Office of Water

Office Science and

Technology EPA 820-D- 14 -007

May 2014



# Draft Update of Human Health

Ambient Water Quality Criteria:

alpha-Endosulfan

959

- 98 -8EPA 820-D- 14 -007

May 2014



# Update of Human Health

Ambient Water Quality Criteria:

alpha-Endosulfan

959

- 98 -8

Draft

Office of Science and Technology

Office of Water

U.S. Environmental Protection Agency

Washington, DC 20460alpha-Endosulfan 959- 98 -8

Table o f Contents

Introduction: Plan and Scope of Update

Problem Formulation

Criteria Formulas- Analysis Plan

Exposure Factors

Body Weight

Drinking Water Intake

Fish Consumption Rate

Bioaccumulation Factor

Hazard Identification and Dose Response

Reference Dose

Relative Source Contribution

Criteria Derivation- Analysis

Criteria Characterization

Chemical Name / Synonyms

References

Introduction: Plan and Scope of Update

Human health ambient water quality criteria (AWQC) are numeric values for pollutant

concentrations in ambient waters that the U.S. Environmental Protection Agency (EPA)

considers to be protective of human health. EPA periodically revises water quality criteria to

ensure that they reflect the latest scientific knowledge. The current revisions of the criteria for

alpha-endosulfan * , contained in this document, incorporate updated information regarding

relative source contribution, body weight, drinking water intake, fish consumption rate, and

bioaccumulation/ Relative source contribution recommendations are identified in EP!’s

‘ Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health

(2000) ’ (USEP!, 2000)/ Updated body weight a nd drinking water intake data are identified in

EP!’s ‘Exposure Factors Handbook. 2011 Edition’ (USEP!, 2011)/ The bioaccumulation factor

data is updated using EP!’s Estimation Program Interface (EPI) Suite modeling program (USEP!,

2012a). The overall fish consumption rate and trophic level breakdowns are updated using

EP!’s ‘Estimated Fish onsumption Rates for the U/S/ Population and Selected Subpopulations

(NHANES 2003- 2010)’ (USEP!, 2014) . Unless otherwise specified, all sources of information

used in this update are from peer reviewed sources.

Note that the term "water quality criteria" can carry one of two possible meanings,

depending on the section of the Clean Water Act (CWA) associated with the particular criteria

at issue/ “Water quality criteria” may refer to national water quality criteria recommendations

issued under CWA § 304/ “Water quality criteria” may also refer to water quality criteria

*

1

The pesticide active ingredient endosulfan, which is a possible source for this compound, is being phased out and

its pesticide registration with EPA will be canceled on July 31, 2016.alpha-Endosulfan 959- 98 -8

components of water quality standards adopted by states, territories, or authorized tribes

under CWA § 303.

National ambient water quality criteria recommendations for human health are issued

by the EPA under CWA § 304. They are based on the latest scientific information on the

re lationship between the effects of a constituent concentration and human health. Protective

assumptions are made regarding the potential human exposure intakes. These criteria do not

reflect consideration of non-human health endpoints or economic impacts. Nor do they reflect

the technological feasibility of meeting the chemical concentrations in ambient water. National

ambient water quality criteria recommendations for human health are not automatically

incorporated into water quality standards adopted by states, territories, or authorized tribes.

Rather, they provide scientific information to states, territories and authorized tribes to assist

them in adopting ambient water quality criteria for human health in water quality standards

that meet CWA requirements. National ambient water quality criteria recommendations for

human health are not regulations themselves and they do not impose legally binding

requirements on EPA, states, territories, authorized tribes, or the public. States, territories, and

authorized tribes have the discretion to adopt, where appropriate, other scientifically

defensible water quality criteria that differ from EP!’s national ambient recommended criteria

for human health.

Ambient water quality criteria components of water quality standards are generally

adopted by the states, territories, and authorized tribes themselves, under § 303(c)(2). (In

certain circumstances EPA also may promulgate this type of criterion itself, pursuant to

§303(c)(4)). State ambient water quality criteria for human health represent a quality of water

that sufficiently protects human health to support a designated use of the state, territory, or

authorized tribe. Such criteria may be expressed in terms of constituent concentrations, levels,

or narrative statements. Once ambient water quality criteria for human health are adopted by a

state, territory, or authorized tribe into their water quality standards, they provide a basis for

controlling discharges or releases of pollutants, for developing permit limits, assessing waters,

and developing total maximum daily loads (TMDLs) for waters that do not meet the water

quality standard. Ambient water quality criteria for human health have a regulatory impact

once they have been adopted into water quality standards by the state, territory, or authorized

tribe under § 303(c)(2) (or alternatively issued by EPA pursuant to § 303(c)(4)).

