days caused severe population density reductions in several species,
and total destruction of the green alga, Cladophora glomerata (Kosinski 1984). The extreme toxicity to
C. glomerata is notable because of the dominant role that it often plays in structuring a benthic
community. Similarly, Moorhead and Kosinski (1986) observed reduced net primary productivity at
18
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100 (ig/L in an assemblage of mixed stream algal species. By contrast, in a mixed stream community,
no effects were observed upon stream macroinvertebrate community structure, periphyton production or
biomass, or the community photosynthesis/respiration ratio following a 30-day exposure at 25 (ig/L
(Lynch etal. 1985).
Malanchuk and Kollig (1985) observed chemical changes in an experimental stream community
consisting of microscopic autotrophs and heterotrophs following the introduction of atrazine at a
nominal concentration of 100 (ig/L for a 2-week exposure period, after which time the atrazine was
removed from the ecosystem. They observed decreased diurnal fluctuations in pH and dissolved oxygen
concentrations, as well as lower mean values for these water characteristics while atrazine treatment was
on-going, but nitrate nitrogen levels increased. Following the cessation of atrazine treatment, there was
a rapid recovery for each of these water characteristics back to control levels.
Biomass reductions were also noted in a stream aufwuchs community exposed to 24 or 134 (ig/L
of atrazine for 12 days (Krieger et al. 1988), although a 24-hour exposure of 77.5 (ig/L had no effect
upon algal cell numbers or biomass in a natural stream periphyton community (Jurgenson and Hoagland
1990). An exposure of as low as 0.5 (ig/L for 6 months resulted in an initial decrease in phytoplankton
species followed by a recovery (Lakshminarayana et al. 1992). Gruessner and Watzin (1996), however,
did not observe any effects of atrazine on a stream community of attached algae and benthic
invertebrates at a concentration of 5 (ig/L when exposed for 14 days. Pearson and Grassland (1996)
reported an inhibition of photosynthesis by the periphyton community of an artificial stream following
exposure of 100 (ig/L of atrazine for 30 days.
In a static pond microcosm (1 L beaker), Brockway et al. (1984) found that a 7-day exposure to
5.0 (ig/L had no effect upon diurnal oxygen production, a measure of photosynthesis, by the various
species of green and blue-green algae present. A 50 (ig/L exposure for 12 days resulted in a 25 to 30
percent reduction in diurnal oxygen production, while 7- to 12-day exposures at 100 to 5,000 (ig/L
further decreased oxygen production. Berard et al. (1999) observed seasonal and species-dependent
effects in a lake microcosm plankton community after 10 to 21 days of exposure to 10 (ig/L atrazine.
During the experiment, growth was generally stimulated for Chryptophytes and Chrysophytes, but
inhibited in Chlorella vulgaris.
Exposure of a freshwater microcosm to 5.1 (ig/L of atrazine for 7 weeks did not affect the
species composition of phytoplankton, zooplankton or benthic macroinvertebrates, but did cause a slight
decrease in photosynthetic activity (Van den Brink et al. 1995). Hamala and Kollig (1985) found an
approximate 75 percent decrease in the productivity/respiration (P/R) ratio in a 14-day exposure to 100
(ig/L of a periphyton-dominated microcosm which contained 33 algal taxa. They also observed reduced
algal densities, decreased species diversity, altered species composition and reduced biomass
19
-------
accumulation. In a 21-day recovery period, net community productivity returned to control values
within 16 days, while very little recovery occurred in community structural characteristics. This fairly
rapid recovery in a functional characteristics indicated that the primary effect of atrazine at this exposure
level was algistatic and not algicidal for those species involved in the recovery.
Stay et al. (1985), using a 3.7 L laboratory microcosm consisting of 10 algal species and 5
animal species (one protozoan, one rotifer, and three crustaceans), found that reduction in the ratio of 14C
uptake/chlorophyll -a was the most sensitive measure of atrazine effect. This suggested that the
effectiveness of the photosynthetic system was impaired. The lowest exposure (i.e., 43.8 (ig/L over 60
days) resulted in significant reductions (approximately 60 to 90 percent) in the ratio throughout most of
the study. Higher exposures (nominal concentrations of 100 to 500 (ig/L) caused further reductions in
this ratio, but not as large a difference as between controls and the lowest exposure.
Peichl et al. (1984) observed changes in the population densities of zooplankton in a pond
mesocosm study after 70 days of exposure to 200 (ig/L of atrazine. In a later study (Peichl et al. 1985),
the authors observed changes in the phytoplankton community after 121 days of exposure to only 10
(ig/L. Experimental ponds in Kansas that were exposed for several years to single annual applications
of atrazine at nominal concentrations of 20 (ig/L or more exhibited reductions in the production and
biomass of phytoplankton, in macrophyte populations and in populations of benthic insect grazers,
bullfrog (Rana catesbeiand) tadpoles, grass carp (Ctenopharyngodon idelld) that had been introduced,
and in bluegills (deNoyelles et al. 1982, 1989, 1994). Initial nominal concentrations of 20, 100, 200 and
500 (ig/L depressed phytoplankton growth within a few days in the ponds. However, after 3 weeks,
phytoplankton production and biomass were similar to controls. deNoyelles and Kettle (1985) observed
reduced photosynthesis of 40 percent or more in short-term (24-hour) bioassays at these same atrazine
concentrations, but longer-term bioassays (20 days) and the experimental pond studies showed a
recovery from this initial reduction.
Benthic insect community structure was studied in the same experimental ponds used in Kansas
following two single annual treatments at 20, 100 and 500 (ig/L (Dewey 1986; Dewey and deNoyelles
1994). Significant reductions of both species richness and total abundance of emerging insects was
observed at the lowest exposure of 20 (ig/L. Abundance of the herbivorous, non-predatory insects was
reduced at 20 (ig/L, but not abundances of the predatory species. This indicated that the observed loss
of total insects was a secondary effect due to feeding habit and loss of plant life, rather than a direct
toxic effect. Loss of insect habitat, particularly in the form of macrophytes, also likely had some effect
upon the insect community. These effects tended to destabilize the ecosystem (Dewey and deNoyelles
1994).
20
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Species composition of macrophytes was altered in a pond mesocosm community following an
8-week exposure to 50 (ig/L of atrazine (Fairchild et al. 1994a). However, functional characteristics
were unaffected, indicating functioning redundancy within the ecosystem. Juttner et al. (1995) did not
observe any effects upon the plankton community of a pond mesocosm following a 2-month exposure to
5 (ig/L, but did observe decreased oxygen production, pH and conductivity at 10 (ig/L, and decreased
phytoplankton populations at 182 (ig/L. At 318 (ig/L, reproduction was affected in Daphnia longispina
and a population of rotifers, Polyarthra sp., was eliminated.
In a laboratory microcosm using a naturally derived microorganism community, Pratt et al.
(1988) observed that a 21-day exposure to a mean measured concentration of 10 (ig/L of atrazine did not
affect the dissolved oxygen, a measure of photosynthetic function, but that a concentration of 32.0 (ig/L
caused significant reductions in this characteristics. This resulted in a calculated maximum acceptable
toxicant concentration (MATC) of 17.9 (ig/L based upon this functional endpoint. Several other
endpoints, such as protozoan colonization, biomass protein, chlorophyll-a and potassium levels, were
less sensitive than dissolved oxygen, and had a calculated MATC of 193 (ig/L.
Stay et al. (1989) studied atrazine effects in 1 L laboratory microcosms containing mixed phyto-
and zooplankton cultured from three Oregon lakes and one pond. A 42-day exposure of approximately
15 (ig/L atrazine did not affect net primary productivity, the P/R ratio, or pH, but these characteristics
were significantly reduced from controls at a mean measured concentration of approximately 84 (ig/L.
Larsen et al. (1986) measured photosynthetic 14C uptake in a 3 L Taub microcosm community at
different time intervals for up to 373 days after treatment with atrazine. EC50 values ranged from 24
(ig/L at 177 days to 131 (ig/L at 43 days after atrazine treatment.
A 50 m2 pond community exposed to atrazine for 4 months at a concentration between 60 and
120 (ig/L eliminated a population of duckweed, Lemna minor, within 27 days (Gunkel 1983). Gunkel
also observed a rapid succession of algal species and a reduced rate of reproduction in Daphnia
pulicaria. Treatments of a pond mesocosm community for 2 years with 20, 100 and 300 (ig/L of
atrazine caused decreases in cell numbers of green algae and of cladoceran populations, but increased
numbers of cryptomonads (Neugebauer et al. 1990).
In experimental ponds treated in May and June with 20 (ig/L of atrazine for two years, there was
decreased abundance of Endochironomus nigricans in June and of total macroinvertebrates in both May
and June, followed by recovery in July (Huggins et al. 1994). Epiphytes, detritovores and generalists
also exhibited initial decreases in populations, followed by a recovery. A short-term exposure (>3 hour)
of pond algae to 10 (ig/L of atrazine was observed to increase the rate of fluorescence for photosystem II
(Ruth 1996).
21
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In two reports of studies conducted at the same site, a lake community was enclosed with a
limnocorral (5mx5mx5m deep) to which atrazine was added. Both studies focused on the
periphyton community. In the first study (Herman et al. 1986), the limnocorrals received two nominal
atrazine applications of 100 (ig/L, one on day 0 and another on day 35. After 34 days of exposure to
measured concentrations ranging between 80 and 140 (ig/L, a reduction in periphyton ash-free dry
weight was observed. Over a 9-week period with two atrazine applications 6 weeks apart, which
resulted in measured concentrations of approximately 80 to 140 (ig/L after the first application and 110
to 190 (ig/L after the second application, reductions occurred in chlorophyll-a, organic matter and total
periphyton algal biomass. In the second study (Hamilton et al. 1987), a 230-day exposure to a mean
measured atrazine concentration of 80 (ig/L caused approximate reductions of 60 percent in biomass, 22
percent in cell numbers and 32 percent in number of species. The results were more pronounced in
exposures to mean measured atrazine concentrations of 140 and 1,560 (ig/L. A shift in community
structure occurred from a chlorophyte-dominated community to a diatom-dominated community.
Aquatic enclosures exposed to a nominal atrazine application of 100 (ig/L on June 1 followed by
a second application of the same concentration 35 days later, exhibited a gradual die-off of the
phytoplankton, a long period of recovery for the green algal community, and a distinct shift in the
taxonomic composition of algae (Hamilton et al. 1988). Thirteen days after the first application,
significant declines occurred in populations of the green algal species Elakatothrix gelatinosa, Tetraedon
minimum, Sphaerocystis schroeteri, and Oocystis lacustris, and of the dinoflagellate, Gymnodinium spp.
Seventy-seven days after the second application, phytoplankton communities were still distinctly
different, and total fresh weight biomass was reduced. By 323 days after the first application, the
phytoplankton assemblages were again similar between control and treated enclosures. From day 1 to
day 114, control enclosures had an average of five more taxa than the atrazine-treated enclosures.
During the period between days 49 and 77, the green algal (Chlorophytd) biomass represented <7
percent of that found in the controls. By the following spring (day 323), the biomass had returned to
control levels. The herbicide treatment did not affect the rotifer or crustacean communities. In the same
exposures, Hamilton et al. (1989) observed that the atrazine-treated enclosures became clearer with
increased Secchi disc readings, while readings of dissolved oxygen, chlorophyll, dissolved organic
carbon, and particulate organic carbon decreased.
Using 1.70 m2 enclosures in a moderately eutrophic lake, Lampert et al. (1989) observed
decreased photosynthesis and decreased populations of certain zooplankters at atrazine concentrations of
0.1 and 1.0 (ig/L. At 0.1 (ig/L, populations ofDaphnia sp. were severely reduced within 15 days, and
oxygen concentrations were reduced after 10 days. At 1.0 (ig/L, concentrations of chlorophyll-a and
oxygen were reduced after 18 days as were populations ofDaphnia, Cyclops, and Bosmina species, and
22
-------
nauplii larvae. At 0.1 (ig/L, there was an apparent recovery after about 25 days. The authors noted,
however, that the effects of atrazine observed in their experimental plastic bag enclosures may have
been exaggerated, because gas exchange and re-colonization from the surrounding medium were
limited. Likewise, the enclosures may have accentuated trophic feeding dynamics of primary
consumers, as fish and larger zooplankton (predators) were excluded. Genoni (1992) observed a
decreased algal population density and a decreased "scope for change in ascendency" in a microcosm
community exposed to 250 (ig/L. The scope for change in ascendency is a biological system response
endpoint, considered to be analogous to the scope for growth endpoint for individual organisms.
Gustavson and Wangberg (1995) observed some minor changes in species composition of the
phytoplankton community in a lake mesocosm community after a 20-day exposure to 20 (ig/L. EC50
values were 58 and 52 (ig/L for the phytoplankton community, and 52 and 54 (ig/L for the periphyton
community. Brown and Lean (1995) found that a short-term exposure (3 hours) of lake phytoplankton
to atrazine resulted in a much lower EC50 based upon photosynthetic carbon assimilation (i.e., 100
(ig/L), than when based upon phosphate or ammonium assimilation (14,000 and >33,000 (ig/L,
respectively). A stream periphyton community exhibited a significant reduction in chlorophyll-a
following a brief exposure (<4 hours) to 109 (ig/L of atrazine (Day 1993). Caux and Kent (1995)
observed a reduction in green algae in Quebec streams following the spring atrazine runoff pulse, with a
maximum stream concentration of approximately 40 (ig/L. Detenbeck et al. (1996) observed a decrease
in the gross productivity of a wetland mesocosm community after 9 to 27 days of exposure at an atrazine
concentration of 15 (ig/L. There also was an increase in the concentrations of dissolved nutrients in the
water.
In the range of 10 to 100 (ig/L, it appears that atrazine changes planktonic community structure
and composition (Berard et al. 1999, Peichel et al. 1984), which may recover in functional
characteristics after cessation of treatment, e.g., productivity, pH, dissolved oxygen production -
deNoyelles et al. 1982, 1989, 1994; Malanchuk and Kollig 1985), but not necessarily structure (Hamala
and Kollig 1985). Planktonic community structure effects are seasonal and species-dependent (Berard et
al. 1999), with the diatom community generally less sensitive than green algae (Lakshminarayana et al.
1992).
Changes in habitat and loss of certain plant species at 20 (ig/L can lead to secondary effects
higher in the food web (Dewey and DeNoyelles 1994), but even at this initial exposure level, structure
and functional integrity of aquatic insect communities are generally maintained, as indicated by only
very small changes in species diversity and evenness indices (Dewey 1986). Concentrations above 50
(ig/L, on the other hand, cause more severe reductions in productivity, plant biomass, and community
structure, as well as indirect effects on herbivorous invertebrates and fish. Changes in species
23
-------
composition without loss of functionality at 50 (ig/L atrazine, however, indicates a great deal of
functional redundancy within some systems (Fairchild et al. 1994a).
Rotifer and crustacean communities are generally less sensitive to direct atrazine toxicity with
an LOEC of about 200 (ig/L (Peichl et al. 1984). Other benthic macroinvertebrate species can be
affected at as low as 20 (ig/L, but the effects (mostly abundance) are seasonal (Huggins et al. 1994).
Studies by Berard et al. (1999), Kosinski and Merkle (1984), Kosinski et al. (1985),
Lakshminarayana et al. (1992), Lampert et al. (1989), and Peichl et al. (1984, 1985) have observed
effects at lower concentrations. The lowest recorded effects of atrazine occurred in experimental
enclosures with natural communities (Lampert et al. 1989).
In summary, aquatic ecosystem structural and functional parameters have most frequently been
observed to be adversely affected by atrazine concentrations exceeding 10 (ig/L. The lowest
concentrations of atrazine that have resulted in temporary negative effects upon abundance of aquatic
plants (primary effect) and animals (secondary effect) have generally occurred at 15-20 (ig/L and above.
It appears that for effects at concentrations up to 15 (ig/L, the communities can recover quite rapidly
following dissipation of the atrazine concentration. In a review of microcosm and mesocosm studies
with atrazine, Giddings and Biever (1994) concluded that concentrations of 20 (ig/L or less typically
caused minor effects, if any, on primary production and plant community composition, and recovery
occurred quickly, even if atrazine remained in the system.
IMPACTS TO PLANT COMMUNITY STRUCTURE AND FUNCTION
Impacts to Plant Community Structure and Function
The Guidelines and the CWA expect that the Agency will establish a sound scientific basis for
all of its water quality criteria for the protection of aquatic life. In light of this expectation and because
of the unique use and chemical characteristics of atrazine, the Agency has selected an approach to
deriving the chronic criterion for the protection of freshwater aquatic life as described below.
In summary, threshold concentrations were determined from realistic and complex time variable
atrazine exposure profiles (chemographs) for modeled aquatic community structure changes. Methods
were developed to estimate ecological community responses for monitoring data sets of interest based
on their relationship to micro- and mesocosm study results, and thus to determine whether a certain
exposure profile at a site may have exceeded a level-of-concern.
24
-------
This required a two step process: (1) Determine the magnitude and duration of exposure of
aquatic plants to atrazine that constitute LOC(s) for aquatic communities and/or ecosystems, and (2)
Determine the best available method(s) to interpret monitoring data relative to these LOC(s).
Endpoints
The initial assessment endpoint was chosen based on the reported results from 77 micro- and
mesocosm studies for which atrazine was tested: change in aquatic community structure and function of
primary producers. This endpoint appeared to be the most sensitive of the effect endpoints affecting
aquatic plants. Further, the effect of atrazine on aquatic plants, whether direct or indirect, appeared to be
more sensitive than effects on other organisms in the aquatic ecosystem, e.g., aquatic invertebrates, fish.
Thus, by focusing on aquatic plant community structural changes, we would be in effect, protecting
against adverse effects on the rest of the aquatic community. The measurement endpoints reported in
available studies which tested atrazine were: laboratory - growth (rate) and biomass; microcosms,
mesocosms and models - reduction in primary production and changes in structure of primary producer
communities.
Community Level Studies
Ecological responses of aquatic communities to atrazine exposures can be assessed using
community level studies, such as micro- and mesocosms. The subgroup reviewed 25 different studies
with 77 reported effects/no effects on aquatic plants (See Appendix 1). Twenty-four results were from
tests on ponds or lakes; 20 on artificial streams; and, 33 were microcosm tests. Eight results were on
macrophytes, 29 on periphyton, and 40 on phytoplankton. However, only a limited number of exposure
profiles could be tested in these studies. Typically, one to three concentrations of atrazine were tested in
these studies each with a single application to the test system at initiation. Atrazine concentrations were
often kept constant for a variable duration period before the concentrations slowly decrease with time.
Unfortunately, the variable quality of these studies and the many different study designs did not always
allow a reliable association of exposure magnitude and duration to a certain community level effect, and
in many cases the duration of the studies was too short to document community recovery.
To better understand the impact of exposure duration and magnitude on aquatic communities,
the effects reported in these studies had to relate to specific exposure durations and magnitudes. First,
25
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the 77 study results had to be quantified as to severity of effects of atrazine on the aquatic plant
community. Brock et al 2000 analyzed a majority of the study results and quantified them as follows:
Effect Scores (Brock et al 2000):
1 = no effect
2 = slight effect
3 = significant effect followed by return to control levels within 56 d
4 = significant effect without return to control levels during an observation period of less than 56 d
5 = significant effect without return to control levels for more than 56 d
Studies not analyzed by Brock but considered in this analysis were scored with the same methods. The
distribution of the scores for the 77 study results were as follows (also see Appendix 1):
Distribution of Effect Scores:
15 were ranked as 1;
12 were ranked as 2;
12 were ranked as3;
23 were ranked as 4;
15 were ranked as 5
Next, the 77 effect scores representing the results from the 25 micro- and mesocosm studies for
atrazine were plotted against the study specific test concentrations and exposure durations in Figure 1.
26
-------
Figure A. Mesocosm / Microcosm Effects Scores (after Brock et al 2000) versus Atrazine
Exposure Concentration (ug/L) and Duration (days)
"re :
o
O)
o
=5, ;
_=_
c
o
re
at
O
O
C
N
2
<
A
A
t
A ?A
A A I
A
IP
H C
A
A
] *
n
]
4
A
4
H
«
«
i
i
»
>
•
fit
T
i
i
i
i
»
i
»
i
Effect Score #1- No Effect
Effect Score #2 - Slight Effect
Effect Score #3 - Signif Effect Recovery
w/in 56-days
A Effect Score #4 - Signif Effect No
Recovery <56-days
• Effect Score #5 - Signif Effect No
Recovery >56-days
1 10 100 1000
Duration (days) [Log Scale]
Figure 1: Micro- and mesocosm study effect concentrations scored according to Brock et al 2000 and
plotted against the study specific exposure duration
As expected, based on the mode of action of atrazine that inhibits primary production by
reversibly blocking photosynthesis, the effects observed in micro- and mesocosm studies generally
become more severe with increasing exposure time and magnitude.
The challenge for step two was to define an appropriate exposure concentration and duration
relationship that properly defines duration specific levels of concern. For that purpose, ecological
modeling was used to simulate a large number of exposure durations and magnitudes for the ecological
response in a generic Midwestern 2nd to 3rd order stream. Two ecological models were initially
considered: (1) the Comprehensive Aquatic Systems Model (CASM) (Bartell et al. 2000, Bartell et al
1999, DeAngelis et al 1989), and (2) AQUATOX2. The decision to use CASM was made after a
preliminary comparison revealed that CASM could include a larger number of species in the community
2 See http://www.epa.gov/waterscience/models/aquatox/about.html and
http://www.myweb.cableone.net/dickpark/AQTXFacts.htm
27
-------
structure, which appeared to better support our assessment endpoint. In addition, CASM had a relatively
uncomplicated exposure profile for a chemical such as atrazine.
Model Parameterization
A large number of single-species laboratory toxicity test results on atrazine toxicity to aquatic
organisms (See Giddings et al 2000), including aquatic plants (macrophytes, periphyton, and
phytoplankton) were available (Figure 2). A subset of these data (CASM EC50 geometric means) was
selected and used to drive the toxicity of atrazine to aquatic organisms in the CASM simulation model
(See Appendix 2). The modeled toxicity profile included twenty-six producer species (10 plankton, 10
periphyton, 6 macrophytes), and 17 consumer species. Three toxicity scenarios were modeled: 10th
centile, geometric mean, and 90th centile for species with more than one toxicity study. The geometric
mean scenario (toxicity scenario 1) was chosen for the reported model results
28
-------
100%
SSD Using Adjusted Mean Slope = 3.42
• EC10
• EC50
• EC90
• CASM EC50
Log.(ECIO)
Log.(ECSO)
Log.(EC90)
Log. (CASM EC50)
10.00 100.00 1000.00
ECx (ug/L) - Log Scale
10000.00
Figure B: Plant Species Sensitivity Distribution for EC 10, EC50, and EC90 values overlaid with the
Plant Species Sensitivity Distribution (EC50 geometric mean) used to parameterize CASM.
29
-------
CASM Model Simulations
CASM is an ecological food chain model. It was set-up to run simulations for exposure
durations from 1 to 260 days, and concentrations from 20 to 220 • g/L atrazine. The scenarios were
designed to simulate a generic 2nd or 3rd order Midwestern stream, typical for the majority of atrazine
use on corn and sorghum. The CASM model provides the following results: production - modeled as
biomass production (g Carbon m"2) for 1 m2 surface area) (Appendix 3a), and community structure
(similarity) - species population size derived from species daily biomass (Appendix 3b). Thus, the
model integrates direct and indirect effects to indicate changes in community structure. The endpoint
selected for the model results was percent (%) change in aquatic community structure (as determined by
Steinhaus Similarity coefficient) of primary producers (phytoplankton, periphyton, macrophytes).
CASM Steinhaus Similarity Analysis
Coefficients of similarity are usei
lysis
;rmine whether the composition of two communities :
i of similarity are used to determine whether the composition of two communities is
similar. The Steinhaus coefficient or similarity index is based on the species abundances (in this case
indicated by the species specific daily biomass) common to two communities. The index is described in
the following equation:
Where ai5k : abundances of species k in sample I
2
S=-
The similarity indices for each possible pair of samples per day are calculated and this results in
a matrix of between (different treatments) similarities as in Figure 3.
30
-------
Idl
Id2
Id3
etc.
Xd260
Idl
Id2
B
Id3
B
B
etc.
B
B
B
B
Xd260
B
B
B
B
B
Figure C. Example of a matrix of similarities resulting
y Index calculations.
from Similarity
Similarity indices were calculated for primary producers, consumers, and fish over exposure
periods from 1 to 20 days (See Appendix 3b). The results show that the changes in percent (%) change
in aquatic community structure of primary producers is a more sensitive (conservative) measurement
endpoint than the same for consumers or fish.
Determining the LOC - CASM Steinhaus similarity vs. the effects of Atrazine exposure in micro-
and mesocosm studies
A wide range of single pulses of different duration and magnitude were simulated and used to
calculate community structure changes. Community structure changes were expressed as percent (%)
change in the Steinhaus similarity index that was calculated based on the simulated daily biomass for
each individual species and plotted over time.
31
-------
Table 1: A) Maximum daily percent changea in community structure (Steinhaus
similarity) of primary producers for a modeled generic 2nd-3rd order Midwestern
stream.
Atrazine
cone. [• g/L]
20
2~5
30
4~0
5"b"
70
90
i"6
i'7"6
22~6
Pulse
1
O.lc
6"7"i
6"7"i
i"7T
i"7T
3"77
4~74
4~75
~6
5"77
duration [d]b
S3 |5
JO. 2 |0.7
|T7"9 j2~79
[i7~9 [279
[O j3~72
[O J3~7T
|I ji~6"77"
I'gTi J12 7 6
[gTe jiY77"
[I™." fi'i' 7"i
[l"."2 EiTS
jio
jO.9
j5
[5
j5"72
[5~72
jTsVs"
iTiTg
jTiVs"
[2~4"7"i
i"2~4
i20
ii
|7'7
[77
fi
[77
jis"
fi'i
fi?
J2~9
[29
a
a
9"
7i
75
71
77
77
ieo
ii.
|Ti
[11
|Ti
[11
|l7
ji~8
|l7
J56
156
2
7?
7?
7?
76
7"3
7"2
7s"
7"3
73
|130
jl.2
jlS
J13
jl"."
|l"."
J18~."
|l8~."
jl"."
|67~."
is"."
1
1
1
3
8
1
1
J260
|2.3
!iT7
iiT7
iiT7
|i77
j2Y7
J23~7
(JoT
|7'2'7
F'JI
5
a
6
5
5
5
1
4
3
B) Year end percent change" in community structure (Steinhaus similarity) of
primary producers for a modeled generic 2nd-3rd order Midwestern stream.
Atrazine
cone. [*g/L]
20
25
30
40
50
70
90
"i"o
"iTo
"Ho
Pulse
1
0 c
o'T?
o'T?
o"77
o'T?
i"7"5
".~7
".~7
2
2
duration
|3
|0
fi'77
iiT?
fiT'g"
[i79"
Is"!?
[4~7i"
[4
i5"74
[573
[d]b
!5
10
[2
[2"
[3
[2'
[5
[5
J5
|i
|i
77
77
79"
72
77
77
7T
7T
Jio
jo.
j4"'7
j4~7
w~.
J4~7
I7'71
fi'71
js"
115
fi'is
2
7
6
9
9
9
5
4
7"5
74"
!20
10. 2
i".~3
[772
["."5
|77"5
iioVg
jl".~6
ii".~5
J2".~9
[J— 8"
ieo
10. 2
[io7'9M
|io7'8"
[ll
|io7'9"
[TiTs"
fi5"75'
ii~573"
[5177'
i5~f7'6"
!130 !260
10 . 2 |2 . 3
[i2~.~i ji~5~7
[i2~.~i |i5'7
[1274 [i"6'7
[i2~.~9 |i77
[l".~6 [2"2"7
[l8~.~3 jY3~7
[J674 J2~o'
[61~.Y J7~l7
[6i~.~i 17T7
5
8
6
5
5
5
1
5
1
C) Average percent change" in community structure (Steinhaus similarity) of
primary producers for a modeled generic 2nd-3rd order Midwestern stream.
Atrazine
cone. [• 5/L]
20
25
30
40
50
70
90
13~0
ITo
Ho
Pulse
1
0 c
0~.~5
0~.~4
oT'i
oT'i
2~.~2
2~.~6
2~.~6
2~.~9
2~.~9
duration
J3
jO
jlTl
fi'72
jiT's"
fi'7'8"
pTs"
[isTe
WTe
feT's"
\6~&
[d]b
!5
J0.1
ji~.~9
[2
p'T'e
J2~.~6
J6~.~4
J7~.~4
|7T4
J9~.~8
IgT's"
iio
|0.4
J3~74
[sTs
J4~7I
PT72
J9~7T
\IQ~2
rio~2
jig"
ii~674"
!20
J0.4
J5~.~l
J5~.~2
J5~.~8~
[e
jll~.~6
|l2~.~8
J12~.~7
[2575
I25"7"5
ieo
J0.5
|7'7"4
[77"6
J8~75
|8~79
fl479
fi5"7'8"
fi5"74"
pr^"
JACK'S"
J130
JO. 5
|8'72
[874
[973
[io~.~i
[l6~.~9
[l~.~5
[l6~.~3
[4673
[46'73
!260
JO. 7
J8~.~5
[i"77
J9~.~7
[i"o'77
ji~7"75
[is
ji~6"74
p'sTi'
i4~874
'Based on the mean values of 100 Monte Carlo simulations using the Comprehensive Aquatic Systems
Model (CASM)
bConsecutive days of constant exposure beginning on model day 105 (April 15)
32
-------
For further evaluation, the maximum daily percent (Table 1 A), year-end percent, i.e. at day 260
post application (Table 1 B), and the average percent change in community structure in the primary
producer community (Table 1 C) were calculated. Maximum daily deviations indicate the short-term
(temporary) maximum change in community structure. The average community structure change
integrates short-term changes and long-term recovery of the communities. A comparison of short- and
long-term %-impact shows that for concentrations >20 • g/L, short-term changes are always between 1-
to 2-fold the average response. For example, an average 5% community structure change may cause a
less than or equal to 10% short-term (temporary) change in primary producer community structure. The
average percent change in community structure was chosen for the reported results since it captures the
short-term changes as well as recovery.
