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Stakeholder's
Meeting: Arsenic in Drinking Water
EXECUTIVE SUMMARY
Wednesday, February 25, 1998
San Antonio, TX
Background
Since 1995, the Office of Ground Water and Drinking Water (OGWDW) in
EPA has held stakeholder meetings to help refocus priorities in the drinking
water program and to improve strong, flexible relationships among EPA,
States, Tribes, local governments, water utilities, and the public. On
February 25, OGWDW held an arsenic stakeholders meeting in San Antonio,
Texas, that followed a two-day American Water Works Association (AWWA)
workshop on inorganics held on February 23 and 24. EPA outlined the statutory
requirements, research activities, the regulatory approach, policy issues
and on-going arsenic work in order to solicit input and obtain continued
stakeholder involvement in the arsenic regulatory development process.
SUMMARY
Legislative Requirements and Regulatory History. EPA's
primary drinking water regulation for arsenic, the Maximum Contaminant
Level (MCL), is based upon a Public Health Service value of 50 parts per
billion (ppb), or micrograms per liter (µ/L). In the 1996 amendments
to the Safe Drinking Water Act (SDWA), Congress directed EPA to expand
arsenic health effects research and propose a new regulation for arsenic
by January 1, 2000. Therefore, EPA will use current and future arsenic
research, to the extent available, to meet the statutory deadlines. Focused
long-term arsenic research efforts will be applied in future reviews of
the regulation. Meeting participants asked whether the regulation would
be a short-term rule subject to re-evaluation following the research,
about the process for revising the risk assessment, and about the role
of external reviews. While acknowledging the tension between the nature
of long term research to further elucidate arsenic health effects and
the relatively short term statutory requirements for a revision of the
current MCL, EPA representatives indicated a commitment to meeting the
statutory deadlines by thoroughly examining all existing information.
In addition, the Agency is committed to a once every 6-year reevaluation
of all its primary drinking water regulations, including arsenic (or sooner,
if warranted).
Regulatory Development. In the 1996 amendments, Congress
directed EPA to emphasize risk communication; use the best available,
peer-reviewed science for decision-making; study populations at greater
risk; list treatment technologies for small systems; assess incremental
costs and benefits; determine whether costs justify the benefits; and
establish a national occurrence database by August 6, 1999. Several risk
management components are considered when developing a drinking water
regulation: treatment technologies; analytical; occurrence assessment;
and cost/benefit assessments. The drinking water standard is set as close
to the nonenforceable health goal as feasible, considering analytical
method capability, occurrence, treatment technologies, and regulatory
costs and benefits. EPA must address a number of other statutes and executive
orders when issuing a regulation. Stakeholders expressed interest in having
time to comment during the development of the proposed rule.
MCLG Development, Revisions, and Peer Reviews. For most
people exposure to arsenic is primarily from ingestion of food and water.
An increased understanding of arsenic-induced carcinogenesis results from
understanding its modes of action and the effect of exposure routes. The
National Research Council (NRC) of the National Academy of Sciences (NAS)
is reviewing EPA's current human health risk estimates, the Taiwanese
data (which were used to derive EPA's surface water criterion and Canada's
drinking water standard), and the adequacy of the MCL and surface water
quality criteria values. EPA had an expert panel review arsenic's mode
of action for EPA's Integrated Risk Information System (IRIS). Stakeholders
were informed that beverage intake was considered in the exposure analysis,
and that organic arsenicals have lower acute toxicity than inorganic ones.
At the present time, it is not possible to adequately assess the potential
long-term effects of organic arsenicals. The NRC/NAS report (expected
out in late summer) will be available for review; and exposure data are
being researched.