The water quality criteria at issue in this document are national ambient water quality

criteria recommendations for human health issued under CWA § 304. Unless expressly

indicated otherwise, all references to “criteria,” “water quality criteria,” “ambient water quality

criteria (!WQ) recommendations,” or similar variants thereof, are references to national

ambient water quality criteria recommendations for human health.

Problem Fo rmulation

Problem formulation provides a strategic framework for water quality criteria

development by focusing on the most relevant endpoints and increasing the transparency of

2alpha-Endosulfan 959- 98 -8

the effects assessment process. The structure of this criteria document is consistent with U.S.

EP!’s ‘Framework for Human Health Risk !ssessment to Inform Decision Making’ (USEP!,

2012b).

In the development of AWQC, EPA currently follows the deterministic assessment

methodology outlined in EP!’s ‘ Methodology for Deriving Ambient Water Quality Criteria for

the Protection of Human Health (2000) ’ (USEP!, 2000), hereafter known as the 2000

Methodology. For pollutants that exhibit a threshold of exposure before deleterious effects

occur, such as is the case for non-carcinogens, the 2000 Methodology applies a relative source

contribution (RSC) to determine the amount of the reference dose (RfD) apportioned to fish

consumption (freshwater and estuarine species) and drinking water intake. The RSC value is

applied to chemicals with an RfD to ensure that exposure to these chemicals from drinking

water and fish ingestion, when combined with all other sources, will not exceed the reference

dose. Other exposures routes, including but not limited to, dermal exposure, inhalation

exposure, marine fish and shellfish consumption (when not included in the fish consumption

rate), and non-fish dietary exposures (fruits, vegetables, grains, meats or poultry) are

accounted for in the percentage of the RfD that remains, after accounting for the RSC.

Criteria Formulas- Analysis Plan

The following formulas are used to develop the human health ambient water quality

criteria. EPA develops criteria for ambient waters typically considering two routes of exposure.

The first formula is for a criterion that assumes exposure through both the consumption of

water and the consumption of aquatic organisms. The second formula is for a criterion that

assumes exposure through the consumption of aquatic organisms, but not water. The use of

one criteri on over the other depends on the designated use of the water bodies in question (i.e.

drinking water source and/or fishable waters).

EPA recommends inclusion of the drinking water exposure pathway for ambient surface

waters where drinking water is a designated use for the following reasons: (1) Drinking water is

a designated use for surface waters under the CWA and, therefore, criteria are needed to

assure that this designated use can be protected and maintained. (2) Although rare, there are

some public water supplies that provide drinking water from surface water sources without

treatment. (3) Even among the majority of water supplies that do treat surface waters, existing

treatments may not necessarily be effective for reducing levels of particular contaminants. (4)

In consideration of the !gency’s goals of pollution prevention, ambient waters should not be

contaminated to a level where the burden of achieving health objectives is shifted away from

those responsible for pollutant discharges and placed on downstream users to bear the costs of

upgraded or supplemental water treatment (USEPA, 2000).

EPA recommends the organism only criterion in those cases where the designated uses

of a water body include only supporting fishable uses under Section 101(a) of the CWA and,

thus, fish or shellfish for human consumption, but not as a drinking water supply source (e.g.,

non-potable estuarine waters) (USEPA, 2000).

34 Where:

AWQC = ambient water quality criteria

RfD = reference dose

RSC = relative source contribution

BW = body weight

DI = drinking water intake

∑

i=2 = summation of values for aquatic trophic levels (T ) where the letter “i” stands for the

trophic levels to be considered, starting with TL 2 and proceeding to TL 4

FCR i = fish consumption rate for aquatic trophic levels 2, 3, and 4

BAF i = bioaccumulation factor for aquatic trophic levels 2, 3, and 4 alpha-Endosulfan 959- 98 -8

The formulas for deriving the criteria values are as follows (USEPA, 2000):

For consumption of water and organisms:

(Eq. 1) AWQC (μg/L) = RfD (mg/kg·d) × RSC × BW (kg) × 1000 μg/mg †

4 DI (L/d) + ∑ (F R i (kg d) ∓ !F i ( L/ kg)) i 2

For cons umption of organisms only:

(Eq. 2) AWQC (μg/L) = RfD (mg/kg·d) × RSC × BW (kg) × 1000 (μg/mg) †

4 ∑ (F R i (kg d) ∓ !F i ( L/ kg))

i 2

T h e f o llo w ing sections identify each of the components of the formulas for the human

health ambient water quality criteria and provide reference sources, previously used values

when available, and the values to be used in the updated criteria.