The modeling results in Table 1C were used to help define duration-specific levels of concern.
Two approaches were used. First, the simulated response (or effect) had to be set in context to the micro-
and mesocosm data. A similarity index value was estimated for each micro- and mesocosm test result by
finding the average model similarity deviations (%) of a simulated exposure profile closest to the
conditions used in each study (test concentration and exposure duration) (See Appendix 1 for assigned
index values for each of the 77 test results). Next, the index values were plotted against the Brock et al
effect scores for each micro- and mesocosm test results for comparison (See Figure 4).
There is a lot of scatter that is reflective of the diversity of this data; however, there is a clear,
strong correlation of the scores with the index. An index value of 5 (vertical red line on the figure)
conservatively separates the 3/4/5 from the 1-2 scores. That means that a 5% change in community
structure (Steinhaus similarity) of the CASM simulations compares to a large majority of the micro- and
mesocosm studies with no to slight effects (leaving only 8% potential false negatives and false positives,
i.e., false negatives - 6 out of 77 studies above the effects score 3 line and to the left of the 5% line; false
positives - 6 out of 77 studies blow the effects score 3 line and to the right of the 5% line).
33
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5 -
4 -
3 -
n -
Potential False Negatives -8%
Potential False Positives -8%
B A
Severity Index based on CASM Max % Comm Struct Change
Figure D. Correlation between the Similarity Index [CASM AVG % change in community structure for 77 atrazine
micro- and mesocosm studies] and the Brock et al 2000 effect scores.
For the second approach, the CASM simulation results in Table 1C were interpolated to develop
a set of concentration / duration pairs equivalent to 5% effect from CASM. The interpolated results
follow:
Time (days) Concentration (• g/L)
1.1 220
1.6 130
3 75
5 63
10 53
20 24.8
60 23.3
130 22.9
260 22.7
34
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For times greater than 3 days, a linear interpolation was performed across the different
concentrations at each time. For times from 60 to 260 days, the abrupt shift in response between 20 and
25:g/L made interpolation tenuous, but the best estimate would seem to be in the mid-part of the range
and this did not involve much uncertainty given the narrow range. For times less than 3 days, the
response did not reach 5%, but the additional points seem to be points needed at high concentrations.
Thus, interpolations were performed across times at a fixed concentration instead of across
concentrations at a fixed time.
Next, these concentration-duration pairs, representing the 5% index points based on
interpolation, were plotted with lines connecting each point on Figure 1 (See Figure 5 below).
"ra
o :
O)
o
^
"6) :
•3- ;
0
re
§ 10:
C
O
HI
c
'N
re
0 1 -
\
\
V^J
9 -
1
A
A
[
A
k A
«V
1
1
A
t
A
_
B *
H
D
]
t
1
k
D
4
4
•
»
F
1
4
4
4
*4
1
I
1
I
Effect Score #1- No Effect
Effect Score #2 - Slight Effect
D Effect Score #3 -Signif Effect
Recovery w/in 56-days
A Effect Score #4 -Signif Effect No
Recovery <56-days
• Effect Score #5 -Signif Effect No
Recovery >56-days
< Interpolated ECS values
10 100 1000
Duration (days) [Log Scale]
Figure E. Micro- and mesocosm study effect concentrations scored according to Brock et al 2000 and plotted
against the study specific exposure duration. Interpolated 5% CASM Similarity Index points plotted.
The plot of the interpolated 5% Similarity index points, like Figure 4, conservatively separates the 3/4/5
from the 1-2 scores. Based on both approaches, an index of 5%, meaning a 5% change in community
structure of primary producers, is a reasonable LOG for atrazine exposures in freshwater environments.
35
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Discussion of Uncertainty in Selection of Data, Methods, and Decisions
Since the potential risk of atrazine to aquatic communities will be based on a set of micro- and
mesocosm tests, the critical decision is which tests to include or exclude. The large set of available
studies for atrazine included in this analysis (Appendix 1) have various strengths and weaknesses and
use many different testing designs and methods. The key point here is that there are a large number of
such studies and the subgroup decided to be relatively inclusive, rather than excluding data for various
limited uncertainties or ambiguities. This approach provides a better data set for weight-of-evidence and
allows for addressing "false-negatives" and "false-positives" in light of the overall frequency/magnitude
of the wide range of possible exposure situations. It would not be prudent to rely on any one or two of
these studies.
Quantification of Results of Micro- and Mesocosm Tests
The effect scores in Brock et al (2000) were used to quantify the results of the micro- and
mesocosm tests. The subgroup reached general agreement that the scores assigned to the 77 results were
reasonable, and that scores of 2 ('slight' effect) do not constitute a level-of-concern, while scores of 3 (a
pronounced 'slight effect') do. Brock et al further characterized a score of 2 as "effects reported in terms
of 'slight'; 'transient', and short-term and/or quantitatively restricted response of sensitive endpoints, and
effects only observed at individual samplings. " Scores of 3 were characterized as a "clear response of
sensitive endpoints, but total recovery within 8 weeks after the last application, and effects reported as
'temporary effects on several sensitive species'; 'temporary elimination of sensitive species'; 'temporary
effects on less sensitive species / endpoints', and effects observed at some subsequent samplings. " This last
decision is perhaps the most critical risk decision here, because these scores define the actual level of
protection being sought. Therefore, Appendix 1 is arranged by decreasing effects score and shows the
range and nature of effects represented by the different scores.
Another aspect of quantification is the exposure duration that any score and concentration relate
to. This might not seem to be an issue because the exposure duration is fixed and specified in any test,
but for long exposures in which severe effects occur early, might not these effects be better related to a
shorter duration? For example, the significant effects (scored as a 5 and described as a decrease in
macrophyte coverage in the pond by 95%) in the Kettle et al. (1987) study were related to a full year's
exposure (actually 300 days). However, the study also reported that there was -60% decrease in
coverage after 60 days. It was decided to stay with the 300 day test duration because (1) the exposures in
the study were constant over the whole time period, (2) Brock et al as well as other authors reported the
36
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test duration as ~1 year, and (3) the most dramatic effect without testing for recovery did occur after the
-year long exposure duration. Yet, some could argue that 60% decrease in macrophyte coverage is
significant and should also be scored as a 5 and included. However, the uncertainty resulting from this
observation for the calculation of the time specific LOC(s) in this document is very small because, as
shown in Figure 5, the concentrations causing community structure changes do not further decrease for
constant exposure periods longer than 20 to 30 days, i.e. longer exposure periods do not significantly
change the effect threshold. The Kettle et al study was conducted at the borderline of this threshold
concentration (ca. 20 • g/L). In the weight-of-evidence approach applied here, it constitutes only one of
the large numbers of such studies that also measured less severe impact at the comparable
concentrations and exposure durations.
Extrapolation of Micro- and Mesocosm Tests to Different Exposure Time Series
Another critical decision was to use an aquatic ecological community model as the extrapolation
tool. It is important to emphasize that EPA is not claiming that the model accurately predicts the effects
in any particular community, but rather that it is a useful means for integrating the kinetics of various
processes (toxic effects on photosynthesis, plant growth dynamics, interactions among plant species
across a growing season) and describing the RELATIVE effects of different exposure time series on the
overall response.
Parameterization of Model
The critical data here are the plant laboratory toxicity data assigned to each species in CASM.
These data are the key factor determining the concentration at which CASM predicts significant effects
(slightly above 20 • g/L) and describing the "step-wise" nature of the effects versus concentration.
Because of the concern about effect levels that reflect the more sensitive organisms, Figure 2 and
Appendix 2 show that the decision to use the geometric mean toxicity values (ECS Os) for CASM
appears to adequately represent plant species sensitivity distribution. However, one consequence of the
limited number of possible species in the model is that only a few species represent sensitivities below
the 10th centile and above the 90th centile. Additional analyses using the 10th and the 90th centile of the
EC50 instead of geometric means was conducted to test for the potential impact of the species sensitivity
on the CASM results (Appendix 5). For the majority of the simulations, the lower toxicity profiles
(scenario 2) did not cause significantly higher responses than the geometric mean scenario. It was also
observed that the higher and lower toxicity scenarios did not necessarily bracket the geometric mean
scenario. This can partly be explained by the complex nature of the food-chain interactions in the
37
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ecological model. The impact of slightly different species sensitivity distributions used to parameterize
the model is therefore probably low, when compared to relative importance of the species composition
in the food-chain model.
EPA recognizes that different species have different relative importance in CASM results and
this varies seasonally. Even if each CASM species is linked to the most relevant laboratory species, the
original selection of CASM species and the assignment of the laboratory data represent a major
uncertainty and further evaluation using model parameterizations representing different generic aquatic
communities are recommended.
Selection of Model Variable to Relate to Micro- and Mesocosm Results
The selection of this endpoint is a critical decision, even if model results are calibrated to the
micro- and mesocosm data, because different endpoints have different time-dependencies. These
differences will affect the relative level of concern for different exposure series. While EPA believes that
the average similarity index is a reasonable choice, we also recognize that its meaning is somewhat
uncertain. The critical point is the time trajectory of the index when the effect on the average community
structure is less than that at the end of the year. EPA recognizes that the recommended average index
combines direct toxic effects and consequent shifts in later seasonal plant succession. However, it is
important to note that this index can have different time dependence than an endpoint such as overall
primary productivity, and thus is a key decision.
38
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ENDOCRINE DISRUPTION EFFECTS DATA
Atrazine has been reported in a number of studies as an endocrine disrupter. Researchers at the
University of California at Berkeley (Hayes et al. 2002) have reported that frogs (Xenopus laevis)
exposed to atrazine in the water at concentrations • i (^g/L suffered abnormalities in gonadal
development, including feminization and hermaphroditism, which could render male frogs sterile. In
addition, these same exposures resulted in a reduction in the size of the laryngeal muscle in male frogs,
an important muscle used for the mating call of the frog. Studies conducted by Carr et al. (2003) and
Carr and Solomon (2003) designed to replicate the Hayes et al. (2002) experiments observed these same
effects at approximately 20-21 (ig/L atrazine. A third study conducted by Sullivan et al. (2003) with
Xenopus laevis looking at the same end-points yielded an effect level of 20 (ig/L atrazine (the lowest
concentration tested). Although the atrazine concentrations reported in this latter study were nominal,
measurements of actual atrazine levels in a more recent experiment by the same authors (unpublished
study) of the same design and methodology showed good agreement between nominal and measured
concentrations. As stated by Sullivan et al. (2003), "these results allow us to confidently indicate actual
atrazine concentrations are likely to have occurred in this study."
Until this issue is resolved, justification and defense of a freshwater chronic criterion based on
the endocrine disrupting effects of atrazine on amphibians is difficult. A recently convened Scientific
Advisory Panel (SAP) reviewed EPA's (2003) evaluation of 17 laboratory and field studies concerning
the potential developmental effects of atrazine on amphibians. The SAP agreed with EPA's conclusion
that additional studies are warranted to reduce the scientific uncertainty regarding whether atrazine
causes replicable effects on amphibians (Scientific Advisory Panel 2003). Substantial additional
research to resolve this issue is currently underway, or planned for the immediate future. Once
additional data are available that conclusively demonstrate a significant reproductive effect (or other
endpoint that significantly impairs the populations ability to survive long term) to aquatic species, then
derivation of the freshwater chronic criterion will be reexamined.
39
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Text Table C. Summary of Endocrine Disruption Effects of Atrazine to Freshwater Organisms
Species
African clawed frog
(larval),
Xenopus laevis
African clawed frog
(larval),
Xenopus laevis
African clawed frog
(larval),
Xenopus laevis
African clawed frog
(larval),
Xenopus laevis
African clawed frog
(9-11 days old),
Xenopus laevis
Method3
R,M
R,M
R,M
R,Mj
R,U
Chemical
-
-
98.6%
k
^98.6^|
99%
Exposure
Medium
10%
Holtfreter's
solution
10%
Holtfreter's
solution
FETAX
solution
Z:
FETAX
solution
Moderately
Hard
Reconstituted
Laboratory
Water
Effect
(metamorphosis completed)
abnormalities in gonadal
development, including
feminization and
hermaphroditism
reduction in the size of the
laryngeal muscle in male
frogs
increased incidence of
intersex animals (based on
assessment of gonadal
morphology)
reduction in the size of the
laryngeal muscle in male
frogs
mean weight at
metamorphosis
Effect
Level
(ug/L)"
M
1
21.3
>21.3
20
References
Hayes et al.
2002a,b
Hayes et al.
2002a,b
Carr et al.
2003
Carr et al.
2003
Sullivan and
Spence 2003
* S = static; R = renewal; F = flow-through; M = measured; U = unmeasured.
b Results are expressed as atrazine, not as the chemical.
BIOACCUMULATION
The data available according to the Guidelines concerning the bioaccumulation of atrazine are
included in Table 5. Only freshwater data are available. Macek et al. (1976) analyzed muscle tissue or
the eviscerated carcasses offish at the end of extended exposure periods. Brook trout exposed to
atrazine at 740 (ig/L for 308 days contained less than 200 (ig/kg of atrazine in muscle tissue, resulting in
a bioconcentration factor (BCF) of <0.27. Fathead minnows exposed to atrazine at 210 (ig/L for 301
days had less than 1,700 (ig/kg of atrazine in pooled samples of eviscerated carcasses, for a BCF of
40
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<8.1. Bluegills exposed to 94 (ig/L for 546 days also contained less than 200 (ig/kg in their muscle
tissue, foraBCF of <2.1.
Dionne (1992) exposed fathead minnows to atrazine for up to 274 days using 14C-labeled
atrazine and measuring the radiolabel in fish tissue. The values obtained represent maximum possible
BCFs. Regardless of the life-stage or exposure duration, maximum BCFs were less than or equal to 8.5
in all cases.
There is no U.S. Food and Drug Administration action level or any other established maximum
allowable concentration of chemical residues in tissue available for atrazine. Therefore, a Final Residue
Value cannot be determined.
OTHER DATA
Many tests with atrazine and various freshwater or saltwater organisms have been conducted
either for a different duration or by different protocols than those specified in the Guidelines for
inclusion in Tables 1, 2, 4 and 5. These test results are presented in Table 6. For example, plant tests
were included in Table 6 rather than Table 4 if the test duration was less than 4 days or the exposure
concentrations were not measured (an exception was the saltwater species phytoplankton data that was
included in Table 4 for comparison purposes). Tests with animals were included in Table 6 for a
number of reasons, including considerations of test duration, type of test, and test endpoints other than
those of toxicity or bioaccumulation. Below is a summary of their results.
At the lowest levels of biological organization, mixed nitrifying bacteria were unaffected
regarding ammonium oxidation at 28-day exposures up to 2,000 (ig/L of atrazine (Gadkari 1988), and
cell growth in the bacterium, Pseudomonas putida, was not inhibited following a 16-hour exposure at
10,000 (ig/L (Bringmann and Kuhn 1976, 1977). Progressing phylogenetically, Rohwer and Fluckiger
(1979) obtained a 14-day growth LOEC of 2,160 (ig/L for Anabaena cylindrica, while Stratton (1984)
obtained a 12 to 14-day EC50 of 1,200 (ig/L in terms of cell number. The latter EC50 value was
approximately 5 to 7 times higher than the 24-hour EC50 values based on 14C uptake of 253, 178 and
182 (ig/L as reported by Larsen et al. (1986) for this same species (Table 6). The other species of
cyanobacteria tested by Stratton (1984), Anabaena inaequalis w& Anabaena variabilis, had highly
different EC50 values of 30 and 4,000 (ig/L after 14 days. A. inaequalis and Pseudoanabaena sp.
exhibited reduced photosynthetic uptake of 14C in the amounts of 65 and 91 percent, respectively,
following a 22-hour exposure to 2,667 (ig/L of atrazine (Peterson et al. 1994).
A number of tests have been performed with the cyanobacterium, Anabaena flos-aquae. Hughes
(1986) and Hughes et al. (1986, 1988) reported an EC50 based on cell number of 230 (ig/L following a
41
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5-day exposure. A concentration of 40 (ig/L non-radiolabeled atrazine reduced 14C uptake by
approximately 50 percent after 1 to 3 days of exposure, after which the reduction was less (Abou-Waly
et al. 1991a). At this concentration of atrazine, chlorophyll-a content was initially reduced but
recovered with time. Using this characteristic, the 3-day EC50 was 58 (ig/L, while the 7-day EC50 was
766 (ig/L (Abou-Waly 1991b). A.flos-aquae had a 4-day EC50 based on chlorophyll-a that exceeded
3,000 ng/L in a study by Fairchild et al. (1998).
The cyanobacterium Microcystis aeruginosa exhibited the onset of cell growth inhibition at a
concentration of 3 (ig/L in an 8-day exposure (Bringmann and Kuhn 1976, 1978a,b). After 5 days of
exposure, cell numbers were significantly reduced at 108 (ig/L, and the minimum algistatic
concentration was 440 (ig/L (Parrish 1978). Kallqvist and Romstad (1994) obtained a 6-day EC50 of
630 (ig/L withM. aeruginosa, while Peterson et al. (1994) reported that photosynthetic 14C uptake was
highly reduced (84-96 percent) in M. aeruginosa following a 22-hour exposure to 2,667 (ig/L of
atrazine. A 4-day EC50 of 90 (ig/L was reported for an unidentified species of Microcystis based on
biomass (Fairchild et al. 1998).
Toxicity studies of atrazine toward several other species of cyanobacteria have been reported.
Peterson et al. (1994) found that Aphanizomenon flos-aquae and Oscillatoria sp. exhibited highly
reduced photosynthetic uptake of 14C (97 and 87 percent, respectively) from a 22-hour exposure to 2,667
(ig/L of atrazine. The latter is consistent with the lowest complete inhibition of growth reported for
Oscillatoria cf. chalybea after 6 days of exposure to 2,160 (ig/L atrazine (Schrader et al. 1997). A 31-
day exposure ofPlectonema boryanum to 10,000 (ig/L of atrazine resulted in a 69 percent decrease in
cell numbers (Mallison and Cannon 1984), whereas, 5-day exposures of Synechococcus leopolensis
yielded an EC50 of 130 (ig/L (Kallqvist and Romstad 1994).
The green alga, Ankistrodesmus braunii, had an 11-day EC50 of 60 (ig/L (Burrell et al. 1985).
Similarly, 14C uptake EC50 values of 72 and 61 (ig/L resulted from 24-hour exposures of
Ankistrodesmus sp. to atrazine (Larsen et al. 1986). The green alga, Chlamydomonas geitleri Ettl, had a
slightly higher EC50 of 311 (ig/L based on CO2 fixation after a 1-hour exposure (Francois and Robinson
1990). Similarly, a growth-based EC50 of 330 (ig/L was obtained for Chlamydomonas noctigama after 3
days of atrazine exposure (Kallqvist and Romstad 1994).
The green alga, Chlamydomonas reinhardtii, appears more sensitive to atrazine, exhibiting
approximately a 32 percent inhibition of photosynthesis in an 8-hour exposure to 10 (ig/L (Valentine and
Bingham 1976), and EC50 values based on reduction in photosynthetic activity (14C uptake) in 24-hour
exposures of 19 to 48 (ig/L of atrazine (Larsen et al. 1986). Atrazine-sensitive and atrazine-resistant
strains of C. reinhardtii responded to 2-minute exposures by a difference of approximately an order of
magnitude in their respective EC50 values of 45 and 484 (ig/L (Hersh and Crumpton 1989). A 65-hour
42
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exposure to 49.6 (ig/L resulted in a 13 percent reduction of chlorophyll (Hiranpradit and Foy 1992), and
Fairchild et al. (1998) obtained a 96-hour chlorophyll-based EC50 of 176 (ig/L for this same species.
Foy and Hiranpradit (1977) exposed an unknown Chlamydomonas sp. to various concentrations
of atrazine for 72 to 96 hours. Concentrations of 50 to 52 (ig/L inhibited growth by 84.9 percent and
reduced chlorophyll by 12.8 percent. Slight additional increases in growth inhibition were observed
with increased atrazine concentrations up to 832 (ig/L. Fairchild et al. (1994a) obtained a 4-day EC50
based on biomass of 176 (ig/L to a different species of Chlamydomonas.
Chlorella fusca cell reproduction was reduced and an EC50 of 26 (ig/L was calculated following
a 24-hour exposure to atrazine (Altenburger et al. 1990). Similarly, Faust et al. (1993) obtained a 24-
hour EC50 of 15 (ig/L for this species, and Kotrikla et al. (1997) report 14-day EC50 values based on
growth inhibition of 53.91 (exponential growth phase) and 75.73 (ig/L (stationary growth phase). In
contrast, Chlorella kessleri exhibited 30 percent growth inhibition following a 72-hour exposure at a
concentration of 1,078 (ig/L (El-Sheekh et al. 1994), while Chlorellapyrenoidosa had 70 to 95 percent
reduced growth following 2-week exposures to atrazine concentrations ranging from 500 to 10,000 (ig/L
(Virmani et al. 1975). Photosynthesis in this species was inhibited by approximately 64 percent
following an 8-hour exposure to 100 (ig/L atrazine (Valentine and Bingham 1976). Stratton (1984)
obtained an EC50 of 300 (ig/L following a 12- to 14-day exposure. A 30 percent reduction in growth
and 40 percent reduction in chlorophyll-a was observed in a 10-day exposure to 53.9 (ig/L (Gonzalez-
Murua et al. 1985), while a 110-hour exposure to 49.6 (ig/L reduced chlorophyll by 39 percent
(Hiranpradit and Foy 1992). Photosynthetic CO2 uptake was inhibited by more than 80 percent in C.
pyrenoidosa following a less than 50-minute exposure to 125 (ig/L (Hannan 1995).
The green alga, Chlorella vulgaris, had 24-hour EC50 values of 325, 305 and 293 (ig/L in three
separate tests based upon 14C uptake (Larsen et al. 1986). Similarly, a 30-minute EC50 value of 305
(ig/L based on decreased oxygen evolution was obtained for the same species by Van der Heever and
Grobbelaar (1997). Following 7 days of exposure to 250 to 5,000 (ig/L (only 2.3 to 4.7 percent
remained on day 7), dry weights of C. vulgaris were reduced from 31 to 62 percent (Veber et al. 1981).
This same species had an EC50 of 94 (ig/L based upon chlorophyll concentration after a 96-hour
exposure (Fairchild et al. 1998). Reduced growth was initially observed for C. vulgaris exposed for 12
days to 10 (ig/L, although signs of recovery were evident by the end of the exposure (Berard et al.
1999).
In an undefined species of Chlorella, a 72- to 96-hour atrazine exposure at 52 (ig/L resulted in a
31 percent inhibition of growth and a 39 percent reduction in chlorophyll (Foy and Hiranpradit 1977).
In that same study, higher exposures generally resulted in greater adverse effects. More recently, a 2- to
3-day atrazine exposure of 21.6 (ig/L reduced the growth rate of one Chlorella sp. by 55 percent (Hersh
43
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and Crumpton 1987), and another study using Chlorella sp. exhibited very rapid responses to atrazine
with EC50 values of 35 to 41 (ig/L based upon photosynthetic oxygen evolution following a 2-minute
atrazine exposure (Hersh and Crumpton 1989). Fairchild et al. (1994a) reported a 4-day biomass-based
EC50 of 92 (ig/L in yet another study using an unidentified species of the genus Chlorella.
Virmani et al. (1975) observed 75 and 92 percent reductions in growth of a much less sensitive
species of green algae, Chlorococcum hypnosporum, following 2-week exposures to 5,000 and 10,000
(ig/L atrazine, respectively. Similarly, a high test concentration (2,157 (ig/L) was necessary to inhibit
calcification in Gloetaenium loitlesbergarianum in a 96-hour test (Prasad and Chowdary 1981). Short
exposures (2 minutes) to Franceia sp. yielded EC50 values between 430 and 774 (ig/L, measured as
photosynthetic oxygen evolution (Hersh and Crumpton 1989).
In three tests with the green alga, Scenedesmus obliquus, the 24-hour EC50 values for 14C uptake
were between 38 and 57 (ig/L (Larsen et al. 1986). The green alga, Scenedesmus quadricauda, exhibited
photosynthesis inhibition of approximately 42 percent after 8 hours at an atrazine exposure of 10 (ig/L
(Valentine and Bingham 1976). Bringmann and Kuhn (1977, 1978a,b) found that 30 (ig/L caused the
onset of cell multiplication inhibition after 8 days of atrazine exposure to this species. S. quadricauda
exhibited a 12- to 14-day EC50 of 100 (ig/L based on cell number (Stratton 1984). Bogacka et al.
(1990) studied photosynthesis reductions in S. quadricauda at various concentrations after 8 days of
atrazine exposure. These authors observed a gradation from 4.5 percent reduction at 4 (ig/L to a 99.3
percent reduction at 337 (ig/L. Similarly, photosynthetic 14C uptake was highly inhibited (96 percent)
after 22 hours at 2,667 (ig/L of atrazine (Peterson et al. 1994). This species had a 96-hour EC50 of 169
(ig/L, based upon chlorophyll concentration (Fairchild et al. 1998).
In this same genera of algae, Scenedesmus subspicatus had a 4-day EC50 of 110 (ig/L (Geyer et
al. 1985), and Schafer et al. (1994) found that 37 (ig/L of atrazine inhibited the effective photosynthetic
rate of this species by 57.4 percent within 24 hours. This latter apparent effect concentration was
corroborated by Kirby and Sheahan (1994) who reported a 2-day EC50 of 21 (ig/L based on cell
numbers, as well as Zagorc-Koncan (1996) who reported a 24-hour EC50 value of 25 (ig/L based on net
assimilation and inhibition. Reinhold et al. (1994) observed a 50 percent reduction in dry mass at 21.5
(ig/L within 24 hours, and Behra et al. (1999) reported a 60-day NOEC based on growth and
photosynthetic oxygen evolution for this species of 20 (ig/L.
Exposure of an unidentified species of Scenedesmus for 72 to 96 hours at 50 (ig/L resulted in
60.2 percent growth inhibition (Foy and Hiranpradit 1977), and increased concentrations resulted in
increased growth inhibition. Fairchild et al. (1994a) obtained a 4-day EC50 based on biomass of 169
jig/L.
44
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The green alga, Selenastrum capricornutum, exhibited a significant reduction in cell numbers
following a 5-day exposure to 54 (ig/L of atrazine (Parrish 1978). In this study, chlorophyll-a reduction
increased as concentrations increased from 32 and 200 (ig/L. The minimum algistatic concentration was
determined to be 200 (ig/L. A similar 5-day LOEC for S. capricornutum growth of 220 (ig/L was
recently reported by Schrader et al. (1998). Interestingly, a 7-day exposure at 100 (ig/L resulted in a
13.8 percent increase in biomass, whereas 1,000 (ig/L resulted in decreases (Johnson 1986). The lowest
complete inhibition concentration of growth after a 6-day exposure was 2,160 (ig/L (Schrader et al.
1997).
There are a number of additional EC50 values from exposures of S. capricornutum to atrazine
(Table 6). Larsen et al. (1986) obtained 24-hour EC50 values of 53, 34 and 42 (ig/L based upon 14C
uptake. In a couple of 21-day exposures (Turbak et al. 1986), biomass-based EC50 values of 58.7 and
410 (ig/L were obtained using algal assay media and creek water for test media, respectively. Likewise,
EC50 values were 69.7 and 854 (ig/L, respectively, using these two media in 24-hour tests that measured
photosynthetic oxygen evolution. Roberts et al. (1990) reported 5-day EC50 values of 100 and 95 (ig/L
based on cell numbers, and an EC50 of 50 (ig/L based on cell numbers was reported in a 4-day exposure
by Versteeg (1990). Similarly, El Jay et al. (1997) found the 4-day IC50 values based on chlorophyll-a
content to be 80 (ig/L. Reductions in chlorophyll content and in 14C uptake occurred at 130 (ig/L in 1- to
7-day exposures (Abou-Waly et al. 1991a). EC50 values were 283, 218 and 214 (ig/L for chlorophyll-a
content at 3, 5, and 7 days, respectively (Abou-Waly et al. 1991b). Fairchild et al. (1994a, 1998)
reported a 4-day EC50 of 117 (ig/L for chlorophyll content, while Kallqvist and Romstad (1994)
obtained 3-day growth-based EC50 values of 200 and 110 (ig/L. Photosynthetic 14C uptake was almost
completely inhibited (99 percent) within 22 hours at an exposure of 2,667 (ig/L (Peterson et al. 1994). A
96-hour EC50 of 147 (ig/L was reported by Gaggi et al. (1995) for chlorophyll-a content. Additional
cell number-based EC50 values reported for 72- to 96-hour exposures include 118.2 (ig/L (Radetski et
al. 1995), 359 (ig/L (Van der Heever and Grobbelaar 1996), 200 and 220 (ig/L (Abdel-Hamid 1996), and
26 (ig/L (Caux et al. 1996). Van der Heever and Grobbelaar (1997, 1998) expanded on their 1996 study
and reported a 30-minute EC50 value based on decreased oxygen evolution of 222 (ig/L (1997) and a 4-
hour EC50 value based on chlorophyll-a fluorescence of 232 (ig/L (1998). Benhra et al. (1997) reported
an EC50 of 164.3 (ig/L based on growth inhibition and Fairchild et al. (1997) reported a biomass-based
EC50of235(ig/L.
