ENVIRONMENTAL RISK AND HAZARD ASSESSMENTS
FOR VARIOUS ISOMERS OF
POLYCHLORINATED BIPHENYLS (MONOCHLOROBIPHENYL THROUGH
HEXACHLOROBIPHENYL AND DECACHLOROBIPHENYL)
HEALTH AND ENVIRONMENTAL REVIEW DIVISION
OFFICE OF TOXIC SUBSTANCES
SEPTEMBER 1, 1983
OFFICE OF PESTICIDES AND TOXIC SUBSTANCES
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
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I. Executive Summary
Potential environmental risk is expected to occur to aquatic
organisms if polychlorinated biphenyl isomers are released into
the aquatic environment at concentrations of 100 ug/L. Expected
risks include: (1) reduction in the reproductive success of fish
through direct toxicity to eggs and embryos which are fish early
life stages; (2) direct lethality and sublethal effects to
juvenile and adult fish; (3) effects to aquatic invertebrates
which are food sources for fish; and (4) possible but not
demonstrated reductions in the growth of phytoplankton, i.e.,
minute floating plants, usually algae, which produce the basic
food for the aquatic ecosystem. Risks to wild mammals and birds
could not be determined because of a lack of toxicological
information for PCS isomers and lack of an appropriate exposure
assessment for terresrial organisms.
Environmental risk for all effects increase with an increase
in the degree of chlorination of the biphenyl (Figure 1).
Environmental risk to aquatic organisms from monochlorobiphenyl
isomers are predicted to occur at 10 to 30% of chemical plant
sites expected to inadvertently produce PCB isomers as
impurities; while risk from hexachlorobiphenyl isomers are
expected to occur at a0-90% of plant sites. This increase in
risk is due to an increase in the toxicity of PCBs with greater
numbers of chlorine atoms. An increase in chlorination of PCBs
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has been related to increases in toxicity for (1) chronic
toxicity to rainbow trout (Figure 2) for monochlorr,oiphnyl
through hexachlorobphenyl isoraers, (2) acute (lethal) toxicity to
rainbow trout (Figure 3) for monochlorobiphenyl through
-tetrachlorobiphenyl isoraers, and (3) acute toxicity to aquatic
invertebrates (Figure 4) for monochlorobiphenyl through
tetrachlorobiphenyl isomers. Acute toxicity of
pentachlorobiphenyl and hexachlorobiphenyl isomers to aquatic
invertebrates is less than would be predicted (Figure 4) because
of the greater water insolubility of these isomers.
Environmental risk to aquatic organisms is shown to increase
to as many as 40% of additional chemical plant sites in the US
under low streamflow conditions. Risk was estimated for two
streamflow conditions for rivers in the US: average streamflow
and low streamflow (Table 5). The increase in risk under low
streamflow conditions can be attributed to lower stream dilution
factors during low streamflow which result in higher predicted
environmental concentratiions.
The environmental risk of monochlorobiphenyl and
dichlorobiphenyl isomers is predicted to increase if discounting
factors are incorporated into the exposure assessment. A
discounting factor of 50 for monochlorobiphenyl isomers is
expected to increase potential risk to an additional 40% of plant
sites over risks associated with no discounting factor. A
discounting factor of 5 for dichlorobiphenyl isomers is expected
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to increase risk to aquatic organisms at about 10% additional
plant sites. A discounting factor means that monitored
concentrations of a PCB isomer will be divided by that factor,
e.g., 50 or 5, and then recorded. For example, an effluent
concentration for a monochlorobiphenyl of 5 mg/L would be
reported as 100 ug/L of isomer. The increase in risk associated
with the use of discounting factors can be entirely attributed to
higher surface water concentrations used in the exposure
assessment.
The environmental concerns for PCB isomers generated by this
risk assessment are similar to the environmental concerns
historically expressed for the commercial mixtures of PCBs
(Aroclors). Environmental concerns held in common are: (1)
impairment of the reproductive success in fish, especially, to
the early life stages of fish; (2) direct adverse effects to
juvenile and adult fish; and (3) reduced survival and growth of
aquatic invertebrates and aquatic plants. Evironmental concerns
attributed to PCB commercial mixtures but not yet demonstrated
for PCB isomers include: (1) correlation of high body burdens of
PCBs in female fish with failure of eggs to hatch; (2) impaired
bone development and testical abnormalities in juvenile fish; (3)
contamination of economically important food resources, e.g.,
closure of fisheries; and (4) impairment of reproductive success
in some wild mammals (e.g., mink) and birds-.
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This environmental risk assessment is a quality-ive risk
assessment and is relatively conservative, i.e., designed to err
on the side of environmental protection. The basis of this risk
assessment was the application of information derived from a
hazard assessment to situations identified by an exposure
assessment. Concentration-effect curves for each group of
aquatic organisms, e.g., early life stages of fish, were
synthesized for each class of PCB isomer, e.g.,
raonachlorobiphenyls, dichlorobiphenyls, etc., and were compared
to hypothetical surface water concentrations downstream from
organic chemical plants. Whenever an effective concentration was
equal to or exceeded a surface water concentration, a potential
risk was noted and the type and degree of risk was determined
(Table 5). No attempt was made to quantify the impact to a
particular population at a particular site over time. Therefore,
this risk assessment can be characterized as more qualitative
than quantitative.
This assessment can also be characterized as relatively
conservative because (1) toxicity information for the most
sensitive species and the most sensitive life stage for a species
was used whenever possible; and (2) it was assumed that all
chemical plants discharged process wastewater containing 100 ug/L
of PCBs and that there was no loss due to sorption,
transformation, or degradation. However, the risk assessment
could have been more conservative. No assessment factor was used
to predict a "safe" concentration of PCB isomer from the toxicity
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information. An assessment factor is defined as a number by
which an effect concentration, e.g., EC50 or NOEC, is adjusted
(by division) to arrive at a "safe" environmental
concentration. In addition, information for the most sensitive
species could not always be used. For example, in some data sets
rainbow trout was the most sensitive fish species tested,
however, data from five other fish species were also used in the
risk assessment.
This risk assessment is as comprehensive as available
information would permit. Concentration-effect curves were
synthesized from all available information: which ranged from
chronic no-observed-effect concentrations for the most sensitive
life stage to acute concentrations which caused 100% lethality in
a test population. For example, potential environment risk to
fish populations to tetrachlorobiphenyl isomers with no chlorines
in the o_r&- positions on the biphenyl (Figure 1 and Table 5) was
characterized in terms of effects to fish early life stages (E),
sublethal effects to juvenile fish (SL), reductions in the growth
of juvenile fish (G), and lethality to juvenile fish (L).
All 18 hypothetical exposure situations (i.e., streamwater
concentrations for the 10th through the 90th percentiles of
chemical plants under two streamwater conditions: low and
average streamflow, Table 5) were evaluated for potential risk
from each class of PCB isomer. In all one hundred forty four
situations were evaluated for four groups of aquatic organisms.
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Including evaluation of discounting factors, a totsi of 612
situations were evaluated for potential environme.-cal risks.
This risk assessment did not address the additional risk of
PCB isomers from bioconcentration, food chain transport, and food
chain concentration (or biomagnification). For example, a female
fish will bioconcentrate PCBs and subsequently pass these
residues to her eggs which could result in inviable eggs and
embryos. The reason for this deficiency in the risk assessment
was a lack of toxicological information on the PCB isomers with
regard to this type of reproductive inhibition in fish, birds,
and wild mammals.
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II. Environmental Risk Assessment of PCS Isomers tv Aquatic
Organisms
A. Basis of Risk Assessment
Risk assessment is the application of information derived
from a hazard assessment to situations identified by an exposure
assessment. The hazard assessment for various PCS isomers can be
found in Sections III through VI. The exposure assessment was
derived from an exposure assessment for incidentally produced
PCBs (Versar 1983). Table H-l from Versar (1983) (see Table 1)
was used to obtain hypothetical surface water concentrations
downstream from organic chemical plants in the US expected to
inadvertently produce PCB isomers as impurities. Versar
estimated 19 hypothetical concentrations: 9 under average
streamflow conditions and 9 under low streamflow conditions.
