United States
Environmental Protection
Agency
Off ice of Water
Regulations and Standards (WH-553)
Washington DC 20460
August 1980
EPA-440/4-81-016
SERA
Water
An Exposure
and Risk Assessment
for Zinc
-------
DISCLAIMER
This is a contractor's final report, which has been reviewed by the Monitoring and Data Support
Division, U.S. EPA. The contents do not necessarily reflect the views and policies of the U.S.
Environmental Protection Agency, nor does mention of trade names or commercial products
constitute endorsement or recommendation for use.
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'REPORT DOCUMENTATION
PAGE
1. REPORT NO.
EPA-440/4-81-016
TRto md SuMttfo
An Exposure and Risk Assessment for Zinc
9. Report On*
August 1980
Perwak, J.; Goyer, M.; Nelken, L.; Schimke, G.;
Scow, K.; Walker, P.; and Wallace, D.
R«pt No.
101 PiajMfcrTMk/Wtork Unit No.
Arthur D. Little, Inc.
20 Acorn Park
Cambridge, MA 02140
IL Cantnet(O or QranMO) No.
(O 68-01-3857
Monitoring and Data Support Division
Office of Water Regulations and Standards
U.S. Environmental Protection Agency
Washington, D.C. 20460
13. lypaof (taooit A
Final
14.
Extensive Bibliographies
(Until: 200
This report assesses the risk of exposure to zinc. This study is part of a program to
identify the sources of and evaluate exposure to 129 priority pollutants. The
analysis is based on available information from government, Industry, and technical
publications assembled in August 1980*
The assessment includes an identification of releases to the environment during
production, use, or disposal of the substance. In addition, the fate of zinc in the
environment is considered; ambient levels to which various populations of humans and
aquatic life are exposed are reported. Exposure levels are estimated and available
data on toxlcity are presented and interpreted. Information concerning all of these
topics is combined in an assessment of the risks of exposure to zinc for various
subpopulations.
Exposure
Risk
Water Pollution
Air Pollution
Effluents
Waste Disposal
Food Contamination
Toxic Diseases
Zinc
idTi
Pollutant Pathways
Risk Assessment
e. C03ATI n«M/Oi«up
Release Co Public
Soantty Out
rTrif 1 aoq-f fi pH
21. Mo. of
180
22. Me*
$17.50
10
OPTIONAL FORM 272 (4-77)
(Fomwrty NTIS-39)
-------
EPA-440/4-81-016
August 1980
AN EXPOSURE AND RISK ASSESSMENT
FOR ZINC
by
Joanne Perwak
Muriel Goyer, Leslie Nelken, Gerald Schimke, Race Scow
Pamela Walker, and Douglas Wallace
Arthur D. Little, Inc.
and
Charles Delos
U.S. Environmental Protection Agency
EPA Contract 68-01-3857
Monitoring and Data Support Division (WH-553)
Office of Water Regulations and Standards
Washington, D.C. 20460
OFFICE OF WATER REGULATIONS AND STANDARDS
OFFICE OF WATER AND WASTE MANAGEMENT
_ U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
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FOREWORD
Effective regulatory action for toxic chemicals requires an
understanding of the human and environmental risks associated with the
manufacture* use, and disposal of the chemical. Assessment of risk
requires a scientific judgment about the probability of harm to the
environment resulting from known or potential environmental concentra-
tions. The risk assessment process integrates health effects data
(e.g., carcinogenicity, teratogenlcity) vith information on exposure.
The components of exposure include an evaluation of the sources of the
chemical, exposure pathways, ambient levels, and an identification of
exposed populations including humans and aquatic life.
This assessment was performed as part of a program to determine
the environmental risks associated with current use and disposal
patterns for 65 chemicals and classes of chemicals (expanded to 129
"priority pollutants") named in the 1977 Clean Water Act. It includes
an assessment of risk for humans and aquatic life and is intended to
serve as a technical basis for developing the most appropriate and
effective strategy for mitigating' these risks.
This document is a contractors' final report. It has been
extensively reviewed by the individual contractors end by the EPA at
several stages of completion. Each chapter of the draft was reviewed
by members of the authoring contractor's senior technical staff (e.g.,
toxicologists, environmental scientists) who had not previously been
directly involved in the work. These individuals were selected by
management to be the technical peers of the chapter authors. The
chapters were comprehensively checked for uniformity in quality and
content by the contractor's editorial team, which also was responsible
for the production of the final report. The contractor's senior
project management subsequently reviewed the final report in Its
entirety.
At EPA a senior staff member was responsible for guiding the
contractors, reviewing the manuscripts, and soliciting comments, where
appropriate, from related programs within EPA (e.g., Office of Toxic
Substances, Research and Development, Air Programs, Solid and
Hazardous Waste, etc.). A complete draft was summarized by the
assigned EPA staff member and reviewed for technical and policy
implications with the Office Director (formerly the Deputy Assistant
Administrator) of Water Regulations and Standards. Subsequent revi-
sions were included in the final report.
Michael W. Sllmak, Chief
Exposure Assessment Section
Monitoring & Data Support Division (WH-553)
Office of Water Regulations and Standards
ii
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TABLE OF CONTENTS
Page
I. EXECUTIVE SUMMARY 1-1
II. INTRODUCTION ' II-l
III. MATERIALS BALANCE III-l
A. Introduction and Methodology III-l
B. Materials Balance Checklist III-l
1. Primary and Secondary Zinc Production III-2
2. Production in which Zinc is a
Byproduct/Contaminant 111-10
3. Environmental Release of Zinc during
Consumptive Use III-ll
4. Other Sources 111-18
5. Municipal Disposal III-21
C. Summary 111-25
D. References ' 111-28
IV. DISTRIBUTION OF ZINC IN THE ENVIRONMENT
A. Monitoring Data IV-1
1. Zinc in Aquatic Environments IV-1
2. Zinc in Aquatic Organisms IV-8
3. Zinc in Plant Tissue IV-8
4. Zinc in Soil ' IV-9
5. Zinc in Air IV-10
B. Environmental Fate IV-10
1. Overview IV-10
2. General Fate Discussion IV-16
3. Physicochemical Pathways IV-21
4. Biological Pathways IV-47
C. References IV-55
V. Effects of Zinc V-l
A. Human Toxicity V-l
1. Introduction V-l
2. Metabolism and Bioaccumulation V-3
3. Animal Studies V-5
4. Human Studies V-13
5. Overview V-l6
iii
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TABLE OF CONTENTS (Continued)
Page
3. Effects of Zinc on Aquatic Organisms V-18
I'.j Introduction V-18
2'i.i Freshwater Organisms V-18
3'i Saltwater Organisms V-26
4. Factors Affecting the Toxicity of Zinc V-28
5. Summary of Aquatic Toxicity V-33
C. References V-35
VI. EXPOSURE VI-1
A. Human Exposure VI-l
1. Introduction VI-1
2. Ingestion VI-1
3. Inhalation VI-2
4. Absorption VI-2
B. Exposure of Zinc to Aquatic Animals VI-2
C. Conclusions VI-9
D. References VI-10
VII. Risk Considerations VII-1
A. Introduction . VII-1
B. Humans VII-1
C. Aquatic Organisms VII-3
APPENDIX A: HUMAN TOXICITY A-l
LIST OF TABLES iv.
LIST OF FIGURES v-
iv
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LIST OF TABLES
TABLE ,1
NUMBER " PAGE
" 5
III-l Summary of U.S. Zinc! Supply and Demand (1977) III-3
III-2 Summary of Environmental Releases of Zinc III-4
III-3 Zinc Releases from Mining and Milling Activities III-7
III-4 Zinc Released by Copper Mining Operations 111-12
III-5 Zinc Releases by Other Metallic Ore Mining Operations 111-13
III-6 Zinc Content in Coal Ash by Region 111-14
III-7 Other Zinc Releases to Environment by Region 111-16
III-8 Regional Distribution of Zinc Accumulation
Near Paved Roads 111-19
HI.9 Summary of POTW Zinc Budget . 111-24
III-10 Sources of Zinc to POTW 111-26
IV-1 Total Zinc in Ambient Waters 17-2
IV-2 Zinc in Sediment in U.S. River Basins 17-3
17-3 Northeast, Major Basin 1, Total Zinc in Water
for 1978 17-5
17-4 Distribution of Zinc in Stream Waters . 17-33
17-5 Profile of Zinc in Selected Sediment Cores I7.-35
17-6 Bioaccumulation of Zinc by Aquatic Organisms 17-51
7-1 Hepatomas Resulting from Zinc in the Diet of Mice 7-7
7-2 Data for Zinc-Related Fish Kills 7-19
7-3 Chronic/Sublethal Effects on Freshwater Fish 7-22
7-4 Acute Tojcicities for Freshwater Fish 7-24
7-5 Sublethal Effects of Zinc on Marine Invertebrates 7-27
7-6 Effects of Zinc on Marine Plants 7-29
71-1 Zinc Concentrations in U.S. Minor River Basins-1978 71-6
VII-1 Adverse Effects of Zinc on Mammals VII-2
711-2 Zinc Exposure to Humans VII-4
711-3 Factors Contributing to Risk to Aquatic Organisms VII-6
A-l « Acute Toxicity of Zinc Salts A-5
A-2 Assessment of Health Risks Due to Environmental
Pollutants - Human Tissue Concentrations A-6
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LIST OF FIGURES
FIGURE
NUMBER PAGE
III-l Environmental Behavior of Zinc III-5
III-2 Typical Flowsheet - Lead/Zinc Ores III-6
III-3 Location of Active and Inactive Mines in the
United States III-8
17-1 Distribution of Total Zinc in Ambient Waters in
the United States IV-4
IV-2 Zinc Concentration in U.S. Minor River Basins IV-6
IV-3 Major Environmental Pathways of Zinc Emissions IV-12
IV-4 Schematic Diagram of Major Pathways of Anthropogenic
Zinc Released to the Environment in the U.S. (1979) IV-14
17-5 Speciation of Zn (II) in Natural Fresh Waters as a
Function of pH in presence of 1.55xlO~4 ha/L SiO. IV-17
17-6 Adsorption of Heavy Metals in Oxidizing Fresh Waters
as a Function of Surface Areas of SiO. in ha/L p3s1-log
(Si02) ha/L. 17-19
17-7 Adsorption of Heavy Metals on Soil Minerals and Oxides 17-20
17-8 Zinc Content of Soils near Smelters 17-24
17-9 Zinc Content of Soils near Smelters vs. Soil Depth 17-24
17-10 Average Zn Content in Soils near Highways at
Different Soil Depths 17-27
17-11 The pH in Kerber Creek 17-31
17-12 Dissolved Zinc Concentrations in Kerber Creek IV-31
17-13 Bicarbonate Concentrations in Kerber Creek 17-32
17-14 Concentrations of Zinc vs. Sediment Depth of a
Polluted Lake 17-40
17-15 Total Zinc in Sewage, Grand Rapids, Michigan 17-44
17-16 Partitioning in Biota, Sediments, and Water 17-52
71-1 Ratio of Observed Zn and Criteria Zn (Acute) 71-4
71-2 Ratio of Observed Zn and Criteria Zn (Chronic) 71-5
vi
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ACKNOWLEDGMENTS
The Arthur 0. Little, Inc., task manager for this study was Joanne
Pervak. Other major contributors vere Muriel Goyer (human effects'),
Leslie Nelken (environmental fate), Gerald Schimke (materials balance),
Kate Scow, (biological fate), Pamela Walker (materials balance),
Douglas Wallace (biotic effects and exposure and monitoring data)',
Melba Wood (monitoring data), and Alfred Wechsler (technical review).
vii
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I. EXECUTIVE SUMMARY
MATERIALS BALANCE
Approximately 1.19 million metric tons (MT) of zinc were consumed in the
U.S. in.1977, about half of vhich was imported. Zinc is used primarily
in metallic form in galvanising (41%), alloys and die casting (36%),
brass (12%), and rolled zinc (3%) in construction, transportation,
electrical, machinery and other industries. The remainder (8%) is used
as zinc oxide and other zinc compounds, which are used in a wide
variety of products, such as plastics, paper, paints and cosmetics.
Less than 10% of the zinc supply is recycled domestically. An unknown
amount is accumulating within the economic system, and the remainder is
released to the environment, primarily as solid wastes disposed of to
land. Refuse comprised of spent products containing zinc, ore mine
tailings, metals working wastes, coal ash, and municipal and industrial
sludges constitute major sources of landfilled zinc. In addition, sig-
nificant quantities of zinc are agriculturally landspread as fertilizer
adjuvant.
The largest input of zinc to water results from erosion of soil particles
containing natural traces of zinc (45,400 MT/yr). Culturally accelerated
erosion accounts for 70% of this soil loss; geologic or natural erosion
constitutes the other 30%. However, as this source is dilute and widely
dispersed it is unlikely to result in significantly elevated aquatic
concentrations. On the other hand, urban runoff (5250 MT/yr), inactive
mine drainage (4060 MT/yr), and municipal and industrial effluents
(17,000 MT/yr combined) are smaller but more concentrated sources,
capable of affecting many local areas. Drainage from active mining
areas is considerably less than from inactive areas due to the disposal
methods currently employed.
1-1
-------
POTW represent the largest total point source zinc discharges, receiving
contributions from water supply and distribution system corrosion, com-
bined sewer area runoff, industrial wastes, and human excrement.
Industries with large discharges of zinc directly to water include
iron and steel, zinc smelting (primarily from a single mill), and
possibly plastics and electroplating.
The total quantity of zinc estimated to be emitted to air (7130 MT/yr)
is a small portion of the total environmental release. Refuse inciner-
ation, coal 'combustion, and some metals working industries constitute
the major sources. Along with releases of zinc through metal corrosion
and tire abrasion, these sources contribute to urban runoff contamination.
DISTRIBUTION OF ZINC IN THE ENVIRONMENT
Zinc in ambient water is usually found at concentrations of less than
50 ug/1. However, in many locations concentrations of 100-1000 ug/1
are -found. The fact that higher concentrations are more common in
New England, the Southeast, the Missouri River Basin, the Rio Grande
River Basin and the Upper Colorado, appears to be correlated with
mining activities in these areas. However, in all river basins there
are some locations with zinc concentrations of 100-1000 ug/1.
Zinc has a tendency to absorb to sedimentary material. Con-
sequently, anthropogenic discharges of zinc in excess of levels naturally
in equilibrium with aquatic sediments result in removal from the water
column and enrichment of sediments. Severe zinc contamination thus
tends to be confined to the region of the source. Zinc in the water
column is primarily in the form of the free ion.
Zinc is generally found in soils at concentrations between 10 mg/kg and
300 mg/kg, with a mean of about SO mg/kg. Soils near highways and
smelters have been found to contain higher concentrations, due to
deposition of zinc released in tire abrasion and stack emissions.
1-2
-------
The mobility of sine in soil depends on Che solubility of the compound
and, to some extent, on the soil properties. Zinc in a soluble form,
such as zinc sulfate, is fairly mobile in most soils. However, as ';:
- - ~ - i \
relatively little land disposed zinc is in soluble form, the slow race
'
of dissolution will limit mobility. Consequently, movement toward ';'
groundwacer is expected to be slow unless zinc is applied to soil in
soluble form (such as in agricultural applications) or accompanied by
corrosive substances (such as in mine tailings). The transport of
soil zinc may also result from surface runoff or entrainment of
.particles into the atmosphere.
Annual average airborne zinc concentrations in urban areas of the United
States are generally less than 1 ug/m . Although data are sparse,
higher airborne concentrations of zinc would be expected in the vicinity
of iron and steel-producing plants and zinc smelters. Atmospheric
emissions of zinc, consisting primarily of zinc sorbed to submicron
particulate matter and the oxide of zinc, are expected to be short-lived
in the atmosphere, with deposition upon soil and pavement occurring as
fallout and washout.
EFFECTS OF~ZINC
Zinc is an essential trace element in human and animal nutrition; the
recommended dietary allowance for humans is 3-15 mg/day in humans.
Zinc deficiency in humans has been associated with such effects as
growth impairments, inhibition of sexual maturation, loss of appetite,
inability to gain weight, skeletal abnormalities, perakeratotic
esophageal and skin lesions, and hair loss.
Moderately high levels of zinc appear to have few adverse effects on
humans or animals; the metal has not been shown to be either carcinogenic
or mutagenic. Human survival has been reported after ingestion of up
to 12,000 mg of metallic zinc, and most individuals appear capable of
ingesting 150 mg zinc on a daily basis without adverse effect.
Vomiting and diarrhea, acting to reduce further assimilation, are
1-3
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generally Che threshold effects. However, it Is zinc's disagreeable
metallic taste which constrains the drinking water criterion to 5 mg/1,
well below any emetic threshold.
Inhalation of zinc oxide at concentrations of 15 mg/m of zinc or above
produces fever, malaise, headache, and occasional vomiting, thus
necessitating the occupational exposure standards currently in effect.
The effects of zinc on aquatic organisms are of more concern. Several
fish kills in recent years have been attributed to zinc from runoff and
discharges from mining areas and smelters. However, the concentrations
causing mortality were generally not well documented, and in many cases,
high levels of other metals were also present.
In the laboratory, avoidance reactions have been observed in rainbow
trout at concentrations as low as 5.6 ug/1. Effects on growth,
reproduction and survival are reported in various freshwater fish
species after chronic exposure to concentrations of 106-1150 ug/1.
There are not enough data to permit generalizations concerning inverte-
brates as a group. The proposed fresh water criterion ranges from
approximately 15-80 ug/1 depending on hardness.
Acute toxicity studies have been conducted for many species of fresh-
water fish. LC.Q values range from 90-103,000 ug/1, with salmonids
and striped bass reported as being the most sensitive. Invertebrates
are, with some exceptions, sensitive to the same range of concentrations.
The limited information available suggests that marine invertebrates
are less susceptible than freshwater species. Marine invertebrates
such as oysters and crabs exhibit growth reductions at 50-125 ug/1.
A strong negative correlation between water hardness and zinc toxicity
has been confirmed for freshwater organisms. The effects of temperature,
pH, and other water quality parameters are not as well understood.
1-4
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EXPOSURE AND RISK
Humans are primarily exposed to zinc through ingestion; the dietary
intake of an average teenage male has been estimated to be 18.6 mg
zinc/day. Dietary supplements may provide up to an additional 75 mg
zinc per tablet. The mean intake of zinc in drinking water is 0.4
mg/day (maximum of 26 mg/day). Negligible quantities are inhaled in
ambient air. Since humans are able to tolerate 150 mg/day without
adverse effects, little risk appears to be associated with these
exposures.
Exposure of aquatic organisms to 100-1000 ug/1 total zinc is common
in the United States, especially in New England, the Western Gulf and
the Southeast regions. Since calcium hardness appears to mitigate the
toxicity of zinc, risk may be greater in New England and parts of the
Southeast, which have soft water.
Salmonids and invertebrates are acutely sensitive to zinc concentration
in the range of 100-1000 ug/1. Over 202 of the water samples taken
nationwide have zinc concentrations exceeding 100 ppb. About 25Z of
all samples exceed the proposed chronic exposure water quality criterion.
However, there is some uncertainty in estimating risk "fronTIaboratory
toxicity data coupled with ambient monitoring data. Organisms in the
environment may be somewhat less susceptible to toxicity than those in
the laboratory due to differences in the make-up of the two systems.
Compared to laboratory waters, where the toxic free ion of zinc can be
expected to predominate, a portion of zinc in environmental waters may
be adsorbed to solids or, under certain conditions, complexed with
organic or inorganic material. In addition, acclimation may occur in
environments receiving chronic exposures.
Consequently, estimation of the actual ecological risk due to zinc
requires closer examination of areas having elevated aquatic zinc levels,
employing both field and laboratory measures of stress. Also needed is
a better understanding of the relationship between toxicity and chemical
speciation of zinc.
1-5
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II. INTRODUCTION
The Office of Water Planning and Standards, Monitoring and Data Support
Division of the Environmental Protection Agency is conducting a program
to evaluate the exposure to and risk of 129 priority pollutants in the
nation's environment. The risks to be evaluated included potential
harm to human beings and deleterious effects on fish and other biota.
The goal of the task under which this report has been prepared is to
integrate information on cultural and environmental flows of specific
priority pollutants and estimate the risk based on receptor exposure to
these substances. The results are Intended to serve as a basis for
developing suitable regulatory strategy for reducing the risk, if such
action is Indicated.
This report is intended to provide a brief, but comprehensive, summary
of the production, use, distribution, fate, effects, exposure, and po-
tential risks of zinc. There are a number of problems with attempting
such an analysis for zinc. Since the purpose of this report is to pro-
vide a basis for regulation, it is important to identify sources. However,
zinc is an element commonly found in the earth's crust and natural sources
to waterways can be significant. Thus in any analysis of discharges or
runoff, it is important to distinguish background concentrations or natural
sources from anthropogenic sources. We have attempted to do this to the extent
possible, but in discharges from Publicly Owned Treatment Works (POTW) facilities,
for example, it is difficult to trace back to the sources, natural or anthropogenic
In addition, the aquatic chemistry of zinc is complex. Other metals are
commonly found with zinc, making the situation more complicated due to
possible interactions. We have used information available on the aquatic
chemistry of zinc to draw conclusions regarding specific fate pathways
as related to sources.
Finally, zinc is a nutritional requirement, and zinc deficiency could be
considered a risk. However, for the purposes of this risk assessment
II-l
-------
we have discussed zinc deficiency cursorily to establish a range of accep-
table doses. We have concentrated on assessing the risks due to exposure
to high levels of zinc.
This report is organized as follows:
Section III contains information on the production* discharge
(point and non-point) and disposal of zinc.
Section IV describes available monitoring data and a consider-
ation of the fate of zinc in five specific pathways.
Section 7 considers reported effect levels for humans and
aquatic organisms.
Section VI discusses exposure scenarios for humans and
aquatic organisms.
Section VIZ discusses risk, to various subpopulations of
humans and aquatic organisms.
II-2
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III. MATERIALS BALANCE
A. INTRODUCTION AND METHODOLOGY
In this section, data on sources of zinc and pathways of entry" into
the environment are identified. Current and past EPA- reports, readjLly
available literature and personal contacts with EPA and industry ex-
perts at Arthur D. Little, Inc., were used to estimate environmental
loadings of zinc. The environmental compartments (air, land, water,
etc.) initially receiving and transmitting the element were studied,
as were the locations at which the environmental loadings take place.
There are many uncertainties in this analysis: current releases have
not been identified from all sources, past releases are not well doc-
umented, and future releases may occur at undefined locations. 'Never-
theless, sufficient information is available to indicate the nature
and scale (temporal and geographical) of environmental discharge of
zinc.
B. MATERIALS BALANCE CHECKLIST
Zinc is one of the major common metals (iron, aluminum, copper, lead,
zinc). It.is moderately abundant in the earth's crust with an average
concentration, of about 70 ppm. Soil content of zinc varies depending
upon geologic composition and land use, ranging between 10 and 330
ppm. Soils.tested near highways have shown higher zinc concentrations
due to runoff from rubber tire wear, automobile transmission oil, and
galvanized highway structures and automobile parts. Industrial areas
contain roughly twice as much zinc as rural areas; a-test at Grand
Rapids, Michigan, showed 56.6 ppm zinc in urban and industrial areas
and 22.1 ppm and 21.1 ppm in nearby agricultural and residential ar-
eas, respectively (NRC, 1979).
In 1977, total U.S. industrial demand was 1.19 million metric tons.
The projected annual growth rate for zinc production is 2.0Z through
-------
the year 2000. Domestic reserves are approximately 21.3 million met-
ric tons; therefore, United States production is not expected to meet
the domestic demand. Worldwide reserves are estimated to be 154.2
million metric tons, sufficient for projected demand (Versar, 1978).
Table III-l summarizes the commercial sources and uses of zinc.
Environmental releases from production as veil as consumption and
uses, disposal and reclamation, are presented in Table II1-2 and vis-
ualized in Figure III-l. Zinc is consumed in galvanizing, metal al-
loys manufacturing and die-casting, brass products, iron and steel
production, vulcanization of rubber, plastic products, paper products,
and in various compounds used in paints and cosmetics. The zinc pro-
duction industry itself, iron and steel industries, and galvanizing
operations or loss from galvanized products account for the major
environmental releases.
1. Primary and Secondary Zinc Production
Zinc is mined at nearly 30 mines and produced at six smelters in the
United States which provide a major source of environmental inputs; a
typical flow sheet for the zinc production process is shown in Figure
III-2. Table III-3 quantifies zinc production and beneficiation by
state with consequent water and land emissions. The major portion of
zinc ore is mined by conventional underground mining methods. The
five states of Missouri, Tennessee, Idaho, New York and Colorado ac-
count for over 85% of all zinc mined. Active zinc mines are shown in
Figure III-3. Following extraction, it is crushed in the mills and
concentrated by differential flotation. Although losses to the atmos-
phere are relatively small, some loss does occur during blasting, ore
handling, crushing, and through fugitive dust emissions from tailings.
Primary production presents a source of waterbome zinc, particularly
when water pumped from Che mine is utilized in the concentrating pro-
cess . Other stages in the production process with potential for wat-
erborne zinc emissions include: grinding at the mill; flotation cells
in zinc, lead and copper operations; thickening (concentrate thick-
rii-2
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Table III-l
Summary of U.S. Zinc Supply and Demand (1977)
Supply Consumed
Metric Tons (MI) (Ml)
Domestic Production
Mine Production (net) 415*406
Secondary Production 77,095
Imports, Exports, Stocks
Imports (metal) 523,339
Imports (ores & concentrates) 111,561
Imports-Exports (compounds) 13,605
Industry Stocks (1/1 - 12/31) 49,885
Consumptive Uses
Galvanizing 488,266
Zinc Alloys Mfg. 428,720
Brass Products 142,906
Zinc Oxide Production 47,637
Rolled Zinc 35,727
Other Zinc Compounds 47.635
Total 1,190,891 1,190,891
Source: Versar, 1978.
Note: The above figures are for one year. There is considerable
statistical variation from year to year; consequently, these
do no.t reflect average values.
Ill-3
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Table III-2
Summary of Environmental Releases of Zinc (MT/Year)
Air
Direct
Aquatic
Mine Production
Smelting
Secondary Productivity
Galvanizing Production
Zinc Alloys Mfg.
Brass Products
Iron & Steel Production
Coal Combustion
Coal Mining
Copper Mining
Other Metallic Ore Mining
Paper Products
Plastic Products
Electroplating
Inactive Mines
flther Industries***
Area Sources:
Galvanized Mat'l Decay
Tire Abrasion
Agricultural
Applications
Suspended Sediment
Incineration/Refuse
»
POTW
Total 7,125
Urban Runoff Component**
1141
7543
9032
no> 2
101'2
8141' 2
1.4201
Al
A1
A2
A2
A1
A
None
N/A
N/A
None
a.ooo1
None
1,100 l2
A2
A2
A2
A2
2,588 2
450 12
1,500 2
I1 '
1,100 2
1,700 2
414 lf
4,06013
270 12
*
*
*
45,4003,8
None
7.81410
66,474
5,250
POTW
None1
None1
I1
None1"
None1
None1
None1
A
N/A , -
1,620!?.9
None
96012
*
*
None
None
2,906
Land
30,660^
22.7101
N/A
N/A 12
2.0901'2
180lf 2
43,0671'2
14.2401
A1
6.5121
None
1
N/A
N/A
966
1'
432,800^
6,808 "H 5
57.0001
14.26910
687,302
*Portions of these .releases enter directly or indirectly through the water compartment
through groundwat'er, surface runoff, etc.; however, due to the uncertain nature of
the release, contribution to water cannot be identified quantitatively.
**Galvanized material decay and tire abrasion are among the sources of zinc to
urban runoff.
***Includes 624 MT to POTW from carwashes.
A Insignificant. - - -
Sources:
'Arthur D. Uccla, lac.,
Induscry Experts
Vrersar. 1978
3SRC. 1979
uChriseensen £C al., 1979
SBOT, 1978
SSRI, 1979
7Andersoo, 1977
^tschmeier, 1976
^Bureau of Mines
1"Table III-9
11EPA, September, 1979
I2Versar, [yec] unpublished
eonauaieaeion, 1979
13Marcln and Mills, 1976
III-4
-------
Imports 698,000 m.t.