Exposure Facto rs:

Body Weight

The updated recommended body weight (BW) is 80 kg which represents the mean

weight for adults 21 years of age and older/ This recommendation is found in EP!’s ‘Exposure

Factors Handbook. 2011 Edition’ in hapter 8/ It was based on data derived from the National

Health and Nutrition Examination Survey (NHANES) 1999

− 2006 (USEPA, 2011). This body

weight replaces the recommended standard weight for adults of 70 kg that was described in

the 2000 Methodology which was approximated from the mean body weight of adults from the

National Health and Nutrition Examination Survey (NHANES) III database (1988-1994) and a

1989 study by the National Cancer Institute (USEPA, 2000).

† 1000 μg/mg is used to convert the units of mass into micrograms from milligrams.

4alpha-Endosulfan 959- 98 -8

Drinking Water Intake

T he updated drinking water intake (DI) is 3 L/day, rounded from 3.091 L/day for

consumer-only estimates of direct and indirect water ingestion based on NHANES 2003-2006

data for all sources of water at the 90 th percentile for adults (≥21 years of age) (USEPA, 2011).

Direct water is defined as water ingested directly as a beverage (from all sources); indirect

water is defined as water added in the preparation of food or beverages, not including indirect

consumption of bottled water. This recommended value is found in EP!’s ‘Exposure Factors

Handbook. 2011 Edition’ in Table 3- 36. It replaces the drinking water intake standard of 2 L/day

described in the 2000 Methodology which represented the 86 th percentile for adults 20 years

and older in the US Department of !griculture’s 1994 -96 Continuing Survey of Food Intake b y

Individuals (CSFII) analysis or the 88 th percentile of adults in the National Cancer Institute study

of the 1977-78 Nationwide Food Consumption Survey (USEPA, 2000).

Fish Consumption Rate

The updated fish consumption rate (FCR) for the general adult population is 22

grams/day (0.022 kg/day) (USEPA, 2014: see Table 9a ). It represents the 90 th percentile per

capita consumption rate of freshwater and estuarine fish for the U.S. adult population 21 years

of age and older based on the Centers for Disease Control and Prevention (CDC) National

Health and Nutrition Examination Surveys (NHANES) conducted from 2003-2010. It replaces the

FCR default of 17.5 grams/day, which represented an estimate of the 90th percentile per capita

consumption rate of freshwater and estuarine fish for the U.S. adult population based on the

U.S. Department of !griculture’s (USD!’s) ontinuing Survey of Food Intake by Individuals

(CSFII) 1994-96 data (USEPA, 2002a).

As recommended in the 2000 Methodology, this update to the criteria distinguishes a

trophic level (TL) breakdown of the fish consumption rate to provide a better representation of

dietary exposure to fish at multiple trophic levels/ !n organism’s trophic p osition in the aquatic

food web can have an important effect on the magnitude of bioaccumulation of certain

chemicals. The trophic levels are numbered 2, 3, and 4 and account for different categories of

fish and shellfish species based on their position in the aquatic food web. TL2 accounts for

benthic filter feeders, TL3 accounts for forage fish, and TL4 accounts for predatory fish.

