A EPA
United States	Office of Water EPA-820-F-14-003
Environmental Protection	4304T	May2014
Agency
Human Health Ambient Water Quality Criteria:
Draft 2014 Update
Summary
EPA is announcing in the Federal Register the
availability of draft updated ambient water
quality criteria for the protection of human
health for the purpose of obtaining public
comments. EPA has updated its national
recommended water quality criteria for human
health for 94 chemical pollutants to reflect the
latest scientific information and EPA policies.
EPA will accept written scientific views from
the public on the draft updated human health
criteria for 60 days. Once finalized, EPA water
quality criteria provide 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 the Clean Water Act 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 2014 update, EPA has revised 94 of the
existing human health criteria to reflect the latest
scientific information, including updated
exposure factors (body weight, drinking water
intake, 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 (2000).
Specific updates are described in detail below.
Due to outstanding technical issues, including
new toxicity factors and bioaccumulation
factors, EPA is not updating 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).
Updated Exposure Assumptions
Body Weight
EPA has updated the default body weight
assumption for human health criteria to 80
kilograms based on National Health and
Nutrition Examination Survey (NHANES) data
from 1999 to 2006. This represents the mean
body weight for adults ages 21 and older.
EPA's previously recommended body weight
assumption was 70 kilograms, which was based
on the mean body weight of adults from the
NHANES III database (1988-1994).
Drinking Water
EPA has updated the default drinking water
intake rate assumption to 3 liters per day based
on NHANES data from 2003 to 2006 for all
sources of water at the 90th percentile for adults
ages 21 and older. This value is based on
consumer-only estimates of direct and indirect
water ingestion. EPA previously recommended
a default drinking water intake rate of 2 liters per
day, which represented 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.

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Fish Consumption
EPA has updated the default fish consumption
rate to 22 grams per day. This rate represents the
90th percentile consumption rate of freshwater
and estuarine fish 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 recommend rate of 17.5 grams per
day was based on the 90th percentile
consumption rate of freshwater and estuarine
fish 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 of fish
intake 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 over the
default values as more representative of their
target population group(s). The four preference
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 intake rates.
Bioaccumulation Factors
EPA's national recommended water quality
criteria for the protection of human health have
been updated using bioaccumulation factors
rather than bioconcentration factors, as
recommended in EPA's human health criteria
methodology (USEPA 2000). Unlike
bioconcentration factors, bioaccumulation
factors 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
human health criteria methodology (USEPA
2000) recommends that bioaccumulation factors
be determined and applied to three trophic levels
of fish. EPA used a peer-reviewed model called
Estimation Program Interface Suite (EPI Suite)
to develop bioaccumulation factors for each
trophic level of fish.
Updated Health Risk Factors
EPA has updated the health risk factors using
the most current toxicity information. EPA's
Integrated Risk Information System (IRIS) is the
primary recommended source for reference dose
and cancer slope factor information. For some
pollutants, more recent assessments may be
found using other resources provided by EPA's
Office of Water, EPA's Office of Pesticide
Programs, and international or state agencies.
Relative Source Contribution
EPA has updated the human health criteria to
reflect the recommended default relative source
contribution (RSC) of 20 percent, as
recommended in EPA's human health criteria
methodology (USEPA 2000). The RSC
component of the human health criteria
calculation for non-carcinogens designates a
percentage of the reference dose that accounts
for exposures from water and fish (freshwater
and estuarine), when there are other possible
exposure routes. Other such routes include, but
are not limited to, exposure to a particular
pollutant from marine fish consumption, non-
fish food consumption, dermal exposure, and
respiratory exposure. For pollutants exhibiting
threshold effects, the use of an RSC ensures that
an individual's total exposure from all sources of
a pollutant does not exceed that threshold level.
In accordance with EPA's human health criteria
methodology (USEPA 2000), an alternative
RSC may be used to derive human health
criteria when there are sufficient data available
to support a scientifically defensible alternative
value.
For More Information
Contact: Heidi Bethel by telephone at (202)
566-2054, by email at bethel,heidi@epa.gov, or
by mail at U.S. EPA, Health and Ecological
Criteria Division (4304T), 1200 Pennsylvania
Ave., N.W., Washington, D.C. 20460.
To access the Federal Register notice, the draft
updated criteria, and supporting documents visit:
http://water.epa.gov/scitech/swguidance/standar
ds/criteria/health/.

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References
USEPA (U.S. Environmental Protection
Agency). 2000. Methodology for Deriving
Ambient Water Quality Criteria for the
Protection of Human Health. Office of Water.
Washington, DC. EPA-822-B-00-004.
USEPA (U.S. Environmental Protection
Agency). 2003. Methodology for Deriving
Ambient Water Quality Criteria for the
Protection of Human Health (2000) Technical
Support Document Volume 2: Development of
National Bioaccumulation Factors. Office of
Water. Washington, DC. EPA-822-R-03-030.
USEPA (U.S. Environmental Protection
Agency). 2011. Exposure Factors Handbook:
2011 Edition. Office of Research and
Development. Washington, DC. EPA-600-R-09-
052F.
USEPA (U.S. Environmental Protection
Agency). 2012. Estimation Programs Interface
Suite™ for Microsoft® Windows, v 4.10.
United States Environmental Protection Agency,
Washington, DC, USA.
USEPA (U.S. Environmental Protection
Agency). 2014. Estimated Fish Consumption
Rates for the U.S. Population and Selected
Subpopulations (NHANES 2003-2010). United
States Environmental Protection Agency,
Washington, DC, USA. EPA 820-R-14-002.

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