Current through Register Vol. 46, No. 39, September 25, 2024
AQUATIC LIFE PROCEDURES
I.
INTRODUCTION
A. This Appendix provides procedures to
derive standards and guidance values to protect aquatic life from acute and
chronic effects. Tier I procedures, sections III through XI, are used where the
required data described in section III.B for freshwater species or section
III.C for saltwater species are available. Tier II procedures, sections XII
through XVI, are used where the data requirements in sections III.B or III.C
are not met.
II.
APPLICABILITY
A. These procedures
will generally be used to derive statewide standards or guidance values
according to the classified uses described in section
702.9 of this Title. Site-specific
modifications to such statewide standards or guidance values are required or
allowed as described below.
B.
Site-specific modifications to chronic or acute aquatic life values may be
developed where:
(1) The local water quality
characteristics such as pH, hardness, temperature, color, etc., alter the
biological availability or toxicity of a pollutant; or
(2) The sensitivity of the aquatic organisms
species that occur at the site differs from the species actually tested in
developing the criteria. The phrase occur at the site includes
the species, genera, families, orders, classes, and phyla that: are usually
present at the site; are present at the site only seasonally due to migration;
are present intermittently because they periodically return to or extend their
ranges into the site; were present at the site in the past, are not currently
present at the site due to degraded conditions, and are expected to return to
the site when conditions improve; are present in nearby bodies of water, are
not currently present at the site due to degraded conditions, and are expected
to be present at the site when conditions improve. The taxa that occur at the
site cannot be determined merely by sampling downstream and/or upstream of the
site at one point in time. Occur at the site does not include
taxa that were once present at the site but cannot exist at the site now due to
permanent physical alteration of the habitat at the site resulting, for
example, from dams, etc.
C. Site-specific modifications also may be
developed to acute and chronic aquatic life values to reflect local physical
and hydrological conditions.
D.
Endangered species considerations.
(1) Any
site-specific modifications that result in less stringent values must not be
likely to jeopardize the continued existence of endangered or threatened
species or result in the destruction or adverse modification of such species'
critical habitat.
(2) More
stringent modifications shall be developed to protect endangered or threatened
species where such modifications are necessary to ensure that water quality is
not likely to jeopardize the continued existence of such species or result in
the destruction or adverse modification of such species' critical habitat.
Procedures for Deriving Aquatic Life Tier I
Standards and Guidance Values; Sections III-XI
III.
REQUIRED
DATA
A. Certain data should be
available to help ensure that each of the major kinds of possible adverse
effects receive adequate consideration.
B. To derive an acute or chronic standard or
guidance value for freshwater aquatic organisms and their uses, the following
must be available:
1. Results of acceptable
acute tests (see section IV or VI of this Appendix) with at least one species
of freshwater animal in at least eight different families such that all of the
following are included:
a. The family
Salmonidae in the class Osteichthyes;
b. One other family (preferably a
commercially or recreationally important, warmwater species) in the class
Osteichthyes (e.g., bluegill, channel catfish);
c. A third family in the phylum Chordata
(e.g., fish, amphibian);
d. A planktonic crustacean
(e.g., a cladoceran, copepod);
e. A benthic crustacean
(e.g., ostracod, isopod, amphipod, crayfish);
f. An insect (e.g., mayfly,
dragonfly, damselfly, stonefly, caddisfly, mosquito, midge);
g. A family in a phylum other than Arthropoda
or Chordata (e.g., Rotifera, Annelida, Mollusca);
h. A family in any order of insect or any
phylum not already represented.
2. Acute-chronic ratios (see section VI of
this Appendix) with at least one species of aquatic animal in at least three
different families provided that of the three species:
a. At least one is a fish;
b. At least one is an invertebrate;
and
c. At least one species is an
acutely sensitive freshwater species (the other two may be saltwater
species).
3. Results of
at least one acceptable test with a freshwater alga or vascular plant is
desirable but not required for standard or guidance value derivation (see
section VIII of this Appendix). If plants are among the aquatic organisms most
sensitive to the material, results of a test with a plant in another phylum
(division) should also be available.
C. To derive a standard or guidance value for
saltwater aquatic organisms and their uses, the following must be available:
1. Results of acceptable acute tests (see
section IV or VI of this Appendix) with at least one species of saltwater
animal in at least eight different families such that all of the following are
included:
a. two families in the phylum
Chordata;
b. a family in a phylum
other than Arthropoda or Chordata;
c. either the Mysidae or Penaeidae
family;
d. three other families not
in the phylum Chordata (may include Mysida or Penaeidae, whichever was not used
above);
e. any other
family.
2. Acute-chronic
ratios (see section VI of this Appendix) with species of aquatic animals in at
least three different families provided that of the three species:
a. at least one is a fish;
b. at least one is an invertebrate;
and
c. at least one is an acutely
sensitive saltwater species (the other two may be freshwater
species).
3. Results of
at least one acceptable test with a saltwater alga or vascular plant is
desirable but not required for standard or guidance value derivation (see
section VIII of this Appendix). If plants are among the aquatic organisms most
sensitive to the material, results of a test with a plant in another phylum
(division) should also be available.