In order to derive the trophic level breakdown of the 22 grams/day freshwater and

estuarine FCR, the trophic level specific freshwater and estuarine FCR data sets for adults 21

years of age and older were identified (USEPA, 2014: see Tables 16a, 17a, and 18a ). In each

trophic level specific data set, the ratio of that trophic level’s 90 th percentile FCR compared to

the summation of all three trophic level specific 90 th percentile FCRs was applied to the 22

grams/day FCR used in this update. The trophic level ratios were calculated as follows: TL ratio

= 90 th percentile FCR for the TL divided by the sum of the 90 th percentile FCRs for all TLs. TL2 =

7.6/21.3 = 0.3568 (35.68%), TL3 = 8.6/21.3 = 0.4038 (40.38%), and TL4 = 5.1/21.3 = 0.2394

(23.94%). Applying these ratios to the updated FCR of 22 grams/day result in trophic level

breakdowns of TL2 = 8 grams/day (0.008 kg/day); TL3 = 9 grams/day (0.009 kg/day); and TL4 = 5

5alpha-Endosulfan 959- 98 -8

grams/day (0.005 kg/day). These resulting trophic level FCRs are well within the confidence

intervals for each of the trophic level specific distributions’ 90 th percentiles and add to the total

of 22 grams/day (USEPA, 2014).

Bioaccumulation Factor

Several attributes of the bioaccumulation process are important to understand when

deriving national BAFs for use in setting national 304(a) criteria. First, the term

“bioaccumulation” refers to the uptake and retention of a chemical by an aquatic organism

from all surrounding media (e/g/, water, food, sediment)/ The term “bioconcentration” refers to

the uptake and retention of a chemical by an aquatic organism from water only. For some

chemicals (particularly those that are highly persistent and hydrophobic), the magnitude of

bioaccumulation by aquatic organisms can be substantially greater than the magnitude of

bioconcentration. Thus, an assessment of bioconcentration alone may underestimate the

extent of accumulation in aquatic biota for these chemicals/ !ccordingly, EP!’s guidelines

presented in the 2000 Methodology emphasize the measurement or estimation of chemical

bioaccumulation by aquatic organisms (USEPA, 2000).

The bioaccumulation factors (!F) have been estimated using EP!’s Estimation Program

Interface (EPI) Suite (USEP!, 2012a)/ The F!FTM program within EPI Suite estimates fish

bioaccumulation factors using octanol-water partition coefficients (K OW ) and biotransformation

data from a model designed by Arnot and Gobas (2003)

. The model includes mechanistic

processes for bioaccumulation such as chemical uptake from the water at the gill surface and

from the diet, chemical elimination at the gill surface, fecal egestion, growth dilution and

metabolic biotransformation. Other processes included in the calculations are bioavailability in

the water column (only the freely dissolved fraction can bioconcentrate) and absorption

efficiencies at the gill and in the gastrointestinal tract. The model requires the octanol-water

partition coefficient (K OW ) of the chemical and the normalized whole-body metabolic

biotransformation rate constant as input parameters to predict BAF values. Model predictions

may be highly uncertain for chemicals that have estimated log K OW values > 9. The model is not

recommended at this time for chemicals that appreciably ionize, for pigments and dyes, or for

perfluorinated substances (USEPA, 2012a).

For alpha-endosulfan, BAFs have been estimated using the EPI Suite model (USEPA,

2012a) as described above for trophic levels 2, 3, and 4. The estimated lower (TL2), mid (TL3),

and upper (TL4) trophic level BAFs for alpha-endosulfan (log K OW = 3.83) are 375.6 L/kg, 409.7

L/kg, and 544.4 L/kg wet-weight, respectively. These estimated BAFs replace the

bioconcentration factor (BCF) of 270 L/kg used in the 2002 criteria derivations. Experimental

bioaccumulation studies are available for a limited number of fish and shellfish species (USEPA,

2010). Additional data is required to provide sufficient information for a three-tiered trophic

level breakdown of bioaccumulation.

6alpha-Endosulfan 959- 98 -8

Hazard Identification and Dose R esponse:

Reference Dose

T he reference dose (RfD) is an estimate (with uncertainty spanning approximately an

order of magnitude) of a daily oral exposure for a chronic duration (up to a lifetime) to the

human population (including sensitive subgroups) that is likely to be without an appreciable risk

of deleterious effects during a lifetime. It can be derived from laboratory animal dosing studies

in which a no observed adverse effect level (NOAEL), lowest observed adverse effect level

(LOAEL), or benchmark dose (with uncertainty factors generally applied to reflect limitations of

the data used) can be obtained. The RfD for alpha-endosulfan is based on the RfD for

endosulfan (CAS Number 115- 29 -7) at 6 × 10 – 3 mg/kg·day (0.006 mg/kg·day) (USEPA, 1994).