Two tests with Stigeoclonium tenue yielded 24-hour EC50 values based on 14C uptake of 127 and
224 (ig/L, while atest with Ulothrix subconstricta yielded an EC50 of only 88 (ig/L (Larsen et al. 1986).
Several diatom species have been tested for their sensitivities to atrazine. Chlorophyll-a content
in the benthic diatom, Craticula cuspidata, was significantly reduced after 12 days exposure to 83 (ig/L
45
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atrazine immediately following 67 days in 1 (ig/L atrazine (Nelson et al. 1999). Cyclotella
meneghiniana yielded 7-minute EC50 values based upon photosynthesis between 99 and 243 (ig/L
(Millie and Hersh 1987), while a 22-hour exposure to 2,667 (ig/L of atrazine inhibited photosynthetic
14C uptake by 97 percent (Peterson et al. 1994). A 6-day growth-based EC50 of 430 (ig/L was obtained
for an unidentified species of Cyclotella by Kallqvist and Romstad (1994). Hughes (1986) and Hughes
et al. (1986, 1988) determined several endpoints in 5-day exposures of Naviculapelliculosa to atrazine,
including a 5-day EC50 of 60 (ig/L based on cell numbers. Using a 9-day recovery period following the
5-day exposure, they determined algistatic and algicidal concentrations of 1,710 and >3,200 (ig/L,
respectively. Likewise, photosynthesis was almost completely inhibited (99 percent) in Nitzschia sp. by
a 22-hour exposure to 2,667 (ig/L of atrazine (Peterson et al. 1994). The cryptomonad, Cryptomonas
pyrinoidifera, which also appears to be somewhat less sensitive to atrazine, had a 6-day EC50 based on
growth of 500 (ig/L (Kallqvist and Romstad 1994).
The duckweed, Lemna minor, when exposed to 20 (ig/L of atrazine for 20 days, did not exhibit
any adverse effects, but reduced growth occurred at concentrations of 50 to 250 (ig/L (Beaumont et al.
1976,a,b, 1978). Peterson et al. (1994), on the other hand, observed that growth was inhibited 95
percent by a 7-day exposure to 2,667 (ig/L. Four-day EC50 values for L. minor based on biomass and
frond production were 153 and 92 (ig/L, respectively (Fairchild et al. 1997, 1998). Biochemical and
ultrastructural changes in the chloroplasts of Lemna minor were observed in 15-day exposures of 100
and 1000 (ig/L of atrazine (Grenier et al. 1979) as well as an exposure of 248 (ig/L (Grenier et al. 1987,
1989; Simard et al. 1990) for 15, 10 and 2 days, respectively. This is very close to the EC50 of 170
(ig/L for frond production obtained when Hughes (1986) and Hughes et al. (1986, 1988) exposed a
different species of duckweed, Lemna gibba, to atrazine for 5 days. Using a 9-day recovery period, the
phytostatic and phytocidal concentrations were 1,720 and >3,200 (ig/L, respectively.
Exposure of wild rice, Zizania aquatica, to 50 (ig/L of atrazine for 83 days resulted in a visible
state of senescence and a 75 percent reduction in chlorophyll-a in the leaves (Detenbeck et al. 1996).
Wild celery, Vallisneria americana, exhibited reduced leaf growth and whole plant biomass at an
exposure of 8 (ig/L and reduced over-wintering success of tubers at 4 (ig/L (Cohn 1985). A 42-day test
using this species resulted in an EC50 based on total leaf length of 163 (ig/L (Davis 1981; Forney and
Davis 1981). A 14-day EC50 based on wet weight of 22 (ig/L was reported for coontail, Ceratophyllum
sp. (Fairchild et al. 1998), and reduced stem elongation occurred within 6 to 8 days at 50 (ig/L
(Detenbeck et al. 1996). These authors also found that cattails, Typha latifolia, were unaffected at 25
(ig/L atrazine after 19 days. The Eurasian watermilfoil, Myriophyllum heterophyllum, had a 14-day wet
weight-based EC50 of 132 (ig/L (Fairchild et al. 1998) while Myriophyllum spicatum had a 28-day EC50
based on length of 1,104 (ig/L (Davis 1981; Forney and Davis 1981). This species also exhibited a 50
46
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percent reduction in branch number at 3,700 (ig/L after 5 days (Bird 1993). Sago pondweed,
Potamogetonpectinatus, on the other hand, had reduced biomass after 28 days at 100 (ig/L (Fleming et
al. 1991), and bushy pondweed, Najas sp., had a 14-day wet weight-based EC50 of 24 (ig/L (Fairchild et
al. 1998). A 14-day biomass-based EC50 of <38 (ig/L was reported for Egeria sp. (Fairchild et al.
1994a).
The exposure ofElodea canadensis to atrazine for 21 and 28 days resulted in EC50 values based
on length of 109 and 80 (ig/L, respectively (Davis 1981; Forney and Davis 1981), and Detenbeck et al.
(1996) reported that growth was unaffected after 19 days at 75 (ig/L. Fairchild et al. (1998) reported a
14-day EC50 of 21 (ig/L for E. canadensis based upon wet weight.
Three species of water moss (Fontinalis antipyretica, Fontinalis hypnoides and Fontinalis
squamosa) were tested by Hoffman and Winkler (1990). While F. squamosa and F. antipyretica were
affected in their photosynthetic production at 10 (ig/L after 24 hours and 20 days, respectively, F.
hypnoides exhibited a much greater reduction (90 percent) in net photosynthesis within 24-hours at an
exposure of only 2 (ig/L. Conversely, Johnson (1986) found that 10 (ig/L stimulated growth of mixed
macrophytes, Ceratophyllum sp. and Elodea sp., but that 100 and 1,000 (ig/L decreased plant biomass
after 30 days.
The protozoan, Acanthamoeba castellanii, had population decreases of from 5 to 40 percent
when exposed for 6 days to atrazine at concentrations from 100 to 10,000 (ig/L (Prescott et al. 1977).
Photosynthesis was inhibited by about 11 percent in Euglena gracilis at 10 (ig/L after 8 hours, and
exhibited increasingly greater inhibition at higher concentrations (Valentine and Bingham 1976). Two
species of protozoans, Colpidium campylum and Tetrahymena pyriformis, had 24-hour EC50 values of
>50,000 (Roberts et al. 1990) and 118,500 ng/L (Huber et al. 1991), respectively. Schafer et al. (1994)
reported a 48-hour EC50 of 96,000 (ig/L for T. pyriformis.
Relatively high concentrations were required to produce notably adverse responses in
representatives from higher animal phyla. A concentration of 5,000 (ig/L reduced the budding rate in
Hydra viridis after 21 days (Benson and Boush 1983). The rotifer, Brachionus calyciflorus, had a 24-
hour LC50 of 7,840 (ig/L (Crisinel et al. 1994). Two species of leeches, Glossiphonia complanata and
Helobdella stagnalis, had LC50 values of 6,300 and 9,900 (ig/L, respectively, after a 27- to 28-day
exposure (Streit and Peter 1978). After 21 weeks, snail (Lymnaeapalustris) growth, fecundity and tissue
glycogen content were unaffected at concentrations up to 125 (ig/L (Baturo et al. 1995), but the
activities of benzo[a]pyrene and glutathione-s-transferase enzymes were inhibited at 5 (ig/L (Baturo and
Lagadic 1996). The 24- and 48-hour LC50 values were greater than 60,000 (ig/L for both larval and
juvenile mussels, Anadonta imbecilis (Johnson et al. 1993).
47
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The anostracan crustacean, Streptocephalus texanus, had a 24-hour LC50 of >30,000 (ig/L
(Crisinel et al. 1994). The cladoceran, Ceriodaphnia dubia, exhibited maximum acceptable toxicant
concentrations (MATCs) of 7,100 and 14,100 (ig/L in two 4-day tests (Oris et al. 1991). A 26-hour
LC50 of 3,600 (ig/L was reported for Daphnia magna (Frear and Boyd 1967). In 48-hour exposures of
Daphnia magna to a nominal atrazine concentration of 10 (ig/L, whole body residues were only 4.4 and
2.2 times greater than the nominal concentration in water (Ellgehausen et al. 1980). Young production
was reduced in D. magna after 21 days at 2,000 (ig/L (Kaushik et al. 1985). After 96 hours of exposure,
Bogacka et al. (1990) observed a 30 percent mortality in D. magna at 16,900 (ig/L, and a 60 percent
mortality at 48,300 (ig/L. Johnson et al. (1993) reported a 48-hour LC50 of 9,400 (ig/L, but the animals
were fed at 24 hours. Crisinel et al. (1994) obtained a 24-hour EC50 of >30,000 (ig/L, while Detenbeck
et al. (1996) observed a significant decrease in the survival of these invertebrates after 48 hours of
exposure at 25 (ig/L, but not at 50 (ig/L. Nishiuchi and Hashimoto (1967, 1969) found the 3-hour LC50
^^k ^^l^^k
to be greater than 40,000 (ig/L for Daphnia pulex. Exposures of D. pulex for 28 to approximately 70
days resulted in decreased survival and reproduction at concentrations ranging from 1,000 and 20,000
(ig/L atrazine, with reproduction affected more than survival (Schober and Lampert 1977). Food
consumption was reduced by 10 percent at 350 (ig/L and by 50 percent at 1,600 (ig/L after 10 minutes
(Pott 1980). Bowman et al. (1981) reported an 18-hour LC50 for D. pulex of approximately 700 (ig/L.
Conversely, the 3-hour LC50 was in excess of 40,000 (ig/L for the cladoceran, Moina macrocopa
(Nishiuchi and Hashimoto 1967, 1969), and a concentration of 1,000 (ig/L was shown to cause 40
percent mortality and reduced population growth after 4 to 6 weeks (Shcherban 1972a,b).
The amphipod, Gammarus fasciatus, had a 48-hour LC50 of 5,700 (ig/L (Macek et al. 1976).
Similarly, exposure ofHyalella azteca for 18 hours resulted in an LC50 of 2,000 (ig/L (Bowman et al.
1981). For the midge, Chironomus riparius, a 10-day exposure to atrazine yielded an LC50 of 18,900
(ig/L (Taylor et al. 1991), while a 96-hour exposure of C. tentans in a fed test had less than 50 percent
mortality at the high concentration of 28,000 (ig/L (McNamara 1991b). Macek et al. (1976) reported a
LC50 of 720 (ig/L for a 48-hour C. tentans midge test initiated with first instar animals, which did not
adhere to the 2nd or 3rd instar life stages requirement specified by the Guidelines. Pape-Lindstrom and
Lydy (1997) and Jin-Clark et al (2002) likewise used 4th instar larvae to initiate C. tentans acute tests that
yielded LC50 values of >20,000 and >1,000 (ig/L atrazine, respectively. The 18-hour LC50 for the
white dotted mosquito, Culex restuans, is considerably higher at approximately 60,000 (ig/L (Bowman
etal. 1981).
Rainbow trout, Oncorhynchus mykiss, embryos and sac fry exposed continuously for 23
(embryos at hatching) and 27 (sac fry, 4 days post-hatch) days had LC50 values between 696 and 888
(ig/L (Birge et al. 1979). Water hardness did not have any appreciable effect. A concentration of 4,020
48
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(ig/L was required to produce over 60 percent teratic larvae. Pluta (1989) reported a 48-hour LC50 of
5,660 (ig/L. Changes in the ultrastructure of trout renal corpuscles and tubules were observed following
28-day exposures to 5 to 10 (ig/L of atrazine (Fischer-Scherl et al. 1991). Similarly, 28-day exposures
resulted in slight ultrastructural changes in trout renal corpuscles at 5 (ig/L, slight histopathological
changes in the liver and increased ultrastructural changes in renal corpuscles at 10 (ig/L, and in further
changes in renal corpuscles and liver cells at 20 (ig/L (Schwaiger et al. 1991). A 14-day exposure to 10
(ig/L of atrazine did not affect survival, body weight, liver weight or liver enzyme activity (Egaas et al.
1993). Exposure to concentrations of 3.0 and 50 (ig/L for 10 days were reported to reduce plasma
protein in rainbow trout, but no effects were observed at 10 (ig/L (Davies et al. 1994b). Oulmi et al.
(1995) observed kidney changes at the cellular level within 5 weeks in O. mykiss in the proximal tubules
at 12.4 (ig/L, and in both the proximal and distal tubules at 24.0 (ig/L.
The 48-hour LC50 for the goldfish, Carassius auratus, was >10,000 (ig/L (Nishiuchi and
Hashimoto 1967, 1969), although Saglio and Trijasse (1998) observed reduced burst swimming
performance in goldfish after a 24-hour exposure to 50 (ig/L. The 48-hour LC50 for the common carp,
Cyprinus carpio, was also >10,000 (ig/L (Nishiuchi and Hashimoto 1967, 1969). Short-term exposures
of from 4 to 24 hours to lesser concentrations between 100 and 500 (ig/L resulted in increased serum
cortisol and serum glucose (Hanke et al. 1983). Serum acetylcholinesterase first increased and then
decreased with time of exposure. Changes were also noted in gill ATPase activity. Longer exposures of
72-hour duration to 1,000 (ig/L and 100 (ig/L of atrazine also yielded decreased liver glycogen (Hanke
et al. 1983), and decreased liver and muscle glycogen as well as serum protein and cholesterol (Gluth
and Hanke 1984, 1985), respectively. Juvenile carp yielded a 48-hour LC50 of 16,100 (ig/L (Pluta
1989), and a 96-hour LC50, in which the fish were fed, of 18,800 (ig/L (Neskovic et al. 1993). It was
noted in the latter study that biochemical changes in the serum, heart, liver and kidneys of carp were
observed after 14 days of exposure to 1,500 (ig/L, as well as hyperplasia of gill epithelial cells
(Neskovic et al. 1993). Conversely, no effects on gill, liver, and histopathology were observed at this
same concentration (1,500 (ig/L) in a study by Poleksic et al. (1997).
Jop (1991c) reported the "no observed effect concentration" (NOEC) to be in excess of 4,900
(ig/L for fathead minnows, P. promelas, exposed to atrazine for 7 days. Also, survival and growth were
shown to be unaffected in fathead minnows exposed to 75 (ig/L for 13 days (Detenbeck et al. 1996). On
the other hand, channel catfish (Ictaluruspunctatus) embryos and sac fry had LC50 values between 176
and 272 (ig/L after exposures of either 4.5 (embryos at hatch) or 8.5 (sac fry, 4 days post-hatch) days
(Birge et al. 1979). Concentrations of approximately 340 (ig/L caused an incidence of 13 to 16 percent
teratic larvae, while concentrations of approximately 3,850 (ig/L resulted in 47 to 69 percent teratic
larvae.
49
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Mosquitofish (Gambusia affinis) survival was unaffected in a 48-hour exposure to 10,000 (ig/L
(Darwazeh and Mulla 1974), and LC50 values as high as 38,200 and 31,600 (ig/L were reported for the
guppy (Poecilia reticulata) after exposures of 48 and 72 hours, respectively (Tscheu-Schluter 1976).
These data are consistent with results reported by Bogacka et al. (1990), in which the authors reported
mortalities of 40 and 53.2 percent after exposing guppies for 96 hours to 28,600 and 37,200 (ig/L,
respectively.
Exposure of the Mozambique tilapia, Tilapia mossambica, to 1,100 (ig/L of atrazine for 30 to 90
days affected blood composition, oxygen consumption, water content, and the biochemistry of the brain
and liver (Prasad et al. 1991a,b; Srinivas et al. 1991). A 90-day exposure also resulted in increased
serum sodium and potassium, and decreased serum calcium, magnesium and bicarbonate (Prasad and
Reddy 1994).
The embryo and larval stages of several amphibian species were exposed to atrazine (Birge et al.
1980), the results of which are quite different between species (Table 6). LC50 values for continuous
exposure of embryos and larvae through 4 days post-hatch were 410 (ig/L for the bullfrog (Rana
catesbeiand), 7,680 (ig/L for the leopard frog (Ranapipiens), 17,960 (ig/L for the pickerel frog (Rana
palustris), and >48,000 (ig/L for the American toad (Bufo americanus). In most of these species,
concentrations of atrazine in excess of 5,000 (ig/L were required to cause an incidence of teratic larvae
in excess of 7 percent. Survival and growth of R. pipiens tadpoles were unaffected after 41 days of
exposure to 25 (ig/L (Detenbeck et al. 1996). A 96-hour exposure of the African clawed frog (Xenopus
laevis) embryos to 8,000 (ig/L resulted in 100 percent abnormal embryos (Morgan et al. 1996). The
lowest observed effect concentration (LOEC; teratogenesis) in the study was 1,100 (ig/L. This
concentration is more than an order of magnitude higher than that which delayed development and
retarded the growth in the tiger salamander, Ambystoma tigrinum, after 86 days of exposure (Larson et
al. 1998).
In summary, cyanobacteria had EC50 values for various exposure durations of 30 (ig/L or
greater, while EC50 values for green algae, diatoms and cryptomonads were • *5 (ig/L. Among
macrophytes, duckweed had a minimal 4-day EC50 of 92 (ig/L. Wild rice was affected at 50 (ig/L, and
wild celery had reduced growth at 8 (ig/L. Several rooted vascular plants (i.e., coontail, bushy
pondweed, egeria, and elodea) had 14-day EC50 values between 21 and <38 (ig/L, while that for a water
milfoil was 132 (ig/L. Two species of water moss (Fontinalis sp.) exhibited reduced photosynthetic
activity at 10 (ig/L, and one species was affected at 2 (ig/L. EC50/LC50 values for protozoans,
coelenterates, annelids, molluscs and rotifers were • 6,300 (ig/L. Various crustaceans had LC50 values
• 5,700 (ig/L. The most sensitive endpoints among fish were rainbow trout plasma protein and kidney
ultrastructural changes at atrazine exposures of 3 and 3.5 (ig/L, respectively. The lowest LC50 values in
50
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fish were 176-272 (ig/L for 4.5 to 8.5-day exposures with early life-stages of channel catfish. Frog
embryo and tadpole life-stages had LC50 values • 410 (ig/L. As noted in the ecosystem effects data
section in this document, most reductions in algal or vascular plant biomass were observed at
concentrations • *5 (ig/L. This commonly resulted in the reduction of herbivore populations, as well.
One exception reported effects at much lower concentrations (as low as 0.1 (ig/L). From these
freshwater Other Data, most of the effect levels of possible biological significance appear to be • *5
(ig/L. This concentration is greater than the freshwater Final Chronic Value based on ecosystem effects
data (10 (ig/L), and therefore does not determine the Criterion Continuous Concentration.
Additional data are available for saltwater algae, kelp, submerged vascular plants, emergent
vascular plants, and aquatic animals (Table 6). EC50 values based on differing endpoints (e.g., oxygen
evolution or growth) for various green algal species ranged from 37 (ig/L to 600 (ig/L (Gaggi et al.
1995; Hollister and Walsh 1973; Hughes 1986; Hughes et al. 1986, 1988; Samson and Popovic 1988;
Walsh 1972). A 48-hour exposure of the green alga, Dunaliella bioculata, to 216 (ig/L of atrazine
resulted in a growth reduction of approximately 35 percent (Felix et al. 1988). Seven-day growth tests
with the green alga, Nannochloris oculata, at concentrations of 50 and 100 (ig/L suggested that atrazine
toxicity was dependent on light and temperature (Karlander et al. 1983; Mayasich et al. 1986), although
the effect was not dramatic. A concentration of 15 (ig/L changed the doubling time in N. oculata
(Mayasich et al. 1987).
Diatom species were similar to green algae in terms of their sensitivities to atrazine. EC50
values for exposures of various durations were generally between 20 and 460 (ig/L (Hollister and Walsh
1973; Walsh 1972; Walsh et al. 1988). Plumley and Davis (1980) observed reduced photosynthesis in
Nitzschia sigma and reduced chlorophyll in Thalassiosira fluviatilis in 7-day exposures to 220 (ig/L.
Mayasich et al. (1987) reported a limited effect on doubling time to Phaeodactylum tricornutum in a 7-
day exposure to 50 (ig/L of atrazine.
The red alga, Porphyridium cruentum, had an EC50 based on oxygen evolution of 79 (ig/L when
exposed for 90 minutes (Hollister and Walsh 1973), and the kelp, Laminaria hyperborea, had a 24-hour
LOEC value for respiration of > 1,000 (ig/L (Hopkins and Kain 1971). The 28-day LOEC for this
species based on growth of new sporophytes was 10 (ig/L. It was shown in another species of kelp,
Laminaria saccharina, that a 2-day exposure to • ¥2.2 (ig/L of atrazine was sufficient to significantly
reduce sexual reproduction, but no effect was detected at 33.2 (ig/L (Thursby and Tagliabue 1990).
Inhibition concentrations of 77 to 120 (ig/L for a 50 percent effect on photosynthesis by vascular
plants in short-term (2- to 4-hour) exposures to atrazine (Jones and Winchell 1984; Jones et al. 1986)
were similar to the effects upon growth and photosynthesis in longer exposures with several other
species (Table 4). Studies involving Vallisneria americana at low salinities for 42 to 47 days resulted in
51
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reduced leaf production in terms of length, leaf area, and dry weight for concentrations ranging from 12
to 320 (ig/L of atrazine (Correll and Wu 1982; Forney 1980; Forney and Davis 1981). Eelgrass, Zostera
marina, had reduced oxygen evolution at 100 (ig/L, and complete inhibition of photosynthesis and
growth at 1,000 (Kemp et al. 1982a) and 1,900 ng/L of atrazine (Schwarzschild et al. 1994). Walsh et
al. (1982) report a 40-hour EC50 of 320 (ig/L for the turtlegrass, Thalassia testudinum. The emergent
salt-marsh rush, Juncus roemerianus, exhibited effects indicative of stress after a 35-day exposure to 30
(ig/L, while the salt-marsh grass, Spartina alterniflora, only exhibited enhanced peroxidase activity at a
concentration as high as 3,100 (ig/L for the same length of time (Lytle and Lytle 1998).
The three LC50 values for the copepod, Acartia tonsa, at 24, 48 and 72 hours showed that the
sensitivity to atrazine increased with increasing duration of exposure (McNamara 1991b; also see Table
1). The 96-hour EC50 in the juvenile Eastern oyster, Crassostrea virginica, as well as the 48-hour LC50
for the juvenile spot, Leiostomas santhurus, were both • 1,000 (ig/L, while the brown shrimp, Penaeus
aztecus, had a 48-hour EC50 of 1,000 (ig/L (Butler 1964; Mayer 1987). Adult fiddler crabs, Uca
pugnax, were not very sensitive to one-time applications of atrazine either in field or laboratory
exposures (Plumley et al. 1980). However, there was a seasonal effect on the sensitivity of this species
even when the laboratory conditions were the same. Animals collected in the summer were more
sensitive to atrazine than those collected in either the spring or fall. Two other species of crabs, Sesarma
cinereum and Panopeus sp., were also insensitive to very high levels of atrazine (Plumley et al. 1980).
The acute and chronic effects of atrazine on an estuarine microbial community were recently
examined by DeLorenzo et al. (1999a,b). Exposure for 9 days to 40 (ig/L of atrazine in dilute seawater
(7-25 g/kg) inhibited the phototrophic component - chlorophyll-a, carbon assimilation, biovolume, and
caused changes in species composition (DeLorenzo et al. 1999a). The same effects were observed in
full strength seawater at an atrazine concentration of 47 (ig/L, but within 24 hours (DeLorenzo et al.
1999b).
UNUSED DATA
Data from some studies were not used in this document, as they did not meet the criteria for
inclusion as specified in the Guidelines (Stephan et al. 1985). The reader is referred to the Guidelines
for further information regarding these criteria.
52
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Studies Were Conducted with Species That Are Not Resident in North America
Alazemi et al. (1996) Gzhetotskii et al. (1977) Nagel (1992)
Biagianti-Risbourg and Bastide (1995) Hussein et al. (1996) Pantani et al. (1997)
Diaz et al. (1998) Juhnke and Luedemann (1978) Portmann (1972)
Forget et al. (1998) Kirby et al. (1998) Prasad et al. (1990, 1995)
Gorge and Nagel 1990 Lewis et al. (1993 Ralph (2000)
Gunkel and Kausch (1976) L'Haridon et al. (1993) Steinberg et al. (1995)
Results were not used if the duration of the exposure was not specified or was unclear (e.g.,
Hopkins and Kain 1968; Portmann 1972; Rojickova-Padrtova and Marsalek 1999; Tellenbach et al.
1983), or if the procedures or test materials were not adequately described or translated (e.g. Braginskii
and Migal 1973; Delistraty 1999; Kross et al. 1992; Moore and Lower 2001; Moore and Waring 1998;
Shcherban 1973; Tang et al. 1998a,b; Wenzel et al. 1997).
Acute toxicity data were not used if an insufficient number of test organisms (Bathe et al. 1973,
1975), or exposure concentrations were used (Allran et al. 2000; Bouilly et al. 2003). Data were also not
used if there was a lack of a dose response (Bester et al. 1995; Britson and Threlkeld 2000). High
control moralities occurred in tests reported by Dodson et al. (1999), as well as in chronic studies with
Daphnia magna, Gammarus fasciatus and fathead minnows (Macek et al. 1976). Studies published only
as abstracts of presentations were not used (e.g., Fairchild et al. 1994b; Palmstrom and Krieger 1983;
Zora and Paladino 1986). Secondary observations reported in a review were not used (e.g., Giddings
and Hall 1998; Hurlbert 1975; Hutchinson et al. 1998; Lange et al. 1998; Mercuric 1998). Similarly,
papers by Birge et al. (1983), Fairchild et al. (Manuscript), Mark and Solbe (1998), and Pratt et al.
(1993, 1997) were not used, as the data they contained had been previously published. A study by
Butler et al. (1975) was not used since data from several algal taxa were grouped in the reporting of
results. Stratton and Giles (1990) expressed toxicity on the basis of cell numbers.
Atrazine Was a Formulation or Emulsifiable Concentrate (and comprised <80% of its weight)
Antychowicz et al. (1979) Hofmann and Winkler (1990) Rojickova-Padrtova & Marsalek 1999
Carder and Hoagland (1998) Howe et al. (1998)
Clements et al. (1997) Lin et al. (1999) Semov and losifov (1973)
deNoyelles et al. (1982) Kettle et al. (1987) Sreenivas and Rana (1991,1994)
Hartman and Martin (1985) Pavlov (1976) Torres and O'Flaherty (1976)
Hiltibran(1967) Walker (1964)
53
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Atrazine Was a Component of a Drilling Mud, Effluent, Mixture, Sediment or Sludge
Berardetal. 1999
Britson and Threlkeld (1998)
Grain etal. (1998)
Goodbred et al. 1997
Guasch and Sabater (1998)
Guaschetal. (1997, 1998)
Hartgers et al. (1998)
Lowcocketal. (1997)
Ortetal. (1994)
PoUehne etal. (1999)
Putt (2003)
Reederetal. (1998)
Vanderpoorten(1999)
Toxicity data from laboratory tests were generally not used if atrazine was dosed in the diet (e.g.,
Cossarini-Dunier et al. 1988), or if the concentration of solvent used in atrazine stock preparation
exceeded 0.5 ml/L (e.g., Cheney etal. 1997; Grain et al. 1997, 1999; Messaad et al. 2000; Pennington
and Scott 2001; Schafer et al. 1994; Tang et al. 1997); the latter representing a value below which
neither acetone nor ethanol are toxic to algae (e.g., El Jay 1996; Stratton and Corke 1981), but where
DMSO and atrazine may interact additively (El Jay 1996).
The results from Langan and Hoagland (1996) were not used because the tests were conducted
in distilled water without addition of the appropriate salts. Toxicity tests by Schmitz et al. (1994) and
Tubbing et al. (1993) were not used because the tests were performed in river water which was likely
contaminated with various other chemicals. Similarly, a cytopathological study offish exposed to a spill
of atrazine plus other pesticides was not used (e.g., Spazier et al. 1992). Effects data were not used if the
atrazine exposure was part of a soil mixture (e.g., Johnson et al. 1999; Jones and Estes 1984; Lytle and
Lytle 1998; Miller and Doxtader 1995; Ruth 1997). McBride and Richards (1975) exposed excised
tissue, and Petit et al. (1997) exposed cell cultures.
A study of atrazine accumulation by Bohm and Muller (1976) was not used due to expression of
results on a volume basis rather than a weight basis. A bioconcentration study by Walsh and Ribelin
(1973) was not used due to the use of nominal atrazine concentrations in the exposure water rather than
measured concentrations. Data were not used if the exposure was to radiolabeled atrazine (e.g., Davis et
al. 1979; Jones et al. 1982; McEnerney and Davis 1979; Neumann et al. 1987; Nikkila et al. 2001; Pillai
et al. 1977, 1979; Weete et al. 1980), or atrazine was not detected in tissue (e.g., Harris et al. 1998).
