Drinking Water Update:
Revisions To The Arsenic MCL
The U.S. Environmental Protection Agency (EPA) is in the process of substantially reducing the current arsenic in drinking water standard. On January 22, 2001 the EPA developed a standard that reduced the Maximum Contaminant Level (MCL) from 50 parts per billion (ppb) to 10 parts per billion (ppb). However in a press release made by the EPA on July 19, 2001 the EPA requested public comment on the analyses it used in developing this standard. EPA is currently considering a standard of either 3, 5, 10 or 20 ppb.
The standard of 50 ppb was put into effect by the EPA in 1975. In 1999, the National Academy of Sciences (NAS) concluded that 50 ppb does not protect human health adequately and the MCL should be lowered. NAS reported the following regarding health effects of Arsenic: Long-term chronic effects of exposure to low concentrations of arsenic in drinking water can lead to cancerous as well as noncancerous health effects. Non-cancerous effects include: cardiovascular, pulmonary, immunological, neurological, and endocrine problems. Cancerous effects include: skin, bladder lung, kidney, nasal passages, liver and prostate cancer.
Ground water sources tend to have higher levels of arsenic than surface water sources. In the United States, the Western states have the most systems that contain levels greater than 10 ppb. EPA projects that 5.5% of water systems, serving approximately 11 million people are likely to exceed the 10 ppb level.
The new MCL standard affects community water systems (CWSs) and non-transient, non-community water systems (NTNCWSs). A CWS is a public water system that serves at least 15 locations or 25 residents regularly and year round. CWSs include cities, towns, apartments, and mobile home parks with their own water supplies. A NTNCWS is a public water system that is not a CWS and serves at least 25 of the same people more than 6 months of the year. These include schools, churches, nursing homes, and factories.
The EPA is proceeding with independent studies that will allow the Agency to develop a standard that is based on the most current information available. The independent review will include scientific and cost benefits analyses. The health science review will be made by a National Academy of Sciences (NAS) subcommittee. NAS will prepare a report updating the scientific analyses,
data uncertainties, and findings and will make recommendations. The cost of compliance estimates will be made by the National Drinking Water AdvisoryCouncil (NDWAC). A review of the benefits will be made by the Arsenic Rule Benefits Review Panel (ARBRP) a panel convened by the EPA Science Advisory Board (SAB).
Various legislative proposals have emerged in response to the scientific studies and to the political aftermath. Both the House and Senate approved arsenic amendments to the FY2002 appropriations bills for the EPA. The House bill states that the EPA may not use funds to delay the January rule or to issue a rule that sets the standard above 10 ppb. The Senate bill directs EPA to put into effect immediately an arsenic standard that protects sensitive subpopulations and that lifts the suspension of the rule’s effective date for systems with arsenic below 50 ppb to provide information to consumers about possible health risks of arsenic exposure at low levels. Legal scholars and Congress watchers have opinioned that the net effect of Congressional action will be an arsenic standard of 10 ppb.
Two of the independent studies are now available for public review. The cost report is available at http://www.epa.gov/safewater, under "What's New". A draft of SAB's benefits report is available on their website at: http://www.epa.gov/sab, under "Draft Reports". Public comments can be submitted until October 31. As of this writing, any affects of the September 11th attacks on the revisions to arsenic drinking water standard are unknown.
Timetable EPA Actions
| Date |
Action |
| 2/22/01 |
EPA issued the rule |
| 3/23/01 |
EPA delayed rule for 60 days |
| 5/22/01 |
EPA delayed effective date |
| 7/19/01 |
EPA requested comments & technical analyses |
| 10/31/01 |
Comments due |
| 2/22/02 |
Rules effective date |
| 01/2006 |
Compliance date for PWS |
Continue to Page 3 |