Domestic 493,000 m.t.
Other 4%
Rolled Zinc 3%
Erosion- \
Suspended
Sediment
45,000 m.t \
Industry
Brass Prod. 12%
Zinc Oxide 4%
Agriculture
56,000
Refuse
60,000
Tires
6,000
Consumptive
Emissions
Air
7,000 m.t.
POTW
Environmental
Compartments
Note: Boundaries between receiving "medium are often undefined and/or changing: Zinc apparently released to one
compartment can result in another.
Includes discharge to POTW » 7814 m.t.
Source: Arthur 0. Little, Inc.
FIGURE III-1 ENVIRONMENTAL BEHAVIOR OF ZINC
III-5
-------
Figure III-2.
TYPICAL FLOWSHEET - LEAD/ZINC ORES
MIME
(Underground^
Mine Water
1
Vacer 1
"" Recycle """7
MILL
(BENEFICIATION)
Zinc
Concentrate
TAILINGS
I
Overflow Unless
Zero Discharge
Lead
Concentrates
Lead
Metal
III-6
-------
Table III-3
Zinc Releases from Mining and Milling Activities
(Zinc - ilead - Lead/Zinc Mines)
VA
New York
Tennessee
Missouri
Pennsylvania
Idaho
New Mexico...
Colorado
Wisconsin
Virginia
Utah
Arizona
Washington
TOTAL
.V
?>
Concentrate Zinc Released
Ore Mined Produced to Water
1000 MT/Yr 1000 MT/Yr MT/Yr
Zinc Deposited
as Solid Wastes
MT/Yr
1,124
2,260
7,663
348
- 1,185
122
903
334
541
196
83
273
15,032
131
137
611
-
144
69
125
16
31
37
5
16
0.712
0.537
1.873
7.877
54.512
0.180
0.947
4.006
1.749
-
-
0.199
72.592
5,000
1,600
10,650
900
3,050
360
2,920
1,800
2,500
600
240
1,040
30,660
Source; Arthur-D. Little, Inc., Estimates and EPA, NPDES data.
III-7
-------
*'Active Copper Mines
I
O Active 7ir.r.Uad Lead/Zinc Mines
A Inactive Or* and Mineral Mines
(Martin and Mill* 1976)
M
I
CO
FIGURE 111-3 LOCATION OF ACTIVE AND INACTIVE MINES IN THE UNITED STATES
Nc N rs -es
/ei In igi >ns
-------
eners are either discharged or recycled); and seeding (treatment
lagoons) (NRG, 1979). The effluent limitation guidelines of the EPA
for zinc content in water effluents from these operations is 0.50 mg/1
(30-day average) effective July 11, 1978 (Federal Register). Prior to
regulation, most discharges were in the range of 0.50 mg/1 with some
higher. Currently all mines and mills operate within that qualifi-
cation except one mill- (in Idaho) which is in the process of upgrading
that situation. At the present time, there are no regulations for
solid wastes. The zinc content in tailings is that zinc which could
not be recovered. It is in the form of zinc sulfides and silicates in
locked silica waste particles and is insoluble. All of the mines
included in the survey presented in Table III-3 are underground mines
and essentially have no solid mining waste piles.
Drainage from mine tailings ponds presents an additional source of
zinc to the environment. At active mine sites, the contribution is
minimal and is accounted for in direct aquatic discharges. Associated
tailing ponds are controlled by containment structures such that or-
dinary runoff is routed through treatment facilities. Therefore, zinc
discharge to streams emanating from active mine tailing piles is in-
cluded in the determination of total mining discharge to water, pre-
sented in Table III-2. Significant storm events in which flooding
occurs can provide a rare additional aquatic discharge from this
source.
Mining operations studied in the above analysis were active; however,
runoff from abandoned or inactive mines represents an additional
source. A study conducted in 1976 compiled local analyses of stream
quality data upstream and downstream of abandoned/inactive mine sites.
Daily loads of various constituents, including zinc, were determined.
Load factors were extrapolated for each mine and combined with asso-
ciated waste areas to obtain an annual loading of 4060 metric tons of
zinc (Martin and Mills, 1976). Emphasis should be placed on the rough
nature of this approximation. This release is independent of active
mine operations and therefore is included in Table III-2.
III-9
-------
The contribution of zinc smelting operations to the environment occurs
in the roasting, sintering and electrolytic process and through verti-
cal retorts. Concentrated zinc ore goes through a roasting procedure
to drive off sulfur dioxide, SC>2, and convert the zinc sulfide, ZnS,
to zinc oxide, ZnO. This process releases over 50% of the total at-
mospheric emission during primary production (EPA, 1972). In sinter-
ing, lead and cadmium impurities are volatilized and discharged into
the stream from which they are extracted. The .sintering process also
prepares the material for the reduction system. Atmospheric emissions
are controlled, usually by bag-houses; therefore, the major portion of
environmental release from the smelting operations is to land disposal
areas.
Secondary or recycled zinc is an important source of zinc in the Unit-
ed States today. Zinc scrap materials are composed of residual scrap
materials and metallic scrap. It can be recovered by rerneIting, as in
the'case of brass, or by a sweating and distillation process for other
scraps. Releases of zinc to the atmosphere from these processes aver-
age 9 kg/ton/produced (NRG, 1979). Total emission from this source is
estimated to be 754 metric tons for 1972. As secondary production
becomes a more important source of zinc in the future, total zinc
emissions will increase.
2. Production in which Zinc is a Byproduct/Contaminant
Zinc is a byproduct/co-product/contaminant in the mining and produc-
tion of several other metals and in the manufacture of various chemi-
cal compounds and products. Lead is frequently mined in conjunction
with zinc. Lead and lead related operations are included in the in-
formation presented in Table III-3. Of the 38 major copper mines in
the United States producing 250 million metric tons of ore, and sub-
sequently 1.50 million metric tons of copper, few have any appreciable
zinc content in effluents or solid wastes. Copper mines indicating
detectable concentrations of zinc are presented in Table III-4; re-
maining copper mines either have no discharge or contain only trace
111-10
-------
Table III-4
Zinc Released by Copper Mining Operations
Effluents
Solid Waste in Tailings
Underground Mine,
Tennessee
Open Fit Mine,
Montana
Underground Mine,
Michigan
Open Pit Mine,
Utah
TOTAL
Daily Accumulated
Discharge Zn Discharge Total Amount Zinc Added
m^/day Per Year MI of Zinc MT per year MT
32,700 0.48
35,960 0.66
121,120 1.77
84,400
1.54
4.45
32,000
72,480
Trace Only
7.500
111,980
4,000
3,020
157
7,177
Mining operations presented are those with detectable zinc concentrations;
others operate without discharge or contain zinc only as a trace element.
Source: Arthur D. Little, Inc., Estimates and EPA, NPDES data.
III-ll
-------
amounts of zinc (Arthur D. Little, Inc., Industry Experts, 1979).
Several additional metallic ores have effluents containing small a-
mounts of zinc; those that are detectable are .shown in Table III-5.
Solid wastes at these sites contain zinc, but"again, only as a trace
element. ,'
Zinc appears in the ash of most coals only in traces. However, the
approximately 400 million metric tons of coal burned each year yields
about 40 million metric tons of coal ash per year containing a total
of 14,240 metric tons of zinc. Table III-6 shows regional variation
of zinc content in coal ash. This solid waste is stored in ponds and
piles, and some is recovered. Atmospheric emission from coal com-
bustion is variable and, to date, poorly documented. Based upon con-
servative estimates that approximately 1.0£ of the coal ash escapes to
the environment, roughly 1420 metric tons of zinc would be emitted
annually.
Zinc oxide is widely used in U.S. industry. Its most important ap-
plication is in production of rubber. Zinc oxide can be produced
chemically or by direct or indirect pyrometallurgic methods. Zinc
emissions to the atmosphere from this production was estimated as high
as 7300 metric tons in 1969 (NRC, 1979).
3. Environmental Release of Zinc During Consumptive Use
Of the 1.19 million metric cons of zinc consumed in 1977, 34% was used
directly in metallic form (Versar, 1978). Emissions from consumptive
uses of zinc are presented in Table III-2. Manufacturing uses of zinc
include galvanizing, brass products, die castings and rolled zinc.
The construction industry consumes the largest quantity of zinc in the
following applications: protective coating for structural steel,
roofing, siding, guttering, and reinforcing bars. Galvanized sheet is
the standard duct material for air conditioning, ventilating, and
heating systems. In architectural construction, brass and zinc-bear-
ing bronze are frequently used for door and window frames, railings,
111-12
-------
Table III-5
Zinc Releases by Other Metallic Ore Mining Operations
South Dakota: Gold Mine
New Mexico: Molybdenum Mine
Idaho: Silver Mine, A
Idaho: Silver Mine, B
Colorado: Molybdenum Mine
California: Tungsten Mine
Arkansas: Bauxite A
Arkansas: Bauxite B
Arkansas: Vanadium
New York: Titanium
TOTAL
ttitLuENTa
Dally Discharge
m3/day
625
11,000
682
3,133
11,000
33,000
41,640
7,190
2,682
21,000
Zinc Dischargi
Per Year MT
0.01
0.08
0.01
0.03
0.12
0.24
0.30
0.05
0.02
0.23
1.09
Source: Arthur D. Little, Inc., Estimates and EPA, NPDES Data.
rn-13
-------
Table III-6
Zinc Content in Coal Ash by Region
Zinc Content per Zinc in Coal Ash
Volume Ash (%) MT/Yr
Eastern Region (Appalachia, etc.) 0.0230 3,340
Interior Province (Illinois,
Kansas, Ohio, etc.) 0.0743 8,090
Western Region (Wyoming, Montana,
Utah, etc.) 0.0258 2.810
TOTAL 14,240
Source: Arthur D. Little, Inc., Estimates and EPA, NPDES data.
111-14
-------
panels, spandrels, and building hardware. Brass fittings are used in
plumbing and heating systems as faucets, valves, traps, pump casings,
and brass condenser and heat exchanger tubes (Versar, 1978). Although
the nature and quantities of these industrial applications are fairly
well defined, the discharges related to use and ultimate disposal
cannot be predicted accurately.
The protective nature of zinc coatings to many metals indicates its
frequent environmental release; its function is to be sacrificially
corroded. Assuming a 15- to 20-year average life span for galvanized
products, up to 430,000 metric tons may be released annually. If
galvanized products are distributed in proportion to population dis-
tribution, regional release would be as shown in Table III-7.
Although the quantity of zinc consumed by the electroplating industry
is relatively small by comparison to other metals, e.g., nickel, the
process releases some zinc to the aquatic environment. Based on esti-
mated consumption by the Bureau of Mines (BOM, 1979; and American Iron
and Steel Institute, 1978) approximately 25,000 metric tons of zinc
are consumed annually for electrolytic galvanizing of sheet and strip
metals; an additional 5,000 metric tons of zinc are consumed annually
for miscellaneous electroplating applications. Because of zinc's
relatively minor role in the industry, these estimates might vary
slightly (-1,000 to 5,000 metric tons). Conservative estimates by
both BOM (1979) and Arthur D. Little, Inc., conclude that no more than
10% of that consumed is released to the environment (i.e., 3,000 met-
ric tons released). EPA reports that 54Z of the electroplating opera-
tions discharge to POTW's; of those remaining, approximately 70% of
the zinc is captured by treatment systems and disposed on land as
sludge and the remainder is discharged directly to water.
An alternate estimate of zinc discharge due co electroplating sug-
gested that approximately 38,900 metric tons are released (Versar,
1979). Considering the approximate consumption of zinc by the in-
111-15
-------
Table III-7
Other Zinc Releases to Environment by Region
Tire Abrasion Galvanized Decay
MT/Yr MT/Yr
New England
(ME, NH, VT, RI, CT, MA) 361 25,500
Middle Atlantic
(NY, NJ, PA) 780 82,600
East North Central
(OH, IN, U, MI, WI) 1,295 87,300
West North Central
(MN, IA, MO, ND, SD,
NE, KS) 580 37,200
South Atlantic
(DE, MD, DC, WV, VA,
NC, SC, GA,FL) 1,217 62,700
East South Central
(KY, TN, AL.MS) 510 29,000
West South Central
(AR, LA, OK, IX) 770 41,100
Mountain
(MT, ID, WY, CO, NM,
AZ, UT, NV) 345 16,400
Pacific
(WA, OR, AK, HI, CA) 950 51.000
TOTAL 6,808 432,800*
Source: Arthur D. Little, Inc., Estimates; DOT, 1978; Christensen,
1979; and Bureau of Mines, 1978.
*
Averaged over five year period, Bureau of Mines.
rii-16
-------
duatry (30,000 *5,000 metric tons), perhaps the sampling used to de-
termine concentrations was unrepresentative.
The transportation industry is a consumer of galvanized sheet steel,
die-cast alloys, and brass. The majority of die castings are used for
automobile components. Brass is used for radiators, tubing, and dec-
orative trim. Galvanizing is effective in protecting steel products
such as railroad equipment, ship hulls, aircraft, buses, trucks,
trailers, and large-scale industrial equipment. Zinc-rich paint,
which is developing a fast growing market, is used to supplement gal-
vanized 'steel for automotive underbody protection. Zinc is a minor
constituent of automobile fuels and lubricating oils.
A remaining 13% of zinc consumed in metal is distributed in a variety
of miscellaneous applications: battery cases, weather-stripping,
litographic plates, sacrificial anodes for ship hulls, offshore drill-
ing rigs and production (Versar, 19/8).
Zinc and its components are being used increasingly in the chemical-
metallurgic, ceramic, fertilizer, paint, paper, plastics, rubber,
textile and electronic industries. As a binding material, zinc oxide
aids in the vulcanization process in tire making; by weight, tires are
estimated to contain 0.73% zinc (Christensen e£ a^., 1979). Abrasion
on road surfaces during normal tire wear contributes 6800 metric tons
zinc to surrounding soil and water systems as shown in Table III-7,
column 1 (Christensen, 1979; DOT, 1978). Zinc concentration in soils
near highways has been reported as a function of distance from the
road and depth below the ground surface at four locations (NRC, 1979).
Concentrations eight meters from the road exceeded 140 ppm above the
background level. Considerable variability was indicated between
different locations, but the data were analyzed to estimate an average
zinc accumulation of 13 pounds per mile. The probable range of values
is estimated at between 6.5 and 20.3 pounds per mile. Using Che aver-
111-17
-------
age value and paved road mileage in Che United States, it is esti-
mated that some 11,537 MT of zinc has accumulated within 60 meters of
U.S-. highways.
Table III-8 shows the geographic regional distribution of the zinc
accumulation along roads, and compares it with the annual amount of
zinc released through tire abrasion. It can be seen that the amount
accumulated generally represents less than two years worth of loss
from tire abrasion. This would indicate that a large percentage of
abrasion loss finds its way directly to water.
4. Other Sources
Urban runoff transports a significant portion of environmentally emit-
ted zinc. Numerous sources are responsible for this occurrence; how-
ever, due to the variable conditions surrounding zinc consumed in the
urban environment, it is difficult to determine quantitative estimates
of specific sources to urban, runoff. As shown in Table III-2, urban
runoff is not an independent emission of zinc, rather is comprised of
the other sources listed in the table; to prevent double counting,
urban runoff is presented separately from the summation of zinc re-
leases .
Zinc contained in urban runoff was estimated using EPA information
gathered nationwide on combined sewer overflows and stormwater dis-
charges (EPA, 1977). Zinc concentrations were obtained from a variety
of field studies (Shaheen, 1975; Pitt, 1978; Illinois EPA, 1978; Mat-
traw; Colston, 1974) and results ranged from 87 ug/litre to 750 ug/li-
tre. Based on a zinc concentration of 250 yg/litre, 5250 metric tons
of zinc is discharged in urban runoff each year.
mileage is based on bituminous (or higher grade) surface roads
in the United States.
III-L8
-------
Table III-8
Regional Distribution of Zinc
Accumulation Near Paved Roads
Accumulation Tire Abrasion Equivalent Time
MT MT/Yr Years
New England
(ME, NH, VT, RI, CT, MA) 504 361 1.4
Middle Atlantic
(NY, NJ, PA) 1,163 780 1.5
East North Central
(OH, IN, IL, MI, WI) 2,104 1,295 1.6
West North Central
(MN, IA, MO, ND, SO,
NE, KS) 1,225 580 2.1
South Atlantic
(DE, MD, DC, WV, VA,
NC, SC, GA, FL) 1,965 1,217 1.6
East South Central
(KX, TN, AL, MS) 1,076 510 2.1
West South Central
(AR, LA, OK, TX) ' 1,366 770 1.8
Mountain
(MT, ID, WY, CO,
NM, AZ, UT, NV) 1,042 345 3.0
Pacific
(WA, OR, AK,. HI, CA) 1.092 950 1.1
TOTAL 11,537 6,808 1.7
wRC (1979) presents data from which average roadside accumulation has
been estimated as 13 -oI5 pounds of zinc per mile of highway. Regional
mileage figures are based on bituminous, or higher grade, surfaced roads.
111-19
-------
Galvanized material decay represents the most significant potential
source to urban runoff; if a correlation between population distri-
bution and galvanized material consumption were assumed, approximately
702 of all galvanized material (roughly 300-,000 MT annually) would be
located in the nation's cities and susceptible to decay. The via-
bility of this assumption is questionable, however, particularly when
considering zinc utilized in highway guardrails and other construction
items used frequently in rural areas. Automobiles are an additional
potential source of zinc in urban runoff. Here again, however, the.
urban component is ambiguous.: tire abrasion occurs .in non-urban areas
. /
due to high speed travel, yet fast stops, tire skidding and dripping
of transmission oil potentially contribute to urban areas. It is dif-
ficult, therefore, to determine what portion of the 6,808 MT of zinc
released by tire abrasion is in urban runoff although undoubtedly it
contributes. These are the most apparent zinc bearing constituents,
however, others might include decay of materials in which zinc is a
constituent (other non-ferrous metals) and atmospheric fallout from
fuel oil and coal combustion, incineration, soil erosion, and other
industrial and construction activities.
As mentioned earlier, zinc is a natural constituent of soil and plant
life. Frequently, crop plants are seriously deficient in zinc
content. Therefore, in agriculture, zinc compounds are used as plant
and animal nutrients as well as fungicides and wood preservatives.
The most common compound used is zinc sulfate, mostly as a micro-
nutrient. In 1977, agricultural fertilizers discharged approximately
33,000 metric tons of zinc (SRI, 1979). Additional agricultural uses
released 26,000 agricultural discharges based upon distribution of
crop lands (Anderson, 1978).
Suspended sediment load in streams and waterbodies is a regularly oc-
curring phenomenon which transports soil elements through the water
compartment. The average total suspended load on the Mississippi
River measured near its mouth is 258 million metric tons annually
111-20
-------
(Todd, 1970). Based on Che assumption chat the Mississippi basin is
roughly 40% of Che total U.S. area, and that natural soil content of
zinc varies between 10 and 300 ppm with a mean of 50 ppm (NRG, 1979),
suspended sediment naturally contributes about 32,200 metric tons of
zinc per year to water. Wischmeier reports an average of 3.6 billion
metric tons of sediment transported by water annually, with about 25%
of that reaching major streams (Wischmeier, 1976). Based on Wischmeier's
determination and the above zinc concentration, suspended sediment
contributes 45,400 metric tons to-water each year. The latter, more
conservative estimate is presented in Table III-2.
5. Municipal Disposal
The total amount of zinc treated in- POTW is estimated to be about
22,000 metric tons. To make this estimate we examined the available
data and used a flow-weighted mean concentration of zinc in POTW
influent and flow-weighted mean removal efficiencies of primary and
secondary treatment plants.
A substantial number of studies addressing the composition of POTW in-
fluent and effluent have been accomplished in recent years. Many of
the studies are of single POTW, and there is considerable variability
in the nature of the study, the quality of the reporting, and the
indicated range of values for zinc concentration. Several studies
i
present data and conclusions based on groups of POTW which were investi-
gated. Of the^studies examined, none present data from a truly repre-
sentative cross section of POTW in the United States. However, one
(Sverdrup and Parcel, 1977) presents a relatively consistent data sec
on 103 POTW clustered mainly in the Midwest, with some additional
plants in California, New Jersey, New York, and elsewhere-in Che South-
east. The authors of the Sverdrup and Parcel study concluded .chat
cheir daca describe "cypical" POTW with regard to heavy metals. The
study emphasized collection of data on secondary treatment plants, and
consequently Che report has only a small number of primary planes in
Che sample. Using daca presented in che study, a flow-weighted mean
111-21
-------
for zinc concentration in Che influent of Che 103 POTW was calculated
by the following formula:
103C.V.
C » I civi » 610 ug/l
£Vt
G£ ° concentration of itn POTW
Vi flow volume of ith POTW
The authors of the Sverdrup and Parcel report concluded that POTW
meeting secondary treatment standards removed an average of 72% (range
45% eo 96%) of the zinc in the influent. This conclusion is drawn
from data on 22 of the 103 plants which both operated Co these
standards and had sufficient data on all parameters of interest to
allow analysis. Sverdrup and Parcel noted that while influent con-
centrations reported elsewhere in the literature agreed with their
data, che removal efficiencies reported elsewhere tended eo be lower.
They suggested that the explanation could be that other analyses in-
cluded some POTW not meeting secondary standards. In any event, 81%
was the flow-weighted mean of the removal efficiencies for the 22
plants. Data were presented on removal efficiency for 10 primary
treatment facilities in addition to the 22 secondary plants. The median
value of removal efficiency for the primary plants was 39% while the
flow-weighted mean was 17%. The latter .was used in our calculations
to estimate partitioning between sludge and release to the aquatic
environment.
We have little data on improved metals removal during advanced treat-
ment. However, we assumed that metal removal efficiencies would be
related eo solids removal, and used data in the 1978 Needs Survey to
characterize metals removal efficiency in Advanced Secondary and Ter-
tiary Treatment plants (EPA, 1978 Needs Survey). Based on the Needs
Survey, 28% of che total flow from POTW undergoes primary treatment,
111-22
-------
39% secondary, 18% advanced secondary, and 14% tertiary treatment.
Advanced secondary is assumed to remove 38% of zinc, while tertiary
treatment is assumed to remove 86%.
Table III-9 summarizes the POTW zinc budget based on the above as-
sumptions and shows a total loading to POTW of 22,083 metric tons, of
which 7814 metric tons of zinc is discharged by POTW to the aquatic
environment, while 14,269 metric tons is discharged to land. An ear-
lier estimate (Versar, 1978) indicated a total loading of 21,300 met-
ric tons which agrees well with that estimated in this study.
POTW discharge represents a major source of zinc to the water en-
vironment. The sources of zinc in POTW influent are not completely
defined. However, assuming that the zinc concentration in tap water
is characterized by the reported 2595 sample average of 194 ug/1 (U.S.
HEW, 1970), 7023 metric tons/year could be contributed from this
source. Human waste is also a contributor to this source. Zinc is
found in every human tissue and tissue fluid; total body zinc for an
average man weighing 70 kg is estimated to be 2.3 g. It is, there-
fore, the most prevalent trace metal in tissue (NRG, 1979). Zinc
content in human excrement varies from 7 to 12 mg daily (NRC, 1979).
Using an average of 9.5 mg/capita/day and 164 million persons served
by POTW (EPA, 1978 Needs Survey), a 568 metric ton loading of zinc
would be contributed from excrement alone.
An average residential loading of 128.5 mg/capita/day was reported
recently on the basis of an extensive sampling survey of four cities
(Arthur 0. Little, Inc., 1979). If this loading is representative of
POTW users throughout the country, then some 7692 metric tons of zinc
would be contributed. However, the average zinc concentration in the
tap water of these four cities was reported to be 67 ug/1 (as opposed
to 194 ug/1 from the HEW sample). At this average concentration the
cap water would contribute 2422 metric tons. Excluding the contribu-
tions due to cap water and body wastes yields a nee residential load-
ing estimate of ^702 metric cons.
111-23
-------
Table III-9
M
Primary treatment
Secondary
Advanced secondary
Tertiary
Total
Summary of
Treated Flow (MGD)*1*
7,525
10,137
4,731
3.812
POTW Zinc Budget
Zinc Loading ,«(
to POTW (MT) l '
6,341
8,543
3,987
3,212
Treatment
Removal
Efficiency
.
.17<»
.81O)
.88«>
.86«>
POTW
Discharge
To Sludge
1,078
6.920
3,509
2,762
(MT)
To Water
5,263
1,623
478
450
26.205
22,083
.65
(overall)
14.269
7,814
(1)liPA 1978 Needs Survey, FRD-2.
(2)l.(MT/yr) = flow (MGD) x 610 (10~6 g/1) x 3.785 (1/gal) x 365 (day/yr) x 10~6 (-M*-) = 0.8427 x flow.
(3) 8
Plow-weighted mean value calculated from Sverdrup and Parcel Associates data, February 1977.
(4)
Assume advanced treatment removes Zn proportionately to TSSestimated from tables 17, 27, 31 of
EPA 1978 Needs Survey, FRD-2.
-------
Urban runoff is another'constituent of zinc in POTW discharge. Al-
though ic is difficult to estimate the percentages of zinc from tire
abrasion, galvanized material decay and other urban sources, POTW
effluent obtains a substantial portion of its zinc from these re-
leases. Table 111-10 summarizes the major sources of zinc to POTW
influent. The 3264 kkg of zinc unaccounted for may have industrial
and commercial sources, or may represent an underestimation of the
contribution from urban runoff.
Reliable data on concentration of trace metals in incineration and
refuse operations throughout the United States are sparse. - Based upon
an assumption that of approximately 200 million metric tons of muni-
cipal refuse disposed of in the United States each year, zinc con-
centration is 0.03Z of the total source. As much as' 5% or 3000 metric
tons is emitted to air via incineration; solids leaving the inciner-
ator or bypassing it altogether release the remaining 952 or 57,000
metric tons to land (NRC, 1979 and SRI, 1979).
C. SUMMARY
The release of zinc to the environment occurs in all environmental
compartments as indicated in Table III-2. The land compartment is the
largest receptor of zinc released to the environment. Primary pro-
duction of zinc, iron and steel production, coal combustion, and ref-
use disposal are the major sources of zinc as solid waste. Highway
surface runoff, galvanized metal decay and agricultural application
provide the major distributive source of zinc to land.
The water compartment receives zinc concentrated discharges from POTW
and directly from industries. Suspended sediment and galvanized ma-
terial decay, tire abrasion, and agricultural applications provide a
major non-point source contribution of zinc to the aquatic environ-
ment .
rir-25
-------
TABLE III-10
Sources of Zinc to POTW (kkg/year)
Tap Water ' 7,023
Car Wash 624
Human Body Wastes 568
Residential Loading 4,702
**
Urban Runoff 2,906
Electroplating <1,620
***
Unknown 4,640
Total 22,083
Excluding contributions from body waste and tap water.
Includes maximum storm water discharge potentially contributing
to POTW1s, however this entire quantity does not necessarily
reach POTW.
***
This estimate is determined to be the difference between known
contributors to POTW and total POTW loading.
111-26
-------
D. REFERENCES
American Iron and Sceel Institute. 1978. Annual Statistics,
Washington, D.C.
Anderson* J.R. 1977. Land use and land cover changes - a framework
for monitoring. J. Research U.S. Geologic Survey 143-152.
Arthur D. Little, Inc. 1979. Sources of toxic pollutants found in
influents to sewage treatment plants. VI. Overall interpretation.
Report on EPA Contract No. 68-01-3857.
Arthur D. Little, Inc. 1972. Economic Impact of Anticipated Pollution
Abatement Costs - Primary Zinc Industry, Parts 1, 2.
Bureau of Mines. 1977. Minerals Year Book 1977: Zinc. Washington,
D.C.
Cammarota, V.A., Jr. 1979. Bureau of Mines, Metals Section, Personal
Communication.
Christensen, E.R. e£ al. 1979. Zinc from automobile tires in urban
runoff. ASCE, J. of Environ. Engineering Div. 165-170.
Council for Agricultural Science and Technology. 1976. Application of
Sewage Sludge to Cropland-Appraisal of Potential Hazards of Heavy
Metals to Plants and Animals. Ames, Iowa (EPA //PB-264-015).
Hydroscience. 1978. Nonpoint Sources; An Assessment of Pollutant
Loadings to Lakes and Rivers in North Central Texas. Arlington, Texas.