Uptake and accumulation from exposures in flasks or microcosms were not used if 14C only was
measured and not atrazine itself (e.g., Huckins et al. 1986; Isensee 1976, 1987; Kearney et al. 1977;
Mailhot 1987).
Biochemical studies of resistant strains of mutated algae (e.g., Boura-Halfon et al. 1997; Forster
et al. 1997; Ottmeier et al. 1991) and results from in vitro genotoxicity and mutagenicity tests (e.g., Ruiz
and Marzin 1997) were not used. A study of atrazine effects upon promutagen activation by
54
-------
Selenastrum capricornutum (e.g., Sauser and Klaine 1990) and alteration in allele and genotype
frequencies of the oyster, Crassostrea gigas (e.g., Moraga and Tanguy 2000) were also not used.
SUMMARY
Atrazine is not highly toxic to aquatic animals on an acute basis. SMAVs for eight freshwater
invertebrate species ranged from 3,000 (ig/L for a hydra, Hydra sp., to 49,000 for Daphnia magna.
SMAVs for nine fish species ranged from 5,300 (ig/L for the rainbow trout, Oncorhynchus mykiss, to
60,000 (ig/L for the goldfish, Carassius auratus (Figure 1). The three amphibian species evaluated each
has a LC50 value of >20,000 (ig/L atrazine. GMAVs for atrazine are available for nine genera of
saltwater animals and range from 2,324 to >30,000 (ig/L; a factor of approximately 12.9 (Figure 2).
GMAVs for the four most sensitive genera (three species of crustaceans and one fish) differed by a
factor of approximately 2.5.
Chronic effects of atrazine exposure to aquatic animals have been studied with six freshwater
species, two of which are invertebrates and four of which are fish (Figure 3). In three tests with
Ceriodaphnia dubia, chronic values were 3,536, 3,536, and 1,732 (ig/L. The growth of a midge,
Chironomus tentans, was retarded at 230 (ig/L of atrazine, but not at 110 (ig/L. A chronic value of 159.1
(ig/L was calculated, and a corresponding acute-chronic ratio of 4.525 was derived.
Brook trout, Salvelinusfontinalis, had reduced growth at 120 (ig/L, but not at 65 (ig/L, in a
chronic exposure. A chronic value of 88.32 (ig/L and an acute-chronic ratio of 71.33 were calculated.
In a life-cycle test with the fathead minnow, Pimephalespromelas, the chronic limits were set at 250 and
460 (ig/L, based upon growth of larval fish, resulting in a chronic value of 339.1 (ig/L and an acute-
chronic ratio of 58.98. Bluegills, Lepomis macrochirus, were unaffected in a chronic exposure to 95
(ig/L, thereby setting the chronic limits at 95 and >95 (ig/L, with a chronic value of >95 (ig/L. Since the
acute value was a "greater than" value, the acute-chronic ratio was >84.21.
Chronic values are available for three species of saltwater organisms. The chronic values for
Eurytemora affinis ranged from 5,020 to 20,920 (ig/L, based on survival. The chronic value for
Americamysis bahia was 123.3 (ig/L, also based on survival. The chronic value for Cyprinodon
variegatus was 2,542 (ig/L, based on mortality of juveniles. The resultant acute-chronic ratio for E.
affinis was 2.629, while the acute-chronic ratios for A. bahia and C. variegatus were 8.110 and >6.294,
respectively.
Effect concentrations for freshwater and saltwater plants are lower than the acute and chronic
values for aquatic animals (Figures 4 and 5). Atrazine toxicity to aquatic plants, both algae and
macrophytes, commonly occurs at concentrations of 10 (ig/L and above, with several reports of toxicity
55
-------
to specific plant taxa at concentrations below 10 (ig/L (primarily freshwater plant species). Effects are
thought to be algistatic rather than algicidal at these lower concentrations, with recovery occurring once
the atrazine is removed. The lowest EC50 values for freshwater green algae with exposure durations of
4 days or longer were 10.2 and 4 (ig/L for Chlamydomonas reinhardtii and Selenastrum capricornutum,
respectively. Mean EC50 values for these species would be considerably higher. The lowest reported
EC50 value for a freshwater vascular plant species, Lemna gibba, was 37 (ig/L in a 14-day exposure,
using wet weight as an endpoint (Figure 4). As stated in the Guidelines (Stephen et al. 1985), the Final
Plant Value (FPV) is the lowest result from a test with an important aquatic plant species in which the
concentrations of test material were measured, and the endpoint was biologically important. In this case,
the freshwater FPV is 17.25 (ig/L atrazine, which is the geometric mean of the two duckweed species
(Lemna gibba and Lemna minor) species mean chronic values (SMCVs) of 6.44 (ig/L (Hoberg 1993b,c)
and 46.19 (ig/L (Text Table A: University of Mississippi 1990; Girling et al. 2000). Using the
geometric mean of the two SMCVs for Lemna is consistent with the Guidelines, and is how all the
SMAVs and GMAVs are calculated in the WQC documents.
Conversely, the lowest EC50 based on growth for a saltwater green algae species, Neochloris
sp., was 82 (ig/L, while the equivalent value for a saltwater vascular plant species, Myriophyllum
spicatum, was 25 (ig/L. For saltwater, the FPV would be the geometric mean of the three Potamogeton
pectinatus (Sago pondweed) measured chronic studies conducted by Hall et al. (1997) at different
salinities, or 16.83 (ig/L atrazine (Text Table B). Using the geometric mean of the SMCVs for the three
Potamogeton pectinatus tests is consistent with the Guidelines, and is how all the SMAVs and GMAVs
are calculated in the WQC documents.
Aquatic ecosystem structural and functional parameters have most frequently been observed to
be adversely affected by atrazine concentrations of 10 (ig/L and above (Figures 4 and 5). Ecosystem
effects have been shown to occur at atrazine concentrations less than 5-10 (ig/L, but data are limited.
Several microcosm and mesocosm studies ranging from 7 days to 2 months report no effect of atrazine
on community structure, composition and functionality at atrazine as low as 5 (ig/L (Gruessner and
Watzin 1996, Brockway et al. 1984, Van den Brink 1995, Juttner et al. 1995). The ecosystem effects
that do occur below 5 (ig/L are generally transient and not well established. Recovery is quite rapid and
functionality is generally not compromised until much higher concentrations are reached. It appears that
for effects at concentrations up to 15 (ig/L, the communities can recover quite rapidly following
dissipation of the atrazine concentration. The median LOEC from 65 community studies using multiple
endpoints, excluding those studies where recovery was known to occur, is 60 (ig/L, and the 5th percentile
LOEC is 10 (ig/L (Figure 6). The observed effects have been on both the plant and animal communities,
with the effects upon the animal community being secondary in nature, mainly a result of decreased
56
-------
availability of shelter and plant matter for food. Thus, permanent ecosystem effects should only occur at
atrazine concentrations greater than 10 (ig/L.
Atrazine has been reported in a number of studies as an endocrine disrupter. Laboratory
exposures of 1 (ig/L atrazine have been reported to cause abnormalities in frog (Xenopus laevis) gonadal
development (feminization and hermaphroditism - which could render male frogs sterile) and reduction
in the size of the laryngeal muscle in male frogs, an important muscle used for the mating call of the
frog (Hayes et al. 2002; Text Table C). However, studies conducted by Carr et al. (2003) and Carr and
Salomon (2003) designed to replicate the Hayes et al. (2002) experiments observed these same gonadal
development effects at approximately 20-21 (ig/L atrazine. A third study conducted by Sullivan et al.
(2003) with Xenopus laevis looking at the same end-points yielded an effect level of 20 (ig/L atrazine
(the lowest concentration tested). Until this issue is resolved, justification and defense of a freshwater
chronic criterion based on the endocrine disrupting effects of atrazine on amphibians is not possible. A
recently convened Scientific Advisory Panel agreed with EPA's conclusion that additional studies are
warranted to reduce the scientific uncertainty regarding whether atrazine causes replicable effects on
amphibians (Scientific Advisory Panel 2003). Substantial additional research to resolve this issue is
currently underway, or planned for the immediate future. Once additional data are available that
conclusively demonstrate a significant reproductive effect (or other endpoint that significantly impairs
the populations ability to survive long term) to aquatic species, then derivation of the freshwater chronic
criterion will be reevaluated.
Atrazine has a limited tendency to accumulate in tissues of aquatic animals. BCFs ranged from
<0.27 to a maximum of 8.5 in three species of freshwater fish. There are no BCFs available for
saltwater species.
The national criteria are determined on the basis of atrazine toxicity to aquatic animals (acute
criteria), ecosystem effects (freshwater chronic criterion), and toxicity to plants (saltwater chronic
criterion). The Criterion Maximum Concentrations (CMC) for fresh water (1,511 (ig/L) and salt water
(759.5 (ig/L) are one-half of the respective Final Acute Values (3,021 and 1,519 (ig/L, respectively).
These values are based on Table 1 acute toxicity values for all invertebrate and vertebrate species. The
Criterion Continuous Concentration (CCC) for freshwater is based on the ecosystem effects of atrazine
to aquatic plants. The saltwater CCC of 16.83 (ig/L is based on the Final Plant Value determined for the
Sago pondweed.
57
-------
NATIONAL CRITERIA
The procedures described in the Guidelines indicate that, except possibly where a locally
important species is very sensitive, freshwater aquatic life and their uses should not be directly affected
unacceptably if the Average Primary Producer Steinhaus Similarity deviation for a site is less than 5%
(as determined using Comprehensive Aquatic Systems Model (CASM)3 or other appropriate model and
index) and is not exceeded more than once every three years (or other appropriate return frequency
sufficient to allow system recovery) and if the one-hour average concentration does not exceed 1,500
ug/L more than once every three years on the average. The 5% index for the protection of aquatic plant
community should also be protective of most freshwater animals.
The procedures described in the Guidelines indicate that, except possibly where a locally
important species is very sensitive, saltwater aquatic organisms and their uses should not be affected
unacceptably if the thirty-day average concentration of atrazine does not exceed 17 (ig/L more than once
every three years on the average, and if the one-hour average concentration does not exceed 760 (ig/L
more than once every three years on the average
IMPLEMENTATION
As discussed in the Water Quality Standards Regulation (U.S. EPA 1983a) and the Foreword to
this document, a water quality criterion for aquatic life has regulatory impact only when it has been
adopted in a State water quality standard. Such a standard specifies a criterion for a pollutant that is
consistent with a particular designated use. With the concurrence of the U.S. EPA, States designate one
or more uses for each body of water, or segment thereof, and adopt criteria that are consistent with the
use(s) (U.S. EPA 1983a,b, 1987, 1994). Water quality criteria adopted in State water quality standards
could have the same numerical values as criteria developed under Section 304, of the Clean Water Act.
However, in many situations States might want to adjust water quality criteria developed under Section
304 to reflect local environmental conditions and human exposure patterns. Alternatively, States may
use different data and assumptions than the U.S. EPA in deriving numeric criteria that are scientifically
3CASM is an aquatic ecological food chain model, specifically, the Comprehensive Aquatic Systems Model
(Bartell et al. 2000, Bartell et al 1999, DeAngelis et al 1989).
Bartell, S.M., K.R. Campbell, C.M. Lovelock, S.K. Nair, and J.L. Shaw. 2000. Characterizing aquatic ecological
risk from pesticides using a diquat dibromide case study III. Ecological Process Models. Environ. Toxicol. Chem.
19(5):1441-1453.
Bartell, S.M., G. Lefebvre, G. aminski, M. Carreau, and K.R. Campbell. 1999. An ecosystem model for assessing
ecological risks in Quebec rivers, lakes, and reservoirs. Ecol. Model. 124:43-67.
58
-------
defensible and protective of designated uses. State water quality standards include both numeric and
narrative criteria. A State may adopt a numeric criterion within its water quality standards and apply it
either state-wide to all waters for the use the criterion is designed to protect or to a specific site. A State
may use an indicator characteristic or the national criterion, supplemented with other relevant
information, to interpret its narrative criteria within its water quality standards when developing NPDES
effluent limitations under 40 CRF 122.44(d)(l)(vi).2.
Site-specific criteria may include not only site-specific criterion concentrations (U.S. EPA
1994), but also site-specific, and possibly pollutant-specific, durations of averaging periods and
frequencies of allowed excursions (U.S. EPA 1991). The averaging periods of "one hour" and "four
days" were selected by the U.S. EPA on the basis of data concerning how rapidly some aquatic species
react to increases in the concentrations of some aquatic pollutants, and "three years" is the Agency's best
scientific judgment of the average amount of time aquatic ecosystems should be provided between
excursions (Stephan et al. 1985; U.S. EPA 1991). However, various species and ecosystems react and
recover at greatly differing rates. Therefore, if adequate justification is provided, site-specific and/or
pollutant-specific concentrations, durations, and frequencies may be higher or lower than those given in
national water quality criteria for aquatic life.
Use of criteria, which have been adopted in State water quality standards, for developing water
quality-based permit limits and for designing waste treatment facilities requires selection of an
appropriate waste load allocation model. Although dynamic models are preferred for the application of
these criteria (U.S. EPA 1991), limited data or other considerations might require the use of a steady-
state model (U.S. EPA 1986). Guidance on mixing zones and the design of monitoring programs is also
available (U.S. EPA 1987, 1991).
59
-------
Figure 1. Ranked Summary of Atrazine GMAVs - Freshwater.
1004
0.0
Ranked Summary of Atrazine GMAVs
Freshwater
A A
• AD
A
Freshwater Final Acute Value = 3,021 ug/L Atrazine
0.2
Criterion Maximum Concentration = 1,500 ug/L Atrazine
0.4 0.6
% Rank GMAVs
0.8 1.0
D Invertebrates
• Fish
A Amphibians
60
-------
Figure 2. Ranked Summary of Atrazine GMAVs - Saltwater.
10 i
C 4
O 104
•+•»
0)
o
§ 1000
O
LU
0)
c
'N
re
100-
10
Ranked Summary of Atrazine GMAVs
Saltwater
Saltwater Final Acute Value = 1519 ug/L Atrazine
Criterion Maximum Concentration = 760 ug/l Atrazine
0.00 0.15 0.30 0.45 0.60
% Rank GMAVs
0.75
D Invertebrates
• Fish
0.90
61
-------
Figure 3. Chronic Toxicity of Atrazine to Aquatic Animals.
Chronic Toxicity of Atrazine to Aquatic Animals
ioS
1Q4
> 1000
o
I
g 100
0)
c
'N
5 10
>RAFT
Saltwater Final Chronic Value = 17 ug/L Atrazine
Freshwater Final Chronic Value = 10 ug/L Atrazine
I I I I I
0.0 0.2 0.4 0.6 0.8 1.0
D Freshwater Invertebrates
% Rank Genus Mean Chronic Value • FreshwaterFish
A Saltwater Invertebrates
A Saltwater Fish
62
-------
Figure 4.
Ranked Summary of Test Values for Freshwater Plants.
Ranked Summary of Test Values for Freshwater Plants
c
o
"re
c
0
o
o
"o
o>
fc
a>
c
'N
s
1000
100
10
1
0.1
-
-
-=
•;
_
-
2
-
-=
{
~_
-_
-
Freshwater Final Acute Value = 3,021 ug/L ** —
^M
.00"°
mmom&&»°fffm
.oo-°°'"
Typical Range of
Atrazine Effect
Levels in Microcosm,
Mesocosm and
Community Studies
(10 ug/L -5,000 ug/L)
Algistatic to 0.1 ug/L
D Freshwater Final Chronic Value = 10 ug/L
noon"0
O
."
I I I I I
1 F
0 20 40 60 80 100
% Rank Individual TeSt
aCMamydomonasreinhardtii
• Selenastrum capricornutum
O Lemna gibba
• Lemna minor
A Elodea canadensis
63
-------
Figure 5.
Ranked Summary of Test Values for Saltwater Plants
Ranked Summary of Test Values for Saltwater Plants
71
Saltwater Final Acute Value = 1519 ug/L
E rJ
wwwwww
TTTTT
0.1
0
Saltwater Final Chronic Value = 17 ug/L
Typlcal Range of
Atrazlne Effect
Levels In Microcosm,
Mesocosm and
Community Studies
(5.8Mg/L-47Mg/L)
Alglstatic to 0.12 ug/L?
I I I I
20 40 60 80
% Rank Individual Test Values
O Platymonas sp. T Potamogeton pectinatus
A Porphyridium cruentum v Myriophyllum spicatum
100
• Skeletonema costatum
D Chlorella sp.
• Neochloris sp.
A Potamogeton perfoliatus » Zostera marina
64
-------
Figure 6. Range of Reported Atrazine Lowest Observed Effect Concentrations (LOECs) and
No Observed Effect Concentrations (NOECs) Excluding Those LOECs Where
Recovery Was Reported to Occur.
1000=i
LOEC NOEC
Effect Type
Median
65
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Table 1. Acute Toxicity of Atrazine to Aquatic Animals
Species
Hydra,
Hydra sp.
Annelid,
Lumbriculus variegatus
Snail,
Physa acuta
Snail (adult),
Physa sp. 1
Cladoceran (<24 hr),
Ceriodaphnia dubia
Cladoceran (<12 hr),
Ceriodaphnia dubia
Cladoceran (<24 hr),
Daphnia magna
Cladoceran (<24 hr),
Daphnia magna
Cladoceran,
Daphnia magna
Amphipod (14-21 d),
Hyalella azteca
Amphipod,
Hyalella azteca
Stonefly (nymph),
Acroneuria sp.
Coho salmon (yearling),
Oncorhynchus kisutch
Rainbow trout
(juvenile),
Oncorhynchus mykiss
Brown trout,
Salmo trutta
Brook trout (juvenile),
Salvelinus fontinalis
Goldfish (juvenile),
Carassius auratus
Fathead minnow
Pimephales promelas
Fathead minnow
(juvenile),
Pimephales promelas
Hardness LC50
(mg/L as or EC50
Method' Chemical CaCO,) (ug/L)b
FRESHWATER SPECIES
R,M • 98.5% 48.9 3.000
F,M • 98.5% 67.3 >37.100
S,M - - >20.000
J I
R.M • 98.5% 48.9 >34.100
/
FS,M 97% 52^ >4.900
S,M >99% 57.1 >30.000
S,U 94% - 6,900
S,U • 96% 250 >39,000
F,M 79.6% 170 49.000
S,M • 98% - >1 0,000
F,M • 98.5% 67.4 14.700
F,M • 98.5% 67.4 6.700
R,M • 80% 101 >18.000
S,U 98.8% 43 5.300
R,U - 11 27.000
F,U 94% - 6.300
S,U 98.8% 43 60.000
R,U 94% - 15,000
S,M 97% 52 >4,900
Species Mean
Acute Value
3,000
>37,100
>20,000
>34,100
>12,120
-
-
49,000
-
14,700
6,700
>18,000
5,300
27,000
6,300
60,000
_
-
References
Brooke 1990
Brooke 1990
Rises etall 1999
Brooke 1990
Jop 1991a
Orisetal. 1991
Maceketal. 1976
Marchini et al. 1988
Putt 1991
Anderson and Lydy 2002
Brooke 1990
Brooke 1990
Lorzetal. 1979
Beliles and Scott 1965
Grande etal. 1994
Maceketal. 1976
Beliles and Scott 1965
Maceketal. 1976
Jop 1991d
FRESHWATER SPECIES
-------
Table 1 (Continued)
Species
Fathead minnow,
Pimephales promelas
Channel catfish
(sac fry),
Ictalurus punctatus
Bluegill (juvenile),
Lepomis macrochims
Bluegill (juvenile),
Lepomis macrochims
Largemouth bass (fry),
Micropterus salmoides
Leopard frog,
Rana pipiens
Wood frog,
Rana sylvatica
American toad,
Bufo americanus
Species
Eastern oyster
(embryo/larval),
Crassostrea virginica
Copepod (nauplius),
Eurytemora affinis
Copepod (nauplius),
Eurytemora affinis
Copepod (nauplius),
Eurytemora affinis
Copepod (adult),
Acartia clausii
Copepod,
Acartia tonsa'
Copepod (adult),
Acartia tonsa
Copepod (adult),
Acartia tonsa
Copepod (adult),
Acartia tonsa
Method" Chemical
F,M 97.1%
S,U 80%
S,U 98.8%
F,U 94%
«I"^K
. J 80%
R,M 99%
R,M 99%
R,M 99%
Method" Chemical
S,U 97.4%
S,M 97.1%
S,M 97.1%
S,M 97.1%
R,U 70%
S,U 97.4%
R,M 70%
R,M 70%
F,M 97.1%
Hardness LC50
(mg/L as or EC50
_CaC03]_ (ug/L)b
20-40 20.000
78 >10.000
43 24.000
1
>8.000
78 >10.000
290 >20.000
290 >20.000
290 >20.000
LC50
Salinity or EC50
(g/kg) (ug/L)b
SALTWATER SPECIES
16 >30.000
5 500
15 2.600
25 13.200
6 7.925
20 94
31-32 210.1
31 91.73
30-34 4.300
Species Mean
Acute Value
(Ug/L)
20,000
>10,000
>13,856
>10,000
>20,000
>20,000
>20,000
Species Mean
Acute Value
(Ug/L)
>30,000
-
-
2,579
7,925
-
-
-
4,300
References
Dionne 1992
Jones 1962
Beliles and Scott 1965
Maceketal. 1976
Jones 1962
Allran and Karasov 2001
Allran and Karasov 2001
Allran and Karasov 2001
References
Ward and Ballantine 1985
Halletal. 1994a,b
Halletal. 1994a,b
Halletal. 1994a,b
Thursbyetal. 1990
Ward and Ballantine 1985
Thursbyetal. 1990
Thursbyetal. 1990
McNamara 1991a
SALTWATER SPECIES
67
-------
Table 1 (Continued)
Species
Mysid,
Americamysis bahia
Mysid,
Americamysis bahia
Pink shrimp,
Penaeus duorarunf
Grass shrimp,
Palaemonetes pugicf
Salinity
Method" Chemical (g/kg)
F,M 97.4%
F,M
S,U
Sheepshead minnow
(larva),
Cyprinodon variegatus
Sheepshead minnow,
Cyprinodon variegatus
Sheepshead minnow,
Cyprinodon variegatus
97.1%
97.4%
20
32
LC50
or EC50
(Ug/L)b
1.000
Fiddler crab,
Uca pugilator
Sheepshead minnow
(larva),
Cyprinodon variegatus
Sheepshead minnow S,M 97.1%
(larva),
Cyprinodon variegatus
S,M 97.1%
F,M 97.4%
F,M 97.1%
Spot, S,U 97.4%
Leiostomus xanthurus'
15
25
13
32
12
2.300
2.000
>16,000d
13,000d
8.500
Species Mean
Acute Value
2,324
6,900
References
Ward and Ballantine 1985
Machado 1994
Ward and Ballantine 1985
•,000 ~ Ward and Ballantine 1985
Halletal. 1994a,b
Halletal. 1994a,b
4,208 Halletal. 1994a,b
Ward and Ballantine 1985
Machado 1994b
!,500 Ward and Ballantine 1985
a S = static; R = renewal; F = flow-through; M = measured; U = unmeasured.
b Results are expressed as atrazine, not as the chemical. Each Species Mean Acute Value was calculated from the associated underlined
number(s) in the preceding column.
0 Test organisms collected from the field.
d Not used in calculations because data are available for a more sensitive life stage.
-------
Table 2a. Chronic Toxicity of Atrazine to Aquatic Animals
Species
Cladoceran,
Ceriodaphnia dubia
Cladoceran,
Ceriodaphnia dubia
Cladoceran,
Ceriodaphnia dubia
Midge,
Chironomus tentans
Rainbow trout
Test' Chemical
LC >99%
LC >99%
LC 97%
LC 94%
ELS Technical
Hardness
Chronic
(mg/L as Limits
CaCO,) (ug/LV
FRESHWATER SPECIES
57.1
57.1
52
43.0
50.0
Oncorhynchus mykiss
Brook trout, LC 94% 35.7
Salvelinus fontinalis
•
Fathead minnow, LC 97.1%
Pimephales promelas
Bluegill, LC 94%
2,500-5,000
2,500-5,000
1,200-2,500
110-230
1,100-3,800
65-120
i
250-460
95->95
Chronic Value
3,536
3,536
1,732
159.1
2,045
B j
LJ
339.1
~>95
References
Orisetal. 1991
Orisetal. 1991
Jop 1991b
Maceketal. 1976
Whale et al. 1994
Maceketal. 1976
Dionne 1992
Maceketal. 1976
Lepomis macrochirus
Species
Test" Chemical
Salinity
(g/kg)
Chronic
Limits
(Ug/LV
Chronic Value
References
SALTWATER SPECIES
Copepod,
Eurytemora affinis
Copepod,
Eurytemora affinis
Copepod,
Eurytemora affinis
Mysid,
Americamysis bahia
Sheepshead minnow
Cyprinodon
variegatus
LC 97.1%
LC 97.1%
LC 97.1%
LC 97.4%
ELS 97.4%
5
15
25
20
13
12,250-17,500
17,500-25,000
4,200-6,000
80-190
1,900-3,400
14,640
20,920
5,020
123.3
2,542
Halletal. 1995
Halletal. 1995
Halletal. 1995
Ward and Ballantine 1985
Ward and Ballantine 1985
a LC = Life-cycle or partial life-cycle; ELS = early life-stage.
b Results are based on measured concentrations of atrazine.
69
-------
Table 2b. Acute-Chronic Ratios
Species
Cladoceran,
Ceriodaphnia dubia
Cladoceran,
Ceriodaphnia dubia
Midge,
Chironomus teutons
Brook trout,
Salvelinusfontinalis
Fathead minnow,
Pimephales promelas
Bluegill,
Lepomis macrochirut
Copepod,
Eurytemora affinis
Copepod,
Eurytemora affinis
Copepod,
Eurytemora affinis
Mysid,
Americamysis bahia
Sheepshead minnow,
Cyprinodon
variesatus
Hardness
(ing/L as
CaCO,}
57.1
52
43.0
35.7
24-36
Acute Value
Cue/Ly
>30,000
>4,900
720"
6,300
20,000
Chronic Value
(Ug/L)
3,536
1,732
159.1
88.32
339.1
20C
13C
1,000
>16,000
123.3
2,542
Ratio Reference
>8.484 Orisetal. 1991
>2.829 Jop 1991a,b
4.525
71.33
58.98
Maceketal. 1976
Maceketal. 1976
Dionne 1992
Macek
cetal. 1976
0.0342 Hall et al. 1994a,b; 1995
0.1243 Hall et al. 1994a,b; 1995
2.629
Halletal. 1994a,b; 1995
Ward and Ballantine 1985
>6.294 Ward and Ballantine 1985
a From Table 1.
' From Table 6.
0 Salinity expressed as g/kg.
70
-------
Table 3. Ranked Genus Mean Acute Values with Species Mean Acute-Chronic Ratios
Genus Mean
Acute Value
Rank"
17
Species
FRESHWATER SPECIES
Goldfish,
Carassius auratus
Cladoceran,
Species Mean
Acute Value
(ug/LV
60,000
Species Mean
Acute-Chronic
Ratio'
49,000
Annel
Lumbriculus variegatus
>37,
12
11
10
>20,000
>20,000
20,000
14,700
>13,856
>12,120
>10,000
>10,000
9,767
6,700
6,300
3,000
Brown trout,
Salmo trutta
Physa acuta
Snail,
Physa sp.
Leopard frog,
Rana pipiens
Wood frog,
Rana sylvatica
American toad,
Bufo americanus
Fathead minnow,
Pimephales promelas
Amphipod,
Hyalella azteca
Bluegill,
Lepomis macrochirus
Cladoceran
Ceriodaphnia dubia
Channel catfish,
Ictalums punctatus
Largemouth bass,
Microptems salmoides
Coho salmon,
Oncorhynchus kisutch
Rainbow Trout,
Oncorhynchus mykiss
Stonefly,
Acroneuria sp.
Brook trout,
Salvelinus fontinalis
Hydra,
Hydra sp.
>20,000
>34,100
>20,000
>20,000
>20,000
20,000
14,700
>13, 856
>12,120
>10,000
>10,000
>18,000
5,300
6,700
6,300
3,000
58.98
>84.21
>4.899
71.33
71
-------
Table 3 (continued)
Genus Mean
Acute Value
Rank"
Species
Species Mean
Acute Value
(ug/LV
Species Mean
Acute-Chronic
Ratio1
SALTWATER SPECIES
>30,000 Eastern oyster,
Crassostrea virginica
Fiddler crab,
Uca pugilator
Grass shrimp,
Palaemonetes pugio
Spot,
Leiostomus xanthun
Pink shrimp,
Penaeus duorarum
6,900
>30,000
6,900
4
3
2
1
5,838 Copepod,
Acartia clausii
Copepod,
Acartia tonsa
4,208 Sheepshead minnow,
Cyprinodon variegatus
2,579 Copepod,
Eurytemora affinis
2,324 Mysid,
Americamysis bahia
7,925
4,300
4,208
2,579
2,324
"
-
>6.294
2.629
8.110
a Ranked from most resistant to most sensitive based on Genus Mean Acute Value. Inclusion of "greater than" value does not necessarily imply a
true ranking, but does allow use of all genera for which data are available so that the Final Acute Value is not unnecessarily lowered.
b From Table 1.