Versar estimated the 10th through the 90th percentiles (9
percentiles) for each streamflow condition (Table 1). For this
risk assessment, the 18 hypothetical streamwater concentrations
were rank-ordered from highest to lowest: 66 to 0.00037 ug/L,
respectively. Versar assumed that all plants discharged process
wastewater containing 100 ug/L of PCBs, that there was
instantaneous mixing, and that there was no loss due to
degradation, transformation, or sorption. For this risk
assessment, eight risk assessments were performed: one each for
monochloro-, dichloro-, trichloro-,. tetrachloro(with 1-4
chlorines at the £,£'-positions)-, tetrachloro(with no chlorines
at the £,£'-positions)-, pentachloro-, hexachlorobiphenyl
isomers, and decachlorobiphenyl (Table 1). It was assumed that
all plants discharged 100 ug/L of one class of PCB isomers, e.g.,
monochlorobiphenyl isomers. Each estimated streamwater
concentration was compared to ths concentration—effect curve for
each class of PCB isomers, and if a risk was predicted (i.e., if
an effective concentration was equal to or greater than a
streamwater concentration), then the type of risk and its degree
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were indicated in Table 1. An empty cell in the matrix under
"Class of PCB" in Table 1 indicates that the strearr.vater
concentration was less than any available effective concentration
in the hazard assessment.
B. Risk Assessment for Fish
1. Monochlorobiphenyls
a. Discharge of 100 ug/L of monochlorobiphenyl
isomers will result in risk to fish populations under only low
streamwater conditions at 30 percent of plants with a low
streamwater dilution factor of 18.9 or less (Table 1). At a
concentration of 66 ug/L, juvenile and adult fish are predicted
to have only sublethal effects, e.g., reduction in growth,
reduced food consumption, disorientation. No lethality of
juveniles and adult fish is expected. The early life stages of
fish, i.e., embryos and sac fry, are expected to be affected by
the monochlorobiphenyl isomers at all concentrations equal to and
higher than 5.3 ug/L. Effects expected to occur are reduced
growth and survival of embryos and sac fry. The percentage of
fish affected cannot be estimated, but at 5.3 ug/L the percentage
will approach 0%.
b. Discharge of monochlorobiphenyl isomers with a
discounting factor of 50 will increase the risk to fish
populations 50 times. A discount of 50 means that monitored
concentrations of monochlorobiphenyls will be divided by 50 and
"then reported. Actual concentrations would be 50 times higher
than PCB surface water concentration estimated in Table 1. Under
these conditions, acute lethality of juvenile and adult fish
would occur at 30% of plants at low strearaflow. Lethality of 50%
or higher, would occur at 20% of these plants. Sublethal effects
and subchronic mortality would occur at 40% of plants at low
streamflow and 10% of plants at average streamflow. Effects to
fish early life stages would occur at 70% of plants at low flow
and 40% of plants at average streamflow.
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2. Dichlorobiphenyls
a. Discharge of dichlorobiphenyls isomers at 100 ug/L
will potentially affect fish populations at 20% of plants at
average streamflow conditions and 50% of plants at low streamflow
(Table 1). Fish early-life stages will be at risk at all the
above plants. Effects will be near zero at 0.47 ug/L and
increase in severity at plants with smaller stream dilution
factors (i.e., as you proceed up Table 1). Juvenile and adult
fish will suffer sublethal effects at only 20% of plants under
low streamflow. The probability of subchronic and acute
lethality is low for dichlorobiphenyls released at 100 ug/L.
b. If a discounting factor of 5 is used for discharge
of dichlorobiphenyl isomers, potential risk to fish will extend
to 10% more plants and acute lethality will probably occur.
Effects to fish early-life stages will occur at 30% of plants
during average streamflow and 60% of plants during low flow.
Sublethal effects to juveniles and adults will occur at 30% of
plants only at low flow and lethality approching approximately
40% will occur at 10% of plants.
3. Trichlorobiphenyls
Trichlorobiphenyl isomers discharged at 100 ug/L have a
potential to affect the early-life stages of fish at 40% of
plants during average streamflow and 60% plants at low flow
(Table 1). Sublethal and subchronic (30d) lethality will occur
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only during low streamflow conditions at 30% of plants.
Subchronic lethality will occur only at 10% of these plants at
low flow and will be much lower than 50%.
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4. Tetrachlorobiphenyl Isomers with 1-4 Chlorines at the
OyO'-Positions of the Biphenyl
Tetrachlorobiphenyl isomers with 1 to 4 chlorine atoms
at the o^o_'-positions of the biphenyl (Figure 1) have the
potential to affect fish populations at 70% of plants during low
streamwater flows and at 40% of plants during average flow. The
early-life stages (i.e., embryos and sac fry) of fish will
exhibit reduced growth and increased mortality at all of the
above plant sites. Juvenile and adult fish will exhibit
sublethai effects at only 10% of plant sites during average
streamflow, but during low streamflow 40% of plants discharging
100 ug/L could affect juveniles and adults (Table 1). Subchronic
lethality will occur only at low streamflow at 20% of plant
sites; these isomers have the potential of killing over 50% of
the fish populations at 10% of plant sites (Table 1).
5. Tetrachlorobiphenyl Isomers with No Chlorines at the
0,0'- Positions of the Biphenyl
Tetrachlorobiphenyl isoraers with no chlorines at the
o./.o.1" positions of the biphenyl appear to present significantly
greater risk to fish populations than tetrachlorobiphenyl isomers
with chlorines at the o_,o^- positions. They also have the
potential of affecting more plant sites (20% more sites at
average streamflow). The early life stages of fish will be
affected at 70% of plant sites at average streamflow and 80% of
plant sites at low flow (Table 1). Sublethal effects to juvenile
and adult fish will (1) begin to occur at 40% of plants during
average streamflow, (2) reduce the growth of juveniles by 30% at
30% of plant sites, (3) reduce growth further by 60% at 20% of
plants during average flows, and (4) could kill 25% of the fish
populations at 10% of plant sites during average flow, but during
low flows 40-50% of sites could be affected (Table 1).
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6. Pentachlorobiphenyls
Pentachlorobiphenyl isoraers were predicted to be
slightly more toxic than the tetrachlorobiphenyl isomers in the
hazard assessment (Section III. E) and, therefore, will present
slightly more risk to resident fish populations than the
tetrachlorobiphenyls given the same discharge conditions at 100
ug/L concentration. Table 1 reflects this increase in risk by
affecting about 10% more plant sites than the
tetrachlorobiphenyls). The subchronic and chronic effects of the
pentachlorobiphenyls are less quantified than they were for the
tetrachlorobiphenyl isomers, because much more experimentation
was available for the tetrachlorobiphenyls and only NOECs could
be predicted for pentachlorobiphenyls in the hazard assessment.
The type of effects could not be quantified but it was assumed
that effects observed for the tetrachlorbiphenyl isomers will
also occur with the pentachlorobiphenyl isomers.
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7. Hexachlo rob iphe nyIs
Hexachlorobiphenyl isomers were predicted to be more
toxic than the pentachlorobiphenyls in the hazard assessment
(Section III.F) and, therefore, are assumed to present more risk
to fish populations given the same exposure conditions. Table 1
indicates this increase in toxicity, and, therefore, risk.
The hexachlorobiphenyls are expected to affect the
early life stages of fish at 80% of the plant sites during
"average strearaflow and over 90% of sites at low flow (Table 1).
These effects will increase in severity at sites with smaller
stream dilution factors. This fact is demonstrated at the 20th
percentile entry. At this surface water concentration (16 ug/L),
100% of the embryo and sac fry'fish are expected to be killed.
Broyles and Noveck (1979b_) observed 100% mortality within 79 days
of lake trout and Chinook salmon sac fry after only an 8 ug/L
exposure for 15 days (Section III.F.2.C).
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8. Decachlorobiphenyl
Decachlorobiphenyl is expected to be similar in
toxicity to the hexachlorobiphenyl isomers (Section III.G), and,
therefore, under the same exposure conditions, are expected to
present similar risks to fish populations. Table 1 reflects this
assumption in that the potential risks for decachlorobiphenyl are
the same as for the hexachlorobiphenyl isomers.
C. Risk Assessment for Aquatic Invertebrates
1. Discharges of 100 ug/L
Discharges of 100 ug/L of the various PCS isomers will
probably result in risks to aqutic invertebrates. These risks
are similar to risks predicted for juvenile and adult fish.
Risks to aquatic invertebrates can best be defined by taking
Table 1 and.eliminating risks to the early life stages of fish
(i.e., .eliminate Es' from Table 1; see Table 2). The rationale
for using the risk assessment for juvenile fish for aquatic
invertebrates is based upon the similar acute toxicity between
fish and aquatic invertebrates (Section IV.A) and a lack of
chronic toxicity information for aquatic invertebrates (Section
IV.B).