Martin, H.W. and W.R. Mills. 1976. Water Pollution Caused by Inactive
Ore and Mineral Mines. Cincinnati, Ohio (EPA #600/2-76-298).
National Research Council. 1979. Zinc. Baltimore: University Park
Press.
Sittig, M. 1975. Environmental Sources and Emissions Handbook. Park
Ridge, N.J.: Noyes Data Corporation.
SRI International, Casey, S.E. 1979. Agricultural Sources of Zinc.
Svedrop and Parcel and Associates, Inc. 1977. Study of Selected
Pollutant Parameters in Publicly Owned Treatment Works. (Draft.)
Task Order No. 7 under EPA Contract 68-01-3289.
Todd, O.K. 1970. The Water Encyclopedia. Port Washington, New York:
Water Information Center.
Tracor-Jitco. Production and Use of Zinc.
Trinity River Authority of Texas. 1978. Planning and Environmental
Division. Watershed Runoff Water Quality and Sediment Analysis in
North Central Texas.
III-Z7
-------
United States Environmental Protection Agency. 1972. AP-42 Compilation
of Air Pollutant Emission Factors. Washington, D.C. "~
United States Environmental Protection Agency. 1976. Considerations
Relating to Toxic Substances in the Application of Municipal Sludge.
to Cropland and Pas tur eland. Washington. D.C.
United States Environmental Protection Agency. 1977. Heavy Metal
Pollution From Spillage at Ore Smelters and Mills. Washington, D.C.
United States Environmental Protection Agency. 1977. Nationwide
Evaluation of Combined Sewer Overflows and Urban Stormwater Discharges.
Volumes I, III. Washington, D.C.
United States Environmental Protection Agency. 1977. State and
Local Pretreatment Programs (Federal Guidelines) . Washington, D.C.
United States Environmental Protection Agency. 1979. Needs
Survev ~ Converence and Treatment of
Sunnaries of Technical Data. (FR D-2) . Washington, D.C.
United States Department of Transportation. 1978. Highway
Statistics" 1977. Washington, D.C.
Versar. 1978. Gross Annual Discharge to Waters/Zinc.
Versar. 1978. Materials Balance of Zinc.
Versar. 1979. Estimates on Electroplating.
Wischmeier, W.H. 1976. Cropland Erosion and Sedimentation."
Agricultural Research Service, USDA. Control of Water Pollution from
Cropland. Vol. II. Washington, D.C.
111-28
-------
IV. DISTRIBUTION OF ZINC IN THE ENVIRONMENT
A. MONITORING DATA
1. Zinc in Aquatic Environments
a. Zinc in Water
Zinc content in seawater is in the range of 1 to 27 ug/1 zinc with a median
at about 8 ug/1, while zinc content in uncontaminated freshwater is usually
somewhat higher, but less than 50 ug/1.
Of the 19 river basins* covered by STORET surveys, several have high ambient
concentrations of zinc in their waters and sediments.
Tables IV-1 and IV-2 provide a complete list of the watersheds surveyed.
Figure IV-1 is a compilation of the data for the entire U.S.; the mode ±n
the graph indicates that the majority of the water samples had zinc concen-
trations in the range of 10-100 ug/1. The corresponding mode for sediment
samples is for 1-10 Ppm.. Of the 19 major river basins, New England (or
the Northeast) had the highest ambient aqueous zinc concentrations. A
breakdown of the data for the Northeast into minor river basins have mean
levels of less than 50 ug/1, several have mean concentrations exceeding
200 ug/1 (the Fiscatagua River and estuary, the Fresumpscot River, and
Lake Champlain). Figure IV-2 shows minor river basins having high levels
of zinc in 1978 (STORET). It is apparent that in many areas the mean con-
centration is greater than 60 ug/1 and observations greater than 120 ug/1
are common. There appears to be some relationship between high concentra-
tions and mining areas (also shown in Figure IV-2). In addition, high concentra-
tions appear around urban/industrial areas.
In a comparison of natural vs. anthropogenic levels of zinc, surface water
samples were taken in 15 of the major EFA water basins. The mean total zinc
in benchmark stations ranges from 12.8 ug/1 to 246 ug/1. Benchmark stations
are located in areas presumably unaffected by anthropogenic sources. Zinc
content in other (non-benchmark) stations ranges from 39.1 ppb to 296 ug/1.
The factor difference (mean benchmark/mean non-benchmark) within basins
ranged from 0.16 to 12.1.
The water quality data base developed by EFA.
IV-L
-------
Table IV-1
Region (Number of
Observations)
New England (7,846)
Mid Atlantic (16,005)
Southeast (11,776)
Great Lakes (7,641)
Ohio (10,551)
Tennessee (5,503)
Upper Mississippi (7,459)
Lower Mississippi (6,360)
Souris & Red of No
Missouri (6,248)
Arkansas & Red (8,697)
Western Gulf (623)
Rio Grande & Fecos (646)
Upper Colorado (2,163)
Lower Colorado (944)
Great Basin (769)
Pacific Northwest (3,395)
California (3,986)
Alaska (322)
Hawaii (537)
United States (102,736)
Total Zinc
in Ambient
Waters
Percentage of Positive Observation:
1-10 10-100
ug/1 us/1
6 40
459)
360)
i (1,265)
)
46)
)
395)
6)
20
16
17
14
17
11
18
13
16
23
12
10
18
21
35
27
21
35
41
16
57
49
64
66
62
64
73
79
57
57
54
50
53
63
55
51
55
55
55
55
100-1,000
UR/1 '
45
18
30
15
19
18
13
7
7
24
17
31
28
26
13
10
14
21
9
4
22
>1,000
us/1
8
5
3
2
1
3
11
<1
<1
2
1
<1
7
3
2
0
7
3
1
<1
4
Source: STORET
IV-2
-------
Table IV-2
Zinc in Sediment
in U.S.
River Basins
Percentage of
Region (Number of
Observations)
New England (457)
Mid Atlantic (842)
Southeast (1,254)
Great Lakes (1,062)
Ohio (372)
Tennessee (95)
Upper Mississippi (185)
Lower Mississippi (625)
Souris & Red of North (11)
Missouri (114)
Arkansas & Red (189
Western Gulf (864)
Rio Grande & Pecos (66)
Upper Colorado (76)
Lower Colorado (29)
Great Basin (0)
Pacific Northwest (54)
California (183)
Alaska (0)
Hawaii (130)
United States (6,608)
1-10
ppm
2
7
20
3
1
0
5
9
18
10
10
6
8
16
24
*
2
5
*
<1
8
10-100
ppm
61
55
70
42
87
65
75
86
73
75
66
80
86
59
76
*
61
79
*
25
65
Positive Observations
100-1,000
ppm
33
36
9
47
12
31
16
4
9
16
16
12
6
24
0
*
33
16
*
75
24
1,000-
10,000 pom
3
2
<1
6
1
4
3
<1
0
0
8
1
0
1
0
*
4
0
*
0
2
*No data
Source: STORE!
IV-3
-------
FIGURE IV-1
30%
I
M
B
M
Eb
CO
a
CO
VI
J
0)
cu
20%
10%
DISTRIBUTION OF TOTAL ZINC IN AMBIENT WATERS
IN THE U.S.
.55
e
i
15.68
2.47
X
X
^M
X
X
X
X
X
X
X
X
X
X
X
»5.33
; <
X
X
X
X
X
X
X
X
/
x
x
x
X
X
X
X
X
X
X
X
X
X
X
x
>
21. S
^
X
X
X
x
X
X
X
X
X
X
X
X
X
X
X
X
>5
2.98
.93
X PX] .j)£
.05
.001 .01 .100 1 10 100 1
ug/1
CONCENTRATION
10 1,000
mg/1
IV-4
-------
Table IV-3
Northeast. Major Basin 1. Total Zinc in Water for 1978*
Minor Basins
(see reference map)
1 Qulnnipiac River &
Western Conn Coastal (1974)
2 Housatonic River
3 Pawcatuck River & Eastern
Conn Coastal (1977)
4 Connecticut River
5 Thames River
6 Narragansett Bay
9 Merrimack River
10 Fiscataqua River & New
Hampshire Coastal (1977)
14 Presumpscot River and Casco Bay
IS Adroscoggin River
16 Kennebec and Sheepscot Rivers
24 Lake Champlain
25 St. Lawrence River
27 Niagara River (1975)
29 Oswego River
30 Mohawk River
32 Middle Hudson River
33 Lower Hudson-New York Metro.
34 New Jersey Coast
35 Lake Erie Shore & Minor Tribs.
(1976)
Number of
Measurements
Total Zn (ug/1)
664
112
60
263
128
29
121
137
24
30
17
10
10
61
31
59
17
288
234
Mean
6.3
85.8
2.4
71.1
50.0
88.3
45.6
353.4
1345.9
19.4
11.9
202.0
19.0
82.9
28.1
25.1
27.6
62.3
56.2
Max.
570.0
1110.0
50.0
1140.0
600.0
360
510
5000
10100
110
49
450
30
1000
130
240
50
862
586
Min.
0.01
0.02
0.0
0.04
0.13
20.0
0.0
10.0
2.0
2.0
0.0
10.0
10.0
0.0
10.0
0.0
0.0
0.0
10.0
88
62.6
405
0.0
*Minor basins with less than 10 observations have been excluded,
data was excluded.
remarked
IV-5
-------
< 60 p|>l> «l«l Ictt HUM
10% ul utiWI V4IHMU > 1 2O IHJll
10% ol ubiei VAIluiik > 120 |J|lb
FIGURE IV- 2 ZINC CONCENTRATION IN U.S.MINOR RIVER BASINS
-------
The mean dissolved zinc range from 5.04 ug/1 Co 42.7 ug/1 in naturally
pristine areas. Dissolved zinc in non-benchmark stations ranged from 20.6
to 13,000 ug/1. The factors of difference ranged from 0.5 to 896.6 (STORE!).
b. Streams Receiving Mined and Milled Wastewaters
«
In 1971, Wilson and Bolter (1972, as reported by NRG, 1979) sampled two
mines for zinc discharge. One mine had a discharge of 1045 ug/1 zinc and
a resultant stream concentration (distance downstream not given) of 231
ug/1. In the other mine, the discharge was 411 mg/1 and the resultant
stream concentration was 328 ug/1. The study noted that zinc content of
the streams returned to baseline levels within a few miles of the source.
Another study (Mink .at, al., 1970, as reported by NRC, 1979) compared the
zinc concentrations in two forks of the Coeur d'Alene River. In the north
fork, which has little mining activity, the zinc concentration 4uring low
volume flow was about 100 ug/1. In the south fork, which has considerable
mining activity, concentrations were as high as 21,000 ug/1.
Jennett and Foil (1979) tested stream waters for zinc content in a lead
and zinc mining area in southeast Missouri. The maximum concentrations
found at 23 sampling sites were 36.0 mg/1.total zinc, and 36.0 mg/1 dissolved
zinc. The average dissolved zinc concentrations between all the stations
was approximately 1.1 mg/1, with a median level of .024 mg/1. All the high
total and dissolved readings were associated with rainfall runoff.
c. Sediment
STORET data indicate that bottom sediments in U.S. river basins normally
contain between 1 and 1,000 ppm . of zinc, which is two to four orders of
magnitude greater than concentrations found in river water. The distribu-
tion of observations is: 8% between 1 and 10 ppm, 65% between 10 and 100
ppm, 24% between 100 and 1,000 ppm, and 2% between 1000 and 10,000 ppm. The
regions with the highest sediment concentrations are the Great Lakes, the
mid-Atlantic states, New England, and the Pacific Northwest (see Table
IV-2 and Section VII). For a more detailed description of zinc in
sediment, see Section VI-3.
17-7
-------
2. Ziac in Aquatic Organisms
The amount of zinc in aquatic tissues is dependent on both the water con-
centration and dietary intake; levels in freshwater fish are similar to
marine species. Whole body zinc concentrations in aquatic animals are
generally at least one order of magnitude higher than in the aqueous
medium. In a study by the National Marine Fisheries Service (as cited
in NRC, 1979), oysters were found to have the highest average whole
body zinc concentration at 202 ppm. Other mollusks and crustaceans
were generally much lower in zinc, with average levels of 12.5 ppm.
Zinc concentrations in finfish range from not detected at the ppb
level for the sablefish to 93.60 ppm for silver perch, with an average
residue of 6.5 ppm (NRG, 1979).
3. Zinc in Plant Tissue
There are two separate mechanisms for zinc uptake, including sorption
(absorption, adsorption and ion exchange) and metabolic assimilation.
For the alga Golenkinia paricispina, zinc uptake involves ion exchange
sites created by photosynthetic removal of CO.. Planktonic algae and
free floating vascular plants can obtain zinc from water but not from
sediments; benthic algae and rooted plants can obtain zinc from both
water and sediments. The concentration in brown seaweed varies with
concentration in seawater. This is also true for the algae Chlorella.
The differences between plant species in concentration factors is due
to differences in ion exchange properties of their surfaces. Seasonal
variations in zinc content range widely and is species dependent
(NRC, 1979).
In terrestrial plants, zinc uptake by plant roots is dependent on
diffusion and is independent of mass flow. Zinc uptake is also
dependent on the soil solution concentration and on the ability of
the soil to replenish zinc. Ranges of zinc uptake are from 2 to 4000
mg/day (by fresh weight). Zinc uptake and translocation in tomatoes,
soybeans and squash plants increase with soil concentration. When zinc
levels drop below 20 ppm dry weight in leaves, deficiencies may occur.
IV-3
-------
Concentrations of zinc in plant tissue are greatest in young plants and
later decrease because of dilution and redistribution as tissues mature
(NRG, 1979).
'J5
?:
Concentration factors of zinc vary widely with species. They range from
a low of 400 for Laminaria digitata to a high of 1100 for Fucus
vesiculosis (both algal species) (NRG, 1979).
4. Zinc in Soil
a. Normal Soil
Normal soils contain between 10 and 300 ppm zinc, averaging about 50 ppm.
In uncontaminated (by man) soil, zinc content is generally the same as
the parent rock from which the soil is formed. Near sulfide deposits
zinc content is generally higher. A recent study of 863 U.S. soils
(see p. 31 of NRG, 1978) indicate an average of 54 ppm zinc in soil.
b. Soil Adjacent to Highways
Zinc levels in soils are generally higher near highways. In one study,
zinc levels eight meters from a road ranged from 54 to 172 ppm in the
top 5 cm of soil. In the top 1Q -to 15 cm of soil, zinc levels ranged
from 11 to 72 ppm (NRG, 1979).
c. Soil Sear Smelters
In studies of zinc contamination in soil near six smelters (Goodman and
Roberts, 1971; Burkett et al., 1972; and Miesch and Huffman, 1972, as
reported by NRG, 1978) high levels were found in the top few cm of soil
(as high as 12,200 ppm in the top 10 cm of the soil 200 m from a smelter
in Poland). Also apparent is considerable downward movement in some
cases (as high as 467 ppm zinc in soil at a depth of 40 to 50 cm 200
meters from the same Poland smelter). Finally, the data also indicate
decreasing concentrations of zinc in soil with increasing distance from
the plant. Zinc levels seem Co return to near normal levels at distances
greater than 10 km from the smelters.
IV-9
-------
Another study (Buchauer, 1973, as reported by NRC, 1979) indicated higher
concentrations of zinc In the soil. Within 1 km of the plant, zinc con-
centrations ranged from 50,000 to 80,000 ppm at a depth of 0 to 15 cm,
with organic matter containing as much as 135,000 ppm of zinc. Again,
in the study the concentration of zinc in soil fell off sharply with
distance from the plant.
5. Zinc in Air
a. In Urban Communities without Mines or Smelters
The concentration of zinc particulates in urban areas throughout the
2
United States range from 0.1 to 1.7 ug/m . Annual average airborne
zinc concentrations throughout the United States, as indicated by data
from the National Air Sampling Network (U.S. HEW, 1968, as reported by
3 3
NRC, 1979) are generally less than 1 ug/m , ranging from <0.01 ug/m to
1.60 ug/m . Sources of zinc in these urban atmospheres include motor
vehicles, fuel oil and coal combustion, incineration, soil erosion,
and industrial, commercial and construction activity.
b. Near Zinc Smelters
Although data are not available on the concentration of zinc in the air
near zinc smelters, the data provided above on soil concentration near
zinc smelters indicate that high concentrations are likely in the
surrounding areas. As discussed above, zinc concentrations in soil
return to near normal levels at distances of approximately 13 km. High
levels of zinc in the soil close to the smelters suggest high concentra-
tions may also be present in air.
B. ENVIRONMENTAL FATE
1. Overview
a. Methodology
The environmental fate of anthropogenic zinc is described as a result
of discharges by processes which contribute significant quantities of
Che metal to the air, water and soil. The discussion emphasizes the
form of zinc specific to Che discharge, and its subsequent transport
IV-10
-------
upon release to the environment. A general overview of the environmental
chemistry of zinc conducted by Versar (1979a) has been used as the .basis
to formulate Judgments concerning the direction and rate of transport
zinc assumes in an ecosystem. Studies available in the literature support
the observations noted. Biological pathways have been treated separately
from physico-chemical and bulk transport pathways. Uptake of zinc by
terrestrial and aquatic biota are discussed in terms of the emission
source. Again, the general uptake and metabolism of zinc by biota was
reviewed by Versar (1979a,b).
b. Major Environmental Pathways
The major pathways of physical transport and qualitative rates at which
transport occurs are designated in Figure IV-3. Atmospheric emissions
(Pathway 1) have been segregated by point source and dispersive emissions.
Combustion processes, such as incineration, smelting and coal combustion
contribute to localized pollution; dispersive sources, such as
emissions of zinc from automobile use, contribute to the concentration
of zinc found in urban runoff. Pathway 2 follows the flow of zinc which
originates from solid waste disposal dumps, and mine tailings. As
environmental controls restrain further discharges to air and water, the
quantity of zinc disposed upon land surfaces can be expected to increase.
Zinc discharged with Industrial process effluents into local surface
waters or publicly owned treatment works (POTW) is reviewed in Pathway
3. The fate of zinc in POTW is described in Pathway 4.
Figure IV-4 gives a more general overview of all major pathways of
anthropogenic zinc. The major impact on the land compartment (mostly
at specific disposal sites) and the underlying groundwaters is to be
noted. The migration of groundwaters containing zinc to nearby surface
waters has not been shown in this figure since (1) the process is very
slow, and (2) the current magnitude of this transport pathway is far
from being well documented. Also noc represented here is the high con-
centration of zinc in sediments with respect to the overlying water and
the steep profile of zinc concentrations in soils subject to contamination
IV-11
-------
No.
i-i
**«
M
10
Atmosplieric Emissions
ZnO. ZnS. Zndn)
ZnO Production
Smelling
Iron & Steel Production
Coal Combustion
Incinaiation
Atmospheric Emissions
ZnO (paniculate). Others
Tire Wear
Oil & Lubricant Combustion
& Leakage
Solid Waste &
Tailings. Coal
Piles & Open Pit Mines
ZnS. ZnCO3
Primary Zn Production
Coal Mining
Ore Mining and Beneficiation
Mostly Local
Soil Surfaces
Pavement & Local
Road Soils
Dissolved Solids
Susn. Sediment
Figure IV- 3 MAJOR ENVIRONMENTAL PATHWAYS OF ZINC EMISSIONS
-------
a.
H
~*
--«
10
X
1 M
T 1
n. .. Treatment E,,,uanl ^
Beneficiation
Smelling " . . ..
sssa*. H"-"-"
Brass * Solid Waste "
Paper Products Dump
POTW Pathway #4
Surface Walor
Sediments
Slow -»
Groumlwaiar
Electropliiting
1 1
POTW | Primary Biological Efllueni
Surlace Wamrs |
Sediments | J
^
-------
Wet and Dry Fallout
Zinc
Mining
Pioduction.
and Use
Other
Anthropogenic'
Sources
of Zinc
Oceans and Ocean Sediments
Solid
Wastes
Land
Surface Soils
Tailings Piles
Landfills
Lagoons
etc.
^
Groundwater
Note:
Quantities of zinc moving in each pathway are roughly proportional to the thickness of each pathway shown. Slow
movement from groundwaters to surface waters not shown.
Figure IV-4 SCHEMATIC DIAGRAM OF MAJOR PATHWAYS OF ANTHROPOGENIC
ZINC RELEASED TO THE ENVIRONMENT IN THE U.S. (1979)
-------
by airborne zinc. This figure also indicates Che relative contributions
of the zinc industry and all other human activities to the major zinc
pathways; the major contribution of the latter category is to be noted.
c. Biological Transport
Biological transport of zinc includes uptake by plants from soils and
water. Terrestrial biota are exposed to zinc from atmospheric deposition
on the soil, landspread sludge and purposeful application as a nutrient
to promote growth, or as a fungicide. In aquatic environments, biota
are subject to zinc contamination by any process which eventually leads
to transport in freshwater surface environments, or oceans.
Zinc is an essential nutrient to all organisms, and large bioconcentration
factors are observed in nature. Bioconcentration factors for zinc go as
high at 10U times the concentration of zinc in the water column. The
most active accumulators of zinc appear to be the periphyton community
(the attached submerged macroscopic plants and animals) and the benthic
feeders. Zinc is not, however, biomagnified through the food chain. The
major mechanisms for bioaccumulation in water are direct ingestion, and
uptake from water via sorptive processes. The rate of bioaccumulation
increases with increasing water temperature, pH, and hardness, although
zinc is more toxic in acidic and soft waters. Documentation exists for
reduced zinc uptake by algae in the presence of competing ions (K , Na ,
^ ^
Mg ), and by oysters as the salinity of the water decreases. One study
found that only 0.6% of the zinc introduced to a model estuary ecosystem
resided with the biotic compartment after 100 days; the remainder
partitioned into the sediments.
d. Important Fate Processes
Zinc is concentrated in the sediments in aerobic waters sorbed primarily
to hydrous iron and manganese oxides. Zinc also sorbs to clays, and Co
a lesser extent, organic materials. The bulk of zinc transported in the
water column is in association with the dissolved solids (Perhac, 1974).
In anaerobic waters, zinc will exist in the reduced phase as zinc
sulfide. Bioaccumulation by the biota is greatest for algae and
IV-15
-------
benchic feeders. In terrestrial plants, accumulation of zinc is promoted
by low soil pH; in contrast, algae accumulate more zinc with increasing
PH.
/'/ :
'';'"
*
Atmospheric emissions of zinc will consist mostly of zinc sorbed to
j1
submicron particulate matter and the oxide of zinc. A large percentage
of the zinc is expected to be short-lived in the atmosphere; dry fallout
and washout of zinc particulates will contribute to deposition upon local
soils.
2. General Fate Discussion
a. Aqueous Complexation
The concentration of soluble zinc in water is directly related to parameters
such as pH, the oxidizing potential of the water (indicated as pE), the
I [ [ [ [ i I
presence of other competing ions (Ca , Mg , Fe ), and the existence
of other precipitating and complexing agents (OH~, S~, CO/*, PO,=).
Generally in a low pH environment, or at low alkalinities, zinc will
remain as the free ion; at pH values above 8.0 or in waters of higher
alkalinity, zinc will begin to complex predominantly with the carbonates,
hydroxides and organic ligands. An early study by Hem (1972) demonstrated
that the theoretical equilibrium species in a system comprised of 10 M
5 |[
carbon dioxide, and sulfur and 10 M zinc would be Zn ion below pH 7.5,
and soluble zinc hydroxide forms above this pH. Within the pE and pH
range considered, solid zinc sulfide, zinc hydroxide and smithsonite
(ZnCO.) were stable forms. For environmental applications, the model
developed by Vuceta and Morgan (1978) may be a more adequate representa-
tion of a real system. Using a number of inorganic and organic cations
and ligands, as well as a compound exemplary of surface sorption sites,
the authors found that the model predicts that the zinc ion is the
predominant species at pH 7. Zinc species present in minor concentra-
-9 -10
tions (10 -10 M) were the chloride, sulfate, carbonate and hydroxide.
Figure IV-5 illustrates the speciation as a function of pH.
IV-16
-------
13 -
62 64 66 68
Source: Vuceta and Morgan (1978).
70 72
pH
FIGURE IV-5 SPEC1ATION OF Zn(ll) IN NATURAL FRESH WATERS AS A
FUNCTION OF pH IN PRESENCE OF 1.55 x 10"4 ha/L Si02
IV-17
-------
b. Absorption to Sediments and Suspended Solids
The above model is also, capable of partitioning zinc between the dissolved
and sorbed state. Using SiO. as a representative of available colloidal
surface area, the model predicted that zinc would remain in the dissolved
state. Introduction of iron and manganese oxides to the system caused
significant adsorption of zinc. This distribution also is dependent upon
the quantity of surface area for adsorption. Figure IV-6 reveals that
copper, mercury, lead, nickel and cobalt will sorb before zinc for the
same quantity of surface area. Metal adsorption to colloidal surfaces
may be enhanced by organic ligands such as humic acids which coat a
thin film over particles (Dana and Ledcie, 1978).
c. Soils
The behavior of zinc in soils is dependent upon the adsorption properties
of the soil, as well as the pH and redox potential of the soil solution.
In aerobic soils, the solubility of zinc is controlled by Zn,(OH),(SO.),
« & 0 H
at a pH of 5 and carbonate and sulfur concentration of 10 M; under
anaerobic conditions, ZnS is the controlling species. Zinc is easily
sorbed in soils; it is exceeded by copper, but not by lead and cadmium
in adsorbing potential. Figure IV-7 illustrates the strong dependence
of heavy metal adsorption onto hydrous oxides and soil particulates as
a function of pH. At a pH of 5-6, adsorption is the principal means of
removing zinc from solution. As the pH continues to increase, pre-
cipitation will become the dominant mechanism of removing zinc. Below
a pH of 5, adsorption of zinc becomes insignificant. The presence of
organic ligands such as humic acids, enhances metal adsorption at low
pH values. Out of five ligands tested, humic acid was the most effective
in this respect.
d. Summary Statement
The concentration and speciation of soluble zinc in che water column is
dependent upon pH, pE, other cations and ligands, as well as colloidal
surface areas. Within the pH range of concern, the Zn ion predominates
in the water column. Sorpcion to hydrous iron and manganese oxides
17-18
-------
Figure IV-6:
Adsorption of Heavy Metals in Oxidizing Fresh Waters
(pH = 7, pE = 12, pC02 10~3'3 acm., pCt-4.16) as a
function of surface area of Si02 in ha/L. pS « -log
(Si02) ha/L.
Reference: Vuceta and Morgan (1978).
IV-19
-------
Rofarvncv: Huang (1977)
Figure IV-?
ADSORPTION OF HEAVY
METALS ON SOIL MINERALS
AND OXIDES
IV-20
-------
concentrates zinc onto suspended solids and sediments. In soils, zinc
adsorbs within a pH range of 5-6, with the presence of organic ligands
such as humic acids, enhancing this tendency. In acid environments,
the zinc iron will be available in the soil solution.
3. Physicochemical Pathways
a. Pathway #1 - Atmospheric Transport
Atmospheric
Emissions
\
N
\,
Smelting
Iron and Steel
Coal Combustion
Incineration
Primary Zinc Producers
Phosphate Processors
Local *.
Soils
1
Surface
Water- t
Sediment^
t
Pavement
E
\
^A
Groundwater
t
Ocean
POTW
Air
Sources; Pathway //I describes the fate of atmospheric emissions of
zinc as a result of thermal processes such as incineration and smelting,
and from automobile use and other dispersion sources. The major
industries which are responsible for zinc emissions into the atmosphere
comprise iron and steel producers, primary zinc producers (from smelting
operations), industries which combust coal, and refuse incineration
operations. All of these emissions can be considered point sources of
pollution and amount collectively to 6,100 kkg/yr. For the most part,
the oxide of zinc (ZnO) is released. Small quantities of ZnSO,, ZnS, as
dust, and elemental zinc, as a vapor, are also a result of these processes.
IV-21
-------
A portion of the zinc found in urban atmospheres is due to the tire
wear and combustion or leaking of lubricants and fuels (NRC, 1979).