0 From Table 2b.
72
-------
Table 3 (continued)
Freshwater
Final Acute Value = 3,021 (ig/L
Criterion Maximum Concentration = (3,021 • g/L)/2 = 1,511 (ig/L
Final Chronic Value = (ecosystem effects - see text)
Saltwater
Final Acute Value = 1,519 (ig/L
Criterion Maximum Concentration = (1,519 (ig/L)/2 = 759.5 (ig/L
Final Chronic Value = 16.83 ^g/L (Final Plant Value - see text)
73
-------
Table 4. Toxicity of Atrazine to Aquatic Plants
Species
Green alga,
Chlamydomonas reinhardtii
Green alga,
Chlamydomonas reinhardtii
Green alga,
Chlamydomonas reinhardtii
Green alga,
Chlamydomonas reinhardtii
Green alga,
Chlamydomonas reinhardti
"*
Green alga,
Chlamydomonas reinhardtii
Green alga,
Chlamydomonas reinhardti,
Green alga,
Selenastrum capricornutum
Green alga,
Selenastrum capricornutum
Green alga,
Selenastrum capricornutum
Green alga,
Selenastrum capricornutum
Green alga,
Selenastrum capricornutum
Green alga,
Selenastrum capricornutum
Green alga,
Selenastrum capricornutum
Green alga,
Selenastrum capricornutum
Green alga,
Selenastrum capricornutum
Green alga,
Selenastrum capricornutum
Green alga,
Selenastrum capricornutum
Hardness
(mg/L as
Chemical CaCO,)
99.1%
97.0%
97.0%
97.0%
Duration
(days)
iSHWAT
4
4
7
10
4
;
10
LJ
4
4
4
4
4
4
4
4
4
4
4
Concentration
Effect (us/L)°
ER SPECIES
EC50 51
(cell number)
EC50 51
(cell number)
EC50 21
(cell number)
EC50 10.2
(cell number)
NOEC ^WB
(growth inhibition)
NOEC ^1
(growth inhibition)
NOEC 1.7
(growth inhibition)
ta. ^M
NOEC 0.5
(cell number, biomass)
NOEC 10
(chlorophyll-a,
phaeophytin-a)
LOEC 1.0
(cell density, biomass)
LOEC 100
(chlorophyll,
phaeophytin-a)
EC50 4
(cell number)
EC50 20
(phaeophytin-a)
EC50 150
(chlorophyll-a)
EC50 128.2
(cell number)
NOEC 76
(cell number)
LOEC 130
(cell number)
EC10 90
(cell number)
Reference
Schaferetal. 1993
Girling et al. 2000
Schaferetal. 1993
Schaferetal. 1993
Schaferetal. 1994
Schaferetal. 1994
Schaferetal. 1994
Univ. of Mississippi
1990
Univ. of Mississippi
1990
Univ. of Mississippi
1990
Univ. of Mississippi
1990
Univ. of Mississippi
1990
Univ. of Mississippi
1990
Univ. of Mississippi
1990
Gala and Giesy
1990
Hoberg 1991a
Hoberg 1991a
Hoberg 1991a
FRESHWATER SPECIES
74
-------
Table 4 (Continued)
Species
Chemical
Hardness
(mg/L as Duration
CaCO,) (days)
Effect
Concentration
(iig/L)"
Reference
Green alga,
Selenastrum capricornutum
Green alga,
Selenastrum capricornutum
Green alga,
Selenastrum capricornutum
Green alga,
Selenastrum capricornutum
Green alga,
Selenastrum capricornutum
Green alga,
Selenastrum capricornutu
Green alga,
Selenastrum capricornutum
Duckweed,
Lemna gibba
Duckweed,
Lemna gibba
Duckweed,
Lemna gibba
Duckweed,
Lemna gibba
Duckweed,
Lemna gibba
Duckweed,
Lemna gibba
Duckweed,
Lemna gibba
Duckweed,
Lemna gibba
Duckweed,
Lemna gibba
Duckweed,
Lemna gibba
Duckweed,
Lemna gibba
97.0%
97.0%
97.1%
97.1%
97.1%
97.1%
97.1%
97.1%
97.1%
97.1%
97.1%
97.1%
97.1%
97.1%
97.1%
14
14
14
14
14
14
14
14
14
EC50
(cell number)
EC90
(cell number)
NOEC
(cell number)
EC10
(cell number)
LOEC
(cell number)
EC50
(cell number)
EC90
(cell number)
EC50
(frond production)
NOEC
(frond number)
LOEC
(frond number)
EC10
(frond number)
NOEC
(frond biomass)
EC10
(frond biomass)
LOEC
(frond biomass)
EC50
(frond number)
EC50
(frond biomass)
EC90
(frond biomass)
EC90
(frond number)
130
190
16
26
31
3.4
6.2
7.7
12
17
37
45
170
220
Hoberg 1991a
Hoberg 1991a
Hoberg 1993a
Hoberg 1993a
Hoberg 1993a
Duckweed,
Lemna gibba
97.4%
14
EC10
(frond number)
FRESHWATER SPECIES
2.2b Hoberg 1993c
75
-------
Table 4 (Continued)
Hardness
Species
Duckweed,
Lemna gibba
Duckweed,
Lemna gibba
Duckweed,
Lemna gibba
Duckweed,
Lemna gibba
Duckweed,^—
Lemna gibba^l
Duckweed,
Lemna gibba 1
Duckweed,
Lemna gibba 1
Duckweed,
Lemna minor
Duckweed,
Lemna minor
Duckweed,
Lemna minor
Duckweed,
Lemna minor
Duckweed,
Lemna minor
Duckweed,
Lemna minor
Duckweed,
Lemna minor
Duckweed,
Lemna minor
Duckweed,
Lemna minor
Elodea,
Elodea canadensis
Elodea,
Elodea canadensis
(mg/L as Duratio
Chemical CaCO,) (days)
97.4% - 14
97.4% - 14
97.4% - 14
97.4% - 14
97.4% —g^^ 14
97.4% - J 14
97.4% 14
- ktJ
14
14
14
98% - 10
98% - 10
98% - 10
28
28
10
10
m
Effect
EC10
(frond biomass)
NOEC
(frond number &
biomass)
LOEC
(frond number &
biomass)
LOEC
(frond biomass)
EC50
(frond number)
EC90
(frond number)
EC90
(frond biomass)
^bNOEfiJ
(biomass)
LOEC
(mature frond
production)
LOEC
(biomass)
EC50
(biomass)
EC50
(frond number)
EC50
(fresh weight)
EC50
(chlorophyll)
NOEC (growth)
LOEC (growth)
NOEC
(biomass)
LOEC
(biomass)
Concentration
Qtg/L)° Reference
4.2"
8.3b
18b
22"
^Ob
r
110b
10
10
100
8,700
56
60
62
38
120
10C
100C
Hoberg 1993c
Hoberg 1993c
Hoberg 1993c
Hoberg 1993c
Hoberg 1993c
Hoberg 1993c
Hoberg 1993c
Univ. of
Mississippi 1990
Univ. of
Mississippi 1990
Univ. of
Mississippi 1990
Univ. of
Mississippi 1990
Kirby and Sheahan
1994
Kirby and Sheahan
1994
Kirby and Sheahan
1994
Girling et al. 2000
Girling et al. 2000
Univ. of
Mississippi 1990
Univ. of
Mississippi 1990
FRESHWATER SPECIES
76
-------
Table 4 (Continued)
Species
Chemical
Hardness
(mg/L as Duration
CaCO,) (days)
Effect
Concentration
(iig/L)"
Reference
Elodea,
Elodea canadensis
Elodea,
Elodea canadensis
Elodea,
Elodea canadensis
Elodea,
Elodea canadensis
Elodea,
Elodea canadensis
10
10
10
10
i^ioaea canaaensis
Elodea,
Elodea canadensis
I tm
Salinity 1
Species Chemical (g/kg)
LOEC
(mature frond
production)
EC50
(biomass)
LOEC
(biomass)
EC50
(biomass)
10C Univ. of
Mississippi 1990
20 NOEC (length)
20
Duration
(days) Effect
SALTWATER SPECIES
1,200C
100d
25,400d
20
Univ. of
Mississippi 1990
Univ. of
Mississippi 1990
Univ. of
Mississippi 1990
Girling et al. 2000
Concentration
g/L)° Reference
Diatom,
Skeletonema costatum
Green alga, 99.7%
Chlorella sp.
Green alga, 99.7%
Neochloris sp.
Green alga, 99.7%
Platymonas sp.
Red alga, 99.7%
Porphyridium cruentum
Redheadgrass pondweed, 96.4%
Potamogeton perfoliatus
Redheadgrass pondweed, 96.4%
Potamogeton perfoliatus
Sago pondweed, 97.1%
Potamogeton pectinatus
Sago pondweed, 97.1%
Potamogeton pectinatus
30
30
30
30
30
28
35
28
28
EC50
(growth)
EC50
(growth)
EC50
(growth)
EC50
(growth)
EC50
(growth)
IC50 (photosynthesis)
IC50
(final biomass)
NOEC
(dry weight)
NOEC
(wet weight)
265
140
82
100
79
55
30
15
15
Walsh 1983
Mayer 1987
Mayer 1987
Mayer 1987
Mayer 1987
Kempetal. 1982b,
1983; Kemp et al.
1985
Kemp et al. 1982b,
1983; Kemp et al.
1985
Hall et al. 1997
Hall et al. 1997
SALTWATER SPECIES
77
-------
Table 4 (Continued)
Species
Salinity Duration
Chemical (g/kg) (days) Effect
Concentration
(iig/L)° Reference
Sago pondweed, 97.1%
Potamogeton pectinatus
Sago pondweed, 97.1%
Potamogeton pectinatus
Sago pondweed, 97.1%
Potamogeton pectinatus
Sago pondweed, 97.1%
Potamogeton pectinatus
Sago pondweed, 97.1%
Potamogeton pectinatus
Sago pondweed,
Potamogeton pectinatus
Sago pondweed,
Potamogeton pectinatus
Sago pondweed,
Potamogeton pectinatus
Sago pondweed,
Potamogeton pectinatus
Sago pondweed, 97.1%
Potamogeton pectinatus
Sago pondweed, 97.1%
Potamogeton pectinatus
Sago pondweed, 97.1%
Potamogeton pectinatus
Sago pondweed, 97.1%
Potamogeton pectinatus
Sago pondweed, 97.1%
Potamogeton pectinatus
Sago pondweed, 97.1%
Potamogeton pectinatus
Sago pondweed, 97.1%
Potamogeton pectinatus
Sago pondweed, 97.1%
Potamogeton pectinatus
Sago pondweed, 97.1%
Potamogeton pectinatus
Sago pondweed, 97.1%
Potamogeton pectinatus
12
12
12
28
28
28
28
NOEC
(rhizome tip mass)
LOEC
(dry weight)
LOEC
(wet weight)
LOEC
(rhizome tip mass)
28 Chronic value
(dry weight)
28 Chronic value
(wet weight)
28 Chronic value
(rhizome tip mass)
NOEC
(dry weight
28
28
28
28
28
28
28
28
28
28
28 NOEC
(wet weight)
NOEC
(rhizome tip
mass)
LOEC
(dry weight)
LOEC
(wet weight)
LOEC
(rhizome tip mass)
Chronic value
(dry weight)
Chronic value
(wet weight)
Chronic value
(rhizome tip mass)
NOEC
(dry weight)
NOEC
(wet weight)
NOEC
(rhizome tip mass)
30
30
30
300
21.2
30
30
30
300
21.2
21.2
94.9
7.5
15
30
Hall et al. 1997
Hall et al. 1997
Hall et al. 1997
Hall et al. 1997
Hall et al. 1997
Hall et al. 1997
Hall et al. 1997
11 et al.
Hall et al. 1997
Hall et al. 1997
Hall et al. 1997
Hall et al. 1997
Hall et al. 1997
Hall et al. 1997
Hall et al. 1997
Hall et al. 1997
Hall et al. 1997
Hall et al. 1997
Hall et al. 1997
Hall et al. 1997
SALTWATER SPECIES
78
-------
Table 4 (Continued)
Species
Salinity Duration
Chemical (g/kg) (days) Effect
Concentration
(ug/L)° Reference
Sago pondweed, 97.1% 12
Potamogeton pectinatus
Sago pondweed, 97.1% 12
Potamogeton pectinatus
Sago pondweed, 97.1% 12
Potamogeton pectinatus
Sago pondweed, 97.1% 12
Potamogeton pectinatus
Sago pondweed, 97.1% 12
Potamogeton pectinatus
Sago pondweed,
Potamogeton pectinatus
Sago pondweed,
Potamogeton pectinatus
Eurasian water milfoil,
Myriophyllum spicatum
Eurasian water milfoil, 96.4%
Myriophyllum spicatum
Wild celery, - 3 & 6
Vallisneria americana
Wild celery, - 3 & 6
Vallisneria americana
Wild celery, - 5
Vallisneria americana
Wild celery, - 5
Vallisneria americana
Eelgrass, - 22
Zostera marina
Eelgrass, - 20
Zostera marina
Eelgrass, - 20
Zostera marina
Eelgrass, - 19
Zostera marina
28
28
28
28
28
28
LOEC
(dry weight)
LOEC
(wet weight)
LOEC
(rhizome tip mass)
Chronic value
(dry weight)
Chronic value
(wet weight)
Chronic value
(rhizome tip mass)
Chronic value
(dry weight)
35
IC50 (photosynthesis)
IC50
(final biomass)
42 NOEC (dry weight)
42 LOEC (dry weight)
42 NOEC (leaf area)
42 LOEC (leaf area)
21 LC50
21 LC50
21 LC50
21 LC50
15
30
300
10.6
21.2
T
117
25
100
320
3.2
12
540
100
365
367
Hall et al. 1997
Hall et al. 1997
Hall et al. 1997
Hall et al. 1997
Hall et al. 1997
Hall et al. 1997
Hall et al. 1997
11 et al. :
Kemp et al. 1982b,
1983; Kemp et al.
1985
Kemp et al. 1982b,
1983; Kemp et al.
1985
Forney and Davis
1981
Forney and Davis
1981
Correll and Wu
1982
Correll and Wu
1982
Delistraty and
Hershner 1984
Delistraty and
Hershner, 1984
Delistraty and
Hershner, 1984
Delistraty and
Hershner. 1984
a Effect concentrations are based upon measured concentrations of atrazine during the exposure period.
b Effect concentration is based upon measured concentration of atrazine on the last day of exposure only.
0 No sediment present.
d Sediment present.
79
-------
Table 5. Bioaccumulation of Atrazine by Aquatic Organisms
Species
Hardness Concentration
(mg/L as in Water Duration
Chemical (CaCo,) (ug/L) (days) Tissue
FRESHWATER SPECIES
BCF
or
BAF Reference
Brook trout,
Salvelinus fontinalis
94% 35.7
740
308 Muscle
<0.27 Maceketal. 1976
Bluegill,
Lepomis macrochims
Fathead minnow,
Pimephales promelas
Fathead minnow
(F0 larvae),
Pimphales promelas
Fathead minnow
(adult males),
Pimephales promelas
Fathead minnow
(adult females),
Pimephales promelas
Fathead minnow
(Fj embryos),
Pimephales promelas
Fathead minnow
(14-day old larvae),
Pimephales promelas
Fathead minnow
(30-day old larvae),
Pimephales promelas
94%
97.1%
97.1% 24-36
97.1% 24-36
97.1% 24-36
97.1% 24-36
97.1% 24-36
2,000
2,000
2,000
2,000
2,000
3 Whole body
composite
sample
14 Whole body
<2.1 Maceketal.
1 Macek et al.
6.5" Dionne 1992
274 Whole body 8.5" Dionne 1992
274 Whole body 8.5" Dionne 1992
4.6" Dionne 1992
Dionne 1992
30 Whole body 6.0" Dionne 1992
" Based on 14C measurements, and therefore, represents a maximum possible bioconcentration factor.
80
-------
Table 6. Other Data on Effects of Atrazine on Aquatic Organisms
Species
Hardness
(ing/L as
Chemical CaCO,) Duration
Effect
Concentration
(ug/L)
Reference
FRESHWATER SPECIES
Mixed nitrifying
bacteria
Mixed nitrifying
bacteria
Bacterium,
Pseudomonas putida
Cyanobacterium,
Anabaena cylindrica
Cyanobacterium,
Anabaena cylindrica
Cyanobacterium,
Anabaena cylindrica
Cyanobacterium,
Anabaena cylindrica
Cyanobacterium,
Anabaena cylindrica
Cyanobacterium,
Anabaena cylindrica
Cyanobacterium,
Anabaena cylindrica
Cyanobacterium,
Anabaena flos-aquae
Cyanobacterium,
Anabaena flos-aquae
Cyanobacterium,
Anabaena flos-aquae
Cyanobacterium,
Anabaena flos-aquae
Cyanobacterium,
y4«afeae«a/Zo,s-a<7wae
Cyanobacterium,
Anabaena flos-aquae
28 days
28 days
214 16 hr
14 days
19 hr
Ihr
>95% - 12-14 days
24 hr
24 hr
24 hr
97% - 5 days
97% - 5 day
exposure,
9 day
recovery
97% - 5 day
exposure,
9 day
recovery
97% - 5 day
exposure,
9 day
recovery
99.9% - 1 day
99.9% - 3 days
Increased
nitrite
oxidation; ammonium
oxidation
unaffected
Ammonium
oxidation
unaffected
Incipient
inhibition
LOEC
(growth)
LOEC
(nitrogenase activity)
LOEC
(O2 production)
EC50
(cell number)
EC50
(14C uptake)
EC50
(14C uptake)
EC50
(14C uptake)
EC50
(cell number)
NOEC
(cell number)
Algistatic concentration
Algicidal
concentration
56.2% reduction
in 14C uptake
50.0% reduction
in 14C uptake
1,000
2,000
>10,000
2,160
2,160
21,600
1,200
253"
178"
182b
230
<100
4,970
>3,200
40
40
Gadkari 1988
Gadkari 1988
Bringmann and Kuhn
1976, 1977
Rohwer and Fluckiger
1979
Rohwer and Fluckiger
1979
Rohwer and Fluckiger
1979
Station 1984
Larsen et al. 1986
Larsen et al. 1986
Larsen et al. 1986
Hughes 1986; Hughes et
al. 1986, 1988
Hughes 1986; Hughes et
al. 1986, 1988
Hughes 1986; Hughes et
al. 1986, 1988
Hughes 1986; Hughes et
al. 1986, 1988
Abou-Waly et al. 1991a
Abou-Waly et al. 1991a
81
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,) Duration
Effect
FRESHWATER SPECIES
Cyanobacterium,
Anabaena flos-aquae
Cyanobacterium,
Anabaena flos-aquae
Cyanobacterium,
Anabaena flos-aquae
Cyanobacterium,
Anabaena flos-aquae
Cyanobacterium,
Anabaena flos-aquae
Cyanobacterium,
^nafeaena/Zos-aguae
Cyanobacterium,
Anabaena flos-aquae
Cyanobacterium,
^4«afeae«a/Zo«-a(jMae
Cyanobacterium,
y4«afeae«a/Zo,s-a<7wae
Cyanobacterium,
Anabaena inaequalis
Cyanobacterium,
Anabaena inaequalis
Cyanobacterium,
Anabaena variabilis
Cyanobacterium,
^pAarazomenon
/Zos-agwae
Cyanobacterium,
Microcystis aeruginosa
Cyanobacterium,
Microcystis aeruginosa
Cyanobacterium,
Microcystis aeruginosa
Cyanobacterium,
Microcystis aeruginosa
Cyanobacterium,
Microcystis aeruginosa
99.9% - 5 days
99.9% - 1 day
99.9% - 3 days
99.9% - 5 days
99.9% - 7 days
99.9% - 3 days
99.9% - 5 days
99.9% - 7 days
92.2% - 4 days
>95% - 12-14 days
Technical - 22 hr
or
analytical
>95% - 12-14 days
Technical - 22 hr
or
analytical
214 8 days
97.4% - 5 days
97.4% - 5 days
6 days
6 days
9. 5% reduction
in 14C uptake
49.0% reduction
in chlorophyll
2.0% reduction
in chlorophyll
2 1.8% reduction
in chlorophyll
29.9% reduction
in chlorophyll
EC50
(chlorophyll-a)
EC50
(chlorophyll-a)
EC50
(chlorophyll-a)
EC50
(chlorophyll-a)
EC50
(cell number)
65% inhibition of
photosynthesis
(14C uptake)
EC50
(cell number)
97% inhibition of
photosynthesis
(14C uptake)
Incipient
inhibition
Reduced cell
numbers
Minimum algistatic c
centration
EC50
(growth)
EC50
(microplate method)
Concentration
Reference
40
100
100
100
100
58
469
766
2,667
4,000
2,667
108
Abou-Waly et al. 1991a
Abou-Waly et al. 1991a
Abou-Waly et al. 1991a
Abou-Waly et al. 1991a
Abou-Waly et al. 1991a
Abou-Waly et al. 1991b
Abou-Waly et al. 1991b
Abou-Waly et al. 1991b
>3,000 Fairchild et al. 1998
30 Station 1984
Peterson et al. 1994
Station 1984
Peterson el al. 1994
3 Bringmann and Kuhn
1976, 1978a,b
Parrish 1978
440 Parrish 1978
630 Kallqvisl and Romslad
1994
630 Kallqvisl and Romslad
1994
82
-------
Table 6 (Continued)
Species
Chemical
Hardness
(mg/L as
CaCO,) Duration
Effect
FRESHWATER SPECIES
Cyanobacterium,
Microcystis aeruginosa
Cyanobacterium,
Microcystis aeruginosa
Cyanobacterium,
Microcystis sp.
Cyanobacterium,
Oscillatoria cf. chalybea
Cyanobacterium,
Oscillatoria cf. chalybea
Cyanobacterium,
Oscillatoria sp.
Cyanobacterium,
Plectonema boryanum
Cyanobacterium,
Pseudoanabaena sp.
Cyanobacterium,
Synechococcus leopolensis
Cyanobacterium,
Synechococcus leopolensis
Green alga,
Ankistrodesmus braunii
Green alga,
Ankistrodesmus sp.
Green alga,
Ankistrodesmus sp.
Green alga,
Chlamydomonas geitleri
Ettl
Green alga,
Chlamydomonas geitleri
Ettl
Green alga,
Chlamydomonas moewssi
Technical
or
analytical
Technical
or
analytical
Technical
or
analytical
99.7%
99.7%
Technical
or
analytical
-
Technical
or
analytical
-
-
99.9%
-
-
96.4%
96.4%
95%
22 hr
22 hr
4 days
6 days
5 days
22 hr
31 days
22 hr
5 days
5 days
1 1 days
24 hr
24 hr
Ihr
Ihr
14 days
96% inhibition of
photosynthesis
(14C uptake)
84% inhibition of
photosynthesis
(" C uptake)
EC50
(biomass)
Lowest complete
inhibition cone.
LOEC
(growth)
87% inhibition of
photosynthesis
(14C uptake)
69% decrease
in cell number
91% inhibition of
photosynthesis
(14C uptake)
EC50
(growth)
EC50
(microplate method)
EC50
(cell number)
EC50
(14C uptake)
EC50
(14C uptake)
EC50
(CO2 fixation)
EC50
(CO2 fixation)
EC50
(growth inhibition)
Concentration
Reference
2,667 Peterson etal. 1994
2,667 Peterson etal. 1994
90
2160
220
Fairchild et al. 1998
Schrader et al. 1997
Schrader at al 1998
2,667 Peterson etal. 1994
10,000 Mallison and Cannon
1984
2,667 Peterson etal. 1994
130 Kallqvist and Romstad
1994
130 Kallqvist and Romstad
1994
60 Burrell et al. 1985
72° Larsen et al. 1986
61° Larsen etal. 1986
311 Francois and Robinson
1990
194° Francois and Robinson
1990
1384 Kotrikla etal. 1997
(exponential
growth phase)
83
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,)
Duration
Effect
Concentration
Reference
FRESHWATER SPECIES
Green alga, 95%
Chlamydomonas moewssi
Green alga,
Chlamydomonas
noctigama
Green alga,
Chlamydomonas
reinhardtii
Green alga,
Chlamydomonas
reinhardtii
Green alga,
Chlamydomonas
reinhardtii
Green alga,
Chlamydomonas
reinhardtii
Green alga,
Chlamydomonas
reinhardtii
Green alga,
Chlamydomonas
reinhardtii
Green alga,
Chlamydomonas
reinhardtii*
Green alga,
Chlamydomonas
reinhardtii'
Green alga, 94%
Chlamydononas
reinhardtii^
Green alga, 94%
Chlamydomonas
reinhardtii'
Green alga,
Chlamydomonas
reinhardtii
Green alga, 92.2%
Chlamydomonas
reinhardtii
14 days
72 hr
8hr
8hr
8hr
24 hr
24 hr
24 hr
1-2 days
1-2 days
2 min
2 min
65 hr
96 hr
EC50
(growth inhibition)
EC50
(growth)
• 32% inhibition
of photosynthesis
• f 4% inhibition
of photosynthesis
• 97% inhibition
of photosynthesis
EC50
(14C uptake)
EC50
(14C uptake)
EC50
(14C uptake)
Growth rate
reduced by 100%
Growth rate
reduced by 13%
EC50
(photosynthetic oxygen
evolution)
EC50
(photosynthetic oxygen
evolution)
13% reduction in
chlorophyll
EC50
(chlorophyll)
1181 Kotriklaetal. 1997
(stationary
growth phase)
330 Kallqvist and Romstad
1994
10 Valentine and Bingham
1976
100 Valentine and Bingham
1976
1,000 Valentine and Bingham
1976
48" Larsen et al. 1986
19" Larsen et al. 1986
44° Larsen et al. 1986
216 Hersh and Crumpton
1987
21.6 Hersh and Crumpton
1987
45 Hersh and Crumpton
1989
484 Hersh and Crumpton
1989
49.6 Hiranpradit and Foy 1992
176 Fairchild et al. 1998
84
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,)
Duration
Effect
FRESHWATER SPECIES
Concentration
Reference
Green alga,
Chlamydomonas sp.
Green alga,
Chlamydomonas sp.
Green alga,
Chlamydomonas sp.
Green alga,
Chlamydomonas sp.
Green alga,
Chlamydomonas sp.
Green alga,
Chlamydomonas sp.
Green alga,
Chlorella fusca
Green alga,
Chlorella fusca
Green alga,
Chlorella fusca
Green alga,
Chlorella fusca
Green alga,
Chlorella fusca
Green alga,
Chlorella fusca
Green alga,
Chlorella kessleri
99%
99%
99%
95%
95%
72-96 hr 36.2%f and 84.9%8
growth inhibition;
12.8% reduction in
chlorophyll
72-96 hr 64.l%f and 93.3%8
growth inhibition;
32.4% reduction in
chlorophyll
72-96 hr 77.5%f and 96.6%8
growth inhibition;
49.9% reduction in
chlorophyll
72-96 hr 76.6%f and 100%8
growth inhibition;
84.2% reduction in
chlorophyll
72-96 hr 78.6% growth
inhibition1; 90.5%
reduction in
chlorophyll
4 days EC50
(biomass)
15min EC50
(photosynthesis)
14 hr EC50
(cell volume growth)
24 hr EC50
(cell reproduction)
24 hr EC50
(cell number)
14 days EC50
(growth inhibition)
14 days EC50
(growth inhibition)
72 hr 30% growth inhibition
and photosynthetic O2
evolution; 6.7%
reduction in protein
synthesis; effects upon
lipids
50-52 Foy and Hiranpradit 1977
100-104 Foy and Hiranpradit 1977
200-208 Foy and Hiranpradit 1977
400-416 Foy and Hiranpradit 1977
832 Foy and Hiranpradit 1977
176 Fairchild et al. 1994a
141 Altenburger et al. 1990
36 Altenburger etal. 1990
26 Altenburger etal. 1990
15 Faust etal. 1993
53.91 Kotrikla etal. 1997
(exponential
growth phase)
75.73 Kotrikla etal. 1997
(stationary
growth phase)
1,078 El-Sheekh etal. 1994
85
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,
Concentration
Duration
Effect
Reference
FRESHWATER SPECIES
Green alga,
Chlorella pyrenoidosa
Green alga,
Chlorella pyrenoidosa
Green alga,
Chlorella pyrenoidosa
Green alga,
Chlorella pyrenoidosa
Green alga,
Chlorella pyrenoidosa
Green alga, >95%
Chlorella pyrenoidosa
Green alga,
Chlorella pyrenoidosa
Green alga,
Chlorella pyrenoidosa
Green alga,
Chlorella pyrenoidosa
Green alga, Analytical
Chlorella pyrenoidosa
Green alga, Analytical
Chlorella pyrenoidosa
Green alga,
Chlorella vulgaris
Green alga,
Chlorella vulgaris
Green alga,
Chlorella vulgaris
Green alga,
Chlorella vulgaris
Green alga,
Chlorella vulgaris
Green alga,
Chlorella vulgaris
2wk
2wk
2wk
8hr
8hr
12-14
10 days
10 days
HOhr
<50 min
<50 min
7 days
7 days
7 days
7 days
24 hr
24 hr
70% reduced
growth
95% reduced
growth
92% reduced
growth
• 64% inhibition
of photosynthesis
• 96% inhibition of
photosynthesis
EC50
(cell number)
30% growth
inhibition; 40%
reduction in
chlorophyll-a
65% growth
inhibition; 70%
reduction in
chlorophyll-a
39% reduction
in chlorophyll
>80% inhibition of
photosynthetic CO2
uptake
100% inhibition of
photosynthetic CO2
uptake
31.0% reduction in dry
wt.