The principle study by Hoechst Celanese Corp. (1989) chosen to calculate the reference

dose for alpha-endosulfan was based on reduced body weight gain and increased incidence of

marked progressive glomerulonephrosis and blood vessel aneurysms as a critical effects in male

rats orally exposed to alpha-endosulfan. The study was a chronic study with a NOAEL of 6× 10 – 1

mg/kg·day. An uncertainty factor of 100× was applied to account for interspecies extrapolation

(10×) and intraspecies variation (10×) (USEPA, 1994 ).

Relative Source Contribution

The relative source contribution (RSC) component of the human health ambient water

quality criteria (AWQC) calculation for threshold non-carcinogens and non-linear carcinogens

allows a percentage of the reference dose’s exposure to be attributed to ambient water and

freshwater and estuarine fish consumption (including estuarine species harvested in near

coastal waters) when there are other potential exposure sources. The RSC describes the portion

of the RfD available for AWQC-related sources (often a 20% default is utilized) (USEPA, 2000).

The remainder of the RfD is allocated for other sources of the pollutant. The rationale for this

approach is that for pollutants exhibiting threshold effects, the objective of the AWQC is to

ensure that an individual’s total exposure from all sources does not exceed that threshol d level.

Exposures outside of the RSC include, but are not limited to, exposure to a particular pollutant

from marine fish consumption (not included in the fish consumption rate), non-fish food

consumption (fruits, vegetables, and grains), dermal exposure, and respiratory exposure. The

percentage of exposure of the reference dose that these other exposures account for is equal

to 100 percent minus the RSC.

In the absence of scientific data, the application of the EP!’s default value of 20 percent

RSC in calculating 304(a) criteria or establishing State or Tribal water quality standards under

Section 303(c) will ensure that the designated use for a water body is protected. This 20

percent default for RSC can only be replaced where sufficient data are available to develop a

scientifically defensible alternative value. If appropriate, scientific data demonstrating that

other sources and routes of exposure besides water and freshwater/estuarine fish are not

7alpha-Endosulfan 959- 98 -8

anticipated for the pollutant in question, then the RSC may be raised to the appropriate level,

based on the data (USEPA, 2000).

Previously, the AWQC for alpha-endosulfan were calculated using a default RSC of 100

percent that does not comply with the 2000 Methodology. EPA recommends a RSC of 20

percent (0.20) for alpha-endosulfan as the default value.

Criteria Derivation- Analysis

Table 1 summarizes model inputs used to derive the 2014 updated human health

ambient water quality criteria for alpha-endosulfan. Criteria calculations are presented below.

These updated alpha-endosulfan criteria recommendations are based on the 2000

Methodology and updated exposure assumptions as described above (Exposure Factors).

Table 1. Summary of input parameters for 2014 hu man health ambient water quality criteria

for alpha-endosulfan

Component Value Source Input Characterization

RfD 0.0 06 mg/kg·day USEPA,

1994 uncertainty factor = 100 (10 for interspecies

extrapolation; 10 for intraspecies variation)

RSC 0.20 USEPA,

2000 default value

BW 80 kg USEPA,

2011 mean weight for adults (≥21 years of age)

DI 3 L/day USEPA,

2011 90 th percentile for adults (≥21 years of age)

FCR TL2 0.00 8 kg/day

USEPA

,

2014 90th percentile consumption rate for the U.S. adult

population (≥21 years of age) TL3 0.00 9 kg/day

TL4 0.00 5 kg/day

BAF TL2 375.6 L/kg

USEPA,

2012 a EPI Suite K OW model estimated steady

- state BAF

values for non

- ionic organic chemicals in 3 general

trophic levels of fish in temperate environments

(10°C) TL3 409.7 L/kg

TL4 544.4 L/kg

For consumption of water and organisms:

8 AWQC (μg/L) = RfD (mg/kg·d) × RSC × BW (kg) × 1000 μg/mg

DI (L/d) + ∑

i 2 (FR

i (kg d) ∓ !F

i ( /k g))

= 0. 0 06 mg/kg·d × 0.20 × 80 kg × 1000 μg/mg

3 L/d + ((0.008 kg/d × 375.6 L/kg) + (0.009 kg/d × 409.7 L/kg) + (0.005 kg/d × 544.4 L/kg))

= 7.733 μg/L (rounded to 8 μg/L because of significant figures)

4alpha-Endosulfan 959- 98 -8

For consumption of organisms only:

AWQC (μg/L) = RfD (mg/kg·d) × RSC × BW (kg) × 1000 (μg/mg)

∑

i 2 (FR

i (kg d) ∓ !F

i ( /k g))

= 0.0 06 mg/kg·d × 0.20 × 80 kg × 1000 μg/mg

(0.008 kg/d × 375.6 L/kg) + (0.009 kg/d × 409.7 L/kg) + (0.005 kg/d × 544.4 L/kg)

= 10.197 μg/L (rounded to 10 μg/L because of significant figures)

The updated human health ambient water quality criteria for alpha-endosulfan are 8

μg/L (water and organism) and 10 μg/L (organism only) (Table 2). These updated criteria

replace the previously published values (USEPA, 2002b).

Table 2. Summary of EP!’s preciously recommended (2002) and updated ( 2014 ) human health

ambient water quality criteria for alpha-endosulfan

2002 Human Health AWQC 2014 Human Health AWQC

Water and Organism 62 μg/L 8 μg/L

Organism Only 89 μg/L 10 μg/L

These AWQC are meant to be protective of human health for the general adult

population for a set percentage (RSC) of the total allowed daily oral exposure for a chronic

duration (up to a lifetime) of alpha-endosulfan.

Criteria Characterization

The updated 2014 human health AWQC for alpha-endosulfan take into account current

data on health effects and exposure input parameters, consistent with the 2000 Methodology.

The updated 2014 human health AWQC for alpha-endosulfan are about six to nine times lower

than EP!’s previously recommended 2002 criteria- i/e/ the water-and-organism criterion

decreased from 62 to 8 μg/L and the organism-only criterion decreased from 89 to 10 μg/L

(Table 2). The following paragraphs describe the individual influence of each of the revised

model inputs and exposure assumptions on the overall change in value.

Body Weight

EPA’s updated AWQC assume a higher body weight compared to the previously

recommended 2002 criteria, reflecting a recent rise in average adult body weight among the

U.S. population. The updated body weight assumption of 80 kg based on recent survey data

from the 1999−2006 NHANES data is 10 kg greater than the previous recommendation of 70 kg.

Assuming all other input parameters remain constant, a higher average body weight in the

AWQC calculations (Eq. 1 and 2 above) results in higher AWQC. That is, as body weight

increases, the level of a contaminant in water at or below which negative health effects are not

anticipated from a lifetime of exposure also increases.

9 4alpha-Endosulfan 959- 98 -8

Drinking Water Intake

The updated drinking water intake assumption is 3 L/day, which is higher than the

previously recommended rate of 2 L/day. Assuming all other input parameters remain constant,

a higher drinking water intake assumption in the AWQC calculations (Eq. 1 and 2 above) results

in lower AWQC. That is, as drinking water intake increases, and thus overall exposure increases,

the level of a contaminant in water at or below which negative health effects are not

anticipated from a lifetime of exposure decreases.

Fish Consumption Rate

The updated fish consumption rate is 22 g/day, divided into trophic level rates of 8

g/day, 9 g/day, and 5 g/day for trophic levels 2, 3, and 4, respectively, which is higher than the

previously recommended rate of 17.5 g/day. Assuming all other input parameters remain

constant, a higher fish consumption rate assumption in the AWQC calculations (Eq. 1 and 2

ab ove) results in lower AWQC. That is, as fish consumption increase, and thus overall exposure

increases, the level of a contaminant in water at or below which negative health effects are not

anticipated from a lifetime of exposure decreases.

Bioaccumulation Factor

The updated AWQC rely on EPI Suite model-estimated BAFs rather than the previously

recommended BCF of 270 L/kg. The lower (TL2), mid (TL3), and upper (TL4) trophic level BAFs

assumed in the updated criteria equations (Eq. 1 and 2 above) are 375.6, 409.7, and 544.4 L/kg

wet-weight, respectively. Assuming all other input parameters remain constant, the higher

ratios of fish tissue concentrations to water concentrations of alpha-endosulfan by aquatic

organisms result in lower AWQC. That is, as bioaccumulation or bioconcentration of a

contaminant in fish and shellfish increases, and thus overall exposure increases, the level of a

contaminant in water at or below which negative health effects are not anticipated from a

lifetime of exposure decreases. The utilization of a bioaccumulation factor rather than a

bioconcentration factor better represents the amount of a contaminant accumulating in an

organism because it accounts not only for the organism’s exposure to the pollutant in the water

column, but also from the food chain and surrounding environment as well as

biotransformation of the pollutant in the organism due to metabolic processes. The utilization

of the three trophic levels of fish and shellfish consumed, as opposed to representing all trophic

levels of fish and shellfish consumed by a single value, allows for better exposure

representation, especially when pollutants bioaccumulate in significantly different amounts for

organisms in different trophic levels at different positions in the food chai n.

