&EPA
United States
Environmental Protection
Agency
Office of Water
EPA 820-F-15-001
June 2015
Human Health Ambient Water Quality
Criteria: 2015 Update
Summary
EPA published final updated ambient water quality
criteria for the protection of human health for 94
chemical pollutants. These updated
recommendations reflect the latest scientific
information and EPA policies, including updated
body weight, drinking water consumption rate, fish
consumption rate, bioaccumulation factors, health
toxicity values, and relative source contributions.
EPA accepted written scientific views from the public
from May to August 2014 on the draft updated
human health criteria and has published responses
to those comments. EPA water quality criteria serve
as recommendations to states and tribes authorized
to establish water quality standards under the Clean
Water Act.
Background
Ambient water quality criteria developed by EPA
under Clean Water Act section 304(a) represent
specific levels of chemicals or conditions in a water
body that are not expected to cause adverse effects
to human health. EPA is required to develop and
publish water quality criteria that reflect the latest
scientific knowledge. These criteria are not rules, nor
do they automatically become part of a state's water
quality standards. States may adopt the criteria that
EPA publishes, modify EPA's criteria to reflect site-
specific conditions, or adopt different criteria based
on other scientifically-defensible methods. EPA
must, however, approve any new water quality
standards adopted by a state before they can be
used for Clean Water Act purposes.
In this 2015 update, EPA revised 94 of the existing
human health criteria to reflect the latest scientific
information, including updated exposure factors
(body weight, drinking water consumption rates, fish
consumption rate), bioaccumulation factors, and
toxicity factors (reference dose, cancer slope factor).
The criteria have also been updated to follow the
current EPA methodology for deriving human health
criteria (USEPA 2000). EPA also developed chemical-
specific science documents for each of the 94
chemical pollutants. The science documents detail
the latest scientific information supporting the
updated final human health criteria, particularly the
updated toxicity and exposure input values. Specific
updates are described below.
Due to outstanding technical issues, EPA did not
update human health criteria for the following
chemical pollutants at this time: antimony, arsenic,
asbestos, barium, beryllium, cadmium, chromium (III
or VI), copper, manganese, methylmercury, nickel,
nitrates, nitrosamines, N-nitrosodibutylamine,
N-nitrosodiethylamine, N-nitrosopyrrolidine,
N-nitrosodimethylamine, N-nitrosodi-n-propylamine,
N-nitrosodiphenylamine, polychlorinated biphenyls
(PCBs), selenium, thallium, zinc, or 2,3,7,8-TCDD
(dioxin).
It is important for states and authorized tribes to
consider any new or updated section 304(a) criteria
as part of their triennial review to ensure that state
or tribal water quality standards reflect current
science and protect applicable designated uses. EPA
recently proposed revisions to its water quality
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standards regulations that would, if finalized without
substantive change, require states during their
triennial reviews to consider new or updated section
304(a) recommended criteria and, if they do not
adopt new or revised criteria for such pollutants,
provide an explanation to EPA as to why the state
did not do so. These final updated human health
criteria recommendations supersede EPA's previous
recommendations.
Updated Exposure Inputs
Body Weight
EPA updated the default body weight for human
health criteria to 80 kilograms based on National
Health and Nutrition Examination Survey (NHANES)
data from 1999 to 2006 (USEPA 2011). This
represents the mean body weight for adults ages 21
and older. EPA's previously recommended default
body weight was 70 kilograms, which was based on
the mean body weight of adults from the NHANES III
database (1988-1994).
Drinking Water
EPA updated the default drinking water
consumption rate to 2.4 liters per day based on
NHANES data from 2003 to 2006 (USEPA 2011). This
represents the per capita estimate of community
water ingestion at the 90th percentile for adults ages
21 and older. EPA previously recommended a
default drinking water consumption rate of 2 liters
per day, which represented the per capita
community water ingestion rate at the 86th
percentile for adults surveyed in the US Department
of Agriculture's 1994-1996 Continuing Survey of
Food Intake by Individuals (CSFII) analysis and the
88th percentile of adults in the National Cancer
Institute study of the 1977-1978 Nationwide Food
Consumption Survey.
Fish Consumption
EPA updated the default fish consumption rate to
22 grams per day. This rate represents the 90th
percentile consumption rate offish and shellfish
from inland and nearshore waters for the U.S. adult
population 21 years of age and older, based on
NHANES data from 2003 to 2010 (USEPA 2014).
EPA's previously recommended rate of 17.5 grams
per day was based on the 90th percentile
consumption rate offish and shellfish from inland
and nearshore waters for the U.S. adult population
and was derived from 1994-1996 CSFII data.
As described in EPA's human health criteria
methodology (USEPA 2000), the level offish
consumption in highly exposed populations varies by
geographical location. Therefore, EPA suggests a
four preference hierarchy for states and authorized
tribes that encourages use of the best local, state, or
regional data available to derive fish consumption
rates. EPA recommends that states and authorized
tribes consider developing criteria to protect highly
exposed population groups and use local or regional
data in place of a default value as more representative
of their target population group(s). The preferred
hierarchy is: (1) use of local data; (2) use of data
reflecting similar geography/ population groups;
(3) use of data from national surveys; and (4) use of
EPA's default consumption rates.