D. If all required data are available, a
numerical standard or guidance value can usually be derived except in special
cases. For example, derivation of a chronic standard or guidance value might
not be possible if the available ACRs vary by more than a factor of 10 with no
apparent pattern. Also, if a standard or guidance value is to be related to a
water quality characteristic (see sections V and VII of this Appendix), more
data will be required.
E.
Confidence in a standard or guidance value usually increases as the amount of
available pertinent information increases. Thus, additional data are usually
desirable.
IV.
FINAL ACUTE VALUE
A. Appropriate
measures of the acute (short-term) toxicity of the material to a variety of
species of aquatic animals are used to calculate the Final Acute Value (FAV).
The Final Acute Value is a calculated estimate of the concentration of a test
material such that 95 percent of the genera (with which acceptable acute
toxicity tests have been conducted on the material) have higher Genus Mean
Acute Values (GMAVs). An acute test is a comparative study in which organisms,
that are subjected to different treatments, are observed for a short period
usually not constituting a substantial portion of their life span. However, in
some cases, the Species Mean Acute Value (SMAV) of a commercially or
recreationally important species is lower than the calculated FAV, then the
SMAV replaces the calculated FAV in order to provide protection for that
important species.
B. Acute
toxicity tests shall be conducted using acceptable procedures.
C. Except for results with saltwater annelids
and mysids, results of acute tests during which the test organisms were fed
should not be used, unless data indicate that the food did not affect the
toxicity of the test material.
D.
Results of acute tests conducted in unusual dilution water,
e.g., dilution water in which total organic carbon or
particulate matter exceeded five mg/L, should not be used, unless a
relationship is developed between acute toxicity and organic carbon or
particulate matter, or unless data show that organic carbon or particulate
matter, etc., do not affect toxicity.
E. Acute values must be based upon endpoints
which reflect the total severe adverse impact of the test material on the
organisms used in the test. Therefore, only the following kinds of data on
acute toxicity to aquatic animals shall be used:
1. Tests with daphnids and other cladocerans
must be started with organisms less than 24 hours old and tests with midges
must be started with second or third instar larvae. It is preferred that the
results should be the 48-hour EC50 based on the total percentage of organism
killed and immobilized. If such an EC50 is not available for a test, the
48-hour LC50 should be used in place of the desired 48-hour EC50. An EC50 or
LC50 of longer than 48 hours can be used as long as the animals were not fed
and the control animals were acceptable at the end of the test. An EC50 is a
statistically or graphically estimated concentration that is expected to cause
one or more specified effects in 50 percent of a group of organisms under
specified conditions. An LC50 is a statistically or graphically estimated
concentration that is expected to be lethal to 50 percent of a group of
organisms under specified conditions.
2. It is preferred that the results of a test
with embryos and larvae of barnacles, bivalve molluscs (clams, mussels, oysters
and scallops), sea urchins, lobsters, crabs, shrimp and abalones be the 96-hour
EC50 based on the percentage of organisms with incompletely developed shells
plus the percentage of organisms killed. If such an EC50 is not available from
a test, of the values that are available from the test, the lowest of the
following should be used in place of the desired 96-hour EC50: 48- to 96-hour
EC50s based on percentage of organisms with incompletely developed shells plus
percentage of organisms killed, 48- to 96-hour EC50s based on percentage of
organisms with incompletely developed shells, and 48-hour to 96-hour
LC50s.
3. It is preferred that the
result of tests with all other aquatic animal species and older life stages of
barnacles, bivalve molluscs (clams, mussels, oysters and scallops), sea
urchins, lobsters, crabs, shrimp and abalones be the 96-hour EC50 based on
percentage of organisms exhibiting loss of equilibrium plus percentage of
organisms immobilized plus percentage of organisms killed. If such an EC50 is
not available from a test, of the values that are available from a test the
lower of the following should be used in place of the desired 96-hour EC50: the
96-hour EC50 based on percentage of organisms exhibiting loss of equilibrium
plus percentage of organisms immobilized and the 96-hour LC50.
4. Tests whose results take into account the
number of young produced, such as most tests with protozoans, are not
considered acute tests, even if the duration was 96 hours or less.
5. If the tests were conducted properly,
acute values reported as "greater than" values and those which are above the
solubility of the test material should be used, because rejection of such acute
values would bias the Final Acute Value by eliminating acute values for
resistant species.
F. If
the acute toxicity of the material to aquatic animals has been shown to be
related to a water quality characteristic such as hardness or particulate
matter for freshwater animals, refer to section V of this Appendix.
G. The agreement of the data within and
between species must be considered. Acute values that appear to be questionable
in comparison with other acute and chronic data for the same species and for
other species in the same genus must not be used. For example, if the acute
values available for a species or genus differ by more than a factor of 10,
rejection of some or all of the values would be appropriate, absent
countervailing circumstances.
H. If
the available data indicate that one or more life stages are at least a factor
of two more resistant than one or more other life stages of the same species,
the data for the more resistant life stages must not be used in the calculation
of the SMAV because a species cannot be considered protected from acute
toxicity if all of the life stages are not protected.