43.6% reduction in dry
wt.
56.4% reduction in dry
wt.
61.8% reduction in dry
wt.
EC50
(14C uptake)
EC50
(14C uptake)
500
2,500
10,000
100
1,000
300
53.9
107.8
49.6
125
1,250
250h
500h
2,500h
5,000h
325'
305"
Virmani et al. 1975
Virmani et al. 1975
Virmani et al. 1975
Valentine and Bingham
1976
Valentine and Bingham
1976
Station 1984
Gonzalez-Murua et al.
1985
Gonzalez-Murua et al.
1985
Hiranpradit and Foy 1992
Hannan 1995
Hannan 1995
Veberetal. 1981
Veberetal. 1981
Veberetal. 1981
Veberetal. 1981
Larsen et al. 1986
Larsen et al. 1986
86
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,
Concentration
Duration
Effect
Reference
FRESHWATER SPECIES
Green alga,
Chlorella vulgaris
Green alga,
Chlorella vulgaris
Green alga,
Chlorella vulgaris
Green alga,
Chlorella vulgaris
Green alga,
Chlorella vulgaris
Green alga,
Chlorella sp.
Green alga,
Chlorella sp.
Green alga,
Chlorella sp.
Green alga,
Chlorella sp.
Green alga,
Chlorella sp.
Green alga,
Chlorella sp.
Green alga,
Chlorella sp.
Green alga,
Chlorella sp.
Green alga,
Chlorella sp.e
24 hr
30 min
92.2% - 96 hr
98% - 12 days
98% - 96 hr
72-96 hr
72-96 hr
72-96 hr
72-96 hr
72-96 hr
1-2 days
2-3 days
94% - 2 min
94% - 2 min
EC50
(14C uptake)
EC50
(Decrease in oxygen
evolution)
EC50
(chlorophyll)
Reduced growth, but
showed signs of
recovery
EC50
3 1.0% growth
inhibition1;
38. 8% reduction in
chlorophyll
45.3% growth
inhibition1;
30.3% reduction in
chlorophyll
52.3% growth
inhibition1;
83. 7% reduction in
chlorophyll
59.2% growth
inhibition1;
93.5% reduction in
chlorophyll
53.7% growth
inhibition1;
95. 4% reduction in
chlorophyll
Growth rate
reduced by 86%
Growth rate
reduced by 55%
EC50
(photosynthetic oxygen
evolution)
EC50
(photosynthetic oxygen
293b
305
94
10
172
52
104
208
416
832
216
21.6
36
41
Larsen et al. 1986
Van der Heever and
Grobbelaar 1997
Fairchild et al. 1998
Berard et al 1999
Seguin et al 2000
Foy and
Hiranpradit 1977
Foy and Hiranpradit 1977
Foy and
Hiranpradit 1977
Foy and
Hiranpradit 1977
Foy and
Hiranpradit 1977
Hersh and
Crumpton 1987
Hersh and Crumpton
1987
Hersh and Crumpton
1989
Hersh and Crumpton
1989
evolution)
87
-------
Table 6 (Continued)
Species
Green alga,
Clorella sp.e
Green alga,
Chlorella sp.
Green alga,
Chlorococcum
hypnosporum
Green alga,
Chlorococcum
hypnosporum
Green alga,
Franceia sp.f
Green alga,
Franceia sp.
Green alga,
Franceia sp.
Green alga,
Franceia sp.
Green alga,
Franceia sp.
Green alga,
Gloetaenium
loitlesbergarianum
Green alga,
P seudokirchnierella
subcapitata
Green alga,
Scenedesmus acutus
Green alga,
Scenedesmus obliquus
Green alga,
Scenedesmus obliquus
Green alga,
Scenedesmus obliquus
Hardness
(ing/L as
Chemical CaCO,l
Duration
Effect
Concentration
(ug/L)
Reference
FRESHWATER SPECIES
94%
_
-
94%
94%
94%
94%
94%
_
98%
98%
_
.
2 min
4 days
2wk
2wk
2 min
2 min
2 min
2 min
2 min
96 hr
96 hr
96 hr
24 hr
24 hr
24 hr
EC50
(photosynthetic oxygen
evolution)
EC50
(biomass)
75% reduced growth
92% reduced
growth
EC50
(photosynthetic oxygen
evolution)
EC50
(photosynthetic oxygen
evolution)
EC50
(photosynthetic oxygen
evolution)
EC50
(photosynthetic oxygen
evolution)
EC50
(photosynthetic oxygen
evolution)
inhibition
of calcification
EC50
EC50
EC50
(14C uptake)
EC50
(14C uptake)
EC50
(14C uptake)
35
92
5,000
10,000
466
774
710
430
720
2,157
118
45
38
57
49
Hersh and Crumpton
1989
Fairchild et al. 1994a
Virmani et al. 1975
Vermanietal. 1975
Hersh and Crumpton
1989
Hersh and Crumpton
1989
Hersh and Crumpton
1989
Hersh and Crumpton
1989
Hersh and Crumpton
1989
Prasad and Chowdary
1981
Seguinetal. 2001
Seguinetal. 2001
Larsen et al. 1986
Larsen et al. 1986
Larsen et al. 1986
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,)
Concentration
Duration
Effect
Reference
Green alga,
Scenedesmus quadricauda
Green alga,
Scenedesmus quadricauda
Green alga,
Scenedesmus quadricauda
Green alga,
Scenedesmus quadricauda
Green alga,
Scenedesmus quadricauda
Green alga,
Scenedesmus quadricauda
Green alga,
Scenedesmus quadricauda
Green alga,
Scenedesmus quadricauda
Green alga,
Scenedesmus quadricauda
Green alga,
Scenedesmus quadricauda
Green alga,
Scenedesmus quadricauda
Green alga,
Scenedesmus quadricauda
Green alga,
Scenedesmus subspicatus
Green alga,
Scenedesmus subspicatus
Green alga,
Scenedesmus subspicatus
Green alga,
Scenedesmus subspicatus
Green alga,
Scenedesmus subspicatus
FRESHWATER SPECIES
8hr
8hr
8hr
214 8 days
>95% - 12-14 days
8 days
8 days
8 days
8 days
8 days
Technical - 22 hr
or
analytical
92.2% - 96 hr
99.0% - 4 days
• 42% inhibition
of photosynthesis
• 84% inhibition
of photosynthesis
• 98% inhibition
of photosynthesis
Incipient
inhibition
EC50
(cell number)
4.5% reduction in
photosynthesis
9.9% reduction in
photosynthesis
18.5% reduction in
photosynthesis
68. 1% reduction in
photosynthesis
99.3% reduction in
photosynthesis
96% inhibition of
photosynthesis
(14C uptake)
EC50
(chlorophyll)
EC50
(cell number)
10
100
1,000
30
100
4
9
30
100
337
2,667
169
110
Valentine and Bingham
1976
Valentine and Bingham
1976
Valentine and Bingham
1976
Bringmann and Kuhn
1977, 1978a,b
Station 1984
Bogackaetal. 1990
Bogackaetal. 1990
Bogackaelal. 1990
Bogackaelal. 1990
Bogackaelal. 1990
Peterson el al. 1994
Fairchild el al. 1998
Geyerelal. 1985
24 hr 24.8% inhibition of
effective photosynthesis
rate
24 hr 57.4% inhibition of
effective photosynthesis
rate
24 hr 93.4% inhibition of
effective photosynthesis
rate
24 hr 100.0% inhibition of
effective photosynthesis
rate
12.3 Schafer etal. 1994
37 Schafer etal. 1994
111.1 Schafer etal. 1994
333.3 Schafer etal. 1994
89
-------
Table 6 (Continued)
Species
Hardness
(mg/L as
Chemical CaCO,)
Duration
Effect
Concentration
Reference
FRESHWATER SPECIES
Green alga, 98%
Scenedesmus subspicatus
Green alga,
Scenedesmus subspicatus
Green alga,
Scenedesmus subspicatus
Green alga,
Scenedesmus subspicatus
Green alga, 99%
Scenedesmus subspicatus
Green alga,
Scenedesmus sp.
Green alga,
Scenedesmus sp.
Green alga,
Scenedesmus sp.
Green alga,
Scenedesmus sp.
Green alga,
Scenedesmus sp.
Green alga,
Scenedesmus sp.
Green alga, 97.4%
Selenastrum
capricornutum
Green alga, 97.4%
Selenastrum
capricornutum
Green alga, 97.4%
Selenastrum
capricornutum
Green alga, 97.4%
Selenastrum
capricornutum
Green alga, 97.4%
Selenastrum
capricornutum
2 days EC50
(cell numbers)
24 hr 50% reduction in dry
mass
24 hr EC50
(net assimilation
inhibition)
72 hr EC50
(growth inhibition)
60 days NOEC
(growth and
photosynthetic oxygen
evolution)
72-96 hr 60.2% growth
inhibition8
72-96 hr 72.4% growth
inhibition8
72-96 hr 81.6% growth
inhibition8
72-96 hr 84.7% growth
inhibition8
72-96 hr 83.7% growth
inhibition8
4 days EC50
(biomass)
5 days Significantly reduced
cell numbers
5 days Minimum algistatic
concentration
5 days 12% chlorophyll-a
reduction
5 days 42% chlorophyll-a
reduction
5 days 76% chlorophyll-a
reduction
21
Kirby and Sheahan 1994
•21.5 Reinoldetal. 1994
25 Zagorc-Koncan 1996
200 Zagorc-Koncan 1996
20 Behraetal. 1999
50 Foy and Hiranpradit 1977
100 Foy and Hiranpradit 1977
200 Foy and Hiranpradit 1977
400 Foy and Hiranpradit 1977
800 Foy and Hiranpradit 1977
169 Fairchild et al. 1994a
54 Parrish 1978
200 Parrish 1978
32 Parrish 1978
54 Parrish 1978
90 Parrish 1978
90
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,) Duration
Effect
FRESHWATER SPECIES
Concentration
Reference
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
97.4%
97.4%
85.5%
85.5%
85.5%
5 days 92% chlorophyll-a
reduction
5 days 96% chlorophyll-a
reduction
47
47
47
7 days
7 days
7 days
24 hr
24 hr
24 hr
21 days
21 days
24 hr
24 hr
5 days
5 days
13.8% increased
biomass
36.2% decreased
biomass
75.9% decreased
biomass
EC50
(14C uptake)
EC50
(14C uptake)
EC50
(14C uptake)
EC50
(biomass)
EC50
(biomass)
EC50
(02 evolution)
EC50
(02 evolution)
EC50
(cell number)
EC50
(cell number)
150 Parrish 1978
200 Parrish 1978
100' Johnson 1986
1,000' Johnson 1986
1,000" Johnson 1986
53" Larsen et al. 1986
34" Larsen et al. 1986
42b Larsen et al. 1986
58.7" Turbaketal. 1986
410b Turbaketal. 1986
69.7k Turbaketal. 1986
854' Turbak et al. 1986
100 Roberts etal. 1990
95 Roberts etal. 1990
91
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,) Duration
Concentration
Effect
Reference
FRESHWATER SPECIES
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum capric-
ornutum
Green alga,
Selenastrum capric-
ornutum
Green alga,
Selenastrum capric-
ornutum
Green alga,
Selenastrum
capricornutum
Reagent 171 30 min
grade
Reagent 171 30 min
grade
Reagent 171 4 days
grade
99.9% - 1 day
99.9% - 3 days
99.9% - 5 days
99.9% - 7 days
99.9% - 3 days
99.9% - 5 days
99.9% - 7 days
92.2% - 4 days
72 hr
72 hr
Technical - 22 hr
or
analytical
EC50
(CO2 fixation)
EC50
(O2 generation)
EC50
(cell number)
22.0% reduction in
chlorophyll; 69.3%
reduction in 14C uptake
53.2% reduction in
chlorophyll; 42.4%
reduction in 14C uptake
24.5% reduction in
chlorophyll; 60.6%
reduction in 14C uptake
1 1.6% reduction in
chlorophyll; 3 1.5%
reduction in 14C uptake
EC50
(chlorophyll-a)
EC50
(chlorophyll-a)
EC50
(chlorophyll-a)
EC50
(chlorophyll)
EC50
(growth)
EC50
(growth)
99% inhibition of
photosynthesis
(14C uptake)
100 Versteeg 1990
380 Versteeg 1990
50 Versteeg 1990
130 Abou-Waly et al. 1991a
130 Abou-Waly et al. 1991a
130 Abou-Waly et al. 1991a
130 Abou-Waly et al. 1991a
283 Abou-Waly et al. 1991b
218 Abou-Waly et al. 1991b
214 Abou-Waly et al. 1991b
117 Fairchild et al. 1994a,
1998
200 Kallqvist and Romstad
1994
110 Kallqvist and Romstad
1994
2,667 Peterson etal. 1994
92
-------
Table 6 (Continued)
Hardness
(ing/L as
Chemical CaCO,) Duration
Effect
FRESHWATER SPECIES
Concentration
Reference
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
100 96 hr EC50
(chlorophyll-a)
72 hr EC50
72 hr EC50
(cell numbers)
72 hr EC50
(chlorophyll-a;
spectrophotometric
measurement)
72 hr EC50
(chlorophyll-a;
fluorometric
measurement)
96 hr EC50
(cell number;
free culture)
96 hr EC50
(cell number;
immobilized culture)
96 hr LC50
96 hr EC50
(cell numbers)
30 min EC50
(decrease in oxygen
evolution)
72 hr EC50
(growth inhibition)
72 hr EC50
(growth inhibition)
4 days 150
(chlorophyll-a)
147
118.2
222
164.3
Gaggietal. 1995
Radetski et al. 1995
359 Van der Heever and
Grobbelaar 1996
902 Van der Heever and
Grobbelaar 1996
960 Van der Heever and
Grobbelaar 1996
200 Abdel-Hamid 1996
220 Abdel-Hamid 1996
26 Cauxetal. 1996
26 Cauxetal. 1996
Van der Heever and
Grobbelaar 1997
Benhra et al. 1997
92.9 Benhra et al. 1997
(Cryoalgotox)
80
EUayetal. 1997
93
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,) Duration
Effect
FRESHWATER SPECIES
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Selenastrum
capricornutum
Green alga,
Stigeoclonium tenue
Green alga,
Stigeoclonium tenue
Green alga,
Ulothrix subconstricta
Benthic diatom,
Craticula cuspidata
Diatom,
Asterionella formosa
Diatom,
Cyclotella meneghiniana
(Arizona race)
Diatom,
Cyclotella meneghiniana
(Iowa race)
Diatom,
Cyclotella meneghiniana
Technical - 96 hr
grade
Technical - 96 hr
grade
Technical - 96 hr
grade
99.7% - 6 days
4hr
ACS - • 3 days
99.7% - 5 days
24 hr
24 hr
24 hr
98% - 67 days
chronic, 12
days acute
98% - 96 hr
7 min
7 min
7 min
NOEC
(biomass)
LOEC
(biomass)
EC50
(biomass)
Lowest Complete
Inhibition Concentration
(growth)
EC50
(chlorophyll-a
fluorescence)
EC50
(growth)
LOEC
(growth)
EC50
(14C uptake)
EC50
(14C uptake)
EC50
(14C uptake)
LOEC
(chlorophyll-a)
EC50
EC50
(photosynthesis)
EC50
(photosynthesis)
EC50
(photosynthesis)
Concentration
Reference
75
150
235
2160
232
164
220
127"
224"
83
261
99
105
243
Fairchild et al. 1997
Fairchild et al. 1997
Fairchild et al. 1997
Schrader et al. 1997
Van der Heever and
Grobbelaar 1998
Mayer et al. 1998
Schrader et al 1998
Larsen et al. 1986
Larsen et al. 1986
Larsen et al. 1986
Nelson etal. 1999
Seguinetal. 2001
Millie and Hersh 1987
Millie and Hersh 1987
Millie and Hersh 1987
(Minnesota race)
94
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,) Duration
Effect
Concentration
Reference
FRESHWATER SPECIES
Diatom,
Cyclotella meneghiniana
Diatom,
Cyclotella sp.
Diatom,
Navicula accomuda
Diatom,
Navicula pelliculosa
Diatom,
Navicula pelliculosa
Diatom,
Navicula pelliculosa
Diatom,
Navicula pelliculosa
Diatom,
Nitzschia sp.
Diatom,
Nitzschia sp.
Mixed algal assemblage
Algal assemblage
Cryptomonad,
Crypfomo«a,s
pyrinoidifera
Duckweed,
Lemna gibba
Duckweed,
Lemna gibba
Duckweed,
Lemna gibba
Technical - 22 hr
or
analytical
6 days
98% - 96 hr
97% - 5 days
97% - 5 day
exposure, 9
day
recovery
97% - 5 day
exposure,
9 day
recovery
97% - 5 day
exposure,
9 day
recovery
98% - 96 hr
Technical - 22 hr
or
analytical
98% - 21 days
28 days
6 days
97% - 5 days
97% - 5 day
exposure
9 day
recovery
97% - 5 day
exposure
9 day
recovery
97% inhibition of
photosynthesis
(14C uptake)
EC50
(growth)
EC50
EC50
(cell number)
NOEC
Algistatic concentration
Algicidal concentration
EC50
99% inhibition of
photosynthesis
(14C uptake)
Shift in dominant algal
abundance
LOEC (biomass)
EC50
(growth)
EC50
(frond production)
NOEC
(frond production)
Phytostatic
concentration
2,667
430
164
60
<100
1,710
>3,200
412
2,667
30
11
500
170
<100
1,720
Peterson et al. 1994
Kallqvist and Romstad
1994
Seguinetal. 2001
Hughes 1986; Hughes et
al. 1986, 1988
Hughes 1986; Hughes et
al. 1986, 1988
Hughes 1986; Hughes et
al. 1986, 1988
Hughes 1986; Hughes et
al. 1986, 1988
Seguinetal. 2001
Peterson et al. 1994
Seguinetal. 2001
Girling etal. 2001
Kallqvist and Romstad
1994
Hughes 1986; Hughes et
al. 1986, 1988
Hughes 1986; Hughes et
al. 1986, 1988
Hughes 1986; Hughes et
al. 1986, 1988
95
-------
Table 6 (Continued)
Hardness
(ing/L as
Chemical CaCO,)
Duration
Effect
Concentration
Reference
FRESHWATER SPECIES
Duckweed,
Lemna gibba
Duckweed,
Lemna minor
Duckweed,
Lemna minor
Duckweed,
Lemna minor
Duckweed,
Lemna minor
Duckweed,
Lemna minor
Duckweed,
Lemna minor
97%
Duckweed,
Lemna minor
Duckweed,
Lemna minor
5 day
exposure
9 day
recovery
20 days
20 days
20 days
20 days
15 days
15 days
15 days
10 days
Phytocidal concentration
No effect upon
growth; increased
soluble protein content;
increased
photosynthesis and
respiration
• 12% reduced growth;
increased water and
soluble protein content;
increased photosynthesis
and respiration
• 23% reduced growth;
increased water and
soluble protein content;
increased photosynthesis
and respiration
• ?4% reduced growth;
increased water,
chlorophyll, and soluble
protein content;
increased photosynthesis
and respiration
Increased total fatty acid
and • 'linolenic acid
content; increased
monogalatosyldia-cyl-
glycerol percentage
Increased total fatty acid
and • 'linolenic acid
content; decreased
linoleic acid content;
increased monoga-
lactosyldiacyl-glycerol
percentage
Increased amounts of
polar lipids in
chlorophyll-protein
complexes of
chloroplasts
Increased [14C]- acetate
incorporation into
chloroplast lipids
>3,200 Hughes 1986; Hughes et
al. 1986, 1988
20 Beaumont et al. 1976a,b
50 Beaumont et al. 1976a,b,
1978
100 Beaumont et al. 1976a,b,
1978
250 Beaumont et al. 1976a,b
100 Grenieretal. 1979
1,000 Grenieretal. 1979
248 Grenieretal. 1987
248 Grenieretal. 1989
96
-------
Table 6 (Continued)
Hardness
(ing/L as
Species Chemical CaCO,l
Concentration
Duration
Effect (us/L)
Reference
FRESHWATER SPECIES
Duckweed,
Lemna minor
Duckweed, Technical
Lemna minor or
analytical
Duckweed, Technical
Lemna minor
Duckweed, Technical
Lemna minor
Duckweed, Technical
Lemna minor
Duckweed, 92.2%
Lemna minor
Wild rice, 85%
Zizania aquatica
Wild celery,
Vallisneria americana
Wild celery,
Vallisneria americana
Wild celery,
Vallisneria americana
Coontail, 85%
Ceratophyllum dermersum
Coontail, 92.2%
Ceratophyllum sp.
Cattail, 85%
Typha latifolia
Water-milfoil, 92.2%
Myriophyllum
heterophyllum
Water-milfoil,
Myriophyllum spicatum
Water-milfoil,
Myriophyllum spicatum
Water-milfoil,
Myriophyllum spicatum
Sago pondweed,
Potamogeton pectinatus
2 days
7 days
96 hr
96 hr
96 hr
4 days
83 days
42 days
-
-
6-8 days
14 days
19 days
14 days
28 days
24 hr
5 days
28 days
Changes in chloroplast 248
ultrastructure; increased
chlorophyll content
95% inhibition of 2,667
growth
NOEC 75
(biomass)
LOEC 150
(biomass)
EC50 153
(biomass)
EC50 92
(frond production)
Visibly senescent; 75% 50
reduction in chlorophyll-
a in leaves
EC50 163
(total leaf length)
Reduced leaf growth 8
and whole plant biomass
Reduced tuber over- 4
wintering success
Reduced stem 50
elongation
EC50 22
(wet weight)
No effect upon growth 25
EC50 132
(wet weight)
EC50 1,104
(length)
30% increase in net 10
photosynthetic rate
50% reduction in branch 3,700
number
Reduced 100
biomass
Simardetal. 1990
Peterson et al. 1994
Fairchild et al. 1997
Fairchild et al. 1997
Fairchild et al. 1997
Fairchild et al. 1998
Detenbeck et al. 1996
Davis 1981;
Forney and Davis 1981
Cohn 1985
Cohn 1985
Detenbeck et al. 1996
Fairchild et al. 1998
Detenbeck et al. 1996
Fairchild et al. 1998
Davis 1981;
Forney and Davis 1981
Hoffmann and Winkler
1990
Bird 1993
Fleming etal. 1991
97
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,) Duration
i
Effect
Concentr
(Ug/I
FRESHWATER SPECIES
Bushy pondweed,
Najas sp.
Egeria,
Egeria sp.
Elodea,
Elodea canadensis
Elodea,
Elodea canadensis
Elodea,
Elodea canadensis
Elodea,
Elodea canadensis
Elodea,
Elodea canadensis
Water moss,
Fontinalis antipyretica
Water moss,
Fontinalis hypnoides
Water moss,
Fontinalis squamosa
Mixed macrophytes,
Ceratophyllum sp.
and Elodea sp.
Mixed macrophytes,
Ceratophyllum sp.
and Elodea sp.
Mixed macrophytes,
Ceratophyllum sp.
and Elodea sp.
Protozoa,
Acanthamoeba castellanii
Protozoa,
Acanthamoeba castellanii
Protozoa,
Acanthamoeba castellanii
Protozoa,
Acanthamoeba castellanii
92.2% - 14 days
14 days
28 days
21 days
20 days
85% - 19 days
92.2% - 14 days
20 days
24 hr
24 hr
85.5% 47 30 days
85.5% 47 30 days
85.5% 47 30 days
6 days
6 days
6 days
6 days
EC50
(wet weight)
EC50
(biomass)
EC50
(length)
EC50
(length)
Dark respiration rate
exceeded net
photosynthesis rate
No effect upon growth
EC50
(wet weight)
Dark respiration rate
exceeded net
photosynthesis rate
90% reduction in net
photosynthesis
20% reduction in net
photosynthesis
18.3% increased
biomass
11.6% decreased
biomass
47.6% decreased
biomass
5% population decrease
14% population
decrease
15% population
decrease
40% population
decrease
24
<38
80
109
10
75
21
10
2
10
10
100
1,00(
100
1,00(
4,00(
10,00
Reference
Fairchild et al. 1998
Fairchild et al. 1994a
Davis 1981;
Forney and Davis 1981
Davis 1981;
Forney and Davis 1981
Hoffmann and Winkler
1990
Detenbeck et al. 1996
Fairchild et al. 1998
Hoffmann and Winkler
1990
Hoffmann and Winkler
1990
Hoffmann and Winkler
1990
Johnson 1986
Johnson 1986
1,000 Johnson 1986
Prescott et al. 1977
Prescott et al. 1977
Prescott et al. 1977
10,000 Prescott et al. 1977
98
-------
Table 6 (Continued)
Species Chemical
Hardness
(mg/L as
CaCO,) Duration
Effect
Concentration
Reference
FRESHWATER SPECIES
Protozoa,
Colpidium campylum
Protozoa,
Euglena gracilis
Protozoa,
Euglena gracilis
Protozoa,
Euglena gracilis
Protozoa,
Tetrahymena pyriformis
Protozoa,
Tetrahymena pyriformis
Hydra,
Hydra viridis
Rotifer,
Brachionus calyciflorus
Leech, 99.2%
Glossiphonia complanata
Leech, 99.2%
Helobdella stagnalis
Snail, 97.8%
Lymnaea palustris
Snail, 97.8%
Lymnaea palustris
Snail,
Physa acuta
Mussel (glochidia larva), 97.3%
Anadonta imbecilis
Mussel (1-2 d old juvenile), 97.3%
Anadonta imbecilis
Mussel (7- 10 d old 97.3%
juvenile),
Anadonta imbecilis
Anostracan,
Streptocephalus texanus
Cladoceran, >99%
Ceriodaphnia dubia
24 hr
8hr
8hr
8hr
24 hr
48 hr
21 days
24 hr
27-28 days
27-28 days
12 wk
12 wk
18 days
40-50 24 hr
40-50 48 hr
40-50 48 hr
24 hr
57.1 4 days
EC50
(cell number)
• 11% inhibition of
photosynthesis
• 28% inhibition of
photosynthesis
• 83% inhibition of
photosynthesis
EC50
EC50
(cell number)
Reduced budding rate
LC50
LC50
LC50
No effect upon growth,
fecundity or glycogen
metabolism
Inhibited BaPH and
GST enzyme activities
Increased grazing
searching velocity and
movement patterns
LC50
LC50
LC50
LC50
MATC
>50,000
10
100
1,000
118,500
96,000
5,000
7,840
6,300
9,900
125
5
15
>60,000
>60,000
>60,000
>30,000
7,100
Roberts etal. 1990
Valentine and Bingham
1976
Valentine and Bingham
1976
Valentine and Bingham
1976
Huberetal. 1991
Schaferetal. 1994
Benson and Boush 1983
Crisinel et al. 1994
Streit and Peter 1978
Streit and Peter 1978
Baturoetal. 1995
Baturo and Lagadic 1996
Roses etal. 1999
Johnson etal. 1993
Johnson etal. 1993
Johnson etal. 1993
Crisinel et al. 1994
Orisetal. 1991
99
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,) Duration
Effect
Concentration
(ug/L)
Reference
FRESHWATER SPECIES
Cladoceran,
Ceriodaphnia dubia
Cladoceran,
Daphnia magna
Cladoceran,
Daphnia magna
Cladoceran,
Daphnia magna
Cladoceran,
Daphnia magna
Cladoceran,
Daphnia magna
Cladoceran,
Daphnia magna
Cladoceran,
Daphnia magna
Cladoceran,
Daphnia magna
Cladoceran,
Daphnia magna
Cladoceran,
Daphnia magna
Cladoceran,
Daphnia magna
Cladoceran,
Daphnia magna
Cladoceran,
Daphnia pulex
Cladoceran,
Daphnia pulex
Cladoceran,
Daphnia pulex
Cladoceran,
Daphnia pulex
Cladoceran,
Daphnia pulex
>99% 57.1 4 days
26 hr
100 48 hr
100 48 hr
21 days
48 hr
96 hr
96 hr
97.3% 40-50 48 hr
24 hr
48 hr
85% - 48 hr
85% - 48 hr
3hr
99.2% - 28 days
99.2% - 28 days
99.2% - -70 days
99.2% - 28 days
MATC
LC50
BCF = 4.4
BCF = 2.2
Reduced young
production
10% mortality
30% mortality
60% mortality
LC50
EC50
EC50
Significantly decreased
survival
No effect upon survival
LC50
11. 7% decreased
survival and 28.2%
decreased reproduction
4.2% decreased survival
and 26. 8% decreased
reproduction
41. 7% decreased
reproduction
20.2% decreased
survival and 45.5%
14,100
3,600
10
10
2,000
22,000
16,900
48,300
9,400m
>30,000
>30,000
25
50
>40,000
1,000
2,000
2,000
3,000
Orisetal. 1991
FrearandBoyd 1967
Ellgehausen et al. 1980
Ellgehausen et al. 1980
Kaushik et al. 1985
Bogackaetal. 1990
Bogackaetal. 1990
Bogackaetal. 1990
Johnson etal. 1993
Crisinel et al. 1994
Crisinel et al. 1994
Detenbeck et al. 1996
Detenbeck et al. 1996
Nishiuchi and Hashimo
1967, 1969
Schober and Lampert
1977
Schober and Lampert
1977
Schober and Lampert
1977
Schober and Lampert
1977
decreased reproduction
100
-------
Table 6 (Continued)
Species
Cladoceran,
Daphnia pulex
Cladoceran,
Daphnia pulex
Cladoceran,
Daphnia pulex
Cladoceran,
Daphnia pulex
Cladoceran,
Daphnia pulex
Cladoceran,
Daphnia pulex
Cladoceran,
Daphnia pulex
Cladoceran,
Daphnia pulex
Cladoceran,
Daphnia pulex
Cladoceran (adult),
Moina macrocopa
Cladoceran,
Moina macrocopa
Amphipod (1st instar),
Gammarus fasciatus
Hardness
(ing/L as
Chemical CaCO,l
Duration
Effect
Concentration
(ug/L)
Reference
FRESHWATER SPECIES
99.2%
99.2%
99.2%
99.2%
99.2%
99.2%
_
_
98%
.