There are three major differences between the risk
assessment for fish (Table 1) and the risk assessment for aquatic
invertebrates (Table 2): (1) risk from acute exposure is expected
to occur to aquatic invertebrates (acute risk was not predicted
for fish), (2) chronic sublethal effects for aquatic
invertebrates cannot be quantified as precisely as was done for
fish, and (3) risk to aquatic invertebrates from the
pentachlorobiphenyl isomers, hexachlorobiphenyl isomers, and
decachlorobiphenyl may not occur at the lower streamwater
concentrations.
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a. Risk from acute exposure is expected io occur to
aquatic invertebrates from trichlorobiphenyl and
tetrachlorobiphenyl isomers at 10% and 20% of plant sites,
respectively, during low streamflow (Table 2). During low
streamflow, a 100 ug/L discharge of trichlorobiphenyl isomers
will kill 50% of the aquatic invertebrates in the receiving
r
stream; discharge of tetrachlorobiphenyl isomers will kill over
50% of the invertebrate population. Acute lethality will also
occur at 20% of plants during low streamflow if tetrachlobiphenyl
isomers are released (Table 2). In the risk assessment for fish,
lethality was expected to occur only from subchronic exposures.
b.- Sublethal effects for aquatic invertebrates cannot
be identified or quantified because no chronic studies have been
done. Sublethal effects will probably include reductions in
weight, fertility, brood size, growth rate, and survival of
offspring. It was assumed that the chronic NOECs for aquatic
invertebrates will be similar to the subchronic NOECs for
juvenile fish (Section IV.B).
c. Risks predicted to occur in Table 2 for
pentachlorobiphenyl and hexachlorobiphenyl isomers, and
decachlorobiphenyl may not occur at some of the lower streamwater
concentrations. The acute toxicity of pentachlorobiphenyl and
hexachlorobiphenyl isomers was shown (Section IV.A) to
decrease. It is possible that the chronic toxicity for these
isomers could also be less, however, under chronic exposures much
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more time is available to take up and accumulate an effective
dose than under acute exposure conditions.
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2. Effect of Discounting Factors
a. Monochlorobiphenyls
Using a discounting factor of 50 for discharge of
monochlorobiphnyl isomers to receiving streams, will result in
(1) acute lethality to aquatic invertebrates at 30% of plants
during low streamflow, and (2) sublethal effects at 40% of plants
during low streamflow, and 10% of plants during average flow.
Acute lethality will be much greater than 50% at the 10
percentile (low flow), greater than 50% at the 20 percentile (low
flow), and less than 50% at the 30 percentile (low flow, Table
2). The net effect of the discounting factor will be to (1)
introduce acute risk to 30% of plant sites, (2) increase risk of
sublethal effects from 10% of plants to more than 40% of plant
sites at low flow, and (3) introduce potential risk from
sublethal effects to 10% of plant sites during average flow.
b. Dichlorobiphenyls
Use of a discounting factor of 5 for the discharge of
dichlorobiphenyl isomers to receiving streams will result in
acute lethality to aquatic invertebrates at 20% of plant sites
during low streaflow: lethality of greater than 50% will occur at
10% of sites and lethality of 50% or less will occur at another
10% of sites. Sublethal effects will occur at 30% of sites
during low streamflow. The result of using a discounting factor
of 5 will be to (1) introduce acute lethality and (2) increase
the occurrence of sublethal effects from 20% to 30% of plant
sites.
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D. Risk Assessment for Algae
A risk assessment for algae cannot be done at this
time. The only toxicity information available is for marine
phytoplankton communities (Section V.A) and the hypothetical
exposure assessment is for freshwater riverine ecosysems (Versar
1983).
E. Risk Assessment for Protozoa
1. Discharges of 100 ug/L
The risk of various PCB isomers to protozoa appears to
be low. The NOECs of 13 PCB isomers ranging from
monochlorobiphenyls through hexachlorobiphenyls were about 100
ug/L or greater. In the exposure assessment, the highest surface
water concentration estimated was 66 ug/L in streams with the
smallest dilution factor at low streamflow. This worst case
exposure condition is lower than the NOECs estimated for protozoa
(Section V.B)
2. Effect of Discounting Factors
a. Monochlorobiphenyls
Use of a discounting factor of 50 will introduce risk
to protozoa at 20% of plant sites during low streamflow
conditions. At 20%. of sites/ protozan growth could be reduced
50'% in 43h (Table 6); at 10% of sites, growth could be reduced
more than 50%.
b. Dichlorobiphenyls
Use of a discounting factor of 5 for the
dichlorobiphenyl isomers could introduce risk to protozoa at 10%
of plant sites during low streamflow. At these sites growth
could be reduced about 10% to 50% in 43h (Table 6).
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III. Toxicity of Various PCB Isomers To Fish
A. Monochlorobiphenyl Isomers
1. The subchronic no-observed-effect concentration (NOEC)
for monochlorobiphenyl isomers using data for the most toxic
isomer to the most sensitive fish species tested is estimated to
be 50. - 80. ug/L to juvenile fish after about a 30-day exposure.
a. The most toxic isomer of monochlorobiphenyl is 2-
chlorobiphenyl. Dill et al. (1982) tested all three
monochlorobiphenyl isomers to three species of freshwater fish
(Table 3). The 2-chlorobiphenyl was the most toxic to all
species.
b. The most sensitive species to 2-chlorobiphenyl was
rainbow trout (Table 3).
c. The only NOEC for the monochlorobiphenyl isomers
is derived from a 32-d toxicity test for fathead minnows to 2-
chlorobiphenyl (Dill et al. 1982). The 96-h LC50 for rainbow
trout (540 ug/L) is about seven times lower than the 96-h LC50
for fathead minnows (4000 ug/L, Table 3). Therefore, the NOEC
for fathead minnows was divided by seven to estimate a NOEC for
rainbow trout (i.e., 380. - 550. ug/L divided by 7 equals
50. - 80. ug/L).
2. The NOEC for the early life stages (embryo-sac fry) of
fish is estimated to be 2. - 3. ug/L.
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a. Broyles and Noveck (1979a_) reported that several
investigators (Schimmel et al. 1974, Nebeker et al. 1374, and Mac
et al. personal communication) have observed that
fish of early developmental stages are more sensitive to PCBs.
Mac et al. indicated that the "highest number of mortalities
occurred before and up to yolk absorption; fewer mortalities were
observed thereafter."
b. Sac fry fish appear to be about 25 times more
sensitive to PCBs than juveniles or adults. Schimmel et al.
(1974, as reported by Broyles and Noveck 1979a_) found that
Aroclor 1254 was 30 times more toxic to sac fry than to juveniles
and adults of the sheepshead minnow (Cyprinodon variegatus).
Nebeker et al. (1974, as reported by Broyles and Noveck 1979a_)
found that Aroclor 1242 was 20 times more toxic to newly hatched
fry of fathead minnows than to 3-mo old fry.
c. The NOEC for embryo-sac fry fish was obtained by
dividing the NOEC for the most sensitive fish (see Section III.
A.I above) by 25.
3. The acute (96-h) LC50 to juvenile rainbow trout for the
monochlorobiphenyl isomers is about 780 ug/L (Figure 2, Table 3).
B. Dichlorobiphenyl Isomers '
1. The 30-day NOEC for the dichlorobiphenyl isomers to
juvenile fish is estimated to be 12. ug/L.
*
a. No data were available for the dichlorobiphenyl
isomers (Table 3). Therefore, the NOEC was estimated through
statistical regression analysis of the relationship between PCB
chlorine number and available NOECs for rainbow trout (Figure 3).
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b. Figure 3 shows that as PCB chlorine number
increases, the bioconcentration potential of a PCB, 3.3 indicated
by it's octanol-water partition coefficient (Row), also
increases. Figure 3 also shows that the toxicity of PCB isomers
increases, as indicated by decreasing NOECs. with increasing
chlorine number.
c. It is assumed that chronic toxicity is directly
related to a chemical's Kow, if the log Row is less than about 6
- 7 and if the chemical is a non-reactive non-electrolyte organic
chemical. Hermens (1982) has shown that 16-d ECSOs for Daphnia
magna reproduction (a chronic toxicity endpoint) are linerally
related to log Kow for a variety of organic chemicals. Ronemann
(1981) has shown a strong relationship between 14-d LCSOs for
guppies and log Kow (up to a log Kow of 6) for a group of non-
reactive, non-electrolyte organic chemicals.