Tires contain 1.5% zinc by weight and wear at a rate of 1.2 kg/million
km. Fuel and lubricating oils contain 30-1500 ppm zinc. The emissions
from motor vehicles are small submicron particles with zinc sorbed in
quantities of 0.1-10 ppm. Other sources contributing to urban area
emissions are soil erosion, oil and coal combustion, and incineration.
The residence time of zinc in the troposphere, and distance travelled
prior to deposition, are functions, in part, of the particle size of
the airborne contaminant. NRC (1979) states that a horizontal retort
distillation operation for the smelting of zinc produces particulates
34% of which are less than 2.5 um in diameter, 35% range from 2.5 - 5.0
urn, and 31% are greater than 5.0 um.
Most of the particulates are scavenged by control systems. However,
submicron particulates from dusts (ZnS) and zinc oxide fumes escape
the collectors. In fact, Jacko et_ al. (1975) found that trace metals
exhibit a preference for smaller particulate sizes, as demonstrated in
the emissions, from a scrubber controlled municipal incinerator. One
reason given to explain this occurrence, in addition to the existence
of submicron metallic oxide fumes, is the selective adsorption of the
trace metals upon small particulates due to the greater surface area
to volume ratio. The work of Coles ££ al. (1979): supports this trend.
Zinc partitioned amongst coal fly ash particulates in the following
manner: 68 ppm on 18.5 um fraction; 189 ppm on 6.0 um; 301 ppm on
3.7 um; 590 ppm on 2.4 um.
Deposition on Soils; Once in the atmosphere, deposition of the parti-
culates via rainout or dry fallout proceeds quickly, resulting in a
mean residence atmospheric time of 7-30 days (Versar, 1979b). Most of
this deposition will occur in the local vicinity of the emission source.
Some of 'the zinc will clearly be transported over much greater distances;
the fallout of this material may vary significantly from location to
IV-22
-------
location depending on climatic and other factors. In one study of marine
sediments about 100 km offshore (south) of Los Angeles* the concentration
of anthropogenic zinc in the surface layers (top 2 cm) was used to estimate
a deposition rate of 0.2 ug Zn/cm2/yr (Bertine and Goldberg, 1977). The
sample location was in an area that would not have been affected by waste-
water discharges to the ocean, but would be affected by surface winds from
the Los Angeles area. Thus, the authors suggested that the deposition
rate calculated was due to atmospheric transport and fallout.
Figure IV-8 illustrates the deposition of zinc particulates from three
smelters as a function of distance away from the smelter. Zinc con-
centrations in surface soils are seen to rise dramatically within a
10 km radius of such sources. The zinc concentrations were measured
within the top few centimers of soils (0-10 cm). In all cases, the
concentration of zinc far exceeds that of background levels, which is
on the order of SO - 54 ppm (NRC, 1979). In one case, the zinc content
in the soil ranged from 30,000 - 80,000 ppm within 1 km of the emission
source.
Most of the particulate zinc which is deposited exists as the oxide.
The more soluble ZnSO, may also be present as well as zinc ion absorbed
to particulate matter. Initial mobility will depend upon the solubility
of the zinc compounds deposited. Zinc oxide is fairly insoluble in water
(*1.6 mg/1 at 29°C) as is zinc sulfide (<6.9 mg/1 at 18°C); zinc sulfate
however, is highly soluble in water (86 g/100 g water at 30°C).
Figure IV- 9 demonstrates the mobility of zinc within the soil profiles
near three different smelters. The bulk of the zinc inhabits the top 0
to 10 cm of soil. The concentrations fall off rapidly below this depth
although the concentrations of zinc encountered exceed typical background
concentrations. Versar (1979b) states that zinc, once soluble, is
highly mobile in the soil environment due, in part, to weak sorption
upon clay minerals, iron and manganese hydrous oxides, and organic
matter. This mobility increases as the pH level of the soil solution
IV-23
-------
500
400
.2
S
~ 200
I 200
100
Montana; Top 2-5-1 Ocm
England; Top 0-5 cm
England; Top 1-5 cm
0 S 10 15
Distance from Smelter
(Kilometers)
Figure IV- 8 ZINC CONTENT OF SOILS NEAR SMELTERS
Source; NRG (1979)
1000
1 800
I 600
|
| 400
200
Key:
_ England. 250M from
Smelter
A Japan, 90QM from
Smelter
- Poland, 200M from
Smelter
10
20
SO
60
30 40
Soil Depth (cm)
Figure IV- 9 " " 21NC CONTENT OF SOILS NEAR SMELTERS vs. SOIL DEPTH
Source: MRC (1979)
-------
decreases." An example of zinc mobility in soils vs pH can be found in
che vork of Huang &t_ al. (1977) which concluded that mobility was great-
est below a pH of 5-6. Transport through the soil profile of oxidized
I |
soils will be dominated by the Zn ion, making possible bioaccumulation
and groundwater contamination (Versar, 1979b).
According to Versar, the deposition of zinc upon the soil surface allows,
of course, for the entrainment of soil particles containing zinc back
into the atmosphere. This cycle is partially dependent on
groundcover and'soil moisture, and will continue indefinitely with the
same type of chemical phenomena dictating the transport of airborne
zinc. Surface runoff of soil particulates will also result in the intro-
duction of zinc to surface waters and sediments. Bioaccumulation of
deposited zinc will be another pathway both among terrestrial and
aquatic organisms, and will be discussed in a later section.
Road Surfaces: Most of the zinc released to the local urban atmospheres
immediately falls out onto road surfaces and local soils. That which
deposits upon a pavement is subject to runoff into the nearest drainage
system. The concentration of zinc found in street surface runoff after
a fairly heavy rain in seven cities ranged from 0.03-0.95 kg/curb mile;
the average was 0.34 (NRC, 1979). Of the metals Cr, Cu, Hi, Hg, Pb and
Cd, zinc comprised the largest percentage (40%) of the total heavy metals
found In street runoff. The zinc distribution on the street by land use
classification was: 38% residential, 44% industrial and 24% commercial.
The runoff will flow in the direction of either natural or man-made
drainage basins. The fate of zinc as it enters a Publicly Owned Treatment
Work (POTW) will be discussed separately. In streams, zinc is quickly
sorbed by clays, hydrous iron and manganese oxides and - to a lesser
degree - by organic matter. The stream sediments become highly enriched
by zinc; the bulk of zinc transported in the water column is associated
with dissolved solids (Perhac, 1974). A more detailed explanation of
this fate process will be discussed in Pathway #2. The ultimate sinks
for zinc transported with stream suspended solids or in the dissolved
state are: 1) lake sediments, and 2) ocean sediments.
17-25
-------
Figure IV-10 illustrates the pattern of deposition of zinc onto soils as
a function of distance from a highway. The plots are derived from the
average of four studies found in Table 3-3 in a review of zinc per-
formed by the NRG (1978). From the graph it appears that soils at the
10-15 cm depth are hardly affected by zinc deposition as a function of
distance whereas the top soil surface layer contains a high of about 112
ppm Zn at an 8 meter (.005 mi.) distance from the highway to about 35 ppm
at 32 m (0.02 mi.) from the highway.
Groundwater; Groundwater contamination by the zinc ion will be a function
of a number of parameters, the two. most obvious being the depth to the
groundwater table, and the composition of the soil.
Jennett and Linneman (1977) state that the potential for heavy metal
(Zn and Fb specifically) contamination of shallow aquifers (<300 ft.
deep) from wastes applied to land may be large. However, one can say
that the transport of zinc from soil to groundwater will be a slow
process (in comparison to deposition) and can be considered the "rate
determining step" in the environmental transport of zinc via the pathway.
Surface Waters and Oceans: Transport of zinc from groundwaters to
surface waters and oceans (in Pathway //I) will have a negligible effect
on these waters due to the slowness of the process and the dispersed
nature of the initial pollution.
Summary Statement: Wet and dry deposition will quickly remove zinc
released to the atmosphere as a result of industrial combustion processes,
and non-point source atmospheric emissions. Zinc will accumulate in the
top few centimeters of the soil as the insoluble oxide, or sorbed to
hydrous iron and manganese oxides, clays and organic matter. A soil
solution pH less than about 6,' promotes the dissolution and transport
of the zinc ion on the soil profile. Groundwater contamination may
occur over time.
IV-26
-------
Distance from Highways'
(Meters)
Figure IV-10 AVERAGE Zn CONTENT IN SOILS NEAR HIGHWAYS AT DIFFERENT SOIL DEPTHS
Source: NRC (1978)
IV-27
-------
Deposition of non-point source atmospheric emissions of zinc in urban
environments will contribute to localized pollution of drainage basins
due to surface runoff. In streams, the major portion of zinc will
partition with the sediments. The remaining zinc in the water column
will be associated predominantly with the dissolved solids.
b. Pathway #2 - Solid Wastes Tailings and Coal Piles, etc.
Air
Solid Wastes,
Coal Files and
Open Mines
Surface
Water *
Sedimen
Ocean
Groundwater
Sources; These materials arise from mineral ore processing, and coal
mining. The solid wastes result from the overburden of surface mining,
and the low grade portions of mineral ore deposits. The tailings which
are highly concentrated in minerals are produced as a final waste
product of mineral concentrating operations (Martin and Mills, 1976).
Since 1873, the production of zinc has contributed 883 million metric
tons of tailings, and 2208 million metric tons of combined tailings
and waste (Martin and Mills, 1976). Disposal of these wastes in the
19th and much of the 20th centuries was without regard to environmental con-
siderations, and thus erosion and weathering contributed to adverse ecological
impacts. Currently, however, tailings are left to settle in lagoons, after
treatment with lime to raise pH and precipitate heavy metals (NRC. 1979).
Backfilling and surface mine reclamation also serve to reduce the amount of
zinc found in surface runoff. Zinc in some solid wastes is now recovered.
IV-28
-------
The nature of the solid wastes and tailings depends upon the nature of
the ore. Zinc ores exist as sphalerite (ZnS), hemimorphite (H.ZnSiO)
and smithsonite (ZnCO.), whose host rocks are carbonates, granites,
slates and quartizes. Sphalerite, the ore most commonly mined (see
Section III) is found concentrated in basaltic rocks, which are of
igneous origin. The gangue of this ore often contains pyrite (FeS) and
fluorite.
Coal piles and solid wastes from coal cleaning processes may also be
considered sources of zinc for the pathway being considered. One
survey of 101 coal samples from U.S. coals showed a mean zinc concen-
tration of 272 ppm with a range of 6 to 5350 ppm and a standard deviation
of 694 ppm (Mezey, 1976). The mineral sphalerite (ZnS) has been identified
in coal and the concentration of zinc has been shown to correlate with
that for cadmium. Other data have shown that the zinc is mostly con-
centrated in the mineral matter in coal and has little affinity for the
organic matter (Mezey, 1976). This implies that zinc may be concentrated
several fold in the solid wastes from any coal cleaning operation designed
to remove pyritic sulfur and/or other mineral matter from coal.
Acid Mine Drainage; Tailings and solid waste from mineral mining aid
in the formation of mineralized acid discharge. This is caused by the
exposure of fine participates to air, upon which the oxidation of metal
sulfides results in the formation of H_SO . The impact of acid mine
drainage (AMD) to local surface waters is largely dependent upon the
alkalinity, or buffering capacity, or the waters upstream and downstream
of the point of discharge. Zinc sulfide is found associated with
igneous rocks and is concentrated in proportion to the concentration
of pyrite found in the ore. Pyrite is easily oxided to Fe(OH)., pro-
ducing acidic waters as a consequence of the reaction. It may be
assumed that sphalerite (ZnS) is also easily oxidized. Igneous rocks
are low in calcerous material and therefore the water which passes over
the gangue has little opportunity to dissolve carbonates and become a
buffered solution. For these reasons, a large potential exists for zinc
releases to the local waters of a mined region.
IV-29
-------
Fate Processes in Streams; Figures IV-11, IV-12, and IV-13 summarize
these observations for a stream which receives mine drainage (Martin and
Mills, 1976). The mine occurs at kilometer 35 and the confluence of two
streams occurs at 0 kilometers. The waters which reach the mine area
experience an immediate drop -in pH, as well as in bicarbonate concentra-
tion. At the same time, the concentration of dissolved zinc increases
dramatically.
These figures also give an indication of how the stream recovers as a
function of distance. Reduction in the concentration of zinc is caused
by precipitation, adsorption and dilution (Martin and Mills, 1976). A
literature review of the fate of zinc performed by Versar (1979a) con-
cludes that sorption is the dominant process affecting the reduction
of zinc in surface waters. Sorption upon hydrous iron and manganese
oxides, organic matter and clays results in enriched sediments and
suspended solids so that Zn concentrations in these fractions are in
the ppm range, while the water column exhibits concentrations of zinc
in the ppb range. Holcombe (1977) found that zinc draining a mined area
sorbed preferentially to manganese oxides rather than iron oxides. Iron
oxides exhibit a positive surface charge at low pH's, repelling the zinc
ions while the opposite is true of manganese oxides.
Perhac (1974) investigated the distribution of zinc within stream bed
sediments and the water column of three rivers in Tennessee. The results
obtained are summarized in Table IV-4. These rivers do not drain mined
areas. The results indicate that the bulk of zinc is transported through
surface waters in the dissolved phase, although the highest concentrations
exist in the particulate fractions. Although these data show a higher
zinc concentration in the coarse particulates than in the colloids, other
data have shown an inverse correlation between zinc concentration and
sediment grain size (Versar, 1979b).
IV-30
-------
\c-
9
8-
7-
6-
X
o. 5-
4-
-
2-
i
i
o
kk ___.
.^T" ' " ""^^.^-^'
""^.-^-j^-:1"'
... 72
\/ OEC 72
w rrn 7^
LJ A V T ^
nn** 1 ( ->
JUNE 73
I I i I i i T " ^ I
40 35 30 25 20 15 10 5 0
KILOMETRES
AMD
O
z
N
O
UJ
O
en
O
Figure IV-11 The pH in Kerber Creek
Source: Martin and Mills (1976)
50
40-
30-
20-
10-
- 11
OCT 72
DEC. 72
FEB 73
MAY 73
JUNE 73
D- INDICATES DATA AT STATION
NOT ABLE TO INTERPOLATE BETWEEN
STATIONS DUE TO LACK OF I1A1A.
40
i
35
30 25
KILOMEinr.S
IS
10
Figure IV-12 Dissolved Zinc Concentrations in Kerber Creek
Source: Martin and Mills(1976)
IV-31
-------
\
o»
E
-'
UJ
<3
ARBON
u
CO
£UU-
180-
160-
140-
120-
100-
80-
60-
40-
20-
n-
,
\
\
IE
V
1
s
V
L
DEC 72 -
FES. 73 -
MAY 73 O
JUNE 73
DO -INDICATES DATA AT StATION -
NOT ABl c TO INTERPOLATE QFTV.iE.IJ . p
STATIONS ['ME TO I ACK nt DATA /
/
/
/
-^ " /
^c^-"-'"
^^-T^^^^^^r----^'^ -""**'
xftf;:^- ^"~
35 30 25 20 15 10
t
AMD
KILOMETRES
Figure IV-13 Bicarbonate Concentrations in Kerber Creek
Source: Martin and Mills (1976)
IV-32
-------
OJ
OJ
Table IV-4
Distribution of Zinc in Stream Waters
Particle Size
ma
% Total Solids
Zinc
Concentration
(ppm)
Water
^Dissolved Solids
Colloids
Coarse Particulate
* Brought to dryness.
Total Zinc
<0.15
>0.15
91.8-98.6
1.3-8.6
0.04-0.35
0.01-0.033
33-185
50-1840
256-2480
-
53-92
0.4-2.4
7-46
Source: Perhac (1974)
-------
The distribution of zinc in rivers, reservoirs and their sediments, and
the effect of stream velocity on these concentrations has also been
reported by Williams e_t al. (1973). A detailed study in one river showed
no correlation existed between stream flow and the concentration of
soluble zinc. However, a strong positive correlation did exist between
stream flow and the concentration of zinc in the resuspended bottom
sediments, mostly in the form of ooze deposits, present in the water
column following increased flow and scour from heavy rain runoff. It
should be noted that any event which leads to the resuspension of such
polluted sediments (e.g., heavy rains, in-stream concentration, dredging,
rapid dam draw-down, etc.) can increase the concentration of zinc in the
water column several fold and lead to heavy kills of aquatic life.
Synergistic effects of zinc with other pollutants in the sediments (as
well as the toxic effects of other pollutants alone) are also important
in these cases.
The profile of 'anthropogenic zinc in freshwater sediments appears to
differ from the sharp, initial drop-off profile seen in soils (described
previously). One example, shown in Table IV-5, indicates that a well-
mixed layer of 15-20 cm may exist for the top sediments; beneath this
level concentrations then drop fairly quickly to background levels. The
data of Mclntosh and Bishop (1976) also indicate such a profile. The
distance zinc travels in streams while sorbed to suspended sediments is
a function of the stream velocity. Therefore, one can expect greater
zinc mobility in April due to rain and snow melt than in August.
Groundwater Contamination; Contamination of groundwaters by metals
leaching through tailing piles has been cited by Martin and Hills (1976)
and Mike .et al. (1972). Leaching of AMD is a function of the tailing
pile porosity. Tailings from years ago were higher in porosity, allowing
for more active leaching to occur.
IV-34
-------
Table IV-5
Profile of Zinc in Selected Sediment Cores
Depth (cm)
0-5 '
5-10
10-15
15-20
20-25
25-30
30-35
35-40
40-45
45-50
50-55
from Foundry Cove
Core
No. 15
316
321
305
224
124
97
90
80
84
80
82
(Hudson River)
Concentration (ppm)
Core
No. 6
358
342
314
235
219
119
79
.
Core
No. 10
309
307
274
238
168
.
106
107
Source: Bower et al., 1978
IV-3S
-------
Groundwater contamination from tailing pond waters was researched by
Mink j|t al. (1972). They found that the high levels of zinc in the
groundwaters was due to leaching of old oine tailings in contact
with a high water table. The waters from the settling pond served only .
as a recharge basin for the aquifers, thereby keeping the old tailings
in constant contact with water. They concluded that the groundwater
pollution was not the result of present day mining waste disposal.
Gibb (1976) investigated the extent of groundwater pollution from a
surficial toxic waste disposal site at a secondary zinc smelting plant.
The site was underlain by low- permeability silts and clays and covered
by a 1-10 foot thick layer of heavy metal rich cinders and ashes which
had been generated by 85 years of smelting. The highest concentrations
of zinc were observed directly beneath the cinders, where concentrations
exceeded 10,000 ppm. However, analysis of well water samples indicated
levels of zinc at less than lmg/1 with very little monthly variation.
Analysis of leachate from a power plant ash pond revealed 26.2 mg/1
particulate zinc, and 4SOmg/l soluble zinc (Theis and Richter, 1979).
Within 100 meters of the pond, zinc was available as the ion, and as
zinc sulfate. At a distance of 400 meters from the pond, most of the
zinc was associated with hydrous iron and manganese oxides. Once in
the groundwater, zinc may follow one of the following routes: 1) surface
water recharge, .or 2) discharge into the ocean. Both of these
processes will be slow.
Ultimate Sinks: Lakes or oceans which are fed by streams or groundwater
from mined areas may serve as the ultimate sink for zinc. The effect
a polluted stream has upon a lake is a function of the volume of pollutants
introduced to the lake, and the natural buffering capacity of the lake.
Martin and Mills (1976) suggest that the most notable effects of acid
mine drainage will result at the mouth of the stream. 'It is likely
that the stream drops its suspended load when its velocity is slowed
upon entry into the lake. An example of adverse effects to fish
IV-36
-------
reproduction in a California lake has been cited by Martin and Mills
(1976). Mclntosh and Bishop (1976) researched the partitioning of zinc
among the dissolved solids, suspended solids and sediments of a lake
fed by a polluted stream. The dissolved solids were categorized as
that fraction of solids which passed through a 45 y filter; the sus-
pended solids were that fraction which was retained. The results are
listed below:
Dissolved Solids - 125 ug/ 1 Zn
Suspended Solids - 32 ug/ 1 Zn
Sediments - 7530 ppm Zn (dry wt; top 5 cm)
Summary Statement! Transport of zinc from mine tailings, and solid
waste piles will primarily affect surface water quality. The coneen-
tration of zinc in stream waters is reduced by precipitation, adsorption,
dilution and reduced stream flow, leading to zinc-enriched sediments.
The trace 'quantity, of zinc remaining in the water column is associated
with the dissolved and suspended solids. The relative importance of
these components is variable, although the larger portion of zinc is
generally transported in the dissolved form.
Evidence of groundwater contamination has been cited. Transport of
zinc from the tailings to the groundwater does not appear to be a
fast process, although transport to surface water may be more important,
especially from old tailings. Sorption of zinc by soil hydrous iron
and manganese oxides retards the movement of zinc in the soil profile.
IV-37
-------
c.
Pathway #3 - Industrial Wastewater Effluents
Effluent
Aqueous
Discharge
Treatment
sludge
Hazardous Waste/
Solid Waste Dump
Pathway
#4
Sources; Pathway 3 considers the fate of zinc discharged with indus-
trial wastewater effluents. The industries which discharge zinc are
numerous. The major ones are involved in the production of brass, zinc
oxide, iron and steel, galvinized items, and ore beneficiation. .Indus-
trial effluents are discharged with or without treatment into natural
waters or municipal wastewater treatment systems. Yost and Masarik
(1977) have investigated the efficiency of "chemical-destruct"
systems or wastewater treatment systems employed by the metal finishing
industries. The results obtained from neutralization and precipita-
tion of zinc oxides for one plant are summarized below.
Zinc Concentration, me/1
Before
Treatment
Distribution of Zinc in
Aqueous Discharge
After % in Dissolved % in Suspended
Treatment % Removal Solids Solids
8.6
0.35
96
0.3-7
93-97.7
These results indicate that zinc removal in this case is a very
efficient process. The bulk of zinc discharged with industrial
effluents is associated with suspended solids.
The effluent of treated industrial process waters will be discharged to
municipal sewers or surface waters. The fate of zinc once it reaches
a Publicly Owned Treatment Work (POTW) will be discussed in Pathway 4.
IV-38
-------
In another study, a creek receiving industrial and municipal waste effluents
was compared to nearby non-industrial use streams (Mathis ejt _al., 1973).
The authors suggested that the extent of urban use is best reflected by
the composition of the river sediments. The contaminated creek had a
mean concentration of 81 ppm; the non-industrial-use streams contained
30 ppm.
The study by Mclntosh and Bishop (1976) reveals the effects of zinc con-
centrations in the water column when a major metal plating operation dis-
continued discharging into a small lake in 1975. The results for the
average zinc concentrations in the lake are listed below:
1974 1975
Dissolved Zinc (ppb) 224 30
Zinc in Suspended Solids (ppb) 51 16
The lake sediments acted as a sink for zinc; the average concentration
in the top 0-5 cm was 7530 ppm. The authors did not distinguish between
1974 and 1975 deposition. Concentrations were found to decrease sig-
nificantly below the top 10 cm as shown in Figure IV-14.
The transport of zinc in surface waters has been reviewed in greater
detail in Pathway #2. Briefly, the concentration of zinc decreases
rapidly downstream from the point of discharge due to sorption, dilution
and precipitation. The work of Perhac (1974) revealed that sorption onto
particulate matter yielded the largest concentrations of zinc in the water
column. However, the bulk of zinc in the water column is transported in
association with dissolved solids, since this fraction makes up about 95%
of the total zinc.
The sludge generated by effluent treatment contains primarily zinc hydroxide
and zinc carbonate in a precipitated form. The sludge is normally disposed
t
of in a solid or hazardous waste dump, or settling pond. A properly
designed hazardous waste dump should prevent further translocation of
zinc due to leaching. Some sites collect the leachate, and send it to
IV-39
-------
0-5
5-10
10-15
e
u
E 15-20
a
o
I
20-25
25-30
1000 2000 3000 4000 5000 6000 7000 8000
Zinc Concentration (ppm-Ory Weight)
Figure IV-14 CONCENTRATION OP ZINC vs. SEDIMENT DEPTH OP A POLLUTED LAKE
Source: Mclntosh and Bishop (1976)
IV-40
-------
a POTW (with or without further treatment). Groundwater contamination
is a possible occurrence in a poorly operated landfill or settling pond.
The speed at which zinc is translocated via this pathway is slow. The
fate of zinc in solid waste sites was reviewed in Pathway 2.
Ultimate Sinks; The sinks of zinc associated with treated industrial
effluents are, in the short-term, hazardous waste dumps, settling ponds,
or sites used for the dispoal of sludge generated by POTW's. The
long-term sinks, as discussed earlier, are the oceans and lake sediments.
Summary Statement; Industrial effluents may contribute to the concentra-
tions of zinc already.present in municipal sewers or surface waters, and
if treated, to industrial waste dump sites associated with the waste
treatment sludge. Stream and lake sediments best reflect the extent of
industrial contributions of zinc over time. Sludge generated from
effluent treatment contains zinc primarily as the hydroxide and carbonate.
Disposal in a properly designed hazardous waste dump should prevent
further translocation of zinc.
IV-41
-------
d. Pathway »4 - POTW
POTW INFLUENT
Effluent
BIOL.
TREAT.
INCINERATION,-LAND
DISPOSAL, OCEAN DISPOSAL
Pathway #4 describes the fate of zinc in wastewaters which are introduced
into a Publicly Owned Treatment Plant (POTW). The inflow to the POTW may
consist of combinations of industrial and commercial effluents, domestic
wastes and surface runoff. The nature of the influent is consequently
quite varied, but typical influent concentrations will be about 1 ppm.
Domestic wastes have been estimated to contribute about 31% of the zinc
(Davis and Jacknow, 1975).
The degree to which zinc is removed from the raw wastewaters, and thus
the concentration of zinc in the discharged wastewaters, depends on the
type of treatment involved. One report provides a summary of data from
various studies including 269 municipal treatment plants in the U.S.
using various treatment methods (EPA, 1977). (See Section III.) The
data for zinc are summarized below.
Effluent Data (Means)
Type of Treatment
Primary
Biological (all types)
Activated sludge
Trickling filter
JBiglpgical with" chemical
addition
Tertiary
% Removal of Zn
(%)
31
52
58
46
72
63
Zn Concentration
(mg/L)
0.55
0.28
0.24
0.32
Not
Available
Not
Available
IV-42
-------
The notion of concentration-dependent removal efficiency for zinc
from FOTW influents can be demonstrated from the data generated from
an activated sludge treatment plant in Grand Rapids, Michigan
(Seiner, 1978). In 1968, the metal platers and other industries were
forced to pretreat their waste prior to discharge into the sewer. Before
this ordinance, 46% of 3.7 ppm zinc in the influent was removed in
the municipal treatment plants; after pretreatment enforcement, 63%
I*
of 0.78 ppm zinc was removed. Figure IV-15 illustrates the reduction
of zinc concentrations in sewage, as well as the effects of inter-
disciplinary environmental controls. The "hump" In Figure IV-15 was
caused by the discharge into sewers of scrubber waters resulting from
newly installed air pollution control devices in brass foundries.
By 1973, suitable pretreatment methods were enacted which drastically
reduced the concentration of zinc in sewage.
Zinc partitions into the sludge portion of the waste during treatment.
The average concentration of zinc in digested sludges has been reported
as 2420 ppm (survey of 100 plants) and 6380 ppm (survey of 80 plants) on
a dry weight basis (NRC, 1979). As- illustrated in the flow diagram
above, disposal of the FOTW effluent usually consists of discharge
into surface waters or oceans. The sludge can be incinerated, dumped
into ocean environments, or spread upon land.
Sludge which is disposed of on land may go to a sanitary landfill, o.r be
spread for the purpose of amending the soil. The form of zinc in sludge
is not known as revealed by a literature review conducted by Hoover
(1978). Sommers et, al. (1976) found that zinc sulfides,
phosphates, and hydroxides were not detected in sludges containing
relatively high concentrations of zinc. They did find a zinc-hydroxy-
carbonate complex, and suggested that the chemistry of zinc in sludge is
relatively complicated. The same study found that the movement of zinc
in sludge-amended soils was unaffected by the soil, pH, or clay content.