_
28 days
28 days
70 days
28 days
70 days
28 days
10 min
10 min
18 hr
3hr
4-6 wk
9.6% decreased survival
and 48.3% decreased
reproduction
42% decreased
reproduction
48.2% decreased
reproduction
14.9% decreased
survival; 53.9%
decreased reproduction
62.6% decreased
reproduction
96.5% decreased
reproduction
10% reduction in food
consumption
50% reduction in food
consumption
LC50
LC50
40% mortality; 10%
4,000
5,000
5,000
10,000
10,000
20,000
350
1,600
•?00
>40,000
1,000
Schober and Lampert
1977
Schober and Lampert
1977
Schober and Lampert
1977
Schober and Lampert
1977
Schober and Lampert
1977
Schober and Lampert
1977
Pott 1980
Pott 1980
Bowmanetal 1981
Nishiuchi and Hashirr
1967, 1969
Shcherban 1972a,b
94%
48 hr
increase in potential
production; reduced
actual population growth
LC50
5,700
Macek et al. 1976
Amphipod (approx 2ntl 98% - 18hr LC50
instar),
Hyalella azteca
White dotted mosquito, 98% - 18hr LC50
Culex restuans
Midge (2nd instar), - 151 10 days LC50
Chironomus riparius
Midge (-10 d),
Chironomus tentans
Midge (4th instar), 99% 80-100 48 hr LC50
Chironomus tentans
2,000
Bowmanetal. 1981
97.1% 42-44 96 hr LC50
(fed)
' 60,000 Bowman et al. 1981
18,900
Taylor etal. 1991
>28,000 McNamara 1991b
>20,000 Pape-Lindstrom and Lydy
1997
101
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,) Duration
Effect
FRESHWATER SPECIES
Midge (1st instar),
Chironomus teutons
Midge (4th instar),
Chironomus tentans
Midge (3rd instar),
Chironomus tentans
Midge (3rd instar),
Chironomus tentans
Midge (3rd instar),
Chironomus tentans
Midge (3rd instar),
Chironomus tentans
Midge (3rd instar),
Chironomus tentans
Rainbow trout (embryo),
Oncorhynchus mykiss
Rainbow trout (embryo),
Oncorhynchus mykiss
Rainbow trout (sac fry),
Oncorhynchus mykiss
Rainbow trout (sac fry),
Oncorhynchus mykiss
Rainbow trout (sac fry),
Oncorhynchus mykiss
Rainbow trout (sac fry),
Oncorhynchus mykiss
Rainbow trout (sac fry),
Oncorhynchus mykiss
Rainbow trout (sac fry),
Oncorhynchus mykiss
Rainbow trout (sac fry),
Oncorhynchuls mykiss
94% - 48 hr
99% - 48 hr
98.5% 40-52 48 hr
98.5% 40-52 10 days
98.5% 40-52 10 days
98.5% 40-52 10 days
98.5% 40-52 10 days
80% 50 23 days
(at hatching)
80% 200 23 days
(at
hatching)
80% 50 27 days
(4 days
post-hatch)
80% 200 27 days
(4 days
post-hatch)
80% 50 27 days
(4 days
post-hatch)
80% 200 27 days
(4 days
post-hatch)
80% 50 27 days
(4 days
post-hatch)
80% 50 27 days
(4 days
post-hatch)
80% 50 27 days
(4 days
post-hatch)
LC50
LC50
LC50 (fed)
LC50
EC50 (growth)
NOEC (survival)
NOEC (growth)
LC50
LC50
LC50
LC50
LCI
LCI
3% teratic larvae
6% teratic larvae
62% teratic larva*
Concentration
Reference
720
5,400
696
864
23.2
43.2
432
4,020
Macek et al. 1976
>1,000 Jin-Clark et al. 2002
>24,000 Springborn Smithers 2002
>24,000 Springborn Smithers 2002
8,300 Springborn Smithers 2002
16,000 Springborn Smithers 2002
Springborn Smithers 2002
736 Birge et al. 1979
888 Birge et al. 1979
Birge et al. 1979
Birge et al. 1979
Birge et al. 1979
Birge et al. 1979
Birge et al. 1979
Birge et al. 1979
Birge et al. 1979
102
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,)
Duration
Effect
Concentration
Reference
FRESHWATER SPECIES
Rainbow trout (sac fry), 80% 200
Oncorhynchuls mykiss
Rainbow trout (sac fry), 80% 200
Oncorhynchus mykiss
Rainbow trout (sac fry), 80% 200
Oncorhynchus mykiss
Rainbow trout (sac fry), 80% 200
Oncorhynchus mykiss
Rainbow trout (juvenile), 99.3%
Oncorhynchus mykiss
Rainbow trout (juvenile),
Oncorhynchus mykiss
Rainbow trout (juvenile),
Oncorhynchus mykiss
Rainbow trout,
Oncorhynchus mykiss
Rainbow trout,
Oncorhynchus mykiss
Rainbow trout,
Oncorhynchus mykiss
Rainbow trout (juvenile), 93.7%
Oncorhynchus mykiss
Rainbow trout (juvenile), • 98%
Oncorhynchus mykiss
Rainbow trout (juvenile), • 98%
Oncorhynchus mykiss
Rainbow trout (juvenile), 99% 380
Oncorhynchus mykiss
27 days 2% teratic larvae
(4 days
post-hatch)
27 days 3% teratic larvae
(4 days
post-hatch)
27 days 4% teratic larvae
(4 days
post-hatch)
27 days 65% teratic larvae
(4 days
post-hatch)
48 hr LC50
28 days Changes in renal
corpuscle ultrastructure
28 days Changes in renal
corpuscle and tubule
ultrastructure
28 days Slight ultrastructural
changes in renal
corpuscles
28 days Slight histopathological
changes in liver;
increased ultrastructural
changes in renal
corpuscles
28 days Ultrastructural changes
in renal corpuscles and
histopathological
changes in liver
14 days No effect upon survival,
body weight, liver
weight, or liver
xenobiotic-metabolizing
enzyme activities
10 days Reduced plasma protein
10 days Reduced plasma protein
5 wk Ultrastructural
alterations in kidney
proximal tubules
13.6 Birge et al. 1979
48.0 Birge et al. 1979
416 Birge et al. 1979
4,020 Birge et al. 1979
5,660 Pluta 1989
Fischer-Scherl et al. 1991
10 Fischer-Scherl et al. 1991
Schwaiger et al. 1991
10 Schwaiger et al. 1991
20 Schwaiger et al. 1991
10 Egaasetal. 1993
3.0 Daviesetal. 1994b
50 Daviesetal. 1994b
12.4 Oulmi et al. 1995
103
-------
Table 6 (Continued)
Species
Rainbow trout (juvenile),
Oncorhynchus mykiss
Atlantic salmon (parr),
Salmo salar
Goldfish,
Carassius auratus
Goldfish (6-9 g),
Carassius auratus
Common carp,
Cyprinus carpio
Common carp (30-50 g),
Cyprinus carpio
Common carp (30-50 g),
Cyprinus carpio
Common carp (30-50 g),
Cyprinus carpio
Common carp (30-50 g),
Cyprinus carpio
Common carp (30-50 g),
Cyprinus carpio
Common carp (30-50 g),
Cyprinus carpio
Common carp (30-50 g),
Cyprinus carpio
Common carp (30-50 g),
Cyprinus carpio
Common carp (30-50 g),
Cyprinus carpio
Common carp (30-50 g),
Cyprinus carpio
Common carp (30-50 g),
Cyprinus carpio
Common carp (30-50 g),
Cyprinus carpio
Hardness
(ing/L as
Chemical CaCO,)
Concentration
99%
97.9%
380
Duration
Effect
Reference
FRESHWATER SPECIES
5 wk
30 min
48 hr
24 hr
(10 min
flowing)
48 hr
12 hr
24 hr
6hr
12 hr
24 hr
12 hr
24 hr
6hr
12 hr
24 hr
72 hr
Ultrastructural
alterations in kidney
proximal and distal
tubules
Reduced olfactory
response to female
pheromone
LC50
Burst swimming
LC50
• 125% increased serum
cortisol
• 300% increased serum
cortisol
• 40% increased serum
cortisol
• 60% increased serum
cortisol
• 250% increased serum
cortisol
• 60% increased serum
glucose
• 35% increased serum
glucose
• 15% increased serum
glucose
• 40% increased serum
glucose
• ?0% increased serum
glucose
• 1 80% increased serum
24.0
2.0
>10,000
0.5
(0.1 test
dripping)
>10,000
100
100
500
500
500
100
100
500
500
500
1,000
Oulmi et al. 1995
Moore and Waring 1998
Nishiuchi and Hashimoto
1967, 1969
Saglio and Trijasse 1998
Nishiuchi and Hashimoto
1967, 1969
Hanke et al. 1983
Hanke et al. 1983
Hanke et al. 1983
Hanke et al. 1983
Hanke et al. 1983
Hanke et al. 1983
Hanke et al. 1983
Hanke et al. 1983
Hanke et al. 1983
Hanke et al. 1983
Hanke et al. 1983
glucose; • 40%
decreased liver glycogen
4 hr • 25% increase in gill
total ATPase activity;
• 20% increase in gill
Na-K dependent ATPase
100
Hanke et al. 1983
104
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,)
Duration
Effect
Concentration
Reference
FRESHWATER SPECIES
Common carp (30-50 g),
Cyprinus carpio
Common carp (30-50 g),
Cyprinus carpio
Common carp (30-50 g),
Cyprinus carpio
Common carp (30-50 g),
Cyprinus carpio
Common carp (30-50 g),
Cyprinus carpio
6 hr • 10% increase in gill 100 Hanke et al. 1983
total ATPase; • S0%
decrease in gill Na-K
dependent ATPase
12 hr • 40% decrease in gill 100 Hanke et al. 1983
total ATPase;
• 30%decrease in gill
Na-K dependent ATPase
24 hr • 5% decrease in gill 100 Hanke et al. 1983
total ATPase; • 25%
decrease in gill Na-K
dependent ATPase
4hr • 60% increase in serum 100 Hanke et al. 1983
AChE
6hr M 5% increase in serum 100 Hanke et al. 1983
AChE
Common carp (30-50 g),
Cyprinus carpio
Common carp (30-50 g),
Cyprinus carpio
Common carp,
Cyprinus carpio
Common carp (juvenile),
Cyprinus carpio
Common carp (juvenile),
Cyprinus carpio
Common carp (juvenile),
Cyprinus carpio
Common carp (50-60 g),
Cyprinus carpio
Fathead minnow (• 24h),
Pimephales promelas
99.3%
93.7%
93.7%
94%
97
12 hr • 35% increase in serum
AChE
24 hr • 25% decrease in serum
AChE
72 hr Increased serum glucose
and cortisol; decreased
liver and muscle
glycogen; decreased
serum protein and
cholesterol
48 hr
141-223 96 hr
(fed)
141-223 14 days
60
LC50
LC50
Increased serum alkaline
phosphatase; decreased
alkaline phosphatase in
heart, liver and kidneys;
increased GPT in liver
and kidneys; hyperplasia
of some gill epithelial
cells
14 days NOEC
(gill, liver, and kidney
histopathology)
7 days NOEC
(biomass)
100
100
1,500
Hanke et al. 1983
Hanke et al. 1983
100 Gluth and Hanke 1984,
1985
16,100 Pluta 1989
18,800 Neskovic et al. 1993
1,500 Neskovic et al. 1993
Poleksic et al. 1997
' 4,900 Jop 1991b
105
-------
Table 6 (Continued)
Species
Fathead minnow (larvae),
Pimephales promelas
Fathead minnow (juvenile),
Pimephales promelas
Channel catfish (embryo),
Ictalurus punctatus
Channel catfish (embryo),
Ictalurus punctatus
Channel catfish (sac fry),
Ictalurus punctatus
Channel catfish (sac fry),
Ictalurus punctatus
Channel catfish (sac fry),
Ictalurus punctatus
Channel catfish (sac fry),
Ictalurus punctatus
Channel catfish (sac fry),
Ictalurus punctatus
Channel catfish (sac fry),
Ictalurus punctatus
Channel catfish (sac fry),
Ictalurus punctatus
Channel catfish (sac fry),
Ictalurus punctatus
Channel catfish (sac fry),
Ictalurus punctatus
Channel catfish (sac fry),
Ictalurus punctatus
Chemical
Hardness
(mg/L as
CaCO,) Duration
Effect
FRESHWATER SPECIES
85%
85%
80%
80%
80%
80%
80%
80%
80%
80%
80%
80%
80%
80%
7
13 days
50 4.5 days
(at
hatching)
200 4.5 days
(at
hatching)
50 8.5 days
(4 days
post-hatch)
200 8.5 days
(4 days
post-hatch)
50 8.5 days
(4 days
post-hatch)
50 8.5 days
(4 days
post-hatch)
50 8.5 days
(4 days
post-hatch)
50 8.5 days
(4 days
post-hatch)
50 8.5 days
(4 days
post-hatch)
200 8.5 days
(4 days
post-hatch)
200 8.5 days
(4 days
post-hatch)
200 8.5 days
(4 days
post-hatch)
No effect upon survi
No effect upon survi
or growth
LC50
LC50
LC50
LC50
1% teratic larvae
4% teratic larvae
13% teratic larvae
69% teratic larvae
100% teratic larvae
1% teratic larvae
4% teratic larvae
16% teratic larvae
Concentration
Reference
75 Detenbeck et al. 1996
75 Detenbeck et al. 1996
272 Birge et al. 1979
248
176
192
22.4
47.2
344
3,864
37,360
26.4
43.2
336
Birge et al. 1979
Birge et al. 1979
Birge et al. 1979
Birge et al. 1979
Birge et al. 1979
Birge et al. 1979
Birge et al. 1979
Birge et al. 1979
Birge et al. 1979
Birge et al. 1979
Birge et al. 1979
106
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,)
Duration
Effect
FRESHWATER SPECIES
Concentration
Reference
Channel catfish (sac fry), 80% 200
Ictalurus punctatus
Channel catfish (sac fry), 80% 200
Ictalurus punctatus
Mosquitofish,
Gambusia affinis
Guppy,
Poecilia reticulata
Guppy,
Poecilia reticulata
Guppy,
Poecilia reticulata
Guppy,
Poecilia reticulata
Mozambique tilapia,
Tilapia mossambica
Mozambique tilapia,
Tilapia mossambica
Mozambique tilapia,
Tilapia mossambica
Mozambique tilapia,
Tilapia mossambicus
Technical
8.5 days
(4 days
post-hatch)
8.5 days
(4 days
post-hatch)
48 hr
48 hr
72 hr
96 hr
96 hr
90 days
30 days
30 days
90 days
47% teratic larvae
86% teratic larvae 37,360
No mortality 10,000
LC50 38,200
LC50 31,600
40% 28,600
mortality
53.2% 37,200
mortality
Decreased red and white 1,100
blood cell counts,
hemoglobin, packed cell
volume, mean
corpuscular hemoglobin;
decreased whole animal
oxygen consumption;
increased mean cell
volume, blood volume
and blood water content
Changed enzyme 1,100
activity and levels of
amino acids, proteins,
ammonia, and urea in
brain and liver
Increased lipase activity, 1,100
free fatty acids,
acetoacetate
concentration, and total
cholesterol in liver and
muscle; decreased total
lipids, glycerol and
phospholipids in liver
and muscle.
Increased body weight, 1,100
percent water, serum
Na+ and serum K+;
decreased serum Ca^,
Mg^ and HCCV
Birge et al. 1979
Birge et al. 1979
Darwazeh and Mulla
1974
Tscheu-Schluter 1976
Tscheu-Schluter 1976
Bogackaetal. 1990
Bogackaetal. 1990
Prasadetal. 1991a
Prasadetal. 1991b
Srinivas et al. 1991
Prasad and Reddy 1994
107
-------
Table 6 (Continued)
Species
Bullfrog (embryo and
tadpole),
Rana catesbeiana
Bullfrog (embryo and
tadpole),
Rana catesbeiana
Bullfrog (embryo and
tadpole),
Rana catesbeiana
Bullfrog (embryo and
tadpole),
Rana catesbeiana
Bullfrog (embryo and
tadpole),
Rana catesbeiana
Bullfrog (embryo and
tadpole),
Rana catesbeiana
Bullfrog (embryo and
tadpole),
Rana catesbeiana
Bullfrog (embryo and
tadpole),
Rana catesbeiana
Bullfrog (embryo and
tadpole),
Rana catesbeiana
Leopard frog (embryo and
tadpole),
Rana pipiens
Leopard frog (embryo and
tadpole),
Rana pipiens
Leopard frog (embryo and
tadpole),
Rana pipiens
Leopard frog (embryo and
tadpole),
Rana pipiens
Leopard frog (embryo and
tadpole),
Rana pipiens
Chemical
Hardness
(mg/L as
CaCO,l
Duration
Effect
FRESHWATER SPECIES
80%
80%
80%
80%
80%
80%
80%
80%
80%
80%
80%
80%
113
113
113
113
113
113
113
113
113
115
115
115
8 days
(4 days
post-hatch)
8 days
(4 days
post-hatch)
8 days
(4 days
post-hatch)
4 days
(to hatch)
4 days
(to hatch)
4 days
(to hatch)
4 days
(to hatch)
4 days
(to hatch)
4 days
(to hatch)
9 days
(4 days
post-hatch)
9 days
(4 days
post-hatch)
9 days
(4 days
post-hatch)
LCI
LC10
LC50
1% teratic surviving
larvae
3% teratic surviving
larvae
7% teratic surviving
larvae
22% teratic surviving
larvae
47% teratic surviving
larvae
100% teratic surviving
larvae
LCI
LC10
LC50
Concentration
Reference
80% 115 5 days 2% teratic
(to hatch) surviving larvae
80% 115 5 days 2% teratic
(to hatch) surviving larvae
7.4 Birge et al. 1980
44.9 Birge et al. 1980
410 Birge et al. 1980
51
410
6,330
14,800
26,400
7,680
110
210
Birge et al. 1980
Birge et al. 1980
Birge et al. 1980
Birge et al. 1980
Birge et al. 1980
45,800 Birge et al. 1980
32.6 Birge et al. 1980
378.9 Birge et al. 1980
Birge et al. 1980
Birge et al. 1980
Birge et al. 1980
108
-------
Table 6 (Continued)
Species
Leopard frog (embryo and
tadpole),
Rana pipiens
Leopard frog (embryo and
tadpole),
Rana pipiens
Leopard frog (embryo and
tadpole),
Rana pipiens
Leopard frog (embryo and
tadpole),
Rana pipiens
Leopard frog (tadpole),
Rana pipiens
Pickerel frog (embryo and
tadpole),
Rana palustris
Pickerel frog (embryo and
tadpole),
Rana palustris
Pickerel frog (embryo and
tadpole),
Rana palustris
Pickerel frog (embryo and
tadpole),
Rana palustris
American toad (embryo
and tadpole),
Bufo americanus
American toad (embryo
and tadpole),
Bufo americanus
American toad (embryo
and tadpole),
Bufo americanus
American toad (embryo
and tadpole),
Bufo americanus
American toad (embryo
and tadpole),
Bufo americanus
Chemical
Hardness
(mg/L as
CaCO,) Duration
Effect
Concentration
(us/L) Reference
FRESHWATER SPECIES
80%
80%
80%
80%
85%
80%
80%
80%
80%
80%
80%
80%
80%
80%
115 5 days
(to hatch)
115 5 days
(to hatch)
115 5 days
(to hatch)
115 5 days
(to hatch)
41 days
103 8 days
(4 days
post-hatch)
103 4 days
(to hatch)
103 4 days
(to hatch)
103 4 days
(to hatch)
7 days
(4 days
post-hatch)
3 days
(to hatch)
3 days
(to hatch)
3 days
(to hatch)
3 days
(to hatch)
5% teratic
surviving larvae
9% teratic
surviving larvae
13% teratic surviving
larvae
46% teratic surviving
larvae
No effect upon growth
or survival
LC50
2% teratic
surviving larvae
5% teratic surviving
larvae
1 8% teratic surviving
larvae
LC50
2% teratic surviving
larvae
2% teratic surviving
larvae
3% teratic surviving
larvae
6% teratic surviving
larvae
1,113 Birge et al. 1980
6,540 Birge et al. 1980
13,200 Birge et al. 1980
48,700 Birge et al. 1980
25 Detenbeck et al. 1996
17,960 Birge et al. 1980
10,400 Birge et al. 1980
20,600 Birge et al. 1980
33,900 Birge et al. 1980
>48,000 Birge et al. 1980
490 Birge et al. 1980
5,560 Birge et al. 1980
10,800 Birge et al. 1980
24,800 Birge et al. 1980
109
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,)
Duration
Effect
Concentration
Reference
FRESHWATER SPECIES
American toad (embryo 80%
and tadpole),
Bufo americanus
African clawed frog
(embryo),
Xenopus laevis
African clawed frog
(embryo),
Xenopus laevis
African clawed frog
(embryo),
Xenopus laevis
Tiger salamander,
Ambystoma tigrinum
American alligator, 99%
Alligator mississippiensis
Stream mixed 80%
algal species
Stream mixed
algal species
Experimental stream
periphyton community
Stream mixed Technical
community
Experimental laboratory 96.5
stream community
3 days
(to hatch)
96 hr
96 hr
333 86 days
15 min
1 day to 3
wk
3 days
14 days
164-202 30 days
2wk
17% teratic surviving
larvae
100% abnormal
embryos
96 hr LC50
Stream aufwuchs
community
12 days
LOEC
(teratogenesis)
Stimulated plasma
thyroxine; delayed
development - retarded
growth
50% inhibition of (3H)
17' 'estradiol binding
39-78% reduction in
gross productivity
Reduced net primary
productivity
Severe population
density reductions in
several species; total
destruction of
Cladophora glomerata
No effect upon
macroinvertebrate
community structure,
periphyton production or
biomass, and
community P/R ratio
Decreased diurnal
fluctuation and mean
values for pH and
dissolved oxygen;
increased nitrate
nitrogen; parameters
rapidly returned to
control levels when
treatment ended
4% biomass reduction at
10°C
48,200
8,000
1,100
82
4,465
10
100
1,000
25
100
Birge et al. 1980
Morgan et al. 1996
126,000 Morgan et al. 1996
Morgan et al. 1996
Larson et al. 1998
Vonier et al. 1996
Kosinski et al. 1985;
Kosinski and Merkle
1984
Moorhead and Kosinski
1986
Kosinski 1984
Lynch et al. 1985
Malanchuk and Kollig
1985
24
Kriegeretal. 1988
110
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,) Duration
Effect
Concentration
(ug/L)
Reference
FRESHWATER SPECIES
Stream aufwuchs
community
Stream aufwuchs
community
Stream aufwuchs
community
Natural stream
periphyton community
Natural stream
plankton community
Stream algal and benthic
invertebrate community
Artificial stream
periphyton community
Pond microcosm,
(static system)
Pond microcosm,
(static system)
Pond microcosm,
(static system)
Pond microcosm,
(static system)
Pond microcosm,
(static system)
Pond microcosm,
(static system)
Pond microcosm,
(static system)
Pond microcosm,
(static system)
12 days
12 days
12 days
98% - 24 hr
Commercial - 6 mo
product
90% - 14 days
30 days
98.2% - 7 days
98.2% - 12 days
98.2% - 7 days
98.2% - 12 days
98.2% - 12 days
Technical - 40 days
Technical - 40 days
Technical - 40 days
24% biomass reduction;
30% chlorophyll-a
reduction at 25°C
47% biomass reduction;
40% chlorophyll-a
reduction at 10°C
31% biomass reduction;
44% chlorophyll-a
reduction at 25°C
No effect upon algal cell
numbers or biomass
Initial decrease in
phytoplankton species (6
wks) followed by a
recovery
No effect upon attached
algal chlorophyll-a
concentrations or
benthic invertebrate
populations
Community
photosynthesis inhibited
No effect upon diurnal
oxygen production
25-30% decreased
oxygen production
40-50% decreased
diurnal oxygen
production
90% decreased diurnal
oxygen production
100% inhibition of
diurnal oxygen
production
NOEC (chlorophyll-a)
NOEC
(macrophyte biomass)
NOEC (gray tree frog,
Hyla versicolor growth)
24
134
134
77.5
•6.5
5
100
5.0
50
100
500
5,000
2,000
20
20
Kriegeretal. 1988
Kriegeretal. 1988
Kriegeretal. 1988
Jurgenson and Hoagland
1990
Lakshminarayana et al.