2. The NOEC for the dichlorobiphenyl isomers to the early
life stages (embryo-sac fry) of fish is estimated to be about 0.5
ug/L.
a. The rationale is the same as presented above in
Section III.A.I.a through c.
3. The acute (96-h) LC50 to juvenile rainbow trout for the
dichlorobiphenyl isomers is estimated to be about 420 ug/L
(Figure 2).
C. Trichlorobiphenyl Isomers
1. The 30-day NOEC for the trichlorobiphenyl isomers to
juvenile fish is estimated to be about 2.1 ug/L.
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a. A NOEC was not available for the trichlorobiphenyl
isomers (Table 3). Therefore, a NOEC was estimated through
regression analysis of the relationship between toxicity and PCB
chlorine number (Figure 3).
b. The rationale for using Figure 3 is the same as
presented in Sections III.B.l.b and c.
2. The NOEC for the trichlorobiphenyl isomers to the early
life stages (embryo-sac fry) of fish is estimated to be about 0.1
ug/L.
a. The rationale is the same as presented above in
Sections III.A.I.a through c.
3. The acute (96-h) LC50 to juvenile rainbow trout for the
trichlorobiphenyl isomers is estimated to be about 220 ug/L
(Figure 2) . .
D.- Tetrachlorobiphenyl Isomers
1. The 30-day NOEC for the non ^/o_'-chlorine (Cl)
substituted (Figure 1) tetrachlorobiphenyl isomers (5 isomers out
of 42 possible isomers) to juvenile fish is less than 0.1 ug/L.
a. Stalling et al. (1979) have demonstrated that the
NOEC for rainbow trout exposed to 3,3 *f4,4'-tetrachlorobiphenyl
(TCB) for 50 d was less than 0.1 ug/L which was the lowest
*
exposure concentration tested (Table 3).
b. Stalling et al. (1979) reported that studies by
Goldstein et al. (1977) and Poland and Glover (1977) concluded
that PCB isomers lacking o^o'-chlorine (Cl) substitution and
having four or more Cl atoms/ may account for a significant
amount of the toxicity of PCB mixtures.
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c. Stalling et al . (1979) determined t':.-= toxicities
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of four groups of PCBs : (1) 3,3 ' ,4,4 '-tetrachlorc oiphenyl (a O
.o^o'-Cl substituted PCB) , (2) a mixture of 1 .o»_o'-Cl PCBs/ (3) a
mixture of 1 and 2 c^/o'-Cl PCBs, and (4) a mixture of 2 - 4 o^1-
Cl PCBs. The 3,3 ' ,4,4 '-TCB was more toxic to rainbow trout than
any of the 1 thru 4 _o_,o_'-Cl mixtures.
d. Bruggeman et al . (1981), Shaw and Connell (1980JD),
Goldstein et al . (1977), Poland and Glover (1977), and Stalling
et al . (1979) have all discussed the importance of the ortho-
ortho chlorine (^,^'-Cl) substitution pattern within a class of
PCB isomers and its effect upon bioconcentration potential or
toxicity. In general, it is suggested that the more chlorines
substituted in the ortho-ortho positions on the biphenyl, the
lower the bioconcentration potential and the toxicologic
activity. Ortho substitution of Cl forces the biphenyl out of a
common plane. In summary, the toxicity of PCBs appears to
increase with the number of chlorines (Figure 3), and, within a
class of PCB isomers, tends to decrease with greater ortho-ortho
Cl substitution.
2. The 42-day NOEC for the 1 thru 4 £,£/-Cl substituted
TCB isomers (37 isomers out of 42 possible isomers) to juvenile
fish is about 1.5 ug/L.
a. Branson et al . (1975) have demonstrated a NOEC for
rainbow trout exposed to 2,2' ,4,4 '-TCB (a 2 jo_,£'-Cl substituted
TCB; one Cl on each side of the biphenyl bond; Figure 1) for 42 d
was 1.5 ug/L (Table 3). Branson et al . also showed a no-
observed-lethal concentration (NOLC) of greater than 14 ug/L.
These data are supported by the data reported by Dill et al.
(1982) who exposed fathead minnows to 2,2 ' ,4,4 '-TCB for 30 d.
Dill et al. reported an LC50 of 29 ug/L and a NOEC of less than
14 ug/L (Table 3) .
20
-------
b. These data suggest that a 0 _o,£'-Cl substituted
TCB is more than 15 times more toxic to juvenile ar.d adult fish
than a 2 o_to^-CI substituted TCB.
3, The NOEC for the 0 o^'-Cl substituted TCB isomers to
the early life stages (embryo-sac fry) of fish is estimated to be
less than 0.004 ug/L.
a. The rationale is the same as presented above in
Sections III. A.I. a through c.
4. The NOEC for the 1 thru 4 ja^o'-Cl substituted TCB
isomers to embryo-sac fry fish is estimated to be about 0.06
ug/L .
a. The rationale is the same as presented in Sections
III. A.I. a through c.
5. The acute (96-h) LC50 to juvenile rainbow trout for the
tetrachlorobiphenyl isomers is estimated to be about 120 ug/L
(Figure 2) .
E. Pentachlorobiphenyl Isomers
1. The 30-day NOEC for the pentachlorobiphenyl isomers to
juvenile fish is estimated to be 0.07 ug/L.
a. No data were available for the pentachlorobiphenyl
isomers (Table 3). Therefore, the NOEC was estimated through
regression analysis of the relationship between toxicity and PCB
chlorine number (Figure 3).
b. The rationale for using Figure 3 is the same as
presented above in Sections III.B.l.b and c.
21
-------
2. The NOEC for the pentachlorobiphenyl isomers to the
early life stages (embryo-sac fry) of fish is estimated to be
about 0.003 ug/L.
a. The rationale is the same as presented in Sections
III.A.I.a through c.
3. The acute (,96-h) LC50 to juvenile rainbow trout for the
pentachlorobiphenyl isomers is estimated to be similar to or less
than the LC50 for tetrachlorobiphenyl isomers (about 120 ug/L).
a. The acute toxicity (96-h ECSOs) of PCB isomers to
aquatic invertebrates decreases with the higher chlorinated
isoraers (pentachlorobiphenyls and hexachlorobiphenyls). This
decrease in toxicity is probably associated with the decreasing
A -
water solubility of these higher chlorinated PCBs. A more
detailed rationale is in Section IV.A.
F. Hexachlorobiphenyl Isomers
1. The 30-day NOEC for the hexachlorobiphenyl isomers to
juvenile fish is estimated to be 0.01 ug/L.
a. No measured NOECs are available for the
hexachlorobiphenyl isomers (Table 3). Therefore, the NOEC was
estimated through regression analysis of the relationship between
toxicity and PCB chlorine number in Figure 3.
b. The rationale for using Figure 3 is the same as
presented above in Sections III.B.l.b and c.
2. The NOEC for hexachlorobiphenyl isomers to the early
life stages (cisbryo-sac fry) of fish is estimated to be less than
0.001 ug/L.
22
-------
a. The rationale is the same as presented above in
Sections III.A.I.a through c.
b. In addition, Shimmel et al. (1974, as reported by
Broyles and Noveck 197 9a_) exposed fry, juvenile, and adult
sheepshead minnows to 0.1 ug/L Aroclor 1254 and demonstrated that
fry were 30 times more sensitive to PCBs than older fish. These
data suggest a NOEC of 0.003 ug/L (i.e., 0.1 ug/L divided by 30)
and support the estimated NOEC for sac fry fish of about 0.001
ug/L hexachlorobiphenyl.
c. The 2,2*,4,4',5,5'-hexachlorobipheny (HCB) isomer
(a 2 o^'-Cl substituted isomer, one Cl on each side of the
biphenyl bond) has been shown to be very toxic to sac fry of lake
trout and Chinook salmon (Table 3). Broyles and Noveck (1979^)
exposed lake trout sac fry to 8 ug/L 2,2',4,4',5,5'-HCB for 15 d;
all fish died within 79 d. All Chinook salmon sac fry died
within 31 d.