I. For each species for which at least one
acute value is available, the SMAV shall be calculated as the geometric mean of
the results of all acceptable flow-through acute toxicity tests in which the
concentrations of test material were measured with the most sensitive tested
life stage of the species. For a species for which no such result is available,
the SMAV shall be calculated as the geometric mean of all acceptable acute
toxicity tests with the most sensitive tested life stage,
i.e., results of flow-through tests in which the
concentrations were not measured and results of static and renewal tests based
on initial concentrations (nominal concentrations are acceptable for most test
materials if measured concentrations are not available) of test material. A
renewal test is a test with aquatic organisms in which either the test solution
in a test chamber is removed and replaced at least once during the test or the
test organisms are transferred into a new test solution of the same composition
at least once during the test. A static test is a test with aquatic organisms
in which the solution and organisms that are in a test chamber at the beginning
of the test remain in the chamber until the end of the test, except for removal
of dead test organisms.
Note 1: Data reported by original
investigators must not be rounded off. Results of all intermediate calculations
must not be rounded off to fewer than four significant digits.
Note 2: The geometric mean of N numbers
is the Nth root of the product of the N numbers. Alternatively, the geometric
mean can be calculated by adding the logarithms of the N numbers, dividing the
sum by N, and taking the antilog of the quotient. The geometric mean of two
numbers is the square root of the product of the two numbers, and the geometric
mean of one number is that number. Either natural (base e) or common (base 10)
logarithms can be used to calculate geometric means as long as they are used
consistently within each set of data, i.e., the antilog used
must match the logarithms used.
Note 3: Geometric means, rather than
arithmetic means, are used here because the distributions of sensitivities of
individual organisms in toxicity tests on most materials and the distributions
of sensitivities of species within a genus are more likely to be lognormal than
normal. Similarly, geometric means are used for ACRs because quotients are
likely to be closer to lognormal than normal distributions. In addition,
division of the geometric mean of a set of numerators by the geometric mean of
the set of denominators will result in the geometric mean of the set of
corresponding quotients.
J.
For each genus for which one or more SMAVs are available, the GMAV shall be
calculated as the geometric mean of the SMAVs available for the
genus.
K. Order the GMAVs from high
to low.
L. Assign ranks, R, to the
GMAVs from "1" for the lowest to "N" for the highest. If two or more GMAVs are
identical, assign them successive ranks.
M. Calculate the cumulative probability, P,
for each GMAV as R/ (N + 1).
N.
Select the four GMAVs which have cumulative probabilities closest to 0.05 (if
there are fewer than 59 GMAVs, these will always be the four lowest
GMAVs)
O. Using the four selected
GMAVs, and Ps, calculate
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P.
If for a commercially or recreationally important species the geometric mean of
the acute values from flow-through tests in which the concentrations of test
material were measured is lower than the calculated Final Acute Value (FAV),
then that geometric mean must be used as the FAV instead of the calculated
FAV.
Q. See section VI of this
Appendix.
V.
FINAL
ACUTE EQUATION
A. When enough data are
available to show that acute toxicity to two or more species is similarly
related to a water quality characteristic, the relationship shall be taken into
account as described in sections V.B through V.G of this Appendix or using
analysis of covariance. The two methods are equivalent and produce identical
results. The manual method described below provides an understanding of this
application of covariance analysis, but computerized versions of covariance
analysis are much more convenient for analyzing large data sets. If two or more
factors affect toxicity, multiple regression analysis shall be used.
B. For each species for which comparable
acute toxicity values are available at two or more different values of the
water quality characteristic, perform a least squares regression of the acute
toxicity values on the corresponding values of the water quality characteristic
to obtain the slope and its 95 percent confidence limits for each species.
Note: Because the best documented
relationship is that between hardness and acute toxicity of metals in fresh
water and a log-log relationship fits these data, geometric means and natural
logarithms of both toxicity and water quality are used in the rest of this
section. For relationships based on other water quality characteristics, such
as pH, temperature, no transformation or a different transformation might fit
the data better, and appropriate changes will be necessary throughout this
section.
C. Decide whether
the data for each species are relevant, taking into account the range and
number of the tested values of the water quality characteristic and the degree
of agreement within and between species. For example, a slope based on six data
points might be of limited value if it is based only on data for a very narrow
range of values of the water quality characteristic. A slope based on only two
data points, however, might be useful it it is consistent with other
information and if the two points cover a broad enough range of the water
quality characteristic. In addition, acute values that appear to be
questionable in comparison with other acute and chronic data available for the
same species and for other species in the same genus should not be used. For
example, if after adjustment for the water quality characteristic, the acute
values available for a species or genus differ by more than a factor of 10,
rejection of some or all of the values would be appropriate, absent
countervailing justification. If useful slopes are not available for at least
one fish and one invertebrate or if the available slopes are too dissimilar or
if too few data are available to adequately define the relationship between
acute toxicity and the water quality characteristic, return to section IV.G of
this Appendix, using the results of tests conducted under conditions and in
waters similar to those commonly used for toxicity tests with the
species.