1992
Gruessner and Watzin
1996
Pearson and Grassland
1996
Brockway et al. 1984
Brockway et al. 1984
Brockway et al. 1984
Brockway et al. 1984
Brockway et al. 1984
Diana et al. 2000
Diana et al. 2000
Diana et al. 2000
111
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,)
Duration
Effect
FRESHWATER SPECIES
Concentration
Reference
Lake microcosm
plankton community
98%
Freshwater microcosm
Periphyton-dominated
microcosm
Periphyton-dominated
microcosm
Phytoplankton,
zooplankton and benthos
microcosm
Phytoplankton,
zooplankton and benthos
microcosm
Pond mesocosm
community
Pond mesocosm
community
Pond mesocosm
community
Pond mesocosm
community
96.5%
96.5%
41%
41%
10-21 days Seasonal and species- 10
dependent effects;
growth generally
stimulated for
Chryptophytes and
Chrysophytes, but
inhibited in Chlorella
vulgaris
7wk No effects upon species 5.1
composition of
phytoplankton,
zooplankton or benthic
macroinvertebrates;
slight decrease in
photosynthetic activity
1 day 77% decrease in daily 100
net productivity
14 days • ?5% decrease in P/R 100
ratio
60 days Reduced 14C 43.8
uptake/chlorophyll-a
ratio
25 days Reduced net primary • $0
productivity
70 days Changed population 200
densities of zooplankton
(rotifers, crustaceans and
insect larvae)
121 days Changed phytoplankton 10
community
composition; increased
rotifer population
805 days Reduced phytoplankton 20
production and biomass,
macrophyte,
populations, and
populations of benthic
insect grazers, Rana
catesbiana tadpoles,
grass carp and bluegills
4 yr single Reduced photosynthesis 20-500
annual in 24 hr bioassays,
application followed by recovery in
20-day bioassays and
long-term pond studies
Berardetal. 1999
Van den Brink 1995
Hamala and Kollig 1985
Hamala and Kollig 1985
Stayetal. 1985
Stayetal. 1985
Peichl et al. 1984
Peichl et al. 1985
deNoyelles et al. 1982,
1989, 1994
deNoyelles and Kettle
1985
112
-------
Table 6 (Continued)
Chemical
Hardness
(mg/L as
CaCO,)
Duration
Effect
Concentration
Reference
FRESHWATER SPECIES
Pond mesocosm
community
97%
Pond mesocosm
community
97%
Pond mesocosm
community
97%
Pond mesocosm
community
Pond mesocosm
plankton community
Pond mesocosm
plankton community
Pond mesocosm
plankton community
9-112 days Significant reductions of 20°
herbivorous benthic
insect species richness,
abundance, and total
insect emergence (89%),
shift to earlier
emergence for some
herbivorous species;
destabilization of
ecosystem
9-112 days Significant reductions of 100°
herbivorous benthic
insect species richness,
abundance, and total
insect emergence (95%),
shift to earlier
emergence for some
herbivorous species;
reduced species
evenness; destabilization
of ecosystem
9-112 days Significant reductions of 500"
herbivorous benthic
insect species richness,
abundance, and total
insect emergence (85%),
shift to earlier
emergence for some
herbivourous species;
reduced species
evenness; destabilization
of ecosystem
8 wk Altered macrophyte 50
community species
composition; no effects
upon primary
productivity, total plant
biomass, zooplankton or
fish
2 mo No effect 5
2 mo Decreased O2, pH and 10
conductivity
2 mo Decreased 182
phytoplankton
populations
Dewey 1986; Dewey and
deNoyelles 1994
Dewey 1986; Dewey and
deNoyelles 1994
Dewey 1986; Dewey and
de Noyelles 1994
Fairchild et al. 1994a
Juttneretal. 1995
Juttner et al. 1995
Juttneretal. 1995
113
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,)
Duration
Effect
Concentration
Reference
FRESHWATER SPECIES
Pond mesocosm
plankton community
Pond microbial microcosm 98.6%
community
Pond microbial microcosm 98.6%
community
Pond microbial microcosm 98.6%
community
Pond microbial microcosm 98.6%
community
Pond microbial microcosm 98.6%
community
Pond microbial microcosm 98.6%
community
Phyto- and zooplankton
microcosm community
Phyto- and zooplankton
microcosm community
Experimental pond
community
Experimental pond
community
2 mo
21 days
' ?0 21 days
21 days
' ?0 21 days
' ?0 21 days
21 days
42 days
42 days
39 days
after
treatment
43 days
after
treatment
Reduced peak egg ratios
in Daphnia longispina
and elimination of
Poly art hr a sp. rotifers
NOEC for
concentrations of Mg,
Ca and dissolved
oxygen
MATC for
concentrations of Mg,
Ca and dissolved
oxygen
LOEC for
concentrations of Mg,
Ca and dissolved
oxygen
NOEC for protozoan
colonization, biomass
protein, chlorophyll-a,
and potassium
concentration
MATC for protozoan
colonization, biomass
protein, chlorophyll-a,
and potassium
concentration
LOEC
for protozoan
colonization, biomass
protein, chlorophyll-a
and potassium
concentration
No or little effect upon
net primary
productivity, P/R ratio,
andpH
Reduced net primary
productivity, P/R ratio,
andpH
EC50
(14C uptake)
EC50
(14C uptake)
318
10
17.9
32.0
110
193
337
•84
96
131
Juttneretal. 1995
Pratt etal. 1988
Pratt etal. 1988
Pratt etal. 1988
Pratt etal. 1988
Pratt etal. 1988
Pratt etal. 1988
Stay etal. 1989
Stay etal. 1989
Larsen et al. 1986
Larsenetal. 1986
114
-------
Table 6 (Continued)
Hardness
(ing/L as
Chemical CaCO,)
Duration
Effect
FRESHWATER SPECIES
Concentration
Reference
Experimental pond
community
Experimental pond
community
Experimental pond
community
Experimental pond
community
Experimental pond
community
Mixed pond
community
Mixed pond
community
Pond mesocosm
community
Pond mesocosm
community
Pond mesocosm
community
99.2%
99.2%
99%
99%
99%
101 days
after
treatment
177 days
after
treatment
249 days
after
treatment
259 days
after
treatment
373 days
after
treatment
4 mo
4 mo
2yr
2yr
2yr
EC50
(14C uptake)
EC50
(14C uptake)
EC50
(14C uptake)
EC50
(14C uptake)
EC50
(14C uptake)
Elimination ofLemna
minor population
Rapid succession of
algal species; reduced
reproduction rate in
Daphnia pulicaria
Decreased green algal
species, cell numbers
and cladoceran
populations; increased
cryptomonad cell
numbers
Decreased green algal
species, cell numbers
and cladoceran
populations; increased
cryptomonad cell
numbers
Decreased green algal
species, cell numbers
and cladoceran
populations; increased
cryptomonad cell
numbers
109 Larsenetal. 1986
24 Larsen et al. 1986
27 Larsen et al. 1986
37 Larsen et al. 1986
100 Larsenetal. 1986
60-120 Gunkel 1983
60-120 Gunkel 1983
20 Neugebauer et al. 1990
100 Neugebauer et al. 1990
300 Neugebauer et al. 1990
115
-------
Table 6 (Continued)
Chemical
Hardness
(mg/L as
CaCO,)
Duration
Effect
Concentration
Reference
FRESHWATER SPECIES
Pond mesocosm
community
Reagent
grade
2yr
Pond mesocosm
community
Reagent
grade
2yr
Pond mesocosm
community
Reagent
grade
2yr
Mixed algae
from pond
Lake limnocorral
community
Lake limnocorral
community
>3hr
34 days
9wk
(2
applications
6 weeks
apart)
Atrazine applied in May
and June each year:
decreased abundance of
Endochironomus
nigricans in June and of
total macroinverte-
brates in both May and
June, followed by
recovery in July;
epiphytes decreased in
abundance in June,
followed by recovery in
July; detritovore
abundance decreased in
May, followed by
recovery in June;
generalists decreased in
May and June, followed
by recovery in July
Results similar to those
at 20 ug/L in May and
June; Caenis sp.
significantly increased
in July; also increased
abundance of Caenis
sp., total macroinverte-
brates, detritovores and
generalists in late July
Results similar to those
at 20 and 100'g/Lin
May and June: Caenis
sp. were significantly
reduced in abundance in
early July but not in late
July; the abundance of
epiphytes decreased,
while the abundance of
total macroinverte-
brates and generalists
increased in late July
Increased fluorescence
rate for photosystem II
Reduced periphyton ash-
free dry weight
36-67% reduction in
chlorophyll-a, organic
matter, and total peri-
phyton algal biomass
20
Huggins et al. 1994
100
Huggins et al. 1994
500
Huggins et al. 1994
10
80-140
80-140
(first
application);
M10-190
(second
application)
Ruth 1996
Herman etal. 1986
Herman etal. 1986
116
-------
Table 6 (Continued)
Chemical
Hardness
(mg/L as
CaCO,)
Duration
Effect
FRESHWATER SPECIES
Concentration
Reference
Lake limnocorral
periphyton community
Lake limnocorral
periphyton community
Lake limnocorral
periphyton community
Lake limnocorral
periphyton community
Lake limnocorral
community
80%
80%
80%
80%
Lake mesocosm plankton
community
Lake mesocosm plankton
community
Lake bacterial and algal
species in microcosm study
50 days • 50% reduction in ash- 80
free dry weight
230 days Reductions of • 60% in 80
biomass, • £2% in cell
numbers, and • §2% in
number of species
56 days Reductions of • 50% in 140
chlorophyll-a, • 32% in
biomass, • 14% in cell
numbers, and • §3% in
number of species
56 days Reductions of • 55% in 1,560
chlorophyll-a, • 68% in
biomass, • 19% in cell
numbers, and • 48% in
number of species
Two Different phytoplankton 100
exposures species assemblages for (P'applic.) 155
35 days up to 114 days after (2ntl applic.)
apart second application;
increased Secchi disc
readings and decreased
levels of dissolved
oxygen, chlorophyll, and
organic carbon; phyto-
plankton communities
were similar by day 323.
18 days Decreased chlorophyl-a, 1
dissolved oxygen,
nauplii, Daphnia,
Cyclops; increased
particulate organic
carbon
10 days" Decreased algal 0.1
photosynthetic
production, dissolved
oxygen and Daphnia
population; apparent
recoveries after about 25
days
Decreased algal 250
population density and
decreased "scope for
change in ascendance"
of community
Hamilton et al. 1987
Hamilton et al. 1987
Hamilton et al. 1987
Hamilton et al. 1987
Hamilton et al. 1988,
1989
Lampertetal. 1989
Lampertetal. 1989
Genoni1992
117
-------
Table 6 (Continued)
Species
Hardness
(ing/L as
Chemical CaCO,)
Duration
Effect
FRESHWATER SPECIES
Concentration
Reference
Lake mesocosm
community
Lake mesocosm
phytoplankton community
Lake mesocosm
phytoplankton community
Lake mesocosm
periphyton community
Lake mesocosm
periphyton community
Lake phytoplankton
Lake phytoplankton
Lake phytoplankton
Stream
periphyton community
Stream
phytoplankton community
Wetland
mesocosm community
85.5%
85%
20 days No effect upon tolerance 20
to atrazine by
phytoplankton and
periphyton communities
or upon length of
Cladocera; minor
changes in species
composition, POC/PON
ratio and chlorophyll
concentration
20 days EC50 58
20 days EC50 52
20 days EC50 52
20 days EC50 54
3 hr EC50 100
(carbon assimilation)
3 hr EC50 14,000
(phosphate assimilation)
3 hr EC50 >33,000
(ammonium
assimilation)
<4 hr LOEC 109
(chlorophyll-a)
Spring Reduction in 40.4
season populations of green maximum
algae
9-27 days Decreased periphyton 15
gross productivity;
increased dissolved
nutrients
Gustavson and Wangberg
1995
Gustavson and Wangberg
1995
Gustavson and Wangberg
1995
Gustavson and Wangberg
1995
Gustavson and Wangberg
1995
Brown and Lean 1995
Brown and Lean 1995
Brown and Lean 1995
Day 1993
Caux and Kent 1995
Detenbeck et al. 1996
118
-------
Table 6 (continued)
Species
Green alga,
Chlamydomonas sp.
Green alga,
Chlorella sp.
Green alga,
Chlorococcum sp.
Green alga,
Chlorococcum sp.
Green alga,
Chlorococcum sp.
Green alga,
Chlorococcum sp.
Green alga,
Chlorococcum sp.
Green alga,
Chlorococcum sp.
Green alga,
Chlorococcum sp.
Green alga,
Chlorococcum sp.
Green alga,
Chlorococcum sp.
Green alga,
Dunaliella tertiolecta
Green alga,
Dunaliella tertiolecta
Green alga,
Dunaliella tertiolecta
Green alga,
Dunaliella tertiolecta
Green alga,
Dunaliella tertiolecta
Green alga,
Dunaliella tertiolecta
Green alga,
Dunaliella tertiolecta
Green alga,
Dunaliella tertiolecta
Green alga,
Dunaliella tertiolecta
Chemical
_
Technical
80.0%
Technical
80.0%
Technical
80.0
Technical
80.0%
_
Technical
80.0%
Technical
80.0%
Technical
80.0%
Technical
80.0%
_
Salinity
(g/kg)
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
Concentration
Duration
Effect
(ug/L)
Reference
SALTWATER SPECIES
90min
90min
90min
90min
90min
90min
10 days
10 days
10 days
10 days
90min
90min
90min
90min
90min
10 days
10 days
10 days
10 days
90min
EC50
(oxygen evolution)
EC50
(oxygen evolution
EC50
(oxygen evolution)
EC50
(oxygen evolution)
EC 100
(oxygen evolution)
EC 100
(oxygen evolution)
EC50
(growth)
EC50
(growth)
EC 100
(growth)
EC 100
(growth)
EC50
(oxygen evolution)
EC50
(oxygen evolution)
EC50
(oxygen evolution)
EC 100
(oxygen evolution)
EC 100
(oxygen evolution)
EC50
(growth)
EC50
(growth)
EC100
(growth)
EC 100
(growth)
EC50
(oxygen evolution)
60
143
100
400
400
800
100
100
500
500
80
300
600
700
1,000
300
400
1,200
1,500
159
Hollister and Walsh
Hollister and Walsh
Walsh 1972
Walsh 1972
Walsh 1972
Walsh 1972
Walsh 1972
Walsh 1972
Walsh 1972
Walsh 1972
Hollister and Walsh
Walsh 1972
Walsh 1972
Walsh 1972
Walsh 1972
Walsh 1972
Walsh 1972
Walsh 1972
Walsh 1972
Hollister and Walsh
1973
1973
1973
1973
119
-------
Table 6 (continued)
Species
Salinity
Chemical (g/kg)
Duration Effect
Concentration
g/L) Reference
SALTWATER SPECIES
Green alga,
Dunaliella tertiolecta
Green alga,
Dunaliella tertiolecta
Green alga,
Dunaliella tertiolecta
Green alga,
Dunaliella tertiolecta
Green alga,
Dunaliella tertiolecta
Green alga,
Dunaliella tertiolecta
Green alga,
Dunaliella tertiolecta
Green alga,
Dunaliella bioculata
Green alga,
Dunaliella bioculata
Green alga,
Dunaliella bioculata
Green alga,
Nannochloris oculata
Green alga,
Nannochloris oculata
Green alga,
Nannochloris oculata
Green alga,
Nannochloris oculata
Green alga,
Nannochloris oculata
Green alga,
Nannochloris oculata
Green alga,
Nannochloris oculata
Green alga,
Nannochloris oculata
97% - 5 days
97% - 5 day
exposure,
9 day
recovery
97% - 5 day
exposure,
9 day
recovery
97% - 5 day
exposure,
9 day
recovery
15 min
15 min
96 hr
Technical - 48 hr
Technical - 48 hr
Technical - 48 hr
15 7 days
15 7 days
15 7 days
15 7 days
15 7 days
15 7 days
15 7 days
15 7 days
EC50
(cell number)
NOEC
(cell numbers)
Algistatic concentration
Algicidal concentration
EC50
(oxygen evolution)
EC50
(complementary area)
EC50
(cell number)
35% reduction in growth
85% reduction in growth
100% growth inhibition
21% change in doubling
time
1 1% change in doubling
time
12% change in doubling
time
34% change in doubling
time
35% change in doubling
time
33% change in doubling
time
42% change in doubling
time
35% change in doubling
time
170
< 100
1,450
>3,200
270
37
132
216
3,240
21,570
50
50
50
50
50
50
50
50
Hughes 1986; Hughes et
al. 1986, 1988
Hughes 1986; Hughes et
al. 1986, 1988
Hughes 1986; Hughes et
al. 1986, 1988
Hughes 1986; Hughes et
al. 1986, 1988
Samson and Popovic
1988
Samson and Popovic
1988
Gaggi et al. 1995
Felix et al. 1988
Felix et al. 1988
Felix etal. 1988
Karlander et al. 1983;
Mayasich et al. 1986
Karlander et al. 1983;
Mayasich et al. 1986
Karlander et al. 1983;
Mayasich et al. 1986
Karlander et al. 1983;
Mayasich et al. 1986
Karlander et al. 1983;
Mayasich et al. 1986
Karlander et al. 1983;
Mayasich et al. 1986
Karlander et al. 1983;
Mayasich et al. 1986
Karlander et al. 1983;
Mayasich et al. 1986
120
-------
Table 6 (continued)
Species
Salinity
Chemical (g/kg)
Duration Effect
Concentration
g/L) Reference
SALTWATER SPECIES
Green alga,
Nannochloris oculata
Green alga,
Nannochloris oculata
Green alga,
Nannochloris oculata
Green alga,
Nannochloris oculata
Green alga,
Nannochloris oculata
Green alga,
Nannochloris oculata
Green alga,
Nannochloris oculata
Green alga,
Nannochloris oculata
Green alga,
Nannochloris oculata
Green alga,
Nannochloris oculata
Green alga,
Nannochloris oculata
Green alga,
Neochloris sp.
Green alga,
Platymonas sp.
Diatom,
Achnanthes brevipes
Diatom,
Amphora exigua
Diatom,
Cyclotella nanna
Diatom,
Isochrysis galbana
Diatom,
Isochrysis galbana
Diatom,
Isochrysis galbana
Diatom,
Isochrysis galbana
15 7 days
15 7 days
15 7 days
15 7 days
15 7 days
15 7 days
15 7 days
15 7 days
15 7 days
15 7 days
15 7 days
30 90 min
30 90 min
30 90 min
30 90 min
30 90 min
Technical 30 90 min
80.0% 30 90 min
Technical 30 90 min
80.0% 30 90 min
28% change in doubling
time
46% change in doubling
time
35% change in doubling
time
21% change in doubling
time
59% change in doubling
time
52% change in doubling
time
47% change in doubling
time
57% change in doubling
time
56% change in doubling
time
54% change in doubling
time
change in doubling time
EC50
(oxygen evolution)
EC50
(oxygen evolution)
EC50
(oxygen evolution)
EC50
(oxygen evolution)
EC50
(oxygen evolution)
EC50
(oxygen evolution)
EC50
(oxygen evolution)
EC 100
(oxygen evolution)
EC 100
(oxygen evolution)
50
100
100
100
100
100
100
100
100
100
15
82
102
93
300
84
100
200
200
500
Karlander et al. 1983;
Mayasich et al. 1986
Karlander et al. 1983;
Mayasich et al. 1986
Karlander et al. 1983;
Mayasich et al. 1986
Karlander et al. 1983;
Mayasich et al. 1986
Karlander et al. 1983;
Mayasich et al. 1986
Karlander et al. 1983;
Mayasich et al. 1986
Karlander et al. 1983;
Mayasich et al. 1986
Karlander et al. 1983;
Mayasich et al. 1986
Karlander et al. 1983;
Mayasich et al. 1986
Karlander et al. 1983;
Mayasich et al. 1986
Mayasich et al. 1987
Hollister and Walsh 1973
Hollister and Walsh 1973
Hollister and Walsh 1973
Hollister and Walsh 1973
Hollister and Walsh 1973
Walsh 1972
Walsh 1972
Walsh 1972
Walsh 1972
121
-------
Table 6 (continued)
Species
Salinity
Chemical (g/kg)
Duration Effect
Concentration
g/L) Reference
SALTWATER SPECIES
Diatom, Technical
Isochrysis galbana
Diatom, 80.0%
Isochrysis galbana
Diatom, Technical
Isochrysis galbana
Diatom, 80.0%
Isochrysis galbana
Diatom,
Isochrysis galbana
Diatom,
Minutocellus polymorphus
Diatom,
Monochrysis lutheri
Diatom,
Navicula inserta
Diatom,
Nitzschia closterium
Diatom,
Nitzschia (Ind. 684)
Diatom,
Nitzschia sigma
Diatom,
Nitzschia sigma
Diatom, Technical
Phaeodactylum
tricornutum
Diatom, 80.0%
Phaeodactylum
tricornutum
Diatom, Technical
Phaeodactylum
tricornutum
Diatom, 80.0%
Phaeodactylum
tricornutum
Diatom, Technical
Phaeodactylum
tricornutum
Diatom, 80.0%
Phaeodactylum
tricornutum
30 10 days
30 10 days
30 10 days
30 10 days
30 90 min
72 hr
30 90 min
30 90 min
30 90 min
30 90 min
20 7 days
20 7 days
30 90 min
30 90 min
30 90 min
30 90 min
30 10 days
30 10 days
EC50
(growth)
EC50
(growth)
EC 100
(growth)
EC 100
(growth)
EC50
(oxygen evolution)
EC50
(cell numbers)
EC50
(oxygen evolution)
EC50
(oxygen evolution)
EC50
(oxygen evolution)
EC50
(oxygen evolution)
Reduced photosynthesis
Reduced chlorophyll
and cell number
EC50
(oxygen evolution)
EC50
(oxygen evolution)
EC 100
(oxygen evolution)
EC 100
(oxygen evolution)
EC50
(growth)
EC50
(growth)
100 Walsh 1972
100 Walsh 1972
200 Walsh 1972
200 Walsh 1972
100 Hollister and Walsh
50 Walsh etal. 1988
77 Hollister and Walsh
460 Hollister and Walsh
287 Hollister and Walsh
434 Hollister and Walsh
220 Plumley and Davis
2,200 Plumley and Davis
100 Walsh 1972
200 Walsh 1972
200 Walsh 1972
600 Walsh 1972
200 Walsh 1972
200 Walsh 1972
1973
1973
1973
1973
1973
1980
1980
122
-------
Table 6 (continued)
Species
Salinity
Chemical (g/kg)
Duration Effect
SALTWATER SPECIES
Diatom, Technical
Phaeodactylum
tricornutum
Diatom, 80.0%
Phaeodactylum
tricornutum
Diatom,
Phaeodactylum
tricornutum
Diatom,
Phaeodactylum
tricornutum
Diatom,
Skeletonema costatum
Diatom,
Stauroneis amphoroides
Diatom,
Thalassiosirafluviatilis
Diatom,
Thalassiosirafluviatilis
Diatom,
Thalassiosirafluviatilis
Red alga,
Porphyridium cruentum
Kelp,
Laminaria hyperborea
Kelp,
Laminaria hyperborea
Kelp, 70%
Laminaria saccharina
Kelp, 70%
Laminaria saccharina
30 10 days
30 10 days
30 90 min
7 days
48 hr
30 90 min
20 7 days
20 7 days
30 90 min
30 90 min
28 days
24 hr
30 2 days
30 2 days
EC 100
(growth)
EC 100
(growth)
EC50
(oxygen evolution)
Limited effect on
doubling time
EC50
(cell numbers)
EC50
(oxygen evolution)
Reduced chlorophyll
Reduced cell number
and photosynthesis
EC50
(oxygen evolution)
EC50
(oxygen evolution)
LOEC
(growth of new
sporophytes)
LOEC
(respiration)
No effect on sexual
reproduction
66% reduction in
fertilization
Redheadgrass pondweed,
Potamogeton perfoliatus
Redheadgrass pondweed,
Potamogeton perfoliatus
Euraisian watermilfoil,
Myriophyllum spicatum
Aquatic vascular plant,
Zannichellia palustris
99.7%
8-12 2hr
10 4hr
8-12 2hr
8-12 2hr
IC50 (photosynthesis)
IC50 (photosynthesis)
IC50 (photosynthesis)
IC50 (photosynthesis)
Concentration
g/L) Reference
500 Walsh 1972
500 Walsh 1972
100 Hollister and Walsh 1973
50 Mayasichetal. 1987
20 Walsh etal. 1988
348 Hollister and Walsh 1973
220 Plumley and Davis 1980
2,200 Plumley and Davis 1980
110 Hollister and Walsh 1973
79 Hollister and Walsh 1973
10 Hopkins and Kain 1971
>1,000 Hopkins and Kain 1971
33.2 Thursby and Tagliabue
1990
72.2 Thursby and Tagliabue
1990
77 Jones and Winchell 1984
80 Jones etal. 1986
104 Jones and Winchell 1984
91 Jones and Winchell 1984
123
-------
Table 6 (continued)
Species
Widgeon grass,
Ruppia maritima
Vallisneria,
Vallisneria americana
Vallisneria,
Vallisneria americana
Salinity
Chemical (g/kg)
Duration Effect
SALTWATER SPECIES
8-12 2hr
42 days
42 days
IC50 (photosynthesis)
47% decrease in growth
as length, and 48%
decrease as dry weight
27% decrease in growth
as length, and 30%
decrease as dry weight
Concentration
g/L) Reference
120 Jones and Winchell 1984
100 Forney 1980; Forney and
Davis 1981
100 Forney 1980; Forney and
Davis 1981
Vallisneria,
Vallisneria americana
Vallisneria,
Vallisneria americana
Vallisneria,
Vallisneria americana
Eelgrass,
Zostera marina
Eelgrass,
Zostera marina
Eelgrass,
Zostera marina
Turtlegrass,
Thalassia testudinum
Salt-marsh grass,
Spartina alterniflora
Salt-march grass,
Spartina alterniflora
Salt-marsh rush,
Juncus roemerianus
Salt-marsh rush,
Juncus roemerianus
3 42 days
6 42 days
5 47 days
24 hr
24 hr
97.2% 14 10 days
Technical 30 40 hr
99.7%
97.1% - 3 5 days
97.1% - 3 5 days
97.1% - 3 5 days
97.1% - 3 5 days
27% decreased in 320
growth as length, and
41% decrease as dry
weight
32% decrease in growth 320
as length, and 29%
decrease as dry weight
67% reduction in leaf 12
production & 76%
reduction in leaf area
Reduced net oxygen 100
evolution
No net oxygen evolution 1,000
100% growth inhibition 1,900
EC50 (photosynthesis) 320
Increased peroxidase 30
activity
No effect upon shoot 3, 100
growth, lipid
peroxidation products or
chlorophyll production;
enhanced peroxidase
activity
Reduced chlorophyl-a; 30
Increased peroxidase
activity and lipid
peroxidation products
Reduced shoot growth, 3,800
chlorophyll-a,
Forney 1980; Forney and
Davis 1981
Forney 1980; Forney and
Davis 1981
Correll and Wu 1982
Kemp et al. 1982a
Kemp et al. 1982a
Schwarzchild et al. 1994
Walsh etal. 1982
Lytle and Lytle 1998
Lytle and Lytle 1988
Lytle and Lytle 1998
Lytle and Lytle 1998
chlorophyll-a; increased
lipid peroxidation
products
124
-------
Table 6 (continued)
Species
Salinity
Chemical (g/kg)
Duration Effect
Concentration
g/L) Reference
SALTWATER SPECIES
Eastern oyster (juvenile), Technical
Crassostrea virginica 99.7%
Copepod, 97.1%
Acartia tonsa
Copepod, 97.1%
Acartia tonsa
Copepod, 97.1%
Acartia tonsa
Brown shrimp (juvenile), Technical
Penaeus aztecus 99.7%
Brown shrimp,
Penaeus aztecus
Brown shrimp,
Penaeus aztecus
Mud crab (field), 80%
Panopeus sp.
80%
Drift line crab (field),
Sesarma cinereum
Fiddler crab (field), 80%
Uca pugnax
Fiddler crab (field), 80%
Uca pugnax
Fiddler crab, 80%
Uca pugnax
(animals collected in
August)
Fiddler crab, 80%
Uca pugnax
(animals collected in
August 1977)
28 96 hr
30-34 72 hr
30-34 48 hr
30-34 24 hr
30 48 hr
24 hr
48 hr
70 days
70 days
70 days
70 days
20 8 days
20 8 days
EC50 >1,000
(shell growth)
LC50 6,100
LC50 8,400
LC50 15,000
EC50 1,000
20% mortality 1,000
30% mortality 1,000
No effect on number per 10,000,000
m2 after a single
application
No effect on number per 10,000,000
m2 after a single
application
No effect on number per 1,000,000
m2 after a single
application
94% reduction in 10,000,000
number per m2 relative
to control after a single
application
25% mortality of large 100,000
males;
100% mortality of large
females;
100% mortality of small
males;
75% mortality of small
females
50% mortality of large 1,000,000
males;
100% mortality of large
females;
Butler 1964; Mayer
McNamara 199 Ib
McNamara 199 Ib
McNamara 199 Ib
Mayer 1987
Butler 1964
Butler 1964
Plumleyetal. 1980
Plumleyetal. 1980
Plumleyetal. 1980
Plumleyetal. 1980
Plumleyetal. 1980
Plumleyetal. 1980
75% mortality of small
males,
50% mortality of small
females
125
-------
Table 6 (continued)
Species
Salinity
Chemical (g/kg)
Duration Effect
Concentration
!/L) Reference
Fiddler crab,
Uca pugnax
(animals collected in
November)
Fiddler crab,
Uca pugnax
(animals collected in
March)
Fiddler crab,
Uca pugnax
(animals collected in
August 1978)
Fiddler crab,
Uca pugnax
(animals collected in
August 1978)
Fiddler crab,
Uca pugnax
(animals collected in
August 1978)
Fiddler crab,
Uca pugnax
(animals collected in
August 1978)
Fiddler crab,
Uca pugnax
(animals collected in
August 1978)
Fiddler crab,
Uca pugnax
(animals collected in
August 1978)
SALTWATER SPECIES
80% 20 30 days No effect on survival of 1,000,000 Plumley etal. 1980
small males
80% 20 9 days No effect on survival of 1,000,000 Plumley etal. 1980
small males
80% 20 9 days 60% mortality 100,000 Plumley etal. 1980
80% 20 9 days 90% mortality 180,000 Plumley etal. 1980
80% 20 9 days 80% mortality 320,000 Plumley etal. 1980
80% 20 9 days 90% mortality 560,000 Plumley etal. 1980
80% 20 9 days 90% mortality 1,000,000 Plumley etal. 1980
80% 20 9 days 100% mortality 10,000,000 Plumley etal. 1980
Spot (juvenile),
Leiostomas santhurus
Estuarine microbial
community
Technical
99.7%
29
48 hr
7-25 9 days
LC50
Effects on phototrophic
component: chlorophyll-
a, carbon assimilation,
biovolume, and changes
in species composition
>1,000 Butler 1964; Mayer 1987
40
DeLorenzo et al. 1999a
126
-------
Table 6 (continued)
Salinity
Chemical (g/kg)
Duration Effect
SALTWATER SPECIES
Concentration
g/L)
Reference
Estuarine microbial
community
97%
24 hr Effects on phototrophic
component:
chlorophyll-a, carbon
assimilation, and
biovolume
47
DeLorenzo et al. 1999b
Mesocosm,
Mixed marine
phytoplankton
Residue
grade
15 days Reduced pH, particulate
carbohydrates,
chlorophyll,
photosynthesis, primary
production; increased
dissolved organic
phosphorus, dissolved
organic nitrogen, and
dissolved amino acids
0.12
Besteretal. 1995
Mesocosm,
Mixed marine
phytoplankton
Residue
grade
15 days Reduced pH, particulate
carbohydrates,
chlorophyll,
photosynthesis, primary
production; increased
dissolved organic
phosphorus, dissolved
organic nitrogen, and
dissolved amino acids
0.56
Besteretal. 1995
Mesocosm,
Mixed marine
phytoplankton
Residue
grade
15 days Reduced pH, particulate
carbohydrates,
chlorophyll,
photosynthesis, primary
production; increased
dissolved organic
phosphorus, dissolved
organic nitrogen, and
dissolved amino acids
5.80
Besteretal. 1995
a Test was run using a Taub and Dollar (1964) medium.
b Test was run using an algal assay medium (U.S. EPA 1971).
0 Algae were pre-conditioned for 4 days with 531 • g/L of atrazine.
d Test performed with an atrazine-sensitive strain.
" Test performed with an atrazine-resistant strain
f Nephelometric determination.
8 Colorimetric determination.
h Only 2.3 to 4.7 percent of this concentration remained on day 7.
1 Test performed with water from microcosm 30 days after atrazine had been introduced.
' Test performed directly with atrazine in water without a microcosm exposure.
k EC50 obtained using an algal assay medium.
1 EC50 obtained using creek water as the test medium.
m Animals were fed at 24 hr.
11 Two single annual applications at nominal concentration indicated.
0 Atrazine concentrations were below detection after 10 days; however, the study continued for 42 days.
127
-------
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