3. The acute (96-h) LC50 to juvenile rainbow trout for the
hexachlorobiphenyl isomers is estimated to be similar to or less
than the 96-h LC50 for tetrachlorobiphenyl isomers (about 120
ug/L).
a. The rationale is the same as for
pentachlorobiphenyls (Section III.E.3).
G. Decachlorobiphenyl
*
1. The 30-day NOEC for decachlorobiphenyl to juvenile fish
is probably similar to the hexachlorobiphenyl isomers: about
0.01 ug/L.
23
-------
a. No data were available for decachlorobiphenyl
(Table 3) and a NOEC was estimated through graphic interpolation
of Figure 3. Estimating a NOEC for decachlorobiphenyl from
available data or other PCB isomers will have a high degree of
uncertainty due to decachlorobiphenyl's greater water
insolubility relative to PCB isomers with six or less chlorines.
b. Konemann (1981) has shown a deviation from a
linear quantative structure-activity relationship between log Row
and subchronic toxicity (14-d LC50) to fish with chemicals whose
log Row's are greater than six. For such chemicals effective
concentrations should be larger than expected from the struture-
activity relationship, and, thus, less toxic.
c. The simplist assumption is that the structure-
activity relationship becomes asymptotic. Sugiura et al. (1978)
have suggested that bioconcentration factors become asymptotic
for chemicals whose log Row's are greater than six.
2. The NOEC for decachlorobiphenyl to embryo-sac fry fish
will probably be similar to the estimated NOEC for
hexachlorobiphenyl: about 0.001 ug/L.
a. The rationale for using the value for
hexachlorobiphenyl is presented above in Sections III.G.I.a
through c.
3. The acute (96-h) LC50 to juvenile rainbow trout for
decachlorobiphenyl will be similar to or less than the LC50
estimated for tetrachlorobiphenyl isomers (about 120 ug/L).
a. The rationale for using the value for
tetrachlorobiphenyls is presented above in Section III.E.3.
24
-------
IV. Toxicity of Various PCS Isomers to Aquatic
Invertebrates
Various PCB isoraers are acutely toxic to aquatic
invertebrates and toxicity increases with an increase in the
number of chlorines on the biphenyl up through
tetrachlorobiphenyl. Acute toxicity ranges from 700 to 30
ug/L. Chronic toxicity of PCB isomers to aquatic invertebrates
is not available, however, aquatic invertebrates are expected to
have lower chronic NOECs than those measured for juvenile fish.
A. Acute Toxicity
1. Various PCB isomers are acutely toxic to aquatic
invertebrates. Toxicity increases with chlorination and reaches
a maximum with the tetrachlorobiphenyls at about 30 ug/L.
a. Static acute (48-h or 96-h) toxicity values
(ECS.Os) have been measured for one or more isoraers of every PCB
class from monochlorobiphenyl through hexachlorobiphenyl (Table
4).
b. The EC50 values of the monochlorobiphenyl isomers
through the tetrachlorobiphenyl isoraers are linerally related
(Figure 4) and this relationship can be defined through
statistical regression analysis: log EC50 (ug/L) = 3.04 - 0.411
chlorine no. (R2 = 0.92, N = 7). These data indicate that the
average EC50 value for the isomers of each class of PCB from one
to four chlorines are:
CLASS VALUE (ug/L)
raonochlorobiphenyls 500.
dichlorobiphenyls 110.
trichlorobiphenyls 70.
tetrachlorobiphenyls 30.
25
-------
2. Acute toxicity of higher chlorinated PCEc (five or more
chlorines) is reduced due to their-water insolubility.
a. Isoraers of higher chlorinated PC3s, i.e.,
pentachlorobiphenyls, hexachlorobiphenyls, and decachlorobiphenyl
are less acutely toxic than tetrachlorobiphenyl isoraers (Table 4,
Figure 4). These higher chlorinated isomers are becoming
relatively more water insoluble which results in reduced uptake
rates into aquatic organisms. Thus, acute exposure to low water
concentrations does not permit enough PCB to be taken up to kill
50% of a test population. Ronemann (1981) and Sugiura et al.
(1978) have observed reduced toxicity and bioconcentration,
respectively, with decreasing water solubility of organic
chemicals whose log Row is greater than six.
B. Chronic Toxicity
1. Chronic toxicity NOECs are not available for individual
PCB isomers, however, NOECs for aquatic invertebrates are
expected to be equal to or less than the subchronic NOECs
measured and estimated for juvenile fish (Table 5).
a. Aquatic invertebrates have been shown to be more
sensitive (i.e., lower EC50 values) to various PCB isomers than
fish during acute (96h) exposures (Mayer et al. 1977; and Tables
3 and 4) or just as sensitive as the most sensitive fish species
tested (Dill et al. 1982, and Tables 3 and 4).
b. It is assumed that trends between .aquatic
invertebrates and fish with regard to acute toxicity of PCB
isomers will also be observed with chronic toxicity information
when it becomes available.
c. A NOEC of Aroclor 1254 (i.e., "a safe level of A-
1254") for an aquatic invertebrate was suggested as being below 1
ug/L by Nebeker and Puglisi (1974). They calculated a 3-wk LC50
26
-------
of 0.45 ug/L of Aroclor 1254 with respect to reproduction
impairment. This NOEC suggested for Aroclor 1254 is consistent
with NOECs for PCB isomers to juvenile fish (Tabla 5).
V. Toxicity of Various PCB Isomers to Algae and Protozoa
A. Algae
The PCB isomers may be just as toxic to algae as they are to
juvenile fish.
t. Only 2,4'-dichlorobiphenyl (DCS) has been tested.
Moore and Harriss (1972) predicted a NOEC of less than 7 ug/L
after a 24h in situ exposure of 2r4'-DCB to a natural marine
phytoplankton community (Table 6). This NOEC is similar to the
30-day (subchronic) NOEC estimated for the DCB isomers to
juvenile fish (12 ug/L, Section III.B.I, Figure 3).
B. Protozoa
The NOECs of PCB isomers (monochlorobiphenyl through
hexachlorobiphenyl) to protozoa appear to be about 100 ug/L or
greater.
1. Dive et al. (1976) measured the effect of 13 PCB
isomers (Table 6) on the growth of the ciliated protozoa
(Colpidium campylum). In general, Dive et al. concluded that
toxicity decreased as the number of chlorines increased.
2. Dive et al. also argued that their results with isomers
were consistent with results from Aroclor mixtures using several
protozoan species. With one exception, all NOECs for Aroclor
mixtures were 100 ug/L or greater.
27
-------
VI. Toxicity of PCS Isomers to Wild Mammals and Birds
Toxicity studies of PCB isomers to wild mammals and birds are
not available.
28
-------
VII. Environmental Concerns of Polychlorinated Biph=nyl (PCS)
Commercial Mixtures
Ambient concentrations and food chain transport of PCBs may
impair the reproductive potential of commercial fisheries and
wild mammals, e.g., mink. PCB residues are also strongly
correlated with reductions in natural populations of marine
mammals and may be correlated with declines in river otter
populations. High PCB residues have been found in various birds,
especially gulls and carnivorous birds, but no resulting effects
have been firmly demonstrated.
A. Commercial Fisheries
PCBs may, even at low concentrations, contribute to a
reduction in populations of sport and economically important
fish.
1. PCBs may affect the reproductive success in fish.
a. High body burdens (120 ug/L in the ovaries) in
wild fish (Baltic flounders) have been correlated with failure of
eggs to hatch. (Von Westernhagen et al. 1981)
b. Experimental data have demonstrated that PCBs can
reduce spawning, hatching, and survival of many species of
.fish. Of the species tested, one (brook trout) is important to
recreational fisheries. (Bengtsson 1980; Mauck et al. 1978;
DeFoe et al. 1978)
c. Seel ye and Mac (-1980) exposed fry hatched from
eggs from Lake Michigan lake trout and fry hatched from hatchery
lake trout to 50 ng/L Aroclor 1254 for 50 days. The observed
mortality was site-specific. Only the Lake Michigan fish, both
29
-------
the exposed fry and the unexposed control fry, sho<-=d
size-specific mortality, i.e., the smaller fry die:: first."