D. For each species,
calculate the geometric mean of the available acute values and then divide each
of the acute values for the species by the geometric mean for the species. This
normalizes the acute values so that the geometric mean of the normalized values
for each species individually and for any combination of species is
1.0.
E. Similarly normalize the
values of the water quality characteristic for each species individually using
the same procedure as above.
F.
Individually for each species perform a least squares regression of the
normalized acute values of the water quality characteristic. The resulting
slopes and 95 percent confidence limits will be identical to those obtained in
section V.B. of this Appendix. If, however, the data are actually plotted, the
line of best fit for each individual species will go through the point 1,1 in
the center of the graph.
G. Treat
all of the normalized data as if they were all for the same species and perform
a least squares regression of all of the normalized acute values on the
corresponding normalized values of the water quality characteristic to obtain
the pooled acute slope, V, and its 95 percent confidence limits. If all of the
normalized data are actually plotted, the line of best fit will go through the
point 1,1 in the center of the graph.
H. For each species calculate the geometric
mean, W, of the acute toxicity values and the geometric mean, X, of the values
of the water quality characteristic. (These were calculated in sections V.D and
V.E of this Appendix).
I. For each
species, calculate the logarithm, Y, of the SMAV at a selected value, Z, of the
water quality characteristic using the equation:
Y = ln W - V(ln X - ln Z)
J. For each species calculate the SMAV at X
using the equation:
SMAV = exp(y)
Note: Alternatively, the SMAVs at Z can
be obtained by skipping step H above, using the equations in steps I and J to
adjust each acute value individually to Z, and then calculating the geometric
mean of the adjusted values for each species individually. This alternative
procedure allows an examination of the range of the adjusted acute values for
each species.
K. Obtain the
FAV at Z by using the procedure described in sections IV.J through IV.O of this
Appendix.
L. If, for a commercially
or recreationally important species the geometric mean of the acute values at Z
from flow-through tests in which the concentrations of the test material were
measured is lower than the FAV at Z, then the geometric mean must be used as
the FAV instead of the FAV.
M. The
Final Acute Equation is written as:
FAV = exp (V[ln(water quality char.)] + A - V[ln
Z])
where:
V = pooled acute slope, and A = ln (FAV at Z).
Because V, A, and Z are known, the FAV can be calculated
for any selected value of the water quality characteristic.
VI.
FINAL CHRONIC
VALUE
A. There are two methods for
calculating a Final Chronic Value (FCV). Selection of the appropriate
methodology is dependent upon the availability of chronic toxicity data. If
chronic toxicity data for the species described in section III.B.1 for
freshwater species or section III.C.1 for saltwater species are available, the
FCV can be calculated in the same manner as the FAV. Otherwise, the FCV can be
calculated by dividing the FAV by the Final Acute-Chronic Ratio (FACR). The
data requirements for calculating the FACR are identified in sections III.B.2
and III.C.2 for freshwater and saltwater species respectively. In some cases,
it might not be possible to calculate a FCV. The FCV is (a) a calculated
estimate of the concentration of a test material such that 95 percent of the
genera (with which acceptable chronic toxicity tests have been conducted on the
material) have higher GMCVs or (b) the quotient of an FAV divided by an
appropriate ACR, or (c) the SMCV of a commercially or recreationally important
species, if the SMCV is lower than the calculated estimate or the quotient,
whichever is applicable.
Note: As the name implies, the ACR is a
way of relating acute and chronic toxicities.
B. A chronic standard or guidance value shall
be based on results of flow-through (except renewal is acceptable for daphnids)
chronic tests in which the concentrations of test material in the test
solutions were properly measured at appropriate times during the test. A
chronic test is a comparative study in which organisms, that are subjected to
different treatments, are observed for a long period or a substantial portion
of their life span.
C. Results of
chronic tests in which survival, growth, or reproduction in the control
treatment was unacceptably low shall not be used. The limits of acceptability
will depend on the species.
D.
Results of chronic tests conducted in unusual dilution water,
e.g., dilution water in which total organic carbon or
particulate matter exceeded five mg/L, should not be used, unless a
relationship is developed between chronic toxicity and organic carbon or
particulate matter, or unless data show that organic carbon, particulate
matter, etc., do not affect toxicity.
E. Chronic values must be based on endpoints
and lengths of exposure appropriate to the species. Therefore, only results of
the following kinds of chronic toxicity tests shall be used:
1. Life-cycle toxicity tests consisting of
exposures of each of two or more groups of individuals of a species to a
different concentration of the test material throughout a life cycle. To ensure
that all life stages and life processes are exposed, tests with fish should
begin with embryos or newly hatched young less than 48 hours old, continue
through maturation and reproduction, and should end not less than 24 days (90
days for salmonids) after the hatching of the next generation. Tests with
daphnids should begin with young less than 24 hours old and last for not less
than 21 days, and for ceriodaphnids not less than seven days. Tests with mysids
should begin with young less than 24 hours old and continue until seven days
past the median time of first brood release in the controls. For fish, data
should be obtained and analyzed on survival and growth of adults and young,
maturation of males and females, eggs spawned per female, embryo viability
(salmonids only), and hatchability. For daphnids, data should be obtained and
analyzed on survival and young per female. For mysids, data should be obtained
and analyzed on survival, growth, and young per female.