Bioaccumulation Factors
EPA's methodology for deriving human health
criteria emphasizes using, when possible, measured
or estimated bioaccumulation factors (BAFs), which
account for chemical accumulation in aquatic
organisms from all potential exposure routes (USEPA
2000). Unlike bioconcentration factors, BAFs account
for more exposure pathways than direct water
contact. As a result, the updated criteria will better
represent exposures to pollutants that affect human
health. In order to account for the variation in
bioaccumulation that is due to trophic position of
the organism, EPA's methodology (USEPA 2000)
recommends that BAFs be determined and applied
to three trophic levels of fish.
EPA selected BAFs using a framework for deriving
national trophic level-specific BAFs (USEPA 2000;
USEPA 2003). EPA used field-measured BAFs and
laboratory-measured bioconcentration factors
available from peer-reviewed, publicly available
databases to develop national BAFs. If this
information was not available, EPA selected octanol-
water partition coefficients (Kow values) from peer-
reviewed sources for use in calculating national
BAFs. As an additional line of evidence, EPA reported
model-estimated BAFs for every chemical based on
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the Estimation Program Interface (EPI) Suite (USEPA
2012) to support the field-measured or predicted
BAFs.
Updated Health Toxicity Values
EPA considered all available toxicity values for both
noncarcinogenic and carcinogenic toxicological
effects to develop the updated human health
criteria. EPA's Integrated Risk Information System
(IRIS) was the primary source for reference dose and
cancer slope factors for this update. For some
pollutants, however, more recent toxicity
assessments were provided by EPA's Office of Water,
EPA's Office of Pesticide Programs, and international
or state agencies. EPA followed a systematic process
to search for and select the toxicity values used to
derive the final updated human health criteria for
noncarcinogenic and carcinogenic effects.
Relative Source Contribution
EPA updated the human health criteria to reflect
chemical-specific relative source contributions (RSC)
ranging from 20 to 80 percent following the
Exposure Decision Tree approach described in EPA's
methodology (USEPA 2000). EPA recommends
inclusion of an RSC when developing human health
criteria for threshold non-carcinogens or non-linear
carcinogens. The RSC allows a percentage of the
reference dose's exposure to be attributed to
ambient water and fish consumption (including fish
and shellfish from inland and nearshore waters)
when there are other potential exposure sources.
The rationale for this approach is that the objective
of the water quality criteria is to ensure that an
individual's total exposure from all sources does not
exceed the criteria. Exposures outside of the RSC
include, but are not limited to, exposure to a
particular pollutant from ocean fish consumption
(not included in the fish consumption rate), non-fish
food consumption (meats, poultry, fruits,
vegetables, and grains), dermal exposure, and
respiratory exposure.
Where can I find more information?
To access the Federal Register notice, the final
updated criteria, and supporting documents visit
EPA's National Recommended Human Health
Criteria website at:
http://water.epa.gov/scitech/swguidance/standards
/criteria/health/.
References
USEPA. 2000. Methodology for Deriving Ambient
Water Quality Criteria for the Protection of Human
Health (2000). EPA-822-B-00-004. U.S.
Environmental Protection Agency, Office of Water,
Office of Science and Technology, Washington, DC.
Accessed February 2015.
http://water.epa.gov/scitech/swguidance/standards/
upload/2005 05 06 criteria humanhealth method
complete.pdf.
USEPA. 2003. Methodology for Deriving Ambient
Water Quality Criteria for the Protection of Human
Health (2000), Technical Support Document. Vol. 2,
Development of National Bioaccumulation Factors.
EPA-822-R-03-030. U.S. Environmental Protection
Agency, Office of Water, Office of Science and
Technology, Washington, DC. Accessed March 2015.
http://www.epa.gov/scipoly/sap/meetings/2008/oct
ober/methodology.pdf.
USEPA. 2011. Exposure Factors Handbook: 2011
Edition. EPA-600-R-09-052F. U.S. Environmental
Protection Agency, Office of Research and
Development, Washington, DC. Accessed February
2015. http://www.epa.gov/ncea/efh/pdfs/efIn-
complete.pdf.
USEPA. 2012. Estimation Programs Interface (EPI)
Suite™ for Microsoft® Windows, v4.10. U.S.
Environmental Protection Agency, Office of Pollution
Prevention and Toxics, Washington, DC. Accessed
February 2015.
http://www.epa.gov/oppt/exposure/pubs/episuite.
htm.
USEPA. 2014. Estimated Fish Consumption Rates for
the U.S. Population and Selected Subpopulations
(NHANES 2003-2010). EPA-820-R-14-002. U.S.
Environmental Protection Agency, Office of Water,
Washington, DC. Accessed February 2015.
http://water.epa.gov/scitech/swguidance/fishshellfi
sh/fishadvisories/upload/Estimated-Fish-
Consumption-Rates-for-the-U-S-Population-and-
Selected-Subpopulations-NHANES-2003-2010.pdf.
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