(Mauck et al. 1978; DeFoe et al. 1978; Seel ye anc Mac 1981)
d. Early life stages (embryos and sac fry) of fish
appear to be about 25 times more sensitive to PCBs than juvenile
and adult fish (Schimmel et al. 1974, Nebeker et al. 1974).
e. Predicted no-observed-effect concentrations (NOEC)
for the early life stages of fish can be found in Table 5 for
each class of PCB isomers and these NOECs are similar to toxicity
data for PCB commercial mixtures.
f. Many fish species spawn in shallow near-shore
areas, and eggs and sac fry rest on the top layer of sediment
where PCBs tend to accumulate in the aquatic environment. The
early life stages of fish have the potential to receive high
exposure of PCBs.
2. PCBs may have direct adverse effects on juvenile and
adult fish.
a. Experimental laboratory data have demonstrated
that both growth and survival of many fish species are reduced at
very low exposure concentrations (0.4 and 4.0 ug/L,
respectively).
b. ..Mauck et al. (1978) exposed brook trout fry to
.Aroclor 1254 for 118 days post-hatch,. Growth was reduced at 1.5
ug/L while survival was reduced at 3.1 ug/L.
c. DeFoe et al. (1978) performed a 240-day life cycle
test with fathead minnows and Aroclcrs 1248 and 126C. The l
effect concentrations were 0.4 ug/L Aroclor 1248 for reduced
growth and 4.0 ug/L Aroclor 1260 for reduced survival.
30
-------
d. Toxicity of PCS Arolors and PCB isorars to fish
appears to be related to the number of chlorines attached to the
biphenyl ring (Figure 1). The greater the number of chlorines
(up through six chlorines)/ the greater the toxicity (Table 3,
Figure 3). This toxicity appears to increase an order-of-
magnitude with each added chlorine.
e. Subchronic NOECs for juvenile fish can be found in
Table 5 for each class of PCB.
f. PCB isomers and mixtures that have no £^p_'-Cl
substitution appear to be more toxic than PCB isomers with 1 to 4
chlorines substituted in the o^rO^ positions on the biphenyl
(Figure 1). See information for tetrachlorobiphenyl in Section
III and Table 3).
g. Impaired bone development and abnormalities in
testes have been observed in two species of fish (brook trout and
Atlantic cod) fed or exposed to low levels of PCBs (0.4 ug/L).
(Mauck et al. 1978; Sangalang et al. 1981)
3. PCBs can affect the survival of aquatic invertebrates
and aquatic plants which are food sources for the fish.
a. PCBs can have lethal and sublethal effects on
environmentally important freshwater invertebrates.
(1) Experimental laboratory data have shown that
.PCBs are toxic to many aquatic invertebrates (Daphnia magna;
juvenile scuds, Gammarus pseudolimnaeus; and midges, Tanytarsus
[Paratanytarsus] disimilis) in the low mg/L range. (Nebeker and
Puglisi 1974)
31
-------
(2) Experimental data have demonstrated that very
low concentrations of PCBs (0.45 ug/L) can result in reproductive
failure of aquatic invertebrates (Daphnia magna; juvenile scuds,
Gammarus pseudolimnaeus; and midges, Tanytarsus [Paratanytarsus]
dissimilis. (Nebeker and Puglisi 1974)
b. PCBs affect productivity of phytoplankton and the
composition of phytoplankton communities.
(1) PCBs (1 ug/L) decrease the photosynthetic
rate of different species of algae. (O'Connors and Mahanty 1979,
Kricher and Bayer 1977)
(2) PCBs are differentially toxic to different
species of algae at or below 1 ug/L. (O'Connors et al, 1978, and
Glooschenko and Glooschenko 1975)
B. Contamination of Food Resources
1. PCBs can be concentrated and transferred in fresh-water
and marine phytoplankton, invertebrates, fish and mammals; and
can result in indirect human exposure by consumption of
economically important food resources, the closure of fisheries,
and economic losses as a result of this contamination.
a. Experimental evidence has demonstrated the
propensity of PCBs to bioconcentrate in aquatic organisms
(32,OOOX-270,OOOX) and to be transferred upward in the food
web. (Keil et al. 1971; Biggs et al. 1980; Anonymous 1980; Shaw
and Connell 198Oa_,J>; Bleavins et al. 1980; Thomann 1978;
Weininger 1978; Peterson and Guiney 1979)
32
-------
b«. Residue data collected in the environnent
demonstrate that PCBs are ubiquitous in aquatic orc?.nisms at
levels (15,OOOX) exceeding those occurring in the physical
environment. (Skea et al. 1979, Anonymous 1980.. Swain 1980,
Davis et al. 1981, Risebrough et al. 1968)
c. Residue data collected from commercial and sport
fisheries demonstrate that significant quantities of PCBs may be
transferred to humans through consumption of fish. (Swain 1982,
Schmitt et al. 1981, Zimmerman 1982)
C. Mammals and Birds
1. PCBs may impair reproductive success in some wild
mammals (e.g., mink) and birds.
a. Clinical signs (e.g., reproductive failure, death
of female breeder mink, impaired growth of kits, excessive early
mortality of kits, reduced birth weights of kits, reduced litter
sizes, emaciation, anoroxia, and blood stools), pathology (e.g.,
liver enlargement, hemorrhagic ulcers, degeneration of the liver
and kidneys, and fatty infiltration of the liver), and mortality
patterns are very similar for mink fed (fish) diets containing
PCBs and for mink fed PCBs. (Aulerich et al. 1977)
b. Dietary exposure to mink to PCBs (5 mg/kg) causes
reduction in number of kits and reduced survival of kits.
(Bleavins et al. 1980, Aulerich et al. 1977, Jensen et al. 1977)
33
-------
c. PCBs accelerate destruction and alter biosynthesis
of normal body steroids (estradiol, testosterone, -osrene-3,17-
dione, pregnenolone, progesterone, and androsteneoione) in birds
and wild mammals. Hormonal alteration can affect mammals that
exhibit delayed implantation and mating behavior in birds.
(Risebrough et al. 1968, Lincer and Peakail 1970, Nowicki and
Norman 1972, Freeman and Sangalang 1977, Reijnders 1980)
d. PCBs are correlated with reductions in natural
populations of marine mammals, such as, harbor seals, ringed
seals, and California sea lions. (Helle et al. 1976; Reijnders
1980)
e. PCB residues higher than those found in
reproductively impaired mink have been found in river otters in
the lower Columbia River Valley in Oregon. River otter harvests
by trapping have declined in this area, but have risen in other
parts of Oregon where PCB residues are negligible or undetectable
(Henny et al. 1981)
f. Experimental laboratory studies have demonstrated
that PCBs in the diet (10 mg/kg) of birds (i.e., ring doves and
ring-neck pheasants) caused early embryonic mortality and reduced
egg production. (Peakall et al. 1972; Dahlgren and Linder 1971)
g. High PCB residues have been found in a number of
avian species, especially in the Great Lakes area. Some birds
(e.g., gulls) have shown population declines, but no cause and
effect relationship has been determined. (Heinz et al.
* •
Unpublished Manuscript, Gilbertson and Hale 1974)
34
-------
Table 1. A qualitive environmental risk assessment for eight classes of PCBs to fish.
Risk Is predicted to occur If a hypothetical surface water concentration exceeded any
point of the done-response curves available for individual PCB isomero. Eighteen
hypothetical situations from Table H-l (Versar 1983) were assessed and characterised
for potential effects to fish populations. L - lethality to juvenile and adult fish
(the subscript indicates percent of a population expected to be affected by a part-
icular effect). B - effects to the early life stages of fish, i.e., embryos and sao
fry. 8L - indicates sublethal effects to juvenile and adult fish. 0 •» reduction in
growth and is a particular sublethal effect.
labU H-t. fttlMltd PCS Surfact MUr ConcMitrttloni
OoMittrtn of Organic Chcnlul Plants
llrff* dllfll'W 'tel*nfc Ml lurfac* mttr concMtritton* (uo/l|
Nrctntm* NrcMlltn*
A»traM |ou Avtraot UrtnnoM lm ifr«^m AvtriM itn«rf1m |py t}r«MfliM
10 LSI a
» •••• ii
M 10.1 I.I
40 M.I |.|
Class of PQI
j
^ -
2 0
A A A > 4 A A A
SL
£.
E
SL
SL
6
e:
L
SL
SL
f
L»
L
SL
CJ
L
L
L
/
L
L
L
i
L
fc/66
L
i
L
£<>b
L
1
10
M.I
I.I
M
"•
0.4*
10
IU
0.41
M
4TI
O.II
O.II
40
1.MO
0.088
70
1.100
0.05*
I.4W
0.023
-------
Table I (Cont.)
w
l.tTO
70
w.soo
w
40.000
M
W
M.wo
110,000
o.on
0.0065
o.ooti
0.0001!