2. Partial life-cycle toxicity tests consist
of exposures of each of two more groups of individuals of a species of fish to
a different concentration of the test material through most portions of a life
cycle. Partial life-cycle tests are allowed with fish species that require more
than a year to reach sexual maturity, so that all major life stages can be
exposed to the test material in less than 15 months. A life-cycle test is a
comparative study in which organisms, that are subjected to different
treatments, are observed at least from a life stage in one generation to the
same life-stage in the next generation. Exposure to the test material should
begin with immature juveniles at least two months prior to active gonad
development, continue through maturation and reproduction, and end not less
than 24 days (90 days for salmonids) after the hatching of the next generation.
Data should be obtained and analyzed on survival and growth of adults and
young, maturation of males and females, eggs spawned per female, embryo
viability (salmonids only), and hatchability.
3. Early life-stage toxicity tests consisting
of 28- to 32-day (60 days post hatch for salmonids) exposures of the early life
stages of a species of fish from shortly after fertilization through embryonic,
larval, and early juvenile development. Data should be obtained and analyzed on
survival and growth.
Note: Results of an early life-stage
test are used as predictions of results of life-cycle and partial life-cycle
tests with the same species. Therefore, when results of a life-cycle or partial
life-cycle test are available, results of an early life-stage test with the
same species should not be used. Also, results of early life-stage tests in
which the incidence of mortalities or abnormalities increased substantially
near the end of the test shall not be used because the results of such tests
are possibly not good predictions of comparable life-cycle or partial
life-cycle tests.
F. A chronic value may be obtained by
calculating the geometric mean of the lower and upper chronic limits from a
chronic test or by analyzing chronic data using regression analysis.
1. A lower chronic limit is the highest
tested concentration:
a. In an acceptable
chronic test;
b. Which did not
cause an unacceptable amount of adverse effect on any of the specified
biological measurements; and
c.
Below which no tested concentration caused an unacceptable effect.
2. An upper chronic limit is the
lowest tested concentration:
a. In an
acceptable chronic test;
b. Which
did cause an unacceptable amount of adverse effect on one or more of the
specified biological measurements; and,
c. Above which all tested concentrations also
caused such an effect.
Note: Because various authors have used
a variety of terms and definitions to interpret and report results of chronic
tests, reported results should be reviewed carefully. The amount of effect that
is considered unacceptable is often based on a statistical hypothesis test, but
might also be defined in terms of a specified percent reduction from the
controls. A small percent reduction (e.g., three percent)
might be considered acceptable even if it is statistically significantly
different from the control, whereas a large percent reduction
(e.g., 30 percent) might be considered unacceptable even if it
is not statistically significant.
G. If the chronic toxicity of the material to
aquatic animals has been shown to be related to a water quality characteristic
such as hardness or particulate matter for freshwater animals, refer to section
VII of this Appendix.
H. If chronic
values are available for the species in eight families
as
described in section III.B.1 or section III.C.1 of this Appendix, respective
SMCVs shall be calculated for each species for which at least one chronic value
is available by calculating the geometric mean of the results of all acceptable
life-cycle and partial life-cycle toxicity tests with the species; for a
species of fish for which no such result is available, the SMCV is the
geometric mean of all acceptable early life-stage tests. Appropriate GMCVs
shall also be calculated. A GMCV is the geometric mean of the SMCVs for the
genus. The FCV shall be obtained using the procedure described in sections IV.J
through IV.O of this Appendix, substituting SMCV and GMCV for SMAV and GMAV
respectively. See section VI.M of this Appendix.
Note: Section VI.I through VI.L are for
use when chronic values are not available for freshwater species in eight
taxonomic families as described in section III.B.1 of this Appendix, or for
saltwater species in eight taxonomic families as described in section III.C.1
of this Appendix.
I. For
each chronic value for which at least one corresponding appropriate acute value
is available, calculate an ACR, using for the numerator the geometric mean of
the results of all acceptable flow-through (except static is acceptable for
daphnids and midges) acute tests in the same dilution water in which the
concentrations are measured. For fish, the acute test(s) should be conducted
with juveniles. The acute test(s) should be part of the same study as the
chronic test. If acute tests were not conducted as part of the same study, but
were conducted as part of a different study in the same laboratory and dilution
water, then they may be used. If no such acute tests are available, results of
acute tests conducted in the same dilution water in a different laboratory may
be used. If no such acute tests are available, an ACR shall not be
calculated.
J. For each species,
calculate the SMACR as the geometric mean of all ACRs available for that
species. If the minimum ACR data requirements for calculation of a freshwater
chronic standard or guidance value (as described in section III.B.2 of this
Appendix are not met with freshwater data alone, saltwater data may be used
along with the freshwater data. Conversely, if the minimum ACR data
requirements for calculation of a saltwater chronic standard or guidance value
(as described in section III.C.2 of this Appendix) are not met with saltwater
data alone, freshwater data may be used along with the saltwater
data.