IV-43
-------
mg/l
5.0
4.0
3.0
£
2.0
1.0
Influent 79% Red.
l I I i
I I l i
1968 '69 *70 '71 72 73 74 75 76 77 78
Source: Seiner (1978)
FIGURE IV-15 TOTAL ZINC IN SEWAGE, GRAND RAPIDS, MICHIGAN
IV-44
-------
Minimal movement of heavy metals was observed in the top 7.5 cm of soil
and no translocation was detected between 7.5 and 15 cm. Zinc specifi-
cally, was found in concentrations of <0.1 ppm in the soil leachate.
However, the control sample also had the same concentration. The authors
concluded that the application of sludge to soils does not enhance the
solubility or movement of zinc. '
The zinc in sewage sludges and other wastes disposed of in sanitary land-
fills may be more mobile than the case described above for soil applica-
tion. Data on the mobility and concentrations of zinc in leachate from
landfills accepting sewage sludges were not available for this study.
Data from other landfills, however, do show zinc concentrations ranging
from 0.01 to 240 mg/L, with 3.mg/L being a typical value. Zinc was con-
sidered to be a significant pollutant in leachate since the concentrations
found were significantly higher than those found in nearby (unaffected)
groundwaters (EPA, 1977). Sludge which is incinerated will contribute
to the concentrations of zinc in the atmosphere. The fate processes
will be similar to the same chain of events described in Pathway #1.
The behavior of zinc discharged with POTW effluents into local surface
waters will be similar to that already described in other aqueous path-
ways. The fate of zinc discharged by the Joint Water Pollution Control
Project (JWPCP) of the Los Angeles County Sanitation District has been
studied in some detail (Morel et al., 1975), and may be generally repre-
sentative of POTW discharges to the ocean. While zinc in this study was
likely to be found in the fairly insoluble sulfide form in the effluent
(^370 mgd effluent, discharged through submarine outfalls at a depth of
60 meters), the studies indicated that the combined processes of dilution
and oxidation resulted in substantial solubilization of zinc (as well as
other metals); this increases their residence time in the water and allows
them to be transported greater distances where the effects would be
The wastes, containing both domestic and industrial wastes, contain
high levels of zinc (2400 ppm) after primary treatment.
IV-45
-------
negligible. It was estimated that only about one percent of the metals
were deposited in the general area of the outfall. The sediments that
do settle near the outfall are likely to be anoxic (Bertline and Goldberg,
1977) and zinc would, thus, be in the sulfide form.
Summary Statement; Wastewater treatment causes zinc to partition into
the sludge, such that effluent concentrations range from 0.24-0.55 mg/1.
Zinc mobility from sludge spread as a amendment to soil is unaffected
»
by the soil, pH, or clay content. Most of the zinc remains in the top
few centimeters of soil. Zinc associated with sludge disposed of in
sanitary landfills, may be slightly more mobile, as determined by con-
centrations found in landfill leachate. Sludge incineration will pro-
mote atmospheric emissions of zinc oxide, the fate of which was covered
in Pathway #1. Ocean disposal will contribute to slightly enriched
sediments in the vicinity of the outfall in which the form of zinc will
likely be the insoluble sulfide.
IV-46
-------
4. Biological Pathways
a. Zinc Uptake from Soils
Zinc Uptake via Aerial Deposition on Soil (Pathway />!) - Zinc uptake
by terrestrial plants is a function of the form of zinc,, as well as
the properties of the soil and plant. The parameters which influence
the translocation of zinc into plants are complex and integrated; reviews
of these variables have been conducted by Cataldo and Wildung (1978),
and NRC (1979).
Cataldo and Wildung (1978) found that the major factor governing the
availability, of heavy metals to terrestrial plants will be the solubility
and thermodynamic activity of the uncomplexed ion. The form of zinc as
a result of aerial deposition is primarily the insoluble oxide; dissociation
is promoted by small particulate sizes, and low pH of the soil solution.
The soils and grasses near a lead smelting complex in Idaho illustrate
the extent of metal uptake by biota in a contaminated area (Ragaini et al.,
1977). The results of zinc uptake grasses grown in the top 2 cm of con-
taminated soils are tabulated below:
Concentration of Zinc Cpom - dry weight)
Ave. Cone, in Grass
Soil Grass
Near Smelter
Background
Ave. Smelter Cone./
Ave. Background Cone. 8 10
The results indicate that zinc is readily translocated from soil to grasses.
The grasses accumulated zinc from contaminated soils as easily as background
zinc was translocated.
Soil
870-13,000
804-940
Grass
560-11,900
420-810
Ave. Cone, in Soil
0.9
0.7
IV-47
-------
Sewage Sludge - Zinc uptake from sewage sludge land dispoal may be sub-
stantial. Generally, if the pH of the sludge treated soil is maintained
above 6.5, the mobility of zinc is limited (Council for Agricultural
Science and Technology, 1976). The Council for Agricultural Science
and Technology cites several examples of studies involving crop bio-
accumulation from sludge amended soils. Giordano and Mays, as reviewed
by the Council, found that zinc sulfate was more immediately available
to string beans and sweet corn than zinc in sludge. In the long term,
however, more zinc was bioaccumulated from the sludge-amended soils.
Over time, Tinchtar et al. (Council of Agricultural Science, -1976)
discovered that the concentration of zinc in coastal bermuda grass
decreased by 50% within three years after sludge application was stopped.
Further discussion of plant uptakes is contained in NRC (1979).
Purposeful Application of Zinc - Zinc is used as an agricultural crop
and animal trace nutrient. It is applied to the soil as the hydrated
sulfate or carbonate at concentrations of about 9-18 kg/acre as the
sulfate (NRC, 1979). Approximately 40% of the zinc sulfate produced
is used for agricultural purposes.
Zinc is also a component in two popular agricultural fungicides, Zineb
and Ziram. Uptake from these uses would be more rapid than from sludge
since it is applied in an Inorganic form.
b. Bioaccumulation of Zinc in Aquatic Organisms
Bioaccumulation of zinc by both terrestrial and aquatic organisms has
been extensively reviewed and the reader is directed to these studies
for more detail (Versar, 1979a; NRC, 1979; Phillips and Russo, 1978).
Although zinc is accumulated in the food chain, it does not appear to
be biomagnified (Versar, 1979a). Baptist and Lewis, as cited by Versar
(1979a) found that the concentration of zinc decreased with each trophic
level of a four-tier study. They found that uptake of zinc via water is
IV-48
-------
Che more efficient pathway for zooplankton, while uptake of zinc by fish
is more efficient via the food chain. Merlin et al., as cited by
Phillips and Russo (1978) found that the diet of the fish determines
how the zinc is accumulated. Fish fed synthetic diets containing zinc
accumulated zinc much quicker than did fish fed snails containing
similar levels. Deposit feeding organisms accumulate zinc more actively;
from biogenic carbonates (e.g., clamshells), than from other sediment-bound
zinc. In turn, the rate of uptake of zinc bound to organic detritus is
faster than from hydrous iron and manganese oxides (Versar, 1979a)
Zinc uptake by aquatic organisms is a function of water temperature, pH,
salinity and hardness. Uptake increases with temperature due to
temperature-related increases in metabolic rate (Phillips and Russo,
1978, NRC, 1979, Namminga and Wllhm, 1977). Zinc uptake and accumulation
by aquatic plants increases with increasing pH. Zinc concentrations
accumulated by algae were found to be twice as high at pH 8 as at pH.7,
and six times as high at pH 9 (NRC, 1979). These data, and other studies,
indicate a pH-dependent adsorption exchange by aquatic plants. Although
zinc toxicity is inversely proportional to water hardness, uptake of zinc
by fish increases as hardness increases. One reason may be"that zinc
precipitates in calcium-free waters on the mucus of fish body surfaces.
Therefore, the zinc is released directly back into water.
Huggett et al. (as cited in NRC, 1979), determined that oysters accumulate
more zinc as the salinity level of the water decreases. This correlation
was observed for all rivers emptying into the Chesapeake Bay. A similar
trend was noted for uptake of zinc by aquatic plants in the absence of
"competing" ions. The presence of sodium, potassium, magnesium and
calcium ions inhibits uptake of zinc. Competition for available bonding
sites on the plants may explain this observation.
Depending on the organism, zinc may or may not be accumulated in one
or more organs preferentially. Although the Atlantic oyster has the
highest known bioconcentration factor (up co 100,000 times the water
IV-49
-------
concentration), zinc is not strongly localized in any particular organs
or tissues (MC, 1979). Mussels, on the other hand, tend to concentrate
..'
zinc mostly in the visceral mass (including the kidneys)/iand gonads, and
least in the foot and shell. In scallops, zinc is concentrated in the
kidneys (NRC, 1979), while in crustacenas the hepatopancreas normally
has the highest levels. Most finfish concentrate zinc in the kidneys
preferentially over other ograns, although Matthiesson and Brafield
(1977) found that the stickleback accumulated zinc primarily in the
gills. They also observed that zinc uptake increased with oxygen con-
sumption, suggesting that the gills serve as an important site for
zinc absorption in this species.
The biological half-life of zinc in aquatic and freshwater organisms
appears to range from three days to 650 days for mollusks, crustaceans
and fish (National Academy of Science, 1978). In all cases in which
the half-life was determined as a function of temperature, the half-life
decreased as the temperature increased. Loss mechanisms for zinc are
excretion and molting.
Table IV-6 briefly summarizes the ranges of bioconcentration factors
for fresh and saltwater organisms.
Zinc uptake by the biota residing in aqueous bodies which receive
industrial and municipal discharges has been investigated. Mathis and
Cummings (1973) studied the partitioning of zinc between the sediment,
water and biota of the Illinois River. The Illinois River receives
domestic and.industrial wastes from Chicago and Feoria. Figure IV-16
demonstrates that the highest concentrations of zinc resided with the
bottom sediments, closely followed by bioaccumulation by clams, tubificid
worms, omnivorous fish, carnivorous fish, and water, respectively.
The results obtained by Namminga and Wilhm (1977) only partially support
those of Mathis and Cummings (1973). The creek tested was che discharge basin
for municipal and industrial wastes from an oil refinery. Zinc partitioned
IV-50
-------
References
a. lil'A (1979)
b. NRC (1979)
c. Versar (1979a)
Table IV-6
Bioaccumulation of Zinc by Aquatic Organisms
Seawater
Bloconcentratlon
Factor
I
Ul
Algae
Decapods
Mussels
Oysters
Clams
Fish
Seaweeds
Fresh Water
Plants
Invertebrates
Insects
Fish
400 - 1,400 (b)
1 - 12,400 (a)
142 - 9,000 (a)
130 - 310 (a)
450 - 27,000 (c)
43 - 500 (a)
11 - 373 (a)
900 (c)
4,000 (c)
10,000 - 40,000 (c)
106 - 1,130 (a)
8 - ' 12 (a)
Concentration in Organisms (ppm - fresh wt.)
24.9 - 44.5 (b)
100.9 - 271.01 (b)
8.0 - 22.5 (b)
2.98 - 23.85 (b)
-------
80
70
5, 50
40
o
N
30
20
10
n
Water Carnivorous Omnivorous Clams
Fish Fish
Source: Mathis and Cummings (1973).
Worms Sediments
FIGURE IV-16 PARTITIONING IN BIOTA, SEDIMENTS. AND WATER
IV-5 2
-------
as follows: water column, 0.010 mg/K; sediments, 9.2 ing/kg; chironomides
(midge larvae), 57.5 mg/kg. The authors hypothesize that zinc accumulates
in chironomids primarily due to surface adsorption and cation exchange.
The low bioconcentration factor for zinc compared to sediments may be
due to frequent molting by the chironomids, thereby eliminating the
adsorbed metal.
Zinc bioconcentration in lake waters has been reviewed by Mclntosh and
Bishop (1978). The history of Little Center Lake was discussed in
Pathway #3. The extent of accumulation by fish and periphyton (sessile
community of organisms) is summarized as follows:
Average
Zinc Concentration (pom) Concentration Factor
Water .044
Sediments (0.5 cm) 7,530 171,000
Periphyton 1,230 28,000
Bluegill (Lepomis 180 4,100
maerochirus)
Pumpkinseed (Lepomis 142 3,200
Sibbosus)
These numbers demonstrate that the largest accumulators of zinc, after
the sediments, are the periphyton community. Both fish species concen-
trated similar levels of zinc which were one order of magnitude less
than the periphyton, and two orders less than the sediments.
The impact of zinc leached from sewage sludge by seawater of a tropical
ecosystem has been studied by Montgomery and Price (1979). The study
investigated the uptake of zinc, in addition to other metals, by the
inhabitants of a turtle grass mangrove ecosystem. The net loss of
zinc from the sewage sludge was paralleled by a net increase of zinc
uptake by the "fouling" organisms. Net uptake of zinc was reported for
IV-53
-------
turtle grass (Thalassia testudlnum), an urchin which grazes on turtle
grass (Lytechinus varlegatus), the sea cucumber (Holothuria mexicana),
and the roots of the red mangrove (Rhizophora mangle). After 125 days,
the turtle grass leaves contained about 3 ug/g zinc, dry weight; the
grazer contained about 17 ug/g- The mean concentration of zinc in the
seawater was 20.1 ug/K.
c. Summary Statement
Biological uptake of zinc from soils appears to occur under many different
conditions. The rate of uptake is likely to be faster for the more soluble
forms of zinc (e.g., ZnSO.) than for zinc encountered as the oxide or in
association with sewage sludge. However, all studies report substantial
uptake by zinc by terrestrial plants over time.
Uptake by aquatic organisms proceeds via ingestion and sorption. It is
unclear which mechanism dominates for fish. Uptake is enhanced by
increased temperature, pH and water hardness. Two examples were cited
in which uptake decreased as a result of increased salinity and
"competing ions."
Bioconcentration is greatest for algae and benthic feeders. No evidence
of biomagnification has been observed. The biological half-life of zinc
is inversely related to temperature. Loss mechanisms are excretion
and molting.
17-54
-------
C. REFERENCES
Seiner, J.A. and W.H. Bourma. 1978. Case History City of Grand Rapids,
Michigan Program of Industrial Waste Control. In: Pretreatment of
Industrial Wastes - Joint Municipal and Industrial Seminar. A.S. Vernick
H.D. Feiler, P.O. Lanik, eds. EPA Seminar Handout.
Bertine, K.K, and E.D. Goldberg. 1977. History of heavy metal pollution
in Southern California coastal zone-reprise. Environ. Sci. Techno1.,
11(3):297-299.
Bower, P.M., H.J. Simpson, S.C. Williams, and Y.H. Li. 1978. Heavy
metals in the sediments of foundry cove, Cold Spring, New York. Environ.
Sci. Technol., 12(6):683-687.
Cataldo, D.A. and R.E. Wilding. 1978. Soil and plant factors influencing
the accumulation of heavy metals by plants. Environ. Health Perspectives,
27:149-159.
Christensen, F.R., J. Scherfig, and M. Koide. 1979. Metals from urban
runoff in dated sediments of a very shallow estuary. Environ. Sci.
Technol., 12(10):1168-1173.
Coles, D.G., R.C. Ragaini, J.H. Ondor, G.L. Fisher, D. Silberman, and
B.A. Prentice. 1979". chemical -studies of stack fly ash from a coal-fired
power plant. Environ. Sci. Technol., 13(4);455-459.
Council for Agricultural Science and Technology. 1976. Application of Sewage
Sludge to Cropland: Appraisal and Potential Hazards of the Heavy
Metals to Plants and Animals. Prepared for U.S. EPA, Office of Water
Program Operations, EPA-430/9-76-013.
Dana, J.A. and J.O. Leckie. 1978. Effects of absorbed complexing ligands on
trace metals uptake by hydrous oxides. Environ. Sci. Technol., 12(12);
1309-1315.
Davis, J. and J. Jacknow. 1975. Heavy metals in wastewater in three
urban areas. JWPCF, 47(9);2292.
Gibb, J.P. 1976. Field Verification of Hazardous Industrial Waste
Migration from Land Disposal Sites, Proceedings of Che Hazardous
Waste Research Symposium, EPA 600/9-76-015, U.S. EPA, Cincinnati, Ohio.
Hamilton-Taylor, J. 1979. Enrichments of zinc, lead, and copper - recent
sediments of Windermere, England. Environ. Sci. Technol., 13(6):693-697.
Hem, J.D. 1972. Chemistry and occurrence of cadmium and zinc in surface
water and groundwater. Water Resources Research, 8/3):661-679.
Holcombe, L.A. 1977. Adsorption and Desorgcion in Mine Drainages.
NTIS, //PB-290 614/7WP.
IV-55
-------
Hoover, T.B. 1978. Inorganic Species in Water; Ecological Significance
and Analytical Needs (A Literature Review). U.S. EPA 600/3-78-064,
Environmental Research Lab, Athens, Georgia.
Huang, C.P., H.A. Elliott, and R.M. Ashmead. 1977. Interfacial reactions
and the fate of heavy metals in soil-water systems. J. Water Pollution
Control Fed., 49(5):745-756.
Jacko, R.B., D.W. Nevendorf, and K.J. Yost. 1975. Trace Metal Emissions
from a Scrubber Controlled Municipal Incinerator. ASME paper #N75-WA/
APC-2.
Jennett, J.C. and S.M. Linnemann. 1977. Disposal of lead and zinc
containing wastes on soils. J. Water Pollution Control Fed., 49(8):
1842-1856.
Martin, H.W. and W.R. Mills, Jr. 1976. Water Pollution Caused by
Inactive Ore and Mineral Mines - A National Assessment. NTIS
#PB-264-956, prepared for the Office of Research and Development,
U.S. EPA, Cincinnati, Ohio.
i
Mathis, E., B.J. and T.F. Cunnings. 1973. Selected metals in sediments,
water, and biota in the Illinois River. J. Water Pollut. Control Fed.,
45(7):1573-1583.
Mclntosh, A. and W. Bishop. 1976. Distribution and Effects of Heavy
Metals - A Contaminated.Lake. Purdue University Water Resources Research
Center, #85.
Mezey, E.J., S. Singh, and D.W."Hissong. 1976. Fuel Contaminants.
Volume 1; Chemistry. Report by Battelle Columbus Laboratories to
U.S. EPA, EPA-600/2-76-177a.
Mink, L.L., R.E. Williams, and A.T. Wallace. 1972. Effect of early.day
mining operations on present day water quality. Groundwater, 10(1);17-26.
Montgomery, J.R. and N.T. Price. 1979. Release of trace metals by
sewage sludge and the subsequent uptake by members of the turtle grass
mangrove ecosystem. Environ. Sci Technol., 13(5);546-549.
Morel, F.M.M., J.C. Westall, C.R. O'Melia, and J.J. Morgan. 1975. Fate
of trace metals in Los Angeles County wastewater discharge. Environ.
Sci. Technol., £(8):756-761.
Namminga, H. and J. Wilhm. 1977. Heavy metals in water, sediments, and
chironomids. J. Water Pollution Control Fed., 49_(7): 1725-1731.
IV-56
-------
National Research Council. 1979. . Zinc. Prepared by Che Subcommittee
on Zinc, Committee on Medical and Biological Effects of Environmental
Pollutants. National Academy of Sciences, Washington, D.C.
Perhac, R.M. 1974. Water Transport of Heavy Metals in Solution and by
Different Sizes of Participate Solids. NTIS #PB-232 427.
Phillips, E., G.R. and R.C. Russo. 1978. Metal Bioaccumulation in
Fishes and Aquatic Invertebrates; A Literature Review. EPA-600/3-78-103,
U.S. EPA, Office of Research and Development.
Ragaini, R.C., H.R. Ralston, and N. Roberts. 1977. Environmental trace
metal contamination in Kellogg, Idaho, near a lead smelting complex.
Environ. Sci. Technol., 11(8):773-784.
Schell, W.R. and A. Nevissi. 1977. Heavy metals from waste disposal
in central Puget Sound. Environ. Sci. Technol., 11(9):887-893.
Sonmers, L.E., D.W. Nelson, R.E. Terry, and D.J. Silviera. 1976.
Nitrogen and Metal Contamination of Natural Waters from Sewage Sludge
Disposal on Land. Purdue University, Resources Research Center.
Theis, T.L. and R.O. Richter. 1979. Chemical speciations of heavy
metals in power plants ash pond leachate. Environ. Sci. Technol., .13_(2):
219-228.
U.S. Environmental Protection Agency. 1977. Information for proposed
general pretreatment regulations. _40 CFR 405, Washington, D.C.
U.S. Environmental Protection Agency. 1977. Report of Pollution-Caused
Fish Kill. Office of Water Planning and Standards, EPA Form 7500-8.
U.S. Environmental Protection Agency. 1977. The Prevalences of Subsur-
face Migrations of Hazardous Chemical Substances at Selected Industrial
Waste Dispoal Sites.
U.S. Environmental Protection Agency. 1979. Ambient Water Quality
Criteria: Zinc.
Versar, Inc. 1979a. Statement of Probable Fate. Draft report to the
Monitoring and Data Support Division, EPA.
Versar, Inc. 1979b. Non-Aquatic Fate of Zinc.
Williams, L.G., J.C. Joyce, and S.T. Monk, Jr. 1973. Stream-velocity
effects on the heavy metal concentrations. J. Am. Water Works Assoc.,
pp. 275-279.
Vuceta, J and J.J. Morgan. 1978. Chemical modeling of trace metals in
fresh waters: Role of complexation and adsorption. Environ. Sci. Technol.,
12(12):1302-1308.
Tost, K.J. and D.R. Masarik. 1977. A Studv of Chemical Destruct Waste
Treatment Systems in the Electroplating Industry: Plating and Surface
Finishing, pp. 35-40.
IV-5 7
-------
V. EFFECTS OF ZINC
A. HOMAN TOXICITY
1. Introduction
Zinc is an essential trace element in human and animal* nutrition and
is present in virtually all mammalian tissues and biological fluids.
Estimates of total body zinc for a hypothetical 70 kg man range from
1.4 to 2.3 grams (Burch et_ al., 1975). The major amount Ov-90%) of body
zinc resides in muscle and bone but the highest concentrations are found
in tissues of the eye and the male reproductive tract (NAS, 1978).
Zinc has two known biological functions: (1) as a necessary component
of certain metalloenzymes (e.g., carbonic anhydrase, alkaline phosphatase,
alcohol dehydrogenase) and (2) for the optimal synthesis of proteins,
nucleic acids and lipids. Dietary requirements for zinc are thus
related to the needs for growth, tissue repair and compensation for
excretion.
Zinc must be supplied in the diet more or less continuously since it is
also excreted at a comparable rate. The recommended human dietary
allowances for zinc are as follows:
Age Zinc (mg/day)
0-6 mo 3
6 mo-1 yr 5
1 yr-10 yr 10
adult 15
pregnant female 20
lactating female 25
Many dietary factors influence the utilization of zinc present in food.
The formation of insoluble complexes with calcium and phyta e in Che
alkaline intestinal environment has been shown co markedly decrease the
availability of zinc for intestinal absorption by experimental animals.
Dietary fiber has also been shown to decrease Che availability of zinc
for intestinal absorption by man (Reinhold ££ al.., 1976).
V-l
-------
Zinc status is also affected by infections, pregnancy, surgical pro-
cedures or stressful situations such as myocardial infarction, etc.
(Lindeman £t al., 1972; Burch e_t al., 1975).
a. Zinc Deficiency
Due to the essential nature of zinc to human health, attention has
focused on marginal or deficient zinc intake rather than zinc toxicity.
Growth is impaired in the young of all species in which zinc deficiency
has been observed (Horvath, 1976). Insufficient zinc in the diet also
results in inhibition of sexual maturation, loss of appetite, inability
to gain weight, skeletal abnormalities (bowing of the legs, joint
stiffness), parakeratotic esophageal and skin lesions and hair loss
(Burch et. al., 197S). Mature animals often display no signs of
deficiency other than poor appetite and decreased growth (NAS, 1978).
Material zinc deficiency is known to cause marked fetal abnormalities
in experimental animals (Hurley and Swenerton, 1966; Hurley et_ al., 1971),
The evidence available at present suggests that congenital malformations
in zinc-deficient embryos may be brought about by impaired synthesis
of nucleic acids. Swenerton £t al. (1969) found DNA synthesis as
measured by uptake of tritiated thymidine was much lower than normal
in zinc-deficient rat embryos at 12 days of gestation.
Prasad and Oberleas (1974) have shown that the activity of thymidine
kinase, an enzyme regarded as essential for DNA synthesis and cell
division, is adversely affected in rapidly regenerating connective
tissue. In.rats, this effect can be demonstrated as early as six
days following the institution of a Zn-deficient diet.
A probable human counterpart to animal zinc deficiency has been observed
in individuals living in Iran and Egypt and subsisting on diets con-
sisting largely of bread and beans and nearly devoid of animal protein
(Halstead £t al., 1972; Prasad _ec al., 1963ab). These individuals
have decreased zinc concencrations in plasma, red blood cells and hair
V-2
-------
and exhibit short stature owing to retarded growth, testicular atrophy
with hypogonadism and geophagia. Their status improves following oral
supplementation with zinc for several months.
Since food consumption is also reduced in a zinc deficient state, some
of the effects of low dietary zinc may be secondary to decreased food
consumption. A more detailed discussion of the various manifestations
of zinc deficiency in both man and animals may be found in Burch and
Sullivan (1976), F.C.T. (1972), NAS (1978), and Vallee (1959).
2. Metabolism and Bioaceumulation
The average adult ingests 10 to 15 mg of zinc daily. Absorption is
rapid but incomplete (about 30%) (Prasad, 1979; Burch et^ al., 1975).
Absorption of zinc seems to take place in the proximal part of the small
intestine but the exact mechanism or the sites of absorption in man is
not clear. Absorption appears to occur at other portions of the small
and large Intestine as well (Prasad, 1979; Methfessel and Spencer, 1973).
Zinc is 'transported throughout the body in the blood, bound mainly to
serum proteins (Prasad and Oberleas, 1970; Parisi and Vallee, 1970;
Suso and Edwards, 1971; Frazier, 1979).
Orally administered Zn appears in the blood of human subjects within
15-20 minutes after ingestion; plasma levels peak 2-4 hours later and
decline rapidly thereafter as tissue uptake occurs (NAS, 1978). The
biological half-life of ZN in man has been calculated to be between
154 and 334 days (Spencer ec al., 1965; Richmond at al., 1962; Andrasi
and Feher, 1967).
Absorbed zinc is excreted in urine, sweat, semen, hair, nails and
desquamated skin (Jameson, 1976). Zinc in feces represents the major
zinc loss from the body. Roughly 70-80% of ingested but unabsorbed
zinc is found in the stool ("O-10 mg daily) (Tsuchiya and Iwao, 1978;
NAS, 1978).
7-3
-------
Urinary loss (300-700 ug/24 hr) represents only a small fraction of
.the daily oral intake, but is fairly constant for a given adult (Burch
at al., 1975; Goolamali and Conaish, 1975).
Prasad jst al. (1963b) have estimated that 1.15 mg of zinc could be
lost per liter of sweat; in hot climates, five or more liters of sweat
may be lost per day.
For women of child-bearing age, zinc losses in menstrual fluid are
estimated to represent an additional 300 to 600 yg of zinc per menses
(Schroeder et al., 1967).
Most of the zinc present in the body is in a state of constant movement'
with the rate of accumulation and turnover varying greatly from tissue
to tissue. For example, zinc is incorporated into the skeleton slowly
but is firmly bound for long periods while zinc entering the hair is
lost as the hair is shed. The most rapid accumulation and turnover of
zinc occurs in liver, spleen and kidneys (NAS, 1978).
Mean serum zinc concentrations in healthy men and women are in the
range of 100 ug/dl but drop in pregnant women (97 ug/dl) and in healthy,
non-pregnant females taking oral contraceptives (81 ug/dl) (Halsted and
Smith, 1970). Patients with liver cirrhosis frequently possess low
serum zinc levels and paradoxically, may excrete several milligrams of
zinc in their urine each day (Burch &t_ al., 1975). Low serum zinc is
also found in patients with uremia, kwashiorkor and sickle-cell anemia
(Zazgornik et al., 1971; Smit and Pretorius, 1964; Prasad ^t al., 1975),
Zinc is also present in human milk but the concentration varies with
time after delivery. Zinc concentration in colostrum is 3 to 6 times
higher than that present in milk one week after parturition (3-4 mg/1)
and gradually falls off over the next 6 months (Prasad, 1966b; NAS,
1978).
-------
Human semen contains. 10-35 mg Zn/100 dl; a positive correlation seems
to exist between the number of spermatozoa and the level of zinc (NAS,
1978).