0.011
0.007)
£
£
£
£
£
e
£
Si
SL
^
£
£
si.
5L
e
£
e
•Ptrccntllt rtftrt to tht ptrcmt of plant! Mltk ttrtM dilation factor* Utt than or tojual to the
titled vatut. For tiaiplt. 20 pirctAt of th« 948 plant* upon which tblt frtqutncy dlttrlbutlon It
bated bavt itrtM dilution factor* of 214 or Ittt at avtrag* ttrtimflow and (.M or Ittt at low
(IrtMflOM.
*AII data obtained frai IPA't IFO/OMC Hit (tat Sactlon H.I. for dtUtlt).
(A»wln| that all plantt dltchargt promt MatttnaUr contalnlnf 100 ug/l of PCBt, tht CO turfaet
Mt«r conctntratlont Mtrt calculattd by dividing 100 ug/l by tht rtipactlvt- dilution factor.
-------
Table 2. A qualltivo environmental risk assessment for eight classes of PCBs to
aquatic invertebrates. Risk ia predicted to occur if a hypothetical surface water
concentration exceeded any-point of the dose-response curves available for individual
PCB isomers. Eighteen hypothetical situations from Table 11-1 (versar 1983) were assessed
and characterized for potential effects to populations of aquatic invertebrates. L -
lethality to aquatic invertebrates (the subscript indicates percent of a population expected
to be affected by a particular effect). SL - indicated sublethal effects to aquatic
invertebrates.
Vftfct* ti i fffltlBilMf tf+ tiirtf*r* Uittr frnrMitnftloM ....
DMtt tr«M of Organic CtiMlut Mw»U
Urt!s.dUyttafl IntorP KP urfm *i\v coMMtritiDfi'.iuifii,
., flYtrm Jat — ..^triat Hmnflat-. tow ^rtMrfiai »vtf|M tlr«Mf 1»t jm nr»»fl«« A
Class
31
of KB
21
0
M
M
40
U.I
U.I
I.I
1.1
10
W.I
1.1
w
m
114
0.41
411
o.u
O.tl
40
10
U2
1.110
».*»
0.11
o.on
l.NO
O.OS4
0.030
SL
SL
SL
L*
SL
SL
U
L<50
SL
SL
SL
L
L
L
L
L
SL
sL
SL
5L
SL
L
L
L
L
L
L
SL
SL
SL
SL
L
L
L
L
L
L
ii.
SL
SL
•SL
SL
SL
L
L
L
L
L
L
SL
SL
SL
5L
SL
SL
-------
Table 2. (Cont.)
M M» •••«
M «,IIO •••'*
TO M.JOO °-oow
w 40.000 o.oon
00 M.IOO 0.0011
•0 .110,000 O.OOOIT
sL
SL
SL
5L
•rtrcentllt.refert to tht ptrctnt of pUntt with tlrtM dilution factort list thin or tqual to tht
titled valu*. for •««^>1*. 20 p*rcmt of the 348 pUntt upon «hlch this frtqutncy distribution It
based havt ttrtan dilution factor* of 214 or last at avaragt ttraanflow and 1.36 or less at low
ilreMflow.
bAII data obtained from IfA't VWWBt FlU (set Section H.I. for detailt).
'Asstnlng that all tlanti dltcharg* procast Masteuatar contalnlnf 100 «|/l of rat, tht PC8 surfaet
«Mter concentrations wire calculated by dividing 100 ug/1 by the respective dilution factor.
38
-------
Table 3, Toxiclty of Various Isomer3 of Polychlorlnatert Rlphenyls (PCRs) to Pish
I some r
Kpeoiea
Method*
Rffect
Value
(ug/L)
Reference
MONOCHLOROBIPHENYLS
2-
2-
2-
2-
2-
3-
3-
3-
4-
Rlueqlll
(Legomls macrochirus)
Fathead Minnow
(Pimephalea promelaa)
Fathead Minnow
(Pimephalea promelaa)
Rainbow Trout
(Salmo gairdnerl)
Sheepahead Minnow
(Cyprinodon varieqatua)
Rlueglll
(Lepomls macrochirus)
Fathead Minnow
(Pimephalea promelaa)
Rainbow Trout
(Salmo gairdneri)
Rlueglll
(Lcipomls macrochirus)
S,N,96h
S,N,96h
PT,M,32d
S,N,9fih
S,N,96h
S,N,46h
S,N,96h
R,N,96h
S,N,9fih
LC50
LC50
LC50
NOEC
LC50
LC50
LC50
LC50
Lcsn
LC50
1100.
4000.
ft20.
3flO.-550.
540.
4100.
2400.
7BOO.
1000.
1300.
Dill et al. 1982
Dill et al. 19R2
Dill et al. 19fl2
Dill et al. 19R2
Dill et al. 19R2
Dill et al. 19f»2
Dill et al. 19fl2
Dill et al. 19fl2
Dill et al. 1982
39
-------
Table 3. (cont.)
Isomer Species Method* Effect
4- Rainbow Trout S,N,96h LCSO
(Salmo qalrdnerl)
4- Sheepshead Minnow 8,N,96h LC50
(Cypri notion varlegatua
DICHLOROBIPHENYLS
No data are available.
TRICHLOROBIPHEMYLS
2, 3', 4- Guppy S,R,N,14d LCSO
(Poecllla retlculata)
2,3,4-
2,4,5-
2,4',5-
2, 3', 5-
2,3,6-
2,4,6-
2, 2', 5
Value
(ug/Ll
900.
fiftO.
100.
350.
1RO.
1»0.
> 290.
150.
400.
100.
Reference
Dili et al. 19«2
Dill et al. 19ft2
Konemann 19fll
40
-------
Table 3. (cont.)
I some r
Species
Method*
Effect
Value
(ug/L)
Reference
TETRACHLOROBIPHENYLS
3,3',4,4'-
Rainbow Trout
(Salino gairdneri)
FT,M,50(1 EXP,
2fld ELIM
NOEC
Growth C50<1)t
29% reduction (wwt)
61% reduction (wwt)
Lflthalityt
25% on d7R
Pood consumption
reduced.
nisorlentation
< 0.1
0.1
0.4
1.4
Stalling et al.
1979
2t I A A « _
, £ i H , 1 -
Rainbow Trout
(Salino gairdneri)
FT,M,42d
NOEC
Feedings less vigorous
Growth! 1 in 5 lost wt.
Livert
2R% reduction (wwt)
NOLC
1.5
> 14.
Branson et al.
1975
41
-------
Table 3. (cont.)
I some r
2,2-4,4'-
Species
Pbthead Minnow
(Pimephales promelas)
Method*
FT,M,30d
Effect
LC50
NORC
Value
(ug/Ll
29.
< 14.
Reference
Dill et al.
19R2
2,2',4,4'-
2,2',4,4'-
2,3,4,5-
2,2',6,6«-
Ra inbow Trout
(3aImp gairdneri)
nlu.eglll
(Lepomis raacrochiruB)
Guppy
(Poecilia reticulata)
S,N,46h
S,R,N,14d
Ma^or effectsi
Lethality,
Melanization, and
Disorientation.
Other effectRi
Positive huoyancn,
Loss of appetite,
Bulging eyes, and
Hemorrhaging.
LC50
LCSO
LC50
PENTACHLOROBIPHENYLS
No data are available.
120.
120.
> 340.
> 340.
Dill et al. 14B2
Dill et al. 14R2
Konemann 14H1
42
-------
Table 3.(cont.)
Species
Method*
Effect
Value
-------
Table 4. Toxicity of Various Isomers of Polychlorinated Biphenyls (PCBs) to Aquatic Invertebrates
Isomer
Species
Method*
Effect
Value
(ug/L)
Reference
MONOCH LOROB IPH ENYLS
2-
3-
4-
2,3-
Daphn ids
(Daphnia magna)
Daphn ids
(Daphnia magna)
Daphn ids
(Daphnia magna)
Oyster
( Crosses trea virginica)
S,N,48h EC50
S,N,48h EC50
.S,N,48h EC50
D ICH LOROBI PH EN Y LS
FT,N,65d
NOEC
700.
430.
420.
>0.06
Dill et al. (1982!
Dill et al. (1982
Dill et al. (1982
Vreeland (1974)
2,4'-
4,4'
2,3,4'
Scud
(Gammarus pseudolimnaeus) S,N,96h
Weight.