K. For some materials, the
ACR seems to be the same for all species, but for other materials the ratio
seems to increase or decrease as the SMAV increases. Thus the FACR can be
obtained in three ways, depending on the data available:
1. If the species mean ACR seems to increase
or decrease as the SMAVs increase, the FACR shall be calculated as the
geometric mean of the ACRs for species whose SMAVs are close to the
FAV.
2. If no major trend is
apparent and the ACRs for all species are within a factor of ten, the FACR
shall be calculated as the geometric mean of all of the SMACRs.
3. If the most appropriate SMACRs are less
than 2.0, and especially if they are less than 1.0, acclimation has probably
occurred during the chronic test. In this situation, because continuous
exposure and acclimation cannot be assured to provide adequate protection in
field situations, the FACR should be assumed to be two, so that the FCV is
equal to the Aquatic (Acute) value A(A). (See section X.B of this Appendix.) If
the available SMACRs do not fit one of these cases, a FACR may not be obtained
and a Tier I FCV probably cannot be calculated.
L. Calculate the FCV by dividing the FAV by
the FACR.
FCV = FAV ÷ FACR
If there is a Final Acute Equation rather than a FAV, see
also section V of this Appendix.
M. If the SMCV of a commercially or
recreationally important species is lower than the calculated FCV, then that
SMCV must be used as the FCV instead of the calculated FCV.
N. See section VIII of this
Appendix.
VII.
FINAL CHRONIC EQUATION
A. A Final
Chronic Equation can be derived in two ways. The procedure described in section
VII.A of this Appendix will result in the chronic slope being the same as the
acute slope. The procedure described in sections VII.B through N of this
Appendix will usually result in the chronic slope being different from the
acute slope.
1. If ACRs are available for
enough species at enough values of the water quality characteristic to indicate
that the ACR appears to be the same for all species and appears to be
independent of the water quality characteristic, calculate the FACR as the
geometric mean of the available SMACRs.
2. Calculate the FCV at the selected value Z
of the water quality characteristic by dividing the FAV at Z (see section V.M
of this Appendix) by the FACR.
3.
Use V = pooled acute slope (see section V.M of this Appendix), and L = pooled
chronic slope.
4. See section VII.M
of this Appendix.
B. When
enough data are available to show that chronic toxicity to at least one species
is related to a water quality characteristic, the relationship should be taken
into account as described in sections C through G below or using analysis of
covariance. The two methods are equivalent and produce identical results. The
manual method described below provides an understanding of this application of
covariance analysis, but computerized versions of covariance analysis are much
more convenient for analyzing large data sets. If two or more factors affect
toxicity, multiple regression analysis shall be used.
C. For each species for which comparable
chronic toxicity values are available at two or more different values of the
water quality characteristic, perform a least squares regression of the chronic
toxicity values on the corresponding values of the water quality characteristic
to obtain the slope and its 95 percent confidence limits for each species.
Note: Because the best documented
relationship is that between hardness and acute toxicity of metals in fresh
water and a log-log relationship fits these data, geometric means and natural
logarithms of both toxicity and water quality are used in the rest of this
section. For relationships based on other water quality characteristics, such
as pH, temperature, no transformation or a different transformation might fit
the data better, and appropriate changes will be necessary throughout this
section. It is probably preferable, but not necessary, to use the same
transformation that was used with the acute values in section V of this
Appendix.
D. Decide whether
the data for each species are relevant, taking into account the range and
number of the tested values of the water quality characteristic and the degree
of agreement within and between species. For example, a slope based on six data
points might be of limited value if it is based only on data for a very narrow
range of values of the water quality characteristic. A slope based on only two
data points, however, might be more useful if it is consistent with other
information and if the two points cover a broad range of the water quality
characteristic. In addition, chronic values that appear to be questionable in
comparison with other acute and chronic data available for the same species and
for other species in the same genus in most cases should not be used. For
example, if after adjustment for the water quality characteristic, the chronic
values available for a species or genus differ by more than a factor of 10,
rejection of some or all of the values is, in most cases, absent countervailing
circumstances, appropriate. If a useful chronic slope is not available for at
least one species or if the available slopes are too dissimilar or if too few
data are available to adequately define the relationship between chronic
toxicity and the water quality characteristic, it might be appropriate to
assume that the chronic slope is the same as the acute slope, which is
equivalent to assuming that the ACR is independent of the water quality
characteristic. Alternatively, return to section VI.H of this Appendix, using
the results of tests conducted under conditions and in waters similar to those
commonly used for toxicity tests with the species.
E. Individually for each species, calculate
the geometric mean of the available chronic values and then divide each chronic
value for a species by the mean for the species. This normalizes the chronic
values so that the geometric mean of the normalized values for each species
individually, and for any combination of species, is 1.0.
F. Similarly, normalize the values of the
water quality characteristic for each species individually.
G. Individually for each species, perform a
least squares regression of the normalized chronic toxicity values on the
corresponding normalized values of the water quality characteristic. The
resulting slopes and the 95 percent confidence limits will be identical to
those obtained in section VII.B of this Appendix. Now, however, if the data are
actually plotted, the line of best fit for each individual species will go
through the point 1,1 in the center of the graph.