Zinc is also present in all human tissues with the highest concentra-
tions present in the choroid (419-562 ppm) of the eye (Galin, 1962),
and prostate (850 wg/g) (Underwood, 1971).
Additional information on the metabolism, storage and excretion of
zinc by man and experimental animals can be found in the Appendix.
None of this information has proved appropriate for inclusion in our
risk assessment calculations.
3. Animal Studies
a. Carcinogenesis
(1) Oral
Reports on the effects of dietary zinc on carcinogensis and tumor growth
have been varied. Davies et al. (1968) reported decreased levels of
serum zinc in patients with cancer of the bronchus and colon, but not
in other forms of cancer. Zinc is required for DNA synthesis
(Swenerton e£ al., 1969; Sandstead and Rinaldi, 1969), and since
tumors often have a high rate of DNA synthesis, these decreased serum
Shiraishi et al. (1969) found that serum zinc decreased in tumor-bearing
rats according to the time elapsed since tumor transplantation (i.e.,
serum zinc values were 166, 153, and 99.8 ug/dl at 10, 20 and 30 days
post-transplant, respectively, compared to 143 ug/dl for controls.
On the other hand, increased zinc concentrations, although highly
variable from patient to patient, have been found in cancerous lung
and breast tissue (Mulay et al., 1971) and in gastric juice of gastric
cancer patients (Matsumoto _ec al., 1969).
7-5
-------
Several workers have demonstrated reduced growth in a number of trans-
planted tumors (Walker 256, Lewis lung, L1210, P388) as well as pro-
longed survival in rats and mice receiving inadequate dietary zinc
(McQuitty at al. , 1970; DeWys.et al., 1970; DeWys and Pories, 1972;
Petering_et al., 1967; Poswillo and Cohen, 1971). These studies suggest
that tumor inhibition is a general effect of zinc deficiency irrespective
of cell type, cell growth rate or site of growth. The results, however,
apply only to the rate of growth of tumor cells and not to the process
of carcinogenesis.
Elevated levels of dietary zinc may also inhibit tumor growth. Duncan
et,al. (1974) .examined the effect of different levels of zinc (0.4-
2500 ug Zn/g ration) on the growth of a transplanted hepatoma (originally
induced by 3'-methyl-4-dimethylaminoazobenzene) in female Wistar rats.
Growth of the transplanted hepatoma was significantly (p <0.1) reduced
in rats maintained on diets either deficient (0.4 ug/g) or high in
zinc (> 500 ug/g) when compared to control animals (60 ug/g). Greater
inhibition of hepatoma growth was not achieved at toxic levels (2500
Ug/g) of Zn intake.
Ciapparelli .et al. (1972) examined the effects of the administration of
drinking water containing 0, 50, 100 or 250 ppm of zinc on DMBA (9, 10-
dimethyl-1, 2-benzanthracene)-induced-submandibular salivary gland
tumors in 4-5 mo-old Wistar strain albino rats. Zinc concentration in
the solid diet was 79 ppm. Tumor growth was retarded during the 31/2
month study in the 250 ppm zinc group. Unfortunately, the daily zinc
intake for individual animals from solid and liquid sources was not
determined. Poswillo and Cohen (1971) have also reported that addition
of 100 ppm ZnSO, to the drinking water of hamsters inhibited the forma-
tion of DMBA-induced tumors in the hamster cheek pouch. At 6 months,
the tumor incidence in Zn-DMBA-treated hamsters was 11% compared to
37% in hamsters treated with DMBA alone.
V-6
-------
On Che other hand, increased levels of dietary zinc (500 pptn) did not
appear to affect the growth of a grafted Walker 236 carcinosarcoma (a
rapidly dividing solid tumor) in rats (McQuitty et_ al., 1970).
Aside from an increased number of hepatomas above control (see Table V-l)
which were not considered to be significantly different from control,
the incidences of malignant lymphomas and pulmonary adenomata were
comparable to controls in Chester Beatty mice given.5000 ppm Zn (as
zinc oleate) in the diet for 3 months followed by 2500 ppm for 3 months
and then 1250 ppm zinc for an additional 21 weeks. The dietary con-
centrations of zinc were reduced due to mortality and severe anemia.
Addition of zinc sulfate to drinking water at 5000 and 1000 ppm for the
same period of time did not increase the incidence of tumors (Walters
and Roe, 1965).
Table V-l
Hepatomas Resulting from Zinc in the Diet of Mice
Hepatomas Malignant Lymphomas Lung Adenomas
Control - 3/24 (12.5%) 3/24 (12.5%) 10/24 (41.1%)
Zn Oleate (diet) 7/23 (30.4%) 2/23 ( 8.7%) 9/23 (39.1%)
5000 ppm ZnS04 (water) 3/22 (13.6%) 2/22 ( 9.1%) 5/22 (22.7%)
1000 ppm ZnS04 (water) 3/28 (10.7%) 4/28 (14.3%) 9/28 (32.1%)
(2) Intratesticular
Zinc has been shown to induce testicular teratomas in hamsters, rats
and roosters when injected directly into the testes (Guthrie and Guthrie,
1974; Riviefe ee_ al., 1966; Guthrie, 1967; Carleton et al., 1953).
These tumors developed in only a small percentage of the test animals but
spontaneously occurring testicular teratomas are rare.
Injection of 2 mg ZnCL. into the testes of 49 Cwo-monch-old Syrian
hamsters during the period of rapid seasonal gonadal growth produced
two embryonal carcinomas of Che eestis (4%) at termination of che study
V-7
-------
10 weeks later (Guthrle and Guthrie, 1974). Similarly, injection of
1.25-5 mg ZnCl. into one or both testis produced six interstitial-cell
tumors and one seminoma in ninety 4-8 mo-old Wistar rats by 28 months.
A second group of 15 rats injected with 2.5 mg ZnCl, plus 200 units of
gonadocropin developed two interstitial-cell tumors and one malignant
teratoma within 24 months (Rivie're ejt al., 1960). '
In the cock testes, teratomata developed only if zinc was administered
during periods of normally high sexual activity (January-March) or
following artificially induced sexual activity by injection of gonado-
troplns.
Guthrie (1967) produced teratomas within 2-4 months in five of forty-
six (10:8%) White Leghorn cockerels injected intratesticularly with
10 mg of ZnCl. during the period of rapid testicular growth. No tumors
(0/45) were found in cockerels injected with 0.2 ml of 1 N hydrochloric
acid suggesting that the production of partial necrosis of the testis
and the resulting gonadotropic-stimulation do not of themselves produce
teratomas.
Similar data were reported by Carleton and co-workers (1953) who noted
a tumor incidence of 25.6% (11/43) 3 to 9 months after injection of
10-25 mg ZnCl. into the testes of 18-month-old White Leghorn roosters.
Except for the ability of zinc to Induce testicular teratomas, no
experimental evidence exists to suggest that ingestion or parenteral
administration of zinc is tumorigenic. Indeed, several studies indicate
that the administration of zinc may inhibit the growth of tumor cells.
Its effect on the process of carcinogenesis is unclear. The significance
of the teratomata following direct injection into the testes during
periods of high or artificially induced sexual activity to human risk
from ingestion of zinc is questionable.
V-8
-------
b. Mutagenesis
No literature was found to suggest that zinc is mutagenic in mammalian
or bacterial systems. Van Rosen (1954) did report that an aqueous zinc
solution (concentration not stated) had weak chromosome-breaking
activity in Pisum rootlets and Herick (1969) noted disturbances in the
differentiation of the chromosomes in the broad bean, Vicia fava.
exposed to a 0.1% aqueous solution of zinc sulfate.
c. Adverse Reproductive Effects
Little is known concerning the effects of excessive zinc on reproduction
in general and embryonic development in particular. Sprague Dawley rats
fed 0.4% Zn, as the oxide, in the diet for 37 days continuously beginning
21 days before breeding through day 15 or 16 of pregnancy resorbed all
fetuses. Other rats fed the same diet from day 0 to day 15 or 16 of
pregnancy produced fetuses of normal appearance but of a smaller body
weight than controls. A variable degree (4-29%) of resorption was noted
in this group as well. Groups of female rats treated according to both
protocols but at 0.2% Zn produced normal fetuses with no effects noted
on fetal weight or the degree of resorptions (Schlicker and Cox, 1967,
1968).
In another study, pregnant rats were fed marginal (10%) protein diets
(30 ppm Zn) supplemented with a much lower level of zinc (150 ppm) as
zinc sulfate. Dams were killed on day 18 of pregnancy. The 13 Zn-
treated dams exhibited a higher rate of fetal resorption (9.4%) than
the 12 controls (1.9%) fed the basal diet containing 30 ppm Zn. Eight
of the 13 dams given excess zinc in the diet had at least one resorption
each compared to two of 12 control dams (p <0.05). The actual require-
ment of zinc during pregnancy in experimental animals is not well
established but it appears that a high rate of resorption can occur with
moderately high levels of zinc in the diet (Kumar, 1976).
Hedges £t al. (1976) saw no adverse effects on reproductive performance
in swine fed normal zinc levels (33-33 ppm) during gestation and lactation.
V-9
-------
Progeny from sous fed 33 ppm zinc did not appear to have the necessary
body stores of zinc for optimum growth, however.
Fern and Carpenter (1967) provoked a dubious response in a small group
of golden hamsters given 2 to 6 tag/kg ZnS0..7 H.O intravenously on day 8
of gestation:
Treatment
Control
2-6 mg ZnSO,.7 H.O
No. of
Dams
10
12
No. Embryos
Recovered
116
142
No. Embryos
Resorbed
"7
4
No. Embryos
Malformed
1 (0.8%)
2 (1.6%)
In a later study Perm and Carpenter (1968) observed a 4.6% incidence of
abnormal embryos (3/65) and 2.8% incidence of resorbed fetuses (2/70) in
embryos from 6 hamsters given 2 mg/kg ZnSO,.7 H.O intravenously on day 8
of gestation. No controls were run. The authors further reported that
intravenous doses of 10-25 mg/kg were well tolerated by the dams but
induced a fetal resorption rate of 12%. At higher dosage levels (not
given but 30 mg/kg was lethal to dams), a few gross malformations (^6%)
consisting of exencephaly and rib fusions were seen but no consistent
pattern of malformations was discernible. Ferm and Carpenter (1968)
have also shown that zinc exerts a remarkable protective effect against
cadmium-induced teratogenesis in hamsters provided zinc is administered
within 12 hours of cadmium administration.
Thus, there is some evidence to suggest that excessive dietary intake
of zinc (0.4% of the diet) prior to conception and throughout gestation
or intravenous administration of high doses of zinc (6 mg/kg) during
gestation may be linked to increased fetal resorption in rats and
hamsters. Confirmations! studies should be conducted. However, normal
to moderately elevated dietary zinc intakes were neither embryotoxic
nor teratogenic in either rats (0.2% diet) or swine (83 ppm).
V-10
-------
d. Other lexicological Effects
Zinc toxicity is an uncommon natural event in mammalian species. The
low toxicity of zinc is probably attributable to the homeostatic
mechanisms which control its absorption, tissue uptake and excretion.
Experimental animals, particularly rats, have tolerated up to 100 times
the normal dietary level of zinc without signs of toxicosis (NAS, 1978).
Heller and Burke (1927) fed young rats a basal diet supplemented with
0.252 Zn for 3 generations. No adverse effects were noted. Later
studies by Sutton and Nelson (1937), Sadasivan (1951) and Walters and
Roe (1965) establish 0.5% zinc in the diet (5000 ppm) to be a toxic
dietary level in young rats. Walters and Roe observed severe anemia in
mice fed 5000 ppm Zn as zinc sulfate for 3 months while Sutton and
Nelson (1937) reported hypochromic microcytic anemia in rats fed 0.5%
zinc in the diet for 39 weeks, and Sadasivan noted reduced body weight
gain, reduced fat content of the liver, skeletal disorders (lowered
calcium/phosphorus ratio in femur) and changes in various clinical
chemistry parameters in rats given 0.5% zinc in the diet.
Drinker and co-workers (1927b) reported that the addition of up to 34.4
mg zinc/day to the diet of rats for 35-53 weeks produced no toxicity.
They reported similar findings for cats and dogs (Drinker e£ al., 1927c).
Male cats fed a diet containing 250 to 300 mg of zinc oxide (200-240 mg
Zn) for 12 to 16 weeks exhibited marked fibrotic changes in the pancreas,
a decrease of 50% in pancreas size and a 25% drop of initial body weight
values when compared to control animals (Scott and Fischer, 1938).
No ill effects other than slight growth retardation were noted in male
albino rats injected intraperitoneally 6 days per week with 780 iig Zn/kg
as zinc sulfate for 66 doses. No growth retardation was seen, however,
in rats given 1560 ug Zn/kg for 33 doses. Growth retardation appeared
to be dependent on the period of treatment rather than dose (Caujolle
et al., 1969).
7-11
-------
With respect co acute zinc toxicity, oral Upvalues for ZnCl^ range
from 200 mg/kg (96 mg Zn/kg) in guinea pigs to 358 mg/kg (168 mg Zn/kg)
in the mouse (RTECS, 1977). For zinc sulfate, oral LD_.values range
from 626 mg/kg (254 mg Zn/kg) in mice to 1396 mg/kg (565 mg Zn/kg) in
rats (Caujolle £t al., 1969). Acute toxicity is increased when zinc
is administered by subcutaneous, intraperitoneal or intravenous routes;
representative values are presented in the Appendix. The toxicity of
various zinc salts in experimental animals were reviewed in detail by
Van Reen (1966) and NAS (1978).
e. Zine-Cadm-turn-Copper Interactions
The toxic effects of metals are often complicated by mutual biological
antagonism of one metal with another at some functional site. For
example, one metal may induce a biological effect by altering the
requirements for another metal through competition for the same bio-
chemical sites. The site of competitive interaction of zinc with copper
appears to be at the point of absorption, cadmium competes with zinc at
cellular binding sites (Task Group on Metal Interaction, 1978).
Studies with experimental animals have shown that cadmium may alter
the metabolism of zinc and interfere with a number of zinc-dependent
enzymes (NAS, 1978). Zinc, on the other hand, counteracts a number of
toxic effects of cadmium. Simultaneous subcutaneous administration of
cadmium and zinc protected against severe testicular injury seen in
rats given cadmium alone (Blinder and Fiscator, 1978; Webb, 1971).
Another interaction Involves the reduction of cadmium-induced elevation
of blood pressure in rats by injections of zinc chelate (Blinder and
Piscator, 1978).
A complete discussion of these complex interactions is beyond the scope
of this report but has been reviewed in detail by the Task Group on
Metal Interactions, 1978; the National Academy of Science, 1978; Elinder
and Fiscator, 1978; and Nordberg, 1976. There are no available data on
the relationship between intakes of zinc, copper and iron and the effaces
V-12
-------
of cadmium in human populations (Task Group on Metal Interaction, 1978)
but there is no question that the toxic effects of zinc are modified to
some extent in the presence of other metals.
4. Human Studies
Controlled studies of -zinc tolerance as well as toxicosis in humans are
sparse. In man, zinc toxicity may occur by 3 routes: ingestion of
toxic amounts of zinc, direct skin contact with zinc or zinc salts, or
inhalation of fairly high concentrations of freshly formed zinc oxide
fumes.
Oral
Pe'coud .e£ al. (1975) reported that five of six fasting subjects who
took 50 mg zinc as zinc sulfate complained of gastric discomfort for a
period of 30 to 60 minutes but no other adverse effects were seen.
Gastric distress was not reported, however, following ingestion of 25
mg zinc under the same conditions.
In man, ingestion of 1-2 grams ZnS04.7 H20 (225-450 mg Zn) results in
immediate emesis. Ingestion of zinc in excess of this amount produces
nausea, vomiting and diarrhea. Thus, the emetic property of zinc salts
results in the rapid removal of a large portion of the ingested zinc
before it can be absorbed.
The available data suggest that in most individuals, 150 mg Zn may be
ingested on a daily basis without adverse effect. Numerous studies
have reported no effect to minimal gastric discomfort and mild diarrhea
in humans given 660 mg zinc sulfate (150 mg Zn) per day in 3 divided
oral doses for periods up to 6 months (Marshak and Marshak, 1973; Pullen,
1970; Greaves and Skillen, 1970; Flynn et_ a_l., 1973; and Czerwinski e£
al., 1974).
Zinc therapy has been utilized as an adjunct to wound healing in patients
with chronic venous leg ulceration. Greaves and Skillen (1970) administered
V-13
-------
220 mg of zinc sulfate orally 3 times per day (150 mg Zn/day) to 13
patients for 16 to 26 weeks. Three patients noted mild nausea after
swallowing each dose. No hematological or biochemical evidence of
zinc toxicosis was detected. In addition, some degree of re-epithelia-
lisation of venous leg ulcers occurred in all 18 subjects with complete
healing in 13 of the 18 patients.
Czerwinski et al. (1974) treated 16 geriatric patients diagnosed with
senile dementia with 220 mg of zinc sulfate 3 times per day for 24
weeks (150 mg Zn/day). Diarrhea occurred in 37.5% of the patients com-
pared to an incidence of 7% in patients given a placebo in a double-
blind study. Treatment was discontinued in two Zn-treated patients
because of persistent diarrhea. No other significant changes were
noted during the 24 weeks of therapy.
Arakawa and co-workers (1976) observed no adverse effects in two male
infants with acrodermatitis enteropathica, a skin disease, following
treatment with 35 mg/day oral zinc sulfate. These doses represented
5.9 and 12 mg/kg of zinc per day.
Murphy (1970) reported the survival of a 16-year old boy who ingested
12 grams of metallic zinc (150 mg/kg) mixed with peanut butter. The
patient exhibited profound lethargy, light-headedness, slight staggering
of gait and experienced difficulty in writing legibly. Eight days after
admission, blood zinc levels remained elevated (8.1 mg/kg liter).
b. Intravenous
Brocks gt al. (1977) reported fatal zinc intoxication in a 72-year-old
woman from an inadvertent Intravenous overdose (46 mM or 7.4g ZnSO, over
60 hours). Her serum zinc concentration was 4184 ug/100 ml compared to
a normal range of 75-124 ug/100 ml.
u
Gallery ££ al. (1972) reported a case of a patient on home dialysis who
suffered acute toxic symptoms (nausea, vomiting and fever) correlating
7-14
-------
with markedly raised blood zinc concentration when using water stored
in a galvanized tank for dilution of dialysis- fluid. Analysis of the
,'i, *
tank water revealed 625 yg Zn/100 ml. She subsequently was found to
5-1 *\
*\\
have severe anemia with raised plasma and erythrocyte concentrations
ii
of zinc (700 and 3500 ug Zn/1001 ml, resp.) 36 hours after dialysis.
Normal ranges are: 70-110 ug Zn/100 ml for plasma; 1000-1400 ug Zn/100
ml for erythrocytes.
Inhalation
When zinc or its alloys are heated above 930°F, particles of zinc oxide
are formed. If inhaled, these particles cause an acute febrile illness
several hours after exposure. Commonly referred to as "metal-fume-fever",
this disease is typically restricted to foundry workers. Inhalation of
zinc oxide at concentrations of 15 mg/m of zinc or above produces fever,
malaise, headache, depression, excessive salivation and a cough which
may be violent enough to induce vomiting (Kemper and Trautman, 1972;
Anseline, 1972; Chmielewski et al., 1974; Jaremin, 1973; Hamdi, 1969).
Drinker et al. (1927a) reported results of 27 experimental inhalations
of freshly generated ZnO in 10 subjects. Concentrations of 14 mg of
ZnO/m (measured as Zn) produi
was tolerated for 20 minutes.
3 3
ZnO/m (measured as Zn) produced no reaction after 8 hours; 45 mg/m
Sturgis et al. (1927) reported on 2 cases of zinc-fume fever in 2
individuals following voluntary inhalation of freshly generated ZnO.
Subjects sat in a 45 m gas cabinet for ^5-12 minutes. The chamber
contained an average of 600 mg/m of zinc. Subject A inspired approxi-
mately 48 mg of zinc, subject B, 74 mg of zinc. Typical febrile
reactions occurred.
Beritic-Stahuljak e£ al. (1976) found a statistically significant
increase in serum albumins and in alkaline phosphatase activity in 42
workers after 5 days exposure to zinc fumes. Schmahl (1974) reported
that inhalation of ZnCl- fumes produced corrosive effects (from HC1
7-15
-------
smoke) on the respiratory tract and lungs. Fischer (1974) observed 2
cases of lethal ZnCl. fume inhalation. The exposed men died 6 and 11 days
following exposure. Lungs revealed bronchitis and confluent broncho-
pneumonia with thrombosis in the vessels, chronic pneumonia and
bronchiolitis obliterans.
d. Dermal
Zinc and zinc salts are generally well tolerated by human skin. A con-
tact dermatis, attributable to exposure to zinc chromate has been
observed. The chromate, however, is presumed to be the prime offender
(Hall, 1944). Belostotskaya et al. (1969) reported that 7 male workers
developed allergic dermititis over large portions of their bodies from
exposure to ZnCl..
e. Ocular
Houle and Grant (1973) reported on 2 cases of accidental splashing of
ZnCl- into the eyes. One case involved soldering paste (pH 6.5): the
other concentrated ZnCl. galvanizing solution (pH 3.53). Corneal edema
developed and permanent cornea! scarring resulted. Both patients
developed persistent gray spots beneath the anterior lens capsule.
Recovery to best stable visual acuity after injury required 6-28 weeks,
\
but visual acuity needed permanent correction.
5. Overview
Zinc is an essential trace element in human and animal nutrition and is
distributed throughout body tissues and fluids. Dietary requirements
for zinc (10-15 mg/day) are linked to the needs for growth, tissue
repair and compensation for excretion.
Diets grossly deficient in zinc have been associated with growth failure,
loss of taste and in the postpubertal male, hypogonadism and decreased
fertility. It is likely that factors in addition to zinc may also be
involved.
V-16
-------
In man, approximately 30% of ingested zinc is absorbed, transported
throughout the body in the blood and excreted in urine, perspiration,
semen, hair, nails and desquamated skin. Roughly 70-80% of ingested
but unabsorbed zinc is found in the stool (^5-10 mg daily).
Except for the ability of zinc to induce testicular tumors when injected
directly into the tastes, no experimental evidence exists to suggest
that ingestion or parenteral administration of zinc is either carcinogenic
or mutagenic.
Excessive dietary intake (4000 ppm) of zinc prior to conception and
throughout gestation appears to be linked to an increased incidence of
fetal resorption in rats. However, rats similarly exposed to 2000 ppm
zinc in the diet were unaffected.
Toxicological studies in experimental animals indicate that up to 2500
ppm in the diet has no effect on rats although 5000-10,000 ppm induce
severe anemia. Acute oral LD,n values in laboratory animals range from
.96 to 168 mg/kg of zinc. Possible interactions of zinc with other metals
may contribute to toxicity of zinc.
In humans, in those cases in which high concentrations of zinc (150 mg
Zn/day) have been Ingested, such as for wound healing, no adverse effects
other than gastric disturbances and diarrhea have been reported. Gastric
discomfort has been reported following ingestion of 50 mg zinc while
ingestion of 1-2 grams of zinc salts produces immediate vomiting.
Survival following ingestion of 12 grams of zinc has been documented.
7-17
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B. EFFECTS OF ZINC ON AQUATIC ORGANISMS
1. Introduction
This section provides information about the levels of zinc at which
the normal behavior and metabolic processes of aquatic organisms are
disrupted. Extensive research has been conducted on the zinc tolerance
of many aquatic plant and animal species.
The toxicity of zinc is strongly influenced by a number of factors.
Among the most important of these parameters is water hardness, which
modified considerably the effects of zinc on aquatic organisms. Less
clear are the relationships between zinc toxicity and pH, temperature,
dissolved oxygen content, competing ions and ligands and salinity.
These parameters cannot always be manipulated as freely as water hard-
ness because of the possible consequences for the test animals, and so
have not been as thoroughly studied. Another important variable is
the species of plant or animal used in the toxicity experiments, as
interspecies tolerances may vary by several orders of magnitude.
Over the past decade, tens of thousands of fish have been reported
killed as a result of heavy metal pollution by mining and industrial
activities, although most of the kills occurred before 1974 (see
Table V-2). While in many cases several metals are implicated, the
evidence in many cases has pointed to zinc as a major cause of the
fish kills. In the context of these incidents, it is appropriate to
attempt an evaluation of the effects of zinc on natural aquatic environ-
ments. Despite the failure of most laboratory experiments to duplicate
natural conditions, the data summarized here can hopefully provide
a basis for understanding the effects of zinc on aquatic life.
2. Freshwater Organisms
a. Chronic/Sublethal
Low concentrations of zinc can cause a wide variety of reactions in
aquatic organisms, ranging from behavioral changes co growth inhibi-
tion and physical deformity. Although zinc in ainute quantities aay
7-18
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Table V-2. Data for Zinc-Related Fish Kills (Since 1971)
Location
Quinnipiac River
Southingcon, Ct
Naugatuck River
Tarrington, Ct
Clark Fork River
Missoula, Mt
Roaring Brook
Glastonbury, Cc
Lamberts Pond
McCall, Id
Caney River
Bartlesville, Ok
Industry Associated
with Kill
Chemical
Chemical
Mining, Power
Generation
Chemicals
Implicated
Phenol, Cu,
Cr, Zn
Cu, Zn, Cr
Number of
Fish Killed
1,000
Construction*
(galvanized material)
Metals*
Lexington, Ky
^Attributed co runoff events.
Zn, 11.2 ppm,
Cu, 4.6, Fe
Phenol, Cu, Zn
Zn, 104 ppb
Zn ?
400
300
200
2,500
Eliza Creek
Bartlesville, Ok
Mokelumne River
Clements, Ca
Mokelumne River
Clements, Ca
Big Creek
Glover, Mo
Mill Creek
Kent, Wa
Housatonic River
Stratford, Ct
Elkhorn Creek
Metals*
Mining*
Mining*
Metals
Telephone Co.
Metals
Metals
Zn
Zn
Zn
Pb,
Zn,
Cd,
Mn,
Pb,
Ni,
Cu,
?
984 ppb
976 ppb
500 ppb
445 ppb
Zn, Cu
Cu, Zn
Zn
123
900
32,823
100
8,000
9,602
V-L9
-------
not be facal to a fish, it may pose a threat to the species by dimin-
ishing reproductive potential or contributing to environmental stress.
Sprague (1968) has observed an avoidance response by rainbow trout
(Salmo gairdneri). a particularly sensitive species, at a zinc concen-
tration of 5.6 parts per billion (ppb). Other effects, however, are
not evident until much higher levels are attained. In a study by
Spehar(1976), 85 ppb zinc caused a significant increase in flagfish
larvae (Jordanella floridae) mortality; at 139 ppb, there was no
survival. Sinley et al. (1974) found rainbow trout fry to be
somewhat more resistant, with an incipient mortality level of 260 ppb
in soft water. Brungs (1969) has reported reduced egg production by
fathead minnows (Pimephales promelas) at 180 ppb. When the concen-
tration was increased to 2,800 ppb, their growth was stunted, spawning
frequency declined, mortality rates rose to 15% (in 96 hours), and
hatching was suppressed entirely.
At varying concentrations of zinc (depending on the species of fish
and other factors), the gills become clogged with mucous. This
apparently occurs in the presence of other heavy metals as well. An
t
often-used indicator of copper or cadmium contamination in water is
the frequency of "coughing", where the fish tries to clear the gills
of mucous. Sparks et al. (1972) as cited in EPA (1979) has reported
this response in the highly tolerant bluegill (Lepomis macrochirus)
at a concentration of 40,000 ppb zinc. When the gill clogging reaches
an advanced state, tissue hypoxia results, and the fish is gradually
asphyxiated..
Bengtsson (1975) has observed several types of sublethal effects in
the minnow (Phoxinum phoxinus) at low levels of aqueous zinc. Between
6 and 70 days after the beginning of exposure to 200 ppb and 300 ppb
zinc, hemorrhages appeared behind the dorsal fins of several specimens,
indicating vertebral damage. Some individuals exhibitad pigmentation
V-20
-------
disturbances with the appearance of dark verticle stripes in the
caudal region, or black pigment in the tail. After 270 days, most of
the fish had developed paralysis and muscular atrophy.