Lip id content.
Average.
mortality.
EC 50
Scud
(Gammarus pseudolimnaeus
S,N,96h EC50
TRICHLOROBIPHENYLS
120.
100
Scub, amphipod.
(Gammarus pseudolimnaeus) S,N,96h
Mayer et al. (197
Mayer el <••.] . (197
EC50
70
Mayer et al. (197
-------
Table 4. (Cont.)
Isomer
Species
Method*
Effect
Value
(ug/L)
Reference
2^73,4-
2,2',4,4'-
2,2',5,5'-
2,2',3,5'-
2,2',4,5,5'
2,2', 3,4,5'-
Oyster
(Grassestrea Virginica)
Daphn ids
(Daphnia magna)
Oyster
(Grassestrea virginca)
Scud, amphipod.
(Gammarus pseudolimnaeus)
Oyster
(Grassestrea virginica)
FT,N,65d
NOEC
Weight
Lipid content.
Average
mortality.
>0.06
TETRACHLOROBIPHENYLS
S,N,48h
FT,N,65d
EC50
NOEC
Weight.
Lipid content.
Average
mortality.
30
>0.06
PENTACHLOROBIPHENYLs
S,N,96h
ET,N,65d
EC 50
NOEC
Weight.
Lipid content.
Average
mortality.
210
>0.06
Vreeland (1974)
Dill et al. (1982
Vreeland (1974)
Mayer et al. (197"
Vreeland ( 1974)
45
-------
Table 4. (Cont.)
Isomer Species Method* Effect Value Reference
(ug/L)
H EX ACH LOROBIPH EN Y LS
2,2',4,4',6,6'- Scud, amphipod.
(Gammarus pseudolimnaeus) SfN,96h EC50 150 Mayer et al. (197
2,2' ,4,4',5,5'- Oyster FT,N,6v5d NOEC >0.06 Vreeland (1974)
(Grassestrea virginica) Weight.
Lip id content.
Average
mortality.
*S = static, N = nominal concentrations used to estimate effect value, FT = flow through, NOEC = no-obs
effect concentration.
46
-------
Table 5. The no-observed-effect concentrations (NOE-) of the
monochlorobiphenyl through hexachlorobiphenyl isoraers and
decachlorobiphenyl determined for juvenile-adult fish and early
li£e stages (i.e., embryos and sac fry) of fish.
Fish NOEC (ug/L)
Chlorine Number Juvenile-Adult Embryo-Sac Fry
1 50. - 80. 2. - 3.
; 2 12. 0.5
3 2.1 0.1
4 < 0.1 - 1.5 < 0.004 - 0.06
5 0.07 0.003
6 0.01 0.001
10 0.01 0.001
47
-------
Table 6. Toxicity of Various Isoroers of Polychlorinated Biphenyls (PCBs) to Algae and Protozoa
Isomer
2,4'-
2-
2,3-
2,5-
4,4'-
2, 2', 5-
Species Method* Effect
ALGAE
Natural marine In situ, 14C uptake
phytoplankton community; N,2~?h~ EC50
NE Gulf of Mexico, FL. NOEC
PROTOZOA
' MONOCHLOROBIPHENYLS
Ciliated protozoa
(Colpidium campylum S,N,43h Growth (%):
LC100
EC50
NOEC
DICHLOROBIPHENYLS
LC100
NOEC
LCI 00
NOEC
NOEC
TRICHLOROBIPHENYLS
LC100
NOEC
Value Reference
(ug/L)
Moore and Harriss
30. (1972)
<7.
Dive et al. (1976
<10000.
>1000.
>100.
<1000.
>100.
<1000.
>100.
>10000.
<1000.
100.
-------
Table 6 (Cont.)
Isomer Species
2,4,6- Ciliated protozoa
(Colpidium campylum
2,4,5-
2, 3', 5-
Method* Effect
S,N,43h Growth (%):
LC100
NO EC
LC100
NO EC
LC100
EC90
NO EC
TETRACHLOROBI PHENYLS
Value Reference
(ug/L)
Dive et al . (197(
<1000.
>100.
<1000.
>100.
<10000.
1000.
>100.
2,2',5,5'-
2,2',4,5,5'
2,2'3',4,5-
2,3',4,4',5-
•) 01 O -31 A* C l_
* I * f J / J 1^ I -J
NOEC
PENTACH LOROBIPH ENYLS
NOEC
NOEC
NOEC
HEXACH LOROBIPH ENYLS
NOEC
100.
10000.
>10000.
>10000.
1000.
*S = static, N = nominal concentrations used to estimate effect value, NOEC = no-observed-effect
concentration, EC50 = median effective concentration, LC100 = concentration which killed 100% of the t<
organisms, and EC90 = concentration which reduced growth of test population 90% below control populatit
49
-------
3' 2'
Figure 1. A polychlorinated biphenyl (PCB) is a family of
compounds which consists of biphenyl that has been chlorinated at
10 possible sites. For example, monochlorobiphenyl has been
chlorinated at a single site and decachlorobiphenyl has been
chlorinated at all 10 sites.
'-Cl substituted PCB refers to
the chlorination of the 2, 2 ',6, and 61 sites which are the ortho-
ortho prime sites on the biphenyl.
50
-------
Figure 2. Relationships between chlorine number of a PCB, n-
octanol/water partition coefficient (Row), and acres (96h) median
lethal concentration (LC50) for rainbow trout. Tlie relationship
for Row and chlorine number was modified from Wasik et al.
(1982, Pig. 3, p. 10). The LCSOs for the monochlorobiphenyl
isomers for tetrachlorobiphenyl are from Table 3. The
relationship between 96-h LC50 and chlorine number of a PCB is
defined by the regression equation: log LC50 (ug/L) = 3.16 - 0.27
Chlorine no. (R2 = 0.92; N = 4) and probably becomes asymptotic
around log Row 6-7. Rationale is provided in Sections
III.G.l.b. and c.
51
-------
10
T I I I
I I
I I
Log LC50 (ug/L) = 3,16 - 0.27 Chlorine no,, R2=0,92
8
J
"3
en
o
456
Chlorine Number
8
-------
Figure 3. Relationships between chlorine number c: a PCB, n-
octanol/water partition coefficient (Row), and nc-observed-effect
concentration (NOEC) for rainbow trout. The relationship for Row
and chlorine number was modified from Wasik et al. (1982, Fig. 3,
p. 10). The NOECs for raonochlorobiphenyl are from Section
III.A.I; the NOECs for tetrachlorobiphenyl are from Section
III.D.I. and Table 3. The relationship bewteen NOEC and chlorine
number of a PCB is defined by the regression equation: log NOEC
2
(ug/L) * 2.53 -0.74 chlorine no. (R = 0.87) and probably becomes
asymptotic around log Row 6-7. Rationale is provided in
Sections III.G.l.b. and c.
53
-------
10
3
Log NOEC - 2,53 - 0,74 Chloride no,, R =0,87
CD
O
10
-------
Figcrre 4. Relationship between chlorine number of a PCB, n-
octanol/water partition coefficient (Row), and acr. ce (96h) median
lethal concentration (EC50) for the aquatic invertebrates:
Gammarus pseudolimnaeus (a scud or amphipod) and Daphnia magna.
The relationship for Row and chlorine number was modified from
Wasik et al. (1982, Fig. 3, p. 10). The ECSOs for the PCB
isomers are from Table 4. The relationship between 96-h EC50 and
chlorine number for PCB isomers from raonochlorobiphenyl to
tetrachlorobiphenyl (for log Row's less than 6} is defined by the
.linear regression equation: log EC50 (ug/L) = 3.04 - 0.411
Chlorine no. (R2 = 0.92, N = 7). The ECSOs for the
pentachlorobiphenyl and hexachlorobiphenyl isomers are greater
than would be predicted by the regression equation (i.e., not as
toxic as tetrachlorobiphenyls). Pentachlorobiphenyl and
hexachlorobiphenyl isomers are apparently becoming to water
insoluble (log Row's of about 6 or greater) to cause acute
toxicity at concentrations lower than about 30 ug/L, which is the
EC50 for tetrachlorobiphenyl.
55
-------
10
8
CD
O
1
0
Log EC50 (ug/L) = 3.04 - 0.411 Chlorine no., R2 «= 0.92
1
456
Chlorine Number
8
10
-------
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