H. Treat all of the normalized data as if
they were all the same species and perform a least squares regression of all of
the normalized chronic values on the corresponding normalized values of the
water quality characteristic to obtain the pooled chronic slope, L, and its 95
percent confidence limits.
If all normalized data are actually plotted, the line of
best fit will go through the point 1,1 in the center of the graph.
I. For each species, calculate the
geometric mean, M, of the toxicity values and the geometric mean, P, of the
values of the water quality characteristic. (These are calculated in sections
VII.E and F of this Appendix.)
J.
For each species, calculate the logarithm, Q, of the SMCV at a selected value,
Z, of the water quality characteristic using the equation:
Q = ln M - L(ln P - ln Z)
Note: Although it is not necessary, it
is recommended that the same value of the water quality characteristic be used
here as was used in section V of this Appendix.
K. For each species, calculate a SMCV at Z
using the equation:
SMCV = exp(Q)
Note: Alternatively, the SMCV at Z can
be obtained by skipping section VII.J of this Appendix, using the equations in
sections VII.J and K of this Appendix to adjust each chronic value individually
to Z, and then calculating the geometric means of the adjusted values for each
species individually. This alternative procedure allows an examination of the
range of the adjusted chronic values for each species.
L. Obtain the FCV at Z by using the procedure
described in sections IV.J through O of this Appendix.
M. If the SMCV at Z of a commercially or
recreationally important species is lower than the calculated FCV at Z, then
that SMCV shall be used as the FCV at Z instead of the calculated
FCV.
N. The Final Chronic Equation
is written as:
FCV = exp (L[ln(water quality characteristic)] + lnS -
L[lnZ])
where:
L = pooled chronic slope and S = FCV at Z.
Because L, S, and Z are known, the FCV can be calculated
for any selected value of the water quality characteristic.
VIII.
FINAL PLANT
VALUE
A. A Final Plant Value (FPV) is
the lowest plant value that was obtained with an important aquatic plant
species in an acceptable toxicity test for which the concentrations of the test
material were measured and the adverse effect was biologically important.
Appropriate measures of the toxicity of the material to aquatic plants are used
to compare the relative sensitivities of aquatic plants and animals. Although
procedures for conducting and interpreting the results of toxicity tests with
plants are not well-developed, results of tests with plants usually indicate
that criteria which adequately protect aquatic animals and their uses will, in
most cases, also protect aquatic plants and their uses.
B. A plant value is the result of a 96-hour
test conducted with an alga or a chronic test conducted with an aquatic
vascular plant.
Note: A test of the toxicity of a metal
to a plant shall not be used if the medium contained an excessive amount of a
complexing agent, such as EDTA, that might affect the toxicity of the metal.
Concentrations of EDTA above 200 ug/L should be considered excessive.
C. The FPV shall be obtained by
selecting the lowest result from a test with an important aquatic plant species
in which the concentrations of test material are measured and the endpoint is
biologically important.
IX.
OTHER DATA
Pertinent information that could not be used in earlier
sections might be available concerning adverse effects on aquatic organisms.
The most important of these are data on cumulative and delayed toxicity,
reduction in survival, growth, or reproduction, or any other adverse effect
that has been shown to be biologically important. Delayed toxicity is an
adverse effect to an organism that results from, and occurs after the end of,
its exposure to one or more test materials. Especially important are data for
species for which no other data are available. Data from behavioral,
biochemical, physiological, microcosm, and field studies might also be
available. Data might be available from tests conducted in unusual dilution
water (see sections IV.D and VI.D of this Appendix), from chronic tests in
which the concentrations were not measured (see section VI.B of this Appendix),
from tests with previously exposed organisms, and from tests on formulated
mixtures or emulsifiable concentrates. Such data might affect a criterion if
the data were obtained with a commercially or recreationally important species,
the test concentrations were measured, and the endpoint was biologically
important.
X.
STANDARDS AND GUIDANCE VALUES, TIER I
A. Standards or guidance values to protect
aquatic life include: the Aquatic (Acute) or A(A) and the Aquatic (Chronic) or
A(C).
B. The A(A) is equal to
one-half the FAV. The A(A) is an estimate of the highest concentration of a
material in the water column to which an aquatic community can be exposed
briefly without resulting in an unacceptable effect.
C. The A(C) is equal to the lowest of the FCV
or the FPV (if available) unless other data (see section IX of this Appendix)
show that a lower value should be used. The A(C) is an estimate of the highest
concentration of a material in the water column to which an aquatic community
can be exposed indefinitely without resulting in an unacceptable effect. If
toxicity is related to a water quality characteristic, the A(C) is obtained
from the Final Chronic Equation or FPV (if available) that results in the
lowest concentrations in the usual range of the water quality characteristic,
unless other data (see section IX) show that a lower value should be
used.
D. Round both the A(A) and
the A(C) to two significant digits.
XI.
FINAL REVIEW
A. The derivation of the standard or guidance
value should be carefully reviewed by rechecking each step of the guidance in
this part. Items that should be especially checked are:
1. If unpublished data are used, are they
well documented?
2. Are all
required data available?
3. Is the
range of acute values for any species greater than a factor of 10?