A summary of chronic values of freshwater fish is presented in
Table V-3.
The only information on chronic toxicity levels for a freshwater
invertebrate species if for the cladoceran, Daphnia magna. (EPA, 1979).
The "chronic value" given is 84.5 ppb zinc; this indicates a mean
level at which growth or reproduction is impaired.
The effects of zinc on freshwater plants range from small reductions
in growth rates to mortality. The most sensitive species testes was
the alga, Selenastrum eaprieornutum. for which the incipient growth
inhibition concentration was 30 ppb. For a description of the
responses of other plant species to different levels of zinc, see
Table 5 in EPA (1979).
b. Acute Effects
The acute effects of zinc on freshwater fish have been studied ex-
tensively. Among the fish tested for sensitivity to zinc, the cut-
throat trout (Salmo elarki) studied by Rabe and Sappington (1970) as
cited in EPA (1979) were the least tolerant, with a 96-hour LC5Q of 90
ppb zinc. For rainbow trout, fathead minnow, and blueglll, there are
many experimental acute toxicity values which cover a wide range.
In Table 7-4, these values have been collected to give only lower and
upper bounds because of the abundance of data for numerous species.
For a more detailed dissussion of acute toxicity, see EPA (1979).
Invertebrate vulnerability to aqueous zinc extends through approx-
imately the same range as for fish, with Che notable exceptions of
Daphnia hvalina and D^ aagna, which are more sensitive. The available
data for acute coxicicies co freshwater invertebrates are outlined in
Table 2 of EPA (1979).
tf-21
-------
Table V-3
' Chronlc/Sublethal
Cone .
(ppb) Species Compound
5.6 Rainbow trout ZnSO,
( Salmo fialrdnerl)
51 Flagflsh adults (females) ZnSO
(Jordanella florldae)
106 Fathead minnow Zn++
(Pjmephalea promelas)
<^
10
180 Fathead minnow ZnSO.
4
187 Chinook salmon Zn++
260 Rainbow trout ZnSO.
4
640
852 Urook trout Zn++
Effects on Freshwater Fish
Hardness Test
(mg/1) Duration Effects
13-15 20 min. ' Threshold avoidance
level -, ^._^
i -. -
44 100 days Growth reduced
46 ? Effect on growth,
survival or repro-
duction In life-
cycle test**
203 10 mo. 83% reduction In
egg production
22 ? Effect on growth,
survival or repro-
duction In embryo
larval test**
25 42 days Chronic bloassay
6.4 mortality
330 6.9 mortality
44 ? Effect on growth
survival, or repro-
duction In life-cycle
test**
Source
Sprague (1968)
Spehar (1976)
Benolt and
Halcombe*
Brungs (1969)
Chapman (1978)*
Slnley et al.
(1974)
Hoi come et al .
(1978)*
As cited in EFA (1979).
val'ue represents the geometric mean of the levels at which there effects are observed. In the case
of liiulu-yo-larval tests the geometric mean Is divided by 2 to obtain a value comparable to life-cycle studies.
-------
Table V-3. Chronic/Sublethal Effects on Freshwater Fish (Continued)
t
U)
Cone.
(PPb)
500-
1000
1000
1150
1680
8700
40,000
Species . Compound
Stickleback
(Gaaterosteus aculeatus) 65ZnCl_
65ZnCl2
Guppy Zn-H
(Poecllla retlculatus)
Rainbow trout Zn-H
Blueg ill Zn-H
(Lepomia macrochirus)
KaJnbow trout Zn-H
Hardness
(mg/1)
282
282
80
320
51
44-55
Test
Duration
3 (days
200 hrs.
30 days
48 hrs.
7 days
9 days
Effects
Gill damage
Increased oxygen
uptake
Growth Inhibition
Increased swimming
velocity, Increased
sensitivity to Zn
Increased breathing
rate
Gill tissue damage
Source
Matthiesson and
Brafleld (1973)*
Bra fie Id and
Matthlesson (1976)*
Crandall and
Goodnight (1962)*
Herbert and
Shurben (1963)*
Cairns and Sparks
(1971)*
Skidmore and
Tovell (1972)*
*As cited in EPA (1976).
-------
Table V-4. Acute Toxicities for Freshwater Fish
Concentration
(ppb)
Species
Hardness (pptn)
as CaCO.
Reference
90 - 420
97 - 463
100 - 6800
240 - 7210
420 - 3130
600 - 33,400
749 - 1000
905 - 4600
1270
1500'
1550 - 6980
1930 - 23,000
6000 - 11,400
6440 - 103,000
7800
Cutthroat trout 24
(Salmo clarki)
Chinook salmon 24
(Oncorhynchus tshawytscha)
Striped bass <53 - 157
(Mo rone saxcitilis)
Rainbow trout . 5 - 500
(Salmo gairdneri)
Atlantic salmon 14 - 352
(Salmo salar)
Fathead Minnow 20 - 360
(Pimephales promelas)
Sockeye salmon 13 - 34
(Oncorhynchus nerka)
Coho salmon 25 - 99
(Oneorhynehua klsutch)
Guppy 20
(Poecilia reticulatus)
Flagfish 44
(Jordanella floridae)
Brook trout 44 - 179
(Salvelinus fontinalis)
Bluegill 20 - 360
(Lepomis macrochirus)
Golden shiner 24 - 96
(Notemigonous crysoleucus)
Goldfish 20 - 50 *
(Carassius auratus)
Carp 53 - 55
(Cyprinus carpio)
Rabe and Sappington
(1970)*
Chapman (1978)*
EPA (1979)
f
EPA (1979)
EPA (1979)
EPA (1979)
EPA (1979)
EPA (1979)
Pickering and
Henderson (1966)*
Spehar (1976)
Holcombe and Andrew
(1978)*
Cairns et al.
(1978)*
Rehwoldt ec al.
(1971, 1972)
As ciced in EPA (1979).
V-24
-------
Table V-4. Acute Toxicities for Freshwater Fish (Continued)
fi Concentrations
'J\i
e?
Hardness (ppm)
(ppb)
12,000
14,300-14,400
14,500-14,600
19,100-19,200
20,000-20,100
Species
Southern platyfish
(Xiphophorus maculatus)
White perch
(Mbrone amerieana)
American eel
(Anguilla rostrata)
Banded killif ish
(Fundulus diaphanus)
Fumpkinseed
as CaCO"
166
53 - 55
53 - 55
53 - 55
53 - 55
Reference
Rochlir and
Ferlmutter, 1968
Rehwoldt et al.
(1971, 1972)
Rehwoldt et al.
(1971, 1972)
Rehwoldt et al.
(1971, 1972)
Rehwoldt jit al.
(Lepomis gibbosus)
(1971, 1972)
V-25
-------
3. Saltwater Organisms
Relatively little research has been conducted on the toxicity of zinc
to marine vertebrates. The mummichog, Fundulus heterroclitus. is the
only marine fish that has been tested in sublethal concentrations of
zinc. Eisler and Gardner (1973 as cited in EPA 1979) observed histo-
logical damage in this species after 24 hours in a 60,000 ppb solution.
A 10,000 ppb concentration caused an increase in live ALA-D enzyme
activity; the long-term consequences of this effect are unclear.
Acute toxicity data for marine vertebrates are also extremely limited.
The mummichog is the only non-anadromous marine fish which tested for
acute sensitivity to zinc. The 96-hour LC-. for the mummichog is
60,000 ppb zinc, according to Eisler and Hennekey (1977 as cited in
EPA 1979), which is considerably higher than for most freshwater fish.
Two anadromous fish, the rainbow trout and the Atlantic salmon, showed
significantly increased resistance to aqueous zinc in saltwater as com-
pared to fresh. The role of salinity in mitigating the effects of
zinc will be discussed in the next section.
Considerably more data are available for invertebrates, and several
species are highly sensitive to zinc. Reish and his associates (1976,
1978 as cited in EPA 1979) reported sublethal effects occurring between
220 and 1,250 ppb in four species of polychaetes. Oyster larvae
(Crassostrea glgas) are among the most vulnerable marine organisms,
according to a study by Nelson (1972 as cited in EPA 1979). At 125
ppb, the larvae exhibited reduced growth rates, and abnormal shell
development occurred in 70 ppb after 48 hours. Crab (Rhithrooanuoeus
harrisi) larvae development has been reported delayed after 16 days
in a 50 ppb solution (Benijts-Claus and Benijts, 1975). See Table
V-5 for more data.
The acute eoxicity of zinc to saltwater invertebrates has been
extensively studied, and there is much more information from which Co
draw conclusions. The interspecies tolerance range is extremely wide,
7-26
-------
Table V-5 Sublethal Effects of Zinc on Marine Invertebrates*
Concentration
(ppb)
50
70
81
125
*
125
200
250
320
2700
3000
Species
Crab (larva)
(Bhithropanopeus harrisi)
Oyster (larva)
(Crassostrea gigas)
Sea urchin (spermatozoa)
(Arbacia punetulata).
Oyster (larva)
(Crassostrea gigas)
Oyster (larva)
(Crassostrea gigas)
Mud snail (adult)
(Nassarius obsoletus)
Sea urchin (egg)
(Anthoeidaris erassispina)
Sea urchin (egg)
(Anthocidaris crassispina)
Starfish (adult)
(Asterias forbesi)
Polychaete (adult)
(Eudistylia vancouveri)
Effect
Delayed develop-
ment
Abnormal shell
development
Decreased motility
Growth inhibition,
reduced development
Substrate attach-
'ment inhibition
Decreased oxygen
consumption
Retarded develop-
ment
Abnormal develop-
ment
Equilibrium loss
Allantolse enzyme
inhibition
Reference
Benijts-Calus and
Benijts (1975)*
Nelson (1972)
Young and Nelson
(1974)
Brereton, et al.
(1973)
Boyden, et al.
(1975)
Mclnnes and
Thurberg (1973)
Kobayoshi (1971)
Okubu and Okubu
(1962)
Galtsoff and
Loosanoff (1939)
May and Brown
(1973)
*Taken from EPA (1979)
7-27
-------
with hard-shell clam larvae (Mereenarla mercenaria) reported as Che
most susceptible organisms with a 48-hr. LC.. of 166 ppb. Table 9 in
EPA (1979) provides a list of these invertebrate species and their
median tolerance limits.
The effects of zinc on marine plants consist primarily of growth or
photosynthesis inhibition. The most sensitive species studied is the
alga, Skeletonema costatum, for which growth was suppressed at a con-
centration of 50 ppb. Table V-6 lists the other plant species and the
toxic zinc concentrations.
4. Factors Affecting the Toxicity of Zinc
There are numerous variables in a natural aquatic environment which
may strongly influence the toxicity of zinc to an organism. The
hardness of the water, its temperature, dissolved solids content, pH,
and the synergy of other substances all modify the toxicity of zinc.
Water hardness is perhaps the most important, and certainly the best
documented, of these factors. The negative correlation between zinc
toxicity and water hardness (as CaCO.) has been confirmed in the
laboratory by many researchers. For a species such as the fathead
minnow, the toxicity of zinc varies by a factor of more than SO, largely
depending upon the water hardness. Correlations between zinc toxicity
and water hardness were computed for the rainbow trout, the bluegill,
and the fathead minnow, since data were most complete for these species.
The correlation coefficients were .788, .764, and .655, respectively,
demonstrating that, despite variations in experimental procedure, the
relationship between the two variables is strong.
Although data are limited for freshwater invertebrates, the LC,Q
values for the snail, Physa hetarotrooha. suggest only a slight
influence by water hardness.
V-23
-------
Table V-6 Effects of Zinc on Marine Plants*
Concentration
(ppb)
50
100
200
250
400
400
500
6500
10,000
25,000
Alga
(Skeletonema costatum)
Kelp
(Laainarla digitata)
Alga
(Skeletonema costatum)
Kelp
(Laminaria hyperiborea)
Alga
(Amphidinium carter!)
Alga
(Thalassiosira pseudomona)
Alga
(Thalassiosira pseudomona)
Alga
(Duraliella tertiolecta)
Kelp
(Macrosystis pyrifera)
Alga
(Phaeodactylum
tricornutum)
Growth inhibition
Growth inhibition
Growth inhibition
Growth inhibition
Growth inhibition
Growth inhibition
Growth inhibition
Reduction in
potassium content
Photosynthesis
inhibition
Growth inhibition
Braek et al.
(1976)
Bryan (1964)
Braek et al.
(1976)
Hopkins and
Kain (1971)
Braek _al al.
(1976)
Braek et al.
(1976)
Braek et al.
(1976)
Overnell (1975)
Clendenning and
North (1959)
Jensen _et al.
(1974)
*Table taken from EPA (1979)
7-29
-------
A study by Judy and Davies (1979) found similar effects on zinc
^.
toxicity levels using Ca(NO.)-. Their results indicated that the Ca
cation is the agent responsible for suppressing the effects of zinc.
Matthiesson and Brafield (1977) hypothesize that the base metals
(including calcium) "impair the toxic action of zinc, either by
reducing the permeability of cell membranes or,by directly protecting
the biochemical processes with which zinc interferes. They may also
facilitate zinc excretion."
s
There are also external influences on zinc which affect its avail-
ability to fish. In the presence of a high concentration of hydroxide
or carbonate anions (usually in hard water or high pH), or in a
reducing environment, zinc precipitates. Mount (1966) noted an inverse
relationship between pH and toxicity levels, such that the lowest
LC.Q value for fathead minnows coincided with the highest pH (8) used.
Mortality rates werehigher in the tanks in which the water was "milky"
as a result of precipitation. In addition, mucosis of the gills and
the accompanying cough response were much more severe among fish in
the more basic water.
Hardness and pH factors are probably insignificant for marine fishes,
which are adapted to a slightly basic, alkaline medium with a high
solute concentration. Because of a lack of data, the effects of
salinity on zinc toxicity are not clear. Duke .at al. (1969) as
cited by NRC (1979) found that zinc-65 accumulation in the Atlantic
oyster was 10% lower at 30 parts per thousand than at 25 ppt salinity.
Herbert and Wakeford (1964) studied the resistance of Atlantic
salmon (Salmo salar) smelts and rainbow trout to zinc in varying
degrees of salinity. In a 35% seawater solution (simulating estu-
arine conditions), their tolerance for zinc was, respectively, 13
and 15 times the level in hard fresh water. When the seawater
proportion was raised to 72%, their resistances decreased, but were
still substantially greater Chan in fresh water. This study suggests
V-30
-------
Chat the relation between toxicity and salinity is complex. At high
salinities, the increased resistance to zinc may be affected by some
/''
other mechanism. ^*\
?!
/
Temperature and dissolved oxygen content (D.O.) have been examined
for their effects on the toxicity of zinc to freshwater fish.
Pickering (1967) observed an inverse relationship between D.O. and
zinc toxicity for the bluegill. At D.O. levels of 1.8, 3.2, and 5.6
mg/1, the LC_. values were 7.4, 10.6 and 11.4, respectively.
The relationship between temperature and toxicity is not so easily
elucidated. Sprague (1968) observed no effects on the avoidance
reactions of rainbow trout over a temperature range of 7.5°C. Smith
and Heath (1979) observed"less resistance to zinc in the goldfish and
the bluegill as the temperature of the water was successively raised
from 5 to 15 to 30*C. However, they did not find this progression
in the two other species tested, the rainbow trout and the shiner.
Rehwoldt £ al. (1972) observed six species of Hudson River fish
in varying temperatures and found only insignificant differences
in their sensitivity to zinc.
Any changes in tolerance to zinc that occur as a result of changes in
dissolved oxygen content or temperature probably arise from environ-
mental stress. It is difficult for many fish to obtain sufficient
oxygen when the D.O. content of the water is 1.3 mg/1. Furthermore,
in the temperature experiments it is difficult to control for a single
variable because the oxygen saturation point in warm water is lower
than in cold water. Consequently, these factors are probably more
important for their direct effects upon the fish than for their
influence on the toxicity of zinc.
In waters which are polluted with zinc from mining or industrial
activities, ocher heavy metals are often found as veil. Lead,
mercury, copper, and cadmium are all toxic Co varying degrees, and
V-31
-------
have some similar effects on aquatic life. The importance of the
presence of combinations of heavy metals lies in their synergistic
effects. One example of this phenomenon is described in the work
of Ozoh and Jacobson (1979) who exposed zebra cichlid (Chichlasoma
nigrofaseiatum) eggs to concentrations of 0, 16, and 32 ppb of zinc
and copper, alone and in combinations. They found that the synergy
of copper and zinc interfered more with hatching and normal growth
than comparable concentrations of a single metal. Lorz et_ al. (1978)
found that copper in the presence of zinc decreased the appetite of
rainbow trout. He hypothesized that copper also increases the metabolic
rate, which causes "a reduction in the condition factor" compared to
fish exposed only to zinc. Brack ^ al. (1976) as cited in EPA
(1979) has also observed adverse effects on growth in several species.
of alga as a result of they synergy between copper and zinc.
The interactions of heavy metals are not always synergistic, however.
A study by Benijts-Claus and Benijts (1975) gives evidence of mutual
suppression by lead and zinc. At concentrations up to 50 ppb, both
metals had a significant adverse impact on the development of the
mudcrab, Rhithrooanuoeus HarrisA. In certain combinations, on the
other hand, zinc apparently suppressed the more toxic lead, and
larval growth actually accelerated. Jackim e£ al. (1977) as cited in
EPA (1979)found that zinc in solution decreased the rate of cadmium up-
take in the mussel, Mytilus edulis.
Synergy between zinc and other heavy metals depends on absolute and
relative concentrations, the age of the solution as it relates to
precipitation and dissociation, and environmental factors such as
water hardness and pH. In natural environments it may be difficult
to gather sufficient or appropriate data in order to determine the
zinc exposure and risk to aquatic life. In the cases where a fish
kill has already occurred, the same complications hinder efforts Co
isolate the effect of a single variable such as zinc..
V-32
-------
Acclimation to zinc has been shown to occur in several areas. Spehar
(1976) has observed that rainbow trout eggs exposed to zinc solution
produce adults with a greater resistance to zinc. The data of Sinley
et al. (1974) indicate that rainbow trout not exposed to zinc in the
egg stage may be up to four times as sensitive to zinc as fish which
were exposed to zinc as eggs. These results suggest that even the
most susceptible species may adapt, within limits, to higher levels
of exposure.
5. Summary of Aquatic Toxicitv
According to the literature surveyed, the lowest concentration of
zinc at which adverse effects in an aquatic organism have been
observed is 30 ppb, a growth inhibition level for the alga, Selenastrum
capricornutum. At 51 ppb, growth rates for female flagfish decreased
significantly after 100 days of exposure. Acute effects appeared at
90 ppb for cutthroat trout. Hard-shell clam larvae are the most
sensitive marine animals tested, for which the lowest 48-hour LC_Q
value found is 166 ppb. The saltwater alga, Skeletonema costatum,
has experienced growth inhibition in concentrations as low as 50 ppb.
The toxicity of zinc in freshwater is strongly influenced by several
environmental factors. Zinc toxicity 'is inversely related to water
hardness such that the lowest LC-- values for a given species are
associated with soft water (with low calcium levels). Low dissolved
oxygen content places an environmental stress on aerobic organisms,
which can increase their sensitivity to zinc. Temperature plays a
similar role, as extremes can also create stress for the organism.
In some cases, fish may adapt to levels of 'zinc which are toxic to
previously unexposed fish.
The presence of other heavy metals is a complicating factor because
their interactions with zinc are not well understood. It appears chat
copper and nickel act synergistically with zinc so thac the overall
toxicity exceeds that of a comparable concentration of a single metal.
V-33
-------
There is some evidence, on the other hand, chat lead and zinc are
mutually suppressive, but the relationship should be further studied.
Zinc has also been shown to decrease the rate of cadmium uptake in
several animal species.
V-34
-------
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Zinc deficiency in two infants during total parenteral alimentation for
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Drinker, P., R.M. Thompson, and J.L. Finn. 1927a. Metal fume fever:
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7-44
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VI. EXPOSURE
A. HUMAN EXPOSURE
1. Introduction
The previous sectton on the effect of zinc on humans indicates that it
has a very low order of toxicicy. In fact, most discussions regarding
human exposure co zinc emphasize zinc deficiency, as opposed to effects
resulting from large doses. As a result, this section will not go into
great detail in estimating zinc exposure to various subpopulations. It
will attempt to provide order of magnitude estimates for exposure to
zinc through various routes.
2. Ingestion
a. Food
NRG (1979) has reviewed the zinc content of various foods extensively
as this subject has been examined in some detail. Briefly, zinc in
the diet is primarily supplied with protein. Oysters have the highest
reported zinc content (pec 100 grams), but other meats, fish, dairy
products and grain products are also important sources. 'FDA (1974), as
part of their total diet studies, found that about 40% of the zinc in
the diet of a 15-20 year old male'was supplied by meat, fish and poultry;
dairy products supplied 24% and grain and cereal supplied 19%. The
total dietary intake was estimated to be 13.6 mg zinc/day. This level
of exposure is well below levels at which any effects are observed, and
is just above the recommended daily allowance for zinc of 15 mg.
Certain subpopulations would be exposed to higher levels of zinc in their
diet, for example, persons eating large amounts of oysters. In addition
zinc may be ingested as a dietary supplement. These persons may ingest
up to 75 tug/day (in zinc gluconate), in addition to intake from food.
b. Drinking Water
Zinc in drinking water is generally low, although it may be picked up in
che distribution system. The U.S. H.E.W. .(1970) reported chat a survey
71-1
-------
of 2595 distribution samples over the U.S. showed a maximum of 13.0 mg/1,
with eight samples exceeding 5 mg/1, the recommended limit for drinking
water. The mean concentration was 0.194 mg/1. Using the maximum value
for distributed drinking water, intake of zinc can be estimated at 26
mg/day. It is evident that in a few locations, intake of zinc in drink-
ing water may be comparable to intake through food.
3. Inhalation
Zinc concentrations in air .have been discussed previously in Section
3
IV-A. Using the maximum 24 hour value near a smelter of 15.7 ug/m
(EPA, 1979), an intake of .314 mg/day can be estimated for residents
near smelters. Thus, even for a worst case situation for inhalation,
this route results in much lower exposures to zinc than food and drinking
water.
Smokers may receive small amounts of zinc in smoke. EPA (1979) has
calculated an inhalation.of up to 0.02 mg might result from smoking 20
cigarettes. This exposure is insignificant when compared to other
routes.
4. Absorption
*>
Due to the low order of toxicity of zinc, absorption would be expected
to be an insignificant exposure route compared to food. Ambient waters
are generally at concentrations of less than 1 mg/1, resulting in a low
potential for exposure.
B. EXPOSURE OF ZINC TO AQUATIC ANIMALS
As one of the most abundant heavy metals in the earth's crust, zinc
occurs naturally in small concentrations in virtually all fresh and
salt water bodies. Levels of zinc in undisturbed environments are
determined largely by the composition of the local substrate, which
varies geographically. Human activities such as mining and manufacturing
can also influence zinc concentrations in the air, soil and water (see
Section III).
VI-2
-------
I
I
Under natural conditions, sea water contains between 1 and 27 ppb zinc,
while uncontaminated fresh waters generally have less than 50 ppb (NRC,
1979). Ambient concentrations of zinc, however, are commonly higher.
In Table IV-1 are given the most commonly observed ranges of concentra-
tions for aqueous zinc in the major river basins of the U.S. Table IV-2
provides the same data for sediment samples.
In areas near zinc smelters and mines or where zinc is used in manu-
facturing, ambient water concentrations may be high (see Section IV-A).
Waste water discharge streams from smelters may have 50 to 243 ppm zinc
(NRC, 1979). Within the mid-Atlantic, Missouri, Arkansas, and Tennessee
river basins are many of the major zinc mines in the U.S. The monitoring
data presented in Figures IV-2 and IV-3 suggest a moderate association
between zinc production and zinc concentrations in water bodies in these
areas. In addition, fate considerations (Section I7-B) suggest that
heavy rainfalls, dredging, or other physical disturbances to the sediment
may result in temporarily high concentrations of zinc.
Hard water has a strongly suppressive effect on the toxicity of zinc
to fish (see Section V-B). In setting criteria for zinc toxicity, EPA
(1979) determined an inverse logarithmic relationship between toxicity
and water hardness as CaCO~. Depending solely on hardness, the LC.Q
for a species may vary by a factor of 100 (EPA, 1979). The river
systems in the U.S. which have the softest water are the New England,
Pacific Northwest, California, and Southeast watersheds.
Figures VI-1 and VI-2 indicate counties in the U.S. where aqueous zinc
levels exceed EPA acute and chronic criteria. This analysis includes
data collected for the last ^20 years on zinc levels in the U.S. As an
alternative approach we analyzed STORET data for 1978. Table VI-1 shows
minor river basins having high concentrations of zinc and very soft
water. It is interesting co note that while mean concentrations of
greater than 120 ppb are common, in many cases 50% of the observations
are not greater than 120 ppb. This distribution indicates that in many
VI-3
-------
Figure Vl-1
Ratio of Observed Zn and Criteria Zn (Acute)
I
*»
i-iuiui i I )'( iMtit
STORET SlTSTtM
ZINC: OBSERVATION / ACUTE CRITERIA
751 H PFRCFNTIIF.S
^ : "" KMKK = 0
j$ i 0^33 'o j a:i:
H ; 02;; 11 i isac
M "I 0323
.<0
-------
Figure VI-2
Ratio of Observed Zn and Criteria Zn (Chronic)
n
I
Ul
tmwnntiiw
STORET SYSTEM
ZINC: OBSERVATION / CHRONIC CRITER
75TII PERCENT II ES
I-033C 10 ; 0332
J oaio
TO ;
-------
Table VI-1
H
I
River Basin
Major/Minor Name
1/9 Mercjmack R.
1/14 Preuuiiipcot R. & Casco Bay
1/24 Lake Chaiuplaln
2/6 Delaware R. - Zone 4
2/ I 5 Rappahannock & York Rivers
5/2 Moiiongahela R.
5/3 Heavei- R.
5/7 Kauawliu R
5/13 Miami R.
5/21 Ohio R., main stem & Cribs
6/3 Cuyahoga R.
6/13 Detroit
7/2 Hudson Bay, Rainy River (23/02)
7/3 Upper portion, upper Mississippi R.
7/6 Lower portion, upper Mississippi R.
7/12 Mississippi, Salt Rivers
7/16 Fox R.
7/19 Meramec R.
8/J Menomlnee
8/24 Green Bay, U. Shore
U/49 Calumet-Burns Ditch Complex
9/14 S. Central Missouri R.
9/7 Big SJoux R.
9/12 Lower Missouri R.
Zinc Concentrations In U.S.
Minor River Basins - 1978
>50% of ppb
Zinc Mean Zn observations
N >120 ppb >120 ppb Zn
126
24
10
305
296
331
25
338
86
257
21
9
5
135
189
9
24
42
50
42
42
70
*
*
*
*
*
>10% of ppb
observations
>300 ppb Zn
of hardness
Measurements <50 ppni
37
-------
Table VI-1 (Continued)
Kiver basin Zinc Mean Zn
Major/Minor Name JN >120 ppb
11/2 Middle Colorado R.- 158 *
11/4 CUa R. 81 *
1L/5 Little Colorado R. 31 *
12/7 Nueces U. 10
13/5 Columbia R. above Yakima R. 34 *
14/4 Central California Coastal 7
14/5** Santa Clara R. 5 *
14/6 Los Angeles R. 87 *
I4/'J Sacramento R. 77 *
15/6 Colorado R. Basin in California 11 *
>50% of ppb
observations
>120 ppb Zn
>10% of ppb
observations
>3QO ppb Zn
>50% of hardness
Measurements <50 ppm
*.
*
*
**Pewer than 10 measurements at this station.
-------
cases there are a few high observations, but that most of the observations
were less than 120 ppb. This premise is confirmed by the fact that numerous
river basins show more than 10% of the observations greater than 300 ppb.
These data are mapped in Figure IV-2. According to the EPA Water Quality
Criteria, at a hardness of 50 ppb, the 24 hr. average criterion would be
27 ug/1 Zn, while at a hardness of 230 ppm the*criterion would be 79 ug/1 Zn.