Relative Source Contribution

The adoption of the recommended default RSC of 20 percent will be replacing the

previous default of 100 percent. Assuming all other input parameters remain constant, a

smaller relative source contribution assumption in the AWQC calculations (Eq. 1 and 2 above)

10alpha-Endosulfan 959- 98 -8

results in lower AWQC. That is, as the relative source contribution decreases, the level of a

contaminant in water at or below which negative health effects are not anticipated from a

lifetime of exposure decreases.

Additional routes of exposure to a particular pollutant besides exposure from water

intake and fish consumption are possible and may be considered when setting criteria for a

state or tribe. Possible additional routes include, but are not limited to, dermal exposure,

inhalation exposure, marine fish and shellfish consumption (when not included in the fish

consumption rate), and non-fish dietary exposures (fruits, vegetables, grains, meats or poultry).

If scientific evidence exists which indicate that one or more of these routes pose a significant

risk of exposure, states and authorized tribes are encouraged to ensure that subpopulations are

adequately protected.

States, territories, and authorized tribes have the flexibility to develop criteria, on a sitespecific basis, that provide additional protection appropriate for highly exposed populations.

EPA is aware that exposure patterns in general, and fish consumption in particular, vary

substantially. EPA understands that highly exposed populations may be widely distributed

geographically throughout a given state, territory, or authorized tribal area. EPA recommends

that priority be given to identifying and adequately protecting the most highly exposed

populations. Thus, if a state, territory, or authorized tribe determines that a highly exposed

population is at greater risk and would not be adequately protected by criteria based on the

general population, and by the national 304(a) criteria in particular, the state, territory, or

authorized tribe may adopt more stringent criteria using alternative exposure assumptions

(USEPA, 2000). Subpopulations that may be considered include, but are not limited to,

recreational fishers, subsistence fishers, women of childbearing age, and children. When

scientific data exist showing one of these subpopulations is at risk of greater exposure to the

pollutant or are biologically more sensitive, then the relevant inputs should be considered in

setting criteria. This could entail raising the fish consumption rate to a level more reflective of

the subpopulation based on collected data or adjusting the body weight and drinking water

intake.

Ch emical Name / Synonyms

 Alpha-endosulfan (CAS Number 959- 98 -8)

 3-alpha,5-alpha,6-alpha,9-alpha,9a-alpha-6,7,8,9,10,10hexachloro-1,5,5a,6,9,9a

he xahydro-6,9-methano-2,4,3-oxide

 End osulfan I

 Endosulfan A

 Endosulfan 1

 Endosulfan-alpha

 1,4,5,6,7,7-Hexachloro-5-norbornene-2,3-dimethanol, cyclic sulfite, endo­

 alpha-Thiodan

11alpha-Endosulfan 959- 98 -8

References

H oechst Celanese Corporation. 1989. MRID No. 40256502, 41099502. HED Doc. No. 007937.

Available from EPA. Write to FOI, EPA, Washington, DC 20460.

USEPA (U.S. Environmental Protection Agency). 1980. Ambient Water Quality Criteria for

Endosulfan. Office of Water. Washington, DC. EPA- 440 -5- 80 -0 46

. http://water.epa.gov/scitech/swguidance/standards/upload/2001_10_12_criteria_ambi

entwqc_endosulfan80.pdf

.

USEPA (U.S. Environmental Protection Agency). 1994

. Endosulfan (CASRN 115

- 29 -7). Integrated

Risk Information System . Retrieved 09 September 2013.

http://www.epa.gov/iris/subst/0235.htm

.

USEPA (U.S. Environmental Protection Agency). 2000

. Methodology for Deriving Ambient Water

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USEPA (U.S. Environmental Protection Agency). 2012 a / Estimation Programs Interface SuiteTM

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the U.S. Population and Selected Subpopulations (NHANES 2003-2010). Office of Water.

Washington, DC. EPA-820-R- 14 -002.

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