Jan 21, 2002

Arsenic in Drinking Water - Part 1

The Development of Drinking Water Regulations

Arsenic is widespread in almost all types of soil, particularly in association with iron and sulfur compounds. Accordingly, much has been made of the natural origins of dissolved arsenic in United States ground waters. However, the broad-spectrum toxicity of arsenic compounds has made them favorites for many agricultural and industrial uses. Therefore, arsenic deposits are mined and tailings created that may leach arsenic into U.S. surface waters.

Arsenic compounds long have been used for their lethal properties in wood preservatives, weed-killers, sheep dip, fungicides, insecticides, rodenticides and, notoriously, in the Middle Ages, for homicides. As early as 1935, it was known that organic arsenic compounds accumulated in shrimp and shellfish.

Although found in human tissue, arsenic is not generally
considered to be an essential element for human physiology. In England (circa
1900), 7,000 clinical cases of subacute poisoning and 70 deaths were attributed
to the consumption of arsenic in beer. Autopsies on winegrowers (1957) showed
that arsenic poisoning progresses even after no more arsenic could be found in
the body. By 1969, it was known that chronic arsenic poisoning could lead to
loss of appetite and weight; diarrhea or, alternately, constipation; neuritis;
conjunctivitis; hyperkeratosis and melanosis of the skin; and skin cancer. More
recent medical findings on adverse human health effects has made arsenic appear
even more formidable.

As shown in the time line, the U.S. Public Health Service
(USPHS) first issued a Drinking Water Standard for arsenic in 1942. The maximum
tolerance limit was set at 50 parts per billion (ppb) or micrograms per liter
(µg/L). The water utilities of the United States were not markedly
affected by these USPHS standards since they applied solely to the limited
number providing water for interstate commerce.

By 1962, USPHS had revised its Drinking Water Standards and
again called for a Maximum Permissible Concentration (MPC) of 50 µg/L of
arsenic. The MPC implied grounds for rejection of the supply. This time, the
USPHS also issued a Recommended Maximum Limit (RML) of 10 µg/L for
arsenic. This limit implied those water sources with more than 10 µg/L
arsenic should not be used when more suitable supplies could be made available.
Though of no practical consequence, the establishment of this RML was
considered noteworthy because it was appreciably (five times) lower than the
MPC. The impact of the 1962 USPHS arsenic standard on water utilities
nationwide was essentially nil. It was not until after the formation of EPA in
1970 that drinking water standards that were applicable to water suppliers
nationwide were promulgated. Even then, little effort was made to monitor water
sources or remove arsenic from drinking water.

EPA began a laconic review of the arsenic standard in 1975.
While several interim deadlines were missed, the issue became more urgent with
a 1999 National Research Council health effects panel recommendation calling
for a stricter arsenic standard “as soon as possible.” An EPA
proposal (2000) to set the drinking water maximum contaminant level (MCL) for
arsenic at 5 µg/L met with strong opposition from mining, wood-preserving
and water industry groups. A compromise was reached with a revised EPA proposal
for a 10 µg/L MCL for arsenic.

The chaotic aftermath of the 2000 presidential election
brought unparalleled attention to the otherwise routine confusion involved in
the establishment of a drinking water standard. Three days prior to going into
effect, the 10 µg/L arsenic standard, approved in the waning days of the
Clinton administration, was withdrawn by the newly-appointed EPA Administrator.
A new National Research Council team was formed to reassess the health effects
of arsenic in drinking water. In addition, EPA reorganized its National
Drinking Water Advisory Committee and asked it to urgently review the arsenic
MCL compliance cost assumptions and methodologies.

For all the political rhetoric, public anxiety and
additional review, little real latitude appeared to exist for the establishment
of an increased, final MCL for arsenic. In appointing the new study panels
amidst calls for the application of “sound science,” EPA proposed
to issue a new arsenic standard in the range of 3 to 20 µg/L by February
22, 2002.

The National Academy of Sciences, National Research Council (NAS-NRC) report was released on September 11, 2001. It concluded that the existing health effects data on arsenic essentially were sound. In addition, their review of three new epidemiological studies indicated that the health risks posed by arsenic in drinking water were greater than previously believed. As a result, in October, well before its self-imposed deadline, EPA rescinded its March implementation ban and endorsed the 10 µg/L arsenic MCL.

Political and Public Reactions to EPA Decision to Delay and Withdraw the Arsenic Rule

•           March
22, 2001—Addressing the Western Governor’s Association, EPA
Administrator Christine Todd Whitman announced she would withdraw the arsenic
rule pending further review and public comment; the arsenic rule’s
compliance date would remain January 2006.

•           March
23, 2001—Federal Register announces EPA will extend the arsenic
rule’s effective date to May 22, the first step in withdrawing the rule.

•           Senator
Joseph Lieberman (D-Conn.) seeks an investigation of EPA’s decision by
the Government Affairs Committee.

•           Senator
Christopher Dodd (D-Conn.) and Representative Bernie Sanders (I-Vt.) introduce
bills to reinstate the 10 µg/L standard and make it subject to revision
only by Congress.

•           Senator
Harry Reid (D-Nev.) introduces a bill to authorize $750 million in grants to
assist small systems in removing arsenic and other contaminants.

•           April
23, 2001—Federal Register announces EPA plans to extend the effective
date of the January 22 final arsenic rule to February 22, 2002; invites public
comment on extension.

•           EPA
receives 14,000 comments, mostly unfavorable.

•           AWWA
calls extension “prudent;” asks EPA to grant full five-year
compliance schedule to avoid undue hardship on utilities.

•           May
22, 2001—Federal Register announces EPA decision to finalize delay to
January 22, 2002; seek appraisal of the benefits of the 10 µg/L arsenic
standard by the Science Advisory Board’s Environmental Economics Advisory

•           June
28, 2001—The Natural Resources Defense Council (NRDC) announces it will
file lawsuit against the EPA and its administrator for ignoring the June 22
congressional deadline for having a new plan to reduce arsenic levels.

•           Sen.
Barbara Boxer (D-Calif.) announces she and several colleagues on the Senate
Environment and Public Works Committee would file papers in support of the
NRDC’s lawsuit; Senators Hillary Rodham Clinton and Charles Schumer of
New York, Jon Corzine of New Jersey, Paul Wellstone of Minnesota and Harry Reid
of Nevada join in support NRDC’s lawsuit.

•           July
27, 2001—Nineteen Republicans join Democrats in 218–189 House vote
to restore 10 µg/L arsenic limit by prohibiting EPA from using funds to
lower standard. Administrator Whitman warns that amendment “will not put
a standard in place any sooner than planned under EPA’s science-based

Part 2 of this series will deal with human exposure and
advances in knowledge concerning human health effects of exposure to arsenic.

About the author

John T. O’Connor, EngD, P.E., is CEO of H2O’C Engineering, Columbia, Missouri. Phone 877-22-WATER email: [email protected]