Exposure Routes
Fish are exposed to zinc in both their diets and the water, and for some
species from the sediment. NRC (1979) theorizes that dietary intake is
'the more important pathway for ingestion because "turnover rates of larger
body pools of zinc cannot be sustained by inflow rates of zinc from water
alone." NRC further states that the use of short-term exposures of fish
to experimental dissolved zinc concentrations in test for acute toxicoses
is of dubious value because the fish die before their body pools have
equilibrated with the environmental level of zinc.
Zinc levels in sediment are generally about two orders of magnitude higher
than in whole water samples (STORE!). The availability of sediment-bound
zinc to aquatic organisms is uncertain because the relative importance of
different exposure routes is not known. Exposure could occur through
ingestion or gill uptake, particularly in benthic biota. Absorption
into tissues is partially dependent on the composition of the sediment
to which the zinc is bound. Luoma and Jenne (1977) reported that zinc
was more available to clams when bound to biogenic calcium carbonate
than to manganese and iron oxides and organic sediments.
Sediment is also a potential source of aqueous zinc because shifts in
pH or hardness could release completed or precipitated zinc into sus-
pended or dissolved form.
A number of aquatic animals bioaccumulate zinc in their tissues.
Unfortunately, existing studies on concentration usually do not give the
accompanying aqueous zinc concentration or the zinc levels in the diet.
VI-S
-------
It is therefore not clear whether zinc is accumulated as a result of
dietary intake or absorption from respiration. Bioconcentration in
aquatic organisms is discussed in more detail in Section VI-B.
C. CONCLUSIONS
Table VI-1 shows areas of the country where zinc concentrations are
high and where waters are very soft. It is evident from this table
that aquatic organisms in the following minor river basins are subject
to exposures commonly greater than 120 ppb and at least occasionally
{
to greater than 300 ppb:
Presumpcot River and Casco Bay
Lake Champlain
Delaware River - Zone 4
Beaver River
Ohio River
Cuyahoga
Detroit
Hudson Bay, Rainy River
Upper portion - Upper Mississippi River
Lower portion - Upper Mississippi River
Mississippi, Salt Rivers
Fox River
Meramec River
Menominee
Green Bay - West Shore
S. Central Missouri River
Gila River
Little Colorado River
Santa Clara River
Los Angeles River
Sacramento River
VI-9
-------
D. REFERENCES
Cooke, M. et al. 1979. Biological availability of sediment-bound
cadmium co Che edible cockle, Cerastoderma edule. Bull. Environ.
Contain. Toxicol 23; 381-86.
Luoma, S.N. and E.A. Jenne. 1977. Proceedings 15th Annual Hartford
Life Sci. Symp.. E.R.D.A. Tech. Inf. Center. CONF 750929, as cited
in Cooke _et_ al., 1979.
Matthiesson, P. and A.E. Brafield. 1977. Uptake and loss of dissolved
zinc by the stickleback Gastrostreus aculeatus. J. Fish. Biol. 10;
399.
National Research Council. 1979. Zinc. Subcommittee on Zinc, Committee
on Medical and Biological Effects of Environmental Pollutants.
Pequenat, J.E. £t .§1 1969. Estimates of the zinc requirements of
marine organisms. J. Fish Res. Board Can. 26;145.
U.S. E.P.A. 1979. Zinc Criterion Document.
U.S. F.D.A. 1974. Total Diet Studies. Compliance Program Evaluation.
U.S. H.E.W. 1970. Community Water Supply Study, Analysis of National
Survey Findings.
VI-10
-------
VII. RISK CONSIDERATIONS
A. INTRODUCTION
Ic is che objeccive of chis section co delineate the population exposed
and quantify the risk associated with that exposure. Zinc has* not been
found to be a carcinogen, teratogen or mutagen. Reproductive effects
have been indicated in rats after ingestion of high levels of zinc in the
diet. It is questionable whether these effects can be extrapolated to
man for two reasons. First, there appears to be little correlation, in
general, between reproductive effects in man and reproductive effects
in laboratory animals. In addition, it is unclear whether humans could
or would accept such a dose due to its undesirable taste and emetic nature.
Human data are available on some acute effects and oral lethality. Since
levels required for human effects are well above expected exposure, a
quantitative discussion of risk is not necessary in this case.
Effects of zinc on aquatic organisms, however, have been observed in the
field in the form of fish kills. Therefore, it is likely that some sub-
populations of aquatic organisms may be at risk. These subpopulations
will be identified by species or class and type of geographic' location.
Further delineation of aquatic subpopulations at risk is not possible
within the time constraints of this project.
B. HUMANS
Table VII-1 summarizes the known adverse effects of zinc on mammals.
As discussed in Section V-A, the levels of zinc which result in adverse
effects vary .from person to person. The 25 mg dose is probably a lower
limit for no effect. Gastric discomfort was observed at an acute dose
of 50 mg zinc. However, lethality, either via an oral or intravenous
exposure requires a dose of at least 1 gram.
VII-1
-------
.f
/"
TABLE VII-1
Adverse Effects of Zinc on Mammals
Lowest Reported Effect Level No Apparent
Adverse Effect
Fetal Resorption
Fetal Resorption
Severe anemia
Gastric discomfort *
Species
Rat
Rat
Mouse
Man
(% Incidence)
4000 ppm diet days - 21 to
+ 15 of gestation (100%)
180 ppm in marginal pro-
tein diet days 0-18 (9.4%)
5000 ppm Zn
50 mg Zn (83%)
Effect Level
2000 ppm
30 ppm
1250 ppm Zn
25 mg
Nausea Man
Lethality Man
LD£* (oral)
Lowest lethal dose
Man
Man
1-2 grams
7.4 grams ZnSC>4 IV
over 60 hours
3.5 g
3.5 g ZnCl2
Survival reported
from--ingestion- of-
12 g
150 mg Zn/day for
26 weeks
* fasting
** lowest observed lethal dose
711-1
-------
Table VII-2 summarizes the exposure levels for zinc. It is obvious
from this table that food is generally the largest source of exposure
for humans, although drinking water exposure may be as important in a
few locations. The expected total intake for an individual would probably
not be greater than 50 mg. This level, according to the results in
Table VII-1, would result in gastric discomfort in some of the population
exposed at this level. In order to achieve this intake, however, an
individual would have to be consuming a diet high in zinc, and be residing
in an area in which water is supplied at a zinc concentration equivalent
to the extreme example of 13 mg/1 zinc. Hence, the population exposed at
this level is small, and the effect expected would not be serious or
irreversible. However, little is known about long term exposures to
zinc at these levels.
A subpopulation ingesting zinc supplements is receiving additional
exposure, and the total intake may be greater than 100 mg. This popu-
lation is probably not geographically or demographically identifiable
without additional study. This level of exposure is probably not cause
for concern, since Table VII-1 indicates that ingestion of 150 mg zinc
per day for 26 weeks had no effect. However, acute sub-lethal effects
may be observed in some persons at this level.
C. AQUATIC ORGANISMS
There are three major concerns in determining the risk of zinc exposure
to aquatic animals. First, regions of the country where zinc concentra-
tions are high (for example, locations where zinc is mined, smelted, or used in manu-
facturing )faQe the possibility of industrial discharges or runoff from
mines or tailings. Incidences such as these have been the cause of
many fish kills in the past. Major river basins which drain areas of
high zinc productivity include the mid-Atlantic, Missouri, Arkansas,
and Tennessee.
VII-3
-------
Table VII-2
Zinc Exposure to Humans*
Intake
Ingestion
Food
Drinking Water
Inhalation of
Ambient Air
Smoking
mg/day mg/kg/day**
18.6
Dietary Supplement 12-75
26
0.38
0.3
0.02
0.27
0.17 - 1.1
0.37
.005
.004
. .0003
Comment
Based on average diet of 15-20
year old male.
Based on maximum reported value
in drinking water and consumption
2 liters/day.
Based on mean concentration in
drinking water.
Based on monitoring data near
smelters and an inhalation of
20 m^/day.
Based on smoking 20 cigarettes,
see EPA (1979).
* Does not include occupational exposures.
** Based on 70 kg person.
VI I-A
-------
Secondly, because of che micigative effect of calcium on zinc toxicity,
rivers and lakes with soft water (low in calcium) are more likely to
experience fisk kills at lower zinc concentrations. Regions with soft
water (<100 ppm as CaCO.) include New England, the Pacific Northwest,
northern California and the Southeast, excluding Florida.
Table 711-3 describes the geographic locations where fish populations
may be exposed to toxic levels of zinc due to high zinc concentrations
and low hardness in general. Specific locations within these large
areas were identified in the previous section. The Western Gulf,
Southeast, Missouri, Upper Colorado, Rio Grande and Pecos River basins
in many instances exceed 100 ppb zinc in their waters. The sediments
of the mid-Atlantic, Great Lakes., Tennessee and Pacific Northwest
commonly contain 10 to 100 ppm of zinc. The New England watershed
poses 'perhaps the greatest problem, as both its water and sediment fall
into these categories. However, detailed analysis has shown that it
is primarily the Presumpcot River and Casco Bay that are the problem
areas in New England, while concentrations elsewhere are lower.
The final parameter to consider in assessing risk to aquatic life is
the sensitivity of various species to zinc. As a group, the salmonids
are probably the most sensitive to aqueous zinc. Species such as the
rainbow trout which are found in the northeast, Great Lakes, and
western states, may be threatened, both in terms of sublethal and acute
toxicosis. Warmwater fish are somewhat more resistant to zinc than
salmonids, but may also be at risk in some locations. For example, the
chronic value for che fathead minnow is 106 ppb, as shown in Table
V-3. According to Figure IV-1 over 25% of the water smples taken
nationwide had zinc concentrations exceeding 100 ppb.
The cladocsran Daphnia magna experiences acute effects in zinc concentra-
tions as low at 100 ppb. Invertebrate life may therefore be endangered
as well in a large portion of the nation's waterways. The growth of
certain species of alga such as Selenascrum eapricomucum is inhibited
VII-5
-------
TABLE VII-3
FACTORS CONTRIBUTING TO RISK TO AQUATIC ORGANISMS
Zinc-Producing River Basins
Mid-Atlantic
Missouri
Arkansas and Red
Tennessee
River Basins with Soft Water
New England
Northern California
Pacific Northwest
Southeast (except Florida)
River Basins with High Aqueous Zinc Concentrations*
New England
Western Gulf
Southeast
Rio Grande and Pecos
Upper Colorado
Missouri
45%
31%
30%
28%
26%
24%
River Basins with High Zinc Concentrations in Sediment**
Great Lakes
Mid-Atlantic
New England
Pacific Northwest
Tennessee
47%
36%
33%
33%
31%
* Percentage of samples in the range of 100-1,000 ppb
** Percentage of samples in the range of 10-100 ppm.
VII-5
-------
completely at 120 ppb (See Section V-B). Although most invertebrate
and plant species are not sensitive to zinc in the 100 to 1,000 ppb
range, ;a\ number of plant and animal species appear to be presently
exposed''to harmful concentrations.
The premise that these species is threatened so broadly seems somewhat
suspicious. There may be a number of reasons that the actual risk is
less than the data imply. First, the monitoring data described here
are for total zinc. Thus, in most cases at least a portion of this will
be in the particulate form, which may be unavailable to aquatic
organisms. It has been shown for other metals, i.e., cadmium and
copper, that the form of the metal is important in determining toxicity.
In general, organic complexes and some inorganic complexes are not
available to aquatic organisms. However, fate considerations discussed
previously (Section IV-B)'. indicated that dissolved zinc exists primarily
as the free ion in natural waters. Thus the presence of organic and
inorganic ligands may not be a determining factor in the toxicity of
zinc. Another factor which may redefine risk is acclimation. Studies
have shown that adults that were hatched in high levels of zinc are
more tolerant than those that were not. The implications and inter-
actions of these factors cannot be determined at this time. However,
the potential for aquatic risk to zinc exists in numerous locations.
VII-7
-------
APPENDIX - HUMAN TOXICITY
Metabolism
Zinc Balance
Zinc balance in mammals is controlled by homeostatic processes chat
have not yet been clearly elucidated. Factors that affect zinc homeostasis
include blood loss, sweating, prolonged intravenous feeding, fasting,
burns, infection, nephrosis, chelating agents, myocardial infarction,
surgery, cirrhosis, hormones, the presence of other heavy metals (i.e.,
cadmium, calcium, copper), pregnancy, lactation, and certain dietary components
Including protein, phytate, fiber, and alcohol (Oberleas and Prasad, 1976;
Lindeman, 1972). In a normal 70 kg adult, zinc balance is maintained at
equilibrium by an intake of M.2.5 mg/day (Spencer e£ al., 1976). This re-
quirement is higher (20-25 mg/day) in pregnant and nursing mothers (MAS, 1978).
Absorption and Distribution
In man, approximately 30% of zinc ingested in the diet is absorbed
(Prasad, 1979). Cases of up to 90% absorption have been reported in zinc-
deficient individuals (Aamodt et al., 197S; Richmond e_t al., 1962). The
exact mechanism or sites of zinc absorption are not well understood, but
absorption in man is believed to occur primarily in the proximal part of
the small intestine although absorption may occur at other portions of the
small and large Intestine as well (Prasad, 1979; Methfessel and Spencer, 1973).
While the precise mechanism by which zinc is transported across the
Intestinal membrane is unknown, considerable data exist to support the exis-
tence of a low-molecular-weight (<100,000 daltons) zinc llgand which facili-
tates zinc transport across the intestinal epithelia. Studies with laboratory
animals have revealed the presence of zinc binding proteins in the intestinal
lumen; in the basal and apical plasma membranes and cytosol of the intestinal
A-l
-------
epithelia; and in pancreatic secretions (Kahn and Evans, 1973; Evans and
Hahn, 1974; Van Campen and Kowalski, 1971; Kowarski ec_ al., 1974; Birnstingl
et al., 1956; Montgomery et al., 1943).
Song and Adham (1978) have identified prostaglandin (MW 800 daltons)
as an important zinc-binding protein in the small intestine of rats. Their
in vitro work with isolated rat small intestine indicates that prostaglandin
E- facilitates the transport of zinc across the intestinal mucosa.
Zinc is transported throughout the body in the blood, bound mainly
to the serum proteins albumin, ceruloplasmin, transferrin, and a-2-macro-
globulin (Frasad and Oberleas, 1970; Farisi and Vallee, 1970; Suso and Edwards,
1971; Frazier, 1979).-
Spencer _et al. (1965) examined the metabolism and tissue distribution
of Zn chloride in eleven terminal cancer patients. The period between the
single intravenous injection of Zn (20-53 uCi) and death due to cancer
ranged from 1 to 71 days. Tissue samples were obtained and assayed for
65
ZA content at the time of autopsy. Urine and blood samples were taken at
regular intervals from the time of injection until the time of death.
65
The authors found that intravenously administered Zn was cleared
rapidly from the blood. In one typical patient, whole blood and plasma con-
tained 22% and 20%, respectively, of the administered dose 13 minutes after
injection. Exponential clearance of zinc from blood lasted for approximately
one hour, at which time the blood and plasma levels of Zn were less than
5% of the administered dose. The blood levels diminished very slowly after
the first hour, with ^1.0% of the administered dose detectable in the blood
40 days after -injection.
65
In both human subjects and laboratory animals, serum-bound Zn exchanges
rapidly with zinc in the soft tissues such as liver, spleen, kidneys, pros-
tate, pancreas, adrenals, and thyroid. Zinc uptake and turnover in bone,
A-2
-------
hair, muscle, nails, and testis occurs more slowly than chat observed in
the soft tissues (Gilbert and Taylor, 19S6; Heath and Liquier-Milward, 1950;
Spencer et al., 1965; Thind and Fischer, 1975). The biological half-life
of Zn in man has been calculated to be between 154 to 334 days (Spencer et_ al.
1965; Richmond et_ al., 1962; Andrasi and Feher, 1967).
Excretion
%
Studies of the excretion of labelled zinc in terminal cancer patients
indicate that the main pathway of Zn excretion in man is the gut. In two
cancer patients surviving 45 days beyond a single intravenous injection of
65 65
Zn, cumulative fecal elemination of Zn was 21.6% and 16.82, respectively,
compared to urinary excretion of 0.87% and 3.4% (Spencer et, al., 1965). In
man, fecal elimination accounts for the major portion of zinc excretion regard-
less of the route of administration (HAS, 1978). In addition, when zinc is
administered orally, wthe 70-80% o-f the ingested zinc which is'not absorbed,
is also cleared in the feces.
Animal Studies
Zinc metabolism appears to occur in essentially the same manner in all
mammals studied, although interspecies differences exist with regard to
tissue distribution and retention. In rats, as in man, the-relative percent
absorption of zinc in the small, intestine decreases as the concentration
of dietary zinc increases (Bohne, ££ al., 1967).
Mice injected intravenously with 0.33 of Zn chloride eliminated 25%
of the administered dose in the feces within the first 24 hours after injection.
At 170 hours post-injection, 50% of the dose had been eliminated in the
feces, while urinary excretion accounted for only 2.0% of the administered
dose (Sheline et_ al., 1943). In a similar study with dogs, approximately 5.0%
of the administered intravenous dose (5.7 y ZaCl2) was eliminated in the
feces within 24 hours of injection. At two weeks, cumulative fecal elimina-
tion accounted for 25.0% of the administered dose. The cumulative urinary
excretion of Zn at 15 days post-injection was 5.0% and 2.0%, respectively
(Sheline et al., 1943).
A-3
-------
Male albino rats eliminated 55.0% of a single 100 yCi intraperitoneal
dose of ZnCl2 in the feces within 23 days of injection; less than 2.0% of
the administered dose was excreted in the urine during this period. Fecal
elimination was reported to have been rapid during the first two or three
days after injection, but much slower thereafter. Rapid uptake of Zn by
soft tissues (particularly the prostate) and the slow turnover in bone and
tastes were also noted (Wakeley e_t al., 1960).
A-4
-------
Zn Salt
ZnCl,
TABLE A-l
ACUTE TOXICITY OF ZINC SALTS
Soecies
Route
Human oral
Guinea pig ' oral
Rat oral
Mouse oral
Human inhalation
Rat intravenous
(mg/Tcg)
Source
50 LDLo*
200
350
350
4800 mg/m 730 mln TCLo**
50 LDLo
RTECS, 1977
it
Guinea pig intraperitoneal 173 LDLo
ZnO
ZnSO.
ZnSO . THjO
Hunan
Human
Human
Rabbit
Rat
Mouse
Rat
Rabbit
Rat
Dog
. Mouse
Dog
Rabbit
Rat
Rabbit
Rat
Rabbit
Rat
Dog
Dog
Rat
Guinea pig
oral
inhalation
oral
oral
oral
oral
oral
intravenous
intravenous
intravenous
intraperitoneal
subcutaneous
subcutaneous
subcutaneous
oral
oral
intravenous
intravenous
intravenous
subcutaneous
subcutaneous
subcutaneous
500 LDLo.
600 mg/m
50 LDLo
2000 LDLo
2200 LDLo
626
1396
44 LDLo
50 LDLo
60 LDLo
29
78 LDLo
300 LDLo
330 LDLo
1914 LDLo
2200 LDLo
44 LDLo
49 LDLo
66 LDLo
78 LDLo
330 LDLo
590 LDLo
TDLo
**
Lowest published lethal dose.
k
Lowest published lethal concentration.
Caujolle et al. (1969
ti
KEGS, 1977
Bienvenu ej al. (1963)
RTECS, 1977
A-5
-------
TABLE A-2
HUMAN TISSUE CONCENTRATIONS
!r
Chemical Zinc
Geographic
Population Region
Adu 1 t
Human Detroit
controls
Sickle-cell
ctiicmlu patients
Pregnant U.S.A.
females
('entitle controls
Male controls
Women takj ng
oral contra-
ceptives
Tissue
Serum or
Plasma
Red blood
cells
Plasma
Red blood
cells
Plasma
Red blood
cells
Plasma
Number
Sampled Distribution
63-170 ug/100 ml
10-14 ug/ml
23 112 + 2.5 ug% + S.E.
23 41+1.2 ng/g Hgb + S.E.
27 102 + 2.7 ugZ + S.E.
27 35.2 + 1.6 ug/g Hgb + S.E.
lig/100 ml + SD (range)
107 63 + 12 (40-102)
27 97 + 11 (76-112)
62 96 + 13 (72-115)
30 81 + 14 (60-110)
Remarks Reference
Halsted et al .,
1974
Prasad et al . ,
1975
Low plasma zinc Halsted and
levels were aaso- Smith, 1970
elated with elevated
copper levels
(249 + 52 pg%) in 70 :
pregnant women and 10
women on oral contra-
ceptives (300 + 70 iig%)
compared to controls
(119 + 20 iig%)
-------
HUMAN TISSUE CONCENTRATIONS
Chemical
t'onulatiim
Uoniun
I'ruguant
women
Geographic
Region Tissue
U.S.A. Serum
Serum
Umbilical
' cord serum
Amnlotlc
fluid
Number
Sampled
15
15
15
Distribution Remarks Reference
pg/100 ml - S.E.
90 + 3 llenkin et al . .
1971
48 + 3
83 + 3
32+12
Patients Austria
with chronic
tuna! failuru-
iindergoiiig
tciuil dialysis
I'ciLlentS wltlt
cliironic cenai
failure - no
dialysis
Plasma
261 + 92 pg%
117 + 95 pg%
Zazgornlk et ul.,'
1971
108 + 20 |Jg%
-------
Chemical
HUMAN TISSUE CONCENTRATIONS
Geographic
Population Region
Children S. Africa
Wltll
KwashioL'kor
Controls
ClillJi-en India
with
Kwudhloirkor
Controls
females
Kts *"
Tissue
Serum
Plasma
Breast
milk
Col os trum
Menstrual
fluid
Number
Sampled Distribution Remarks
we/100 ml - SD
29 62 + 20.9
113 + 14.7
28 41.3 + 1.5 |ig/100 ml + S.E.
102+4.7 ug/100 ml + S.E.
3-4 mg/1
20 mg/1
308-616 |ig/cycle Assumes menstrual
loss of 25-70 ml
blood per cycle
Reference
Smlt and Pre-
torlus, 1964
Kumar and Rao,
1973
Prasad, 1966
Schroeder et a 1 .
1967
IllllUdllS
Sweat
1.15 mg/1
In hot climate,
as much as 5 liters
of sweat may be lost
per day
Prasad et al.,
1963b
-------
Chemical Zinc
HUMAN TISSUE CONCENTRATIONS
Geographic
Population Region
Humans
Sweden
.Tissue
Urine
Number
Sampled
96
Distribution
Remarks
1.04 + 0.14 ppm
Reference
Wester. 1975
liij-lit-to Poland
ten-year-old
cli I Id ren
UrJne
0.602 mg/dm
Industrial region
;0.605 mg/dm3
Agricultural region
Dutklewicz e_L al
1978
Sickle-cell Detroit
anemia
AdiiU
ma I tm
(age: -
> 50 yrs)
Urine
Japan Feces
- Polluted area
- Control area
- Tokyo
21-24 yra)
ue/e creatine + S.E.
12
739 + 60
10
495 + 35
Prasad et al..
1975
nig/day + S.D.
(dry fecea wet.)
Tsucliiya and
Iwao, 1978
30
21.61 4- 12.48
30
10.27 + 4.73
19
10.45 + 6.48
-------
HUMAN TISSUE CONCENTRATIONS
Chemical Zinc
Geographic
Population Region .Tissue
Unmans Skin
Teenagers Norway Teetli
undergoing
orthodontic
procedures
Eight- to- Poland Hair
ten-year-
old children
Unman Detroit Hair
Sickle-cell
anemia
puLJtMits
Healthy U.S.A. Scalp
pregnant hair
of delivery Pubic
(Age 16-39 hair
yra)
Number
Sampled Distribution
10 iig/g (dry wgt)
8 76-204 ppm
1 542 ppm
177-213 mg/kg
192 mg/kg
17 193 ± 4.3 ug/g + S.E.
21 149 ±10.3
109 143.3 ug/g
158 110.1 ug/g
Remarks Reference
Goolamali aud
Comalsh, 1975
Oehu. -ot ul . .
1978
Industrial area Dutkiewlcz e_»_ aj.
1978
Agricultural area
Prasad et al. ,
1975
Creason et al . ,
1976
-------
Chemical Zinc
HUMAN TISSUE CONCENTRATIONS
'r
Geographic
Population Region
Illllllclll, |)OUt-
IIIUCC em
tiLiiup I eu
Mules
AiluU
mules
Tissue
Retina
Number
Sampled
3
Distribution
ppm (dry)
385 - 571
Chorold
419 - 562
Ciliary body 3
189 - 288
Prostate(biopsy)
Normal 12
dry tissue
520 ug/g
Hyperplasla 9
2300 ug/g
Remarks
Reference
Galin, 1962
Schrodt et al.,
1964
Carcinoma 10
285 ug/g
Bone
150 - 250
Underwood. 1971
Prostate
Semen
850
3000
Sperm
2000
-------
HUMAM TISSUE CONCENTRATIONS
Chemical
h-
10
Geographic
I'npuJacloii Region .Tissue
NomiuL human Japan Liver
(obtained by Brain
85-185 of Kidney
pi truancy
NoLinal human Japan Whole
uml>ryos embryo
(oh Lai ncd by
aliOL'Cluil)
Agu days: 31
35
39
41
45
64
70
78
Number
Sampled
14
14
14
4
10
3
10
6
1
1
1
Distribution .
ug/g wet tissue .£ S.D.
167.7 + 39.4
5.6 + 1.2
15.77 ± 2.9
«
< jig Zn/g wet tissue (range)
2.8 (2.6 - 3.0)
19.7
18.2
18.0 (14.5 - 20.9)
20.62 (12.3 - 27.08)
20.5
22.6
24.8
Remarks
Reference
Chaube et at.,
1973
-------
Chemical ZJnc
HUMAN TISSUE CONCENTRATIONS
Geographic
Population Region
Adults, Norway
Sillll|ilei>
Age yrs:
16-18
26-29
'JO- 33
4J-46
50-59
60-69
70-79
80-U9
Number
.Tissue Sampled Distribution
(% male) pg/g tissue dry wgt
Renal
Liver Cor rex
670 503
2 (100) (462-878) (289-716)
3 (100) 215 201
J Uuu;( 64_296) (131-273)
t f^\ 507 307
J 10°) (285-647) (184-463)
3(100) 242 227
JUUUJ ( 74-384) (159-283)
, f . 326 240
10 (O/) (113_990) (iQO-312)
17 fSM 292 229
I/ W ( 97_915) (105-443)
273 229
17 (50) (146_4U) (150-353)
.. ,.,. 366 255
" ^ ' ' (214-715) (142-564)
306 236
1(100) ( 64_990) (100-716)
Remarks Reference
i (Range) Syverson et al.,
i 1976
Renal
Medulla
376
(181-570)
163
(134-206)
251
(118-418)
136
(119-149)
201
( 67-323)
170
( 72-327)
176
( 80-350)
184
( 76-452)
179
( 67-570)
-------
Chemical Zinc
HUMAN TISSUE CONCENTRATIONS
Geographic
Population Region
Adult mdJet., St. Louis,
rice. Uuul Missouri
vJctJiiis
Tissue
Liver
Number
Sampled
10
Distribution
4570 ug/g tissue ash
Adit I it., |)ost- Sweden
mortem
Liver
39
79.2 + 45.1 Mg/e wet tissue
10-19
20-29
iO-39
40-49
50-59
70-
6
9
6
16
4
19
4
10
11
33
65
57
56
62
45
60
56
60
.9 + 1.4
.01
.20
.25
.72
.82
.58
.81
.59
+
jh
+
±
t
±
+
+
1.
1.
1.
1.
1.
1.
1.
1.
53
20
56
26
80
31
54
21
17.
38.
33.
47.
56.
61.
55.
72.
48.
43
78
42
16
99
47
83
43
00
j;
±
+
+
+
+
j;
+
+
1
1
1
1
1
1
1
1
1
.19
.87
.33
.65
.11
.64
.19
.64
.31
Remarks
Reference
Perry et al.,
1978
Wester. 1975
Adults, Japan
accident
;,. V i C L i IDS
,'. Ayt! (yirs)
4- X i
Mg/B wet
Liver
£ ** O J. 1 A 1
tissue + S.D.
Renal Cortex
i T /. » j. i ia
Tsuchlya and
Iwao, 1978
-------
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A-3.3
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