U.S. Water Systems Respond to Bioterrorism

The government is not the only entity evaluating its security procedures and vulnerability to attack since the tragic events of September 11. Several industries and services also are heightening security; after the initial bombing raids of sites in Afghanistan, U.S. drinking water utilities looked to fortify their premises. Despite taking new precautions, many government officials note the unlikelihood of an attack on public water systems, and emphasize that normal water treatment procedures such as chlorination provide protection from most pathogens. According to Greg Evans, director of the CDC-funded Center for Bioterrorism and Emerging Diseases, most cities use chlorine to disinfect their water, which would "kill off or tremendously weaken" biological agents. In addition to disinfection barriers, concentrations of most biological agents would also be diluted in large volumes of water.

The improbability of attack does not warrant complacency. Aiding the efforts of water utilities, the U.S. Environmental Protection Agency (EPA) announced the inception of an EPA-led water protection task force charged with helping federal, state and local partners expand their capabilities to safeguard the nation's drinking water supply from potential terrorist attack. EPA Administrator Christine Todd Whitman stated, "While EPA already has a strong coordinated partnership program for protecting our drinking water, this task force will have specific duties to expand EPA's service to the community water systems." Complementing existing notification systems that allow quick information sharing between drinking water providers, law enforcement and emergency response officials, Whitman articulated that the new task force seeks to ensure that all community drinking water utilities have access to the best scientific information and technical expertise in the event of and in preparation for an emergency.

Naturally, physical site security is paramount. To that end, Ronald Dick, Director of the FBI's National Infrastructure Protection Center, notes, "In order to prevent contamination of a water supply, local water works or utilities should maintain a secure perimeter around the source and the treatment facility. In addition, security should be maintained around critical nodes such as tunnels, pumping facilities, storage facilities, and the network of water mains and subsidiary pipes."

While the FBI is providing guidance on site security, the U.S. Centers for Disease Control and Prevention (CDC) is coordinating a study that investigates various water treatment technologies to determine which methods best guard drinking water from potential bioterrorist pathogens. The study, to be released in six months, is being conducted in conjunction with the EPA, the American Water Works Association and the U.S. Department of Defense. The effectiveness of moist heat inactivation, ozone, chlorine and ultraviolet technologies will be the primary focus of the study.

Stage 2 Disinfectants and Disinfection Byproducts Rule Progressing

EPA is preparing to formally propose its Stage 2 Disinfectants and Disinfection Byproducts Rule (DBPR) and the Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) by mid 2002. Prompted by 1996 amendments to the Safe Drinking Water Act, the two rules are designed to lower exposure to disinfection byproducts while still protecting the public from bacteria, viruses and other disease-causing organisms in water. Compliance requirements will be phased-in over the next ten years.

The Stage 2 DBPR focuses on reducing peak DBP levels by requiring water utilities to meet specified average DBP levels in particular locations within the system, in addition to meeting requirements for system wide averages. LT2ESWTR primarily focuses on safeguarding surface water systems against microbial pathogens, in particular, cryptosporidium outbreaks.

From March 1999 through September 2000, a Federal Advisory Committee consisting of representatives of the EPA, chemical and equipment manufacturers, public interest groups, public health officials, drinking water suppliers and others met to determine a sound DBPR policy. In September 2000, Committee members signed an Agreement in Principle outlining the Committee's broad recommendations for both the Stage 2 DBPR and the LT2ESWTR.

EPA has released drafts of both rules for comments from interested parties. The EPA specifically requested comments on whether the pre-the draft rules accurately reflect the Advisory Committee recommendations. EPA will formally propose both rules after considering these comments.

Arsenic Standard Announced

On October 31, 2001, EPA Administrator Christine Whitman announced that the new arsenic standard for drinking water will be 10 parts per billion (ppb), a substantial modification from the current standard of 50 ppb.

Whitman stated, "The Bush Administration is committed to protecting the environment and the health of all Americans. This standard will improve the safety of drinking water for millions of Americans, and better protect against the risk of cancer, heart disease and diabetes."

The Clinton Administration originally proposed the 10 ppb arsenic standard after reviewing conclusions drawn from a 1999 National Academy of Sciences (NAS) study finalized in January 2001. The Bush Administration initially decided to delay implementation of the stricter standard, drawing criticism from environmental groups and other stakeholders. Whitman insisted more time was needed to evaluate new science and data and examine the potential costs incurred by small water utilities as a result of new regulations.

Addressing this criticism, Whitman stressed that the review period did not delay the compliance date for implementing a new arsenic standard in 2006. She asserted, "Instead it has reinforced the basis for the decision…. As required by the Safe Drinking Water Act, a standard of 10 ppb protects public health based on the best available science and ensures that the cost of the standard is achievable."

Understanding cost issues was particularly important, as almost 97 percent of the systems affected by the new standard are small, serving less than 10,000 people each. To help these small water systems comply with the rule by 2006, the EPA plans to allocate $20 million over the next two years for researching and developing more cost-effective technologies.

Chloroform Toxicity Assessment Recognizes Cancer Threshold

A new evaluation of the toxicity data concerning chloroform that establishes a safe dose for the chemical was posted on the Integrated Risk Information System (IRIS) in October 2001.

The IRIS evaluation establishes an updated reference dose of 0.01 micrograms per kilogram per day. A reference dose is the amount of a chemical that EPA estimates an individual could ingest every day over a 70-year lifetime without harm. EPA concludes that the reference dose is protective for cancer and non-cancer effects. In addition to listing the new reference dose, the IRIS entry summarizes human and animal data about the toxicity and carcinogenicity of chloroform, but does not include a "slope factor" for carcinogenicity. This is the first update to the chloroform reference dose since 1992.

The action comes in response to the federal appeals court decision in March 2000 striking down a drinking water standard that assumed there was no safe dose for chloroform. On March 31, 2000, the U.S. Court of Appeals for the District of Columbia Circuit overturned EPA's Maximum Contaminant Level Goal (MCLG) for chloroform, which EPA had set at zero(Chlorine Chemistry Council v. EPA). The appeals court found EPA had extensive, peer-reviewed scientific evidence showing there is a safe dose of chloroform below which exposure would be unlikely to cause cancer or other health problems. The draft Stage 2 DBPR discussed above includes a revised, non-zero MCLG for chloroform (seven parts per billion) based on the new IRIS assessment.

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