Treatment Technology. EPA presented an overview of seven
treatment options that were considered for rulemaking efforts in the early
1990's, the point-of-use and point-of-entry devices that are now options
for small systems, and waste disposal issues. Future ORD work will include
performance evaluation of full scale systems, oxidation of arsenic, and
reporting on the February 25 arsenic "state of the science" treatment
workshop. ORD's residual disposal studies will complement a new AWWA Research
Foundation (AWWARF) residual study. Participants asked EPA to consider
several experimental technologies, data being developed by a utility,
small system controls, and increased water usage and water costs from
adding treatments.
Analytical Methods and Monitoring. EPA reviewed currently
approved analytical methods that measure total arsenic in the 2 ppb (µg/L)
range which have performance evaluation data to help derive a practical
quantitation level (PQL). Analytical capability is only one aspect considered
in setting an MCL, so the MCL is not set purely on the basis of a value
that can be measured. Future ORD research involves speciation analysis
in water, food, and urine. EPA provided background on current monitoring
requirements for arsenic. Stakeholders discussed whether there will be
waivers for the arsenic monitoring requirements; the higher PQL determined
by AWWA; the availability of arsenic speciation techniques; and the fact
that EPA intends to establish a total arsenic MCL.
Occurrence Data. EPA discussed the databases used to
draft national arsenic occurrence projections in 1992. New sources of
occurrence data include 25 State databases, three industry surveys, and
the U.S. Geological Survey (USGS) ambient ground water database (scheduled
for release in fall 1998). EPA will evaluate the data, develop statistical
methods, and establish occurrence and exposure projections to assess costs
and benefits. Stakeholders were requested to share other occurrence studies
and comments on how EPA should combine databases. Participants appreciated
the complexity of developing a national estimate and mentioned sources
of databases. The USGS ambient ground water database will be linked by
county to populations served and may assist in evaluating treatment costs.
A stakeholder found out that the national projection will not reflect
site-specific concentration changes over time that occur when pumping
from aquifers. Stakeholders suggested that varying regional patterns of
water usage can affect the national occurrence and cost estimates.
Arsenic Research Plan. The arsenic research plan identifies
short-term and long-term studies of modes of action, human exposure and
susceptibility, methods to measure exposures, cancer and non-cancer health
effects, and risk management areas. Short term outcomes will mostly be
in the area of risk management concerning arsenic control technologies.
Long-term outcomes will be in the areas of bioavailability assessment,
dose response interactions, and epidemiological study gaps. The draft
plan submitted for peer review in 1998 is now final, and will be on EPA's
ORD website in April.
EPA Health Effects Research -- Current and Future. Arsenic
is a known human carcinogen that can also produce non-cancer effects including
neurological, vascular, and developmental effects. Risk assessment issues
include the determination of a linear or non-linear dose response curve;
epidemiology studies to assess exposure, dose-response, and health effects;
and better understanding of arsenic metabolism and mode of action. EPA
presented ongoing U.S. health studies and international collaborations.
Laboratory studies will provide the greatest returns beyond the year 2000
by reducing uncertainties in quantitative estimates and understanding
endpoints. A stakeholder mentioned a pilot study in Inner Mongolia addressing
the dose-response curve for skin lesions that should be completed in June
1999.
Public Participation Process Alternatives. EPA seeks
to involve all interested parties before the proposed rule public comment
period. Approaches include having EPA hold additional stakeholder meetings,
prepare meeting summaries, schedule in-depth meetings, time arsenic meetings
to coincide with other EPA or association meetings, utilize the OGWDW
website, contribute to trade newsletters, and maintain mailing lists as
methods for increasing communication. Consultations with the Science Advisory
Board and National Drinking Water Advisory Council are open to the public.
A stakeholder asked that the scientific community be viewed as a stakeholder
and that scientists be alerted about the next meeting. Another stakeholder
voiced concerns about the arsenic rule's impact on small systems.
Next Steps. The Safe Drinking Water Hotline, (800) 426-4791,
will accept registrations for EPA's third stakeholder meeting May 5 in
California. Stakeholders are encouraged to contact EPA staff who made
presentations.
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