4. Is the range of SMAVs for any genus
greater than a factor of 10?
5. Is
there more than a factor of 10 difference between the four lowest
GMAVs?
6. Are any of the lowest
GMAVs questionable?
7. Is the FAV
reasonable in comparison with the SMAVs and GMAVs?
8. For any commercially or recreationally
important species, is the geometric mean of the acute values from flow-through
tests in which the concentrations of test material were measured lower than the
FAV?
9. Are any of the chronic
values used questionable?
10. Are
any chronic values available for acutely sensitive species?
11. Is the range of acute-chronic ratios
greater than a factor of 10?
12. Is
the FCV reasonable in comparison with the available acute and chronic
data?
13. Is the measured or
predicted chronic value for any commercially or recreationally important
species below the FCV?
14. Are any
of the other data important?
15. Do
any data look like they might be outliers?
16. Are there any deviations from the
guidance in this part? Are they acceptable?
B. On the basis of all available pertinent
laboratory and field information, determine if the standard or guidance value
is consistent with sound scientific evidence. If it is not, another standard or
guidance value, either higher or lower, shall be derived consistent with the
guidance in this part.
Procedures for Deriving Aquatic Life Tier II
Standards and Guidance Values, Sections XII-XVII
XII.
SECONDARY ACUTE
VALUE
If all eight minimum data requirements for calculating an
FAV using Tier I are not met, a Secondary Acute Value (SAV) shall be calculated
for a chemical as follows:
To calculate a SAV, the lowest GMAV in the database is
divided by the Secondary Acute Factor (SAF) (Table 1 of this Appendix)
corresponding to the number of satisfied minimum data requirements listed in
the Tier I methodology (section III.B.1 of this Appendix for freshwater species
and section III.C.1 for saltwater species). Data requirements contained in
sections I, II, and IV shall be applied to calculation of a SAV. If all eight
minimum data requirements are satisfied, a Tier I value calculation may be
possible. In order to calculate a freshwater SAV, the database must contain, at
a minimum, a genus mean acute value (GMAV) for one of the following three
genera in the family Daphnidae - Ceriodaphnia sp., Daphnia
sp., or Simocephalus sp. In order to calculate a
saltwater SAV, it would be desirable if the database contained, at a minimum: a
genus mean acute value (GMAV) for a species or genus in one of the following
families - Mysidae or Penaeidae; and a GMAV for a saltwater fish.
If appropriate, the SAV shall be made a function of a
water quality characteristic in a manner similar to that described in Tier
I.
Table 1. Secondary Acute Factors
| Number of minimum data requirements
satisfied |
Secondary Acute
Factor |
| 1 |
21.9 |
| 2 |
13.0 |
| 3 |
8.0 |
| 4 |
7.0 |
| 5 |
6.1 |
| 6 |
5.2 |
| 7 |
4.3 |
XIII.
SECONDARY ACUTE-CHRONIC
RATIO
If three or more experimentally determined ACRs, meeting
the data collection and review requirements of section VI of this Appendix, are
available for the chemical, determine the FACR using the procedure described in
section VI. If fewer than three acceptable experimentally determined ACRs are
available, use enough assumed ACRs of 18 so that the total number of ACRs
equals three. Calculate the Secondary Acute-Chronic Ratio (SACR) as the
geometric mean of the three ACRs. Thus, if no experimentally determined ACRs
are available, the SACR is 18.
XIV.
SECONDARY CHRONIC VALUE
Calculate the Secondary Chronic Value (SCV) using one of
the following:
A. SCV = FAV ÷
SACR (use FAV from Tier I)
B. SCV =
SAV ÷ FACR
C. SCV = SAV
÷ SACR
If appropriate, the SCV will be made a function of a
water quality characteristic in a manner similar to that described in Tier
I.
XV.
COMMERCIALLY OR RECREATIONALLY IMPORTANT SPECIES
If for a commercially or recreationally important species
the geometric mean of the acute values or chronic values from flow-through
tests in which the concentrations of the test materials were measured is lower
than the calculated SAV or SCV, then that geometric mean must be used as the
SAV or SCV instead of the calculated SAV or SCV.
XVI.
STANDARDS AND GUIDANCE VALUES,
TIER II
A. Standards or guidance values
to protect aquatic life shall include: the Aquatic (Acute) or A(A) value and
the Aquatic (Chronic) or A(C) value.
B. The A(A) is equal to one-half of the
SAV.
C. The A(C) is equal to the
lowest of the SCV or the Final Plant Value, if available, unless other data
(see section IX of this Appendix) show that a lower value should be used.
If toxicity is related to a water quality characteristic,
the A(C) is obtained from the Secondary Chronic Equation or FPV, if available,
that results in the lowest concentrations in the usual range of the water
quality characteristic, unless other data (see section IX of this Appendix)
show that a lower value should be used.
D. Round both the A(A) and the A(C) to two
significant digits.
XVII.
APPROPRIATE MODIFICATIONS
On the basis of all available pertinent laboratory and
field information, determine if the Tier II value is consistent with sound
scientific evidence. If it is not, another value, either higher or lower, shall
be derived consistent with the guidance in this Appendix.
