Arsenic and permissible limits

By Dr Deepu

Arsenic is a semi-metal element in the periodic table. It is odorless and tasteless. It enters drinking water supplies from natural deposits in the earth or from agricultural and industrial practices. 

Non-cancer effects can include thickening and discoloration of the skin, stomach pain, nausea, vomiting; diarrhea; numbness in hands and feet; partial paralysis; and blindness. Arsenic has been linked to cancer of the bladder, lungs, skin, kidney, nasal passages, liver, and prostate.

EPA has set the arsenic standard for drinking water at .010 parts per million (10 parts per billion) to protect consumers served by public water systems from the effects of long-term, chronic exposure to arsenic.  Water systems must comply with this standard by January 23, 2006, providing additional protection to an estimated 13 million Americans.

EPA proposed arsenic regulations to revise the existing NPDWR on June 22, 2000 (65 FR 38888), which proposed a Maximum Contaminant Level (MCL) of 0.005 mg/L (5 μg/L). The October 2000 appropriations bill for EPA amended the SDWA, directing EPA to promulgate a final arsenic standard no later than June 22, 2001. The Final Rule, published on January 22, 2001, established the MCL at 0.01 mg/L (10 μg/L) (40 CFR 141.62(b)(16)). The Rule was to become effective on March 23, 2001, 60 days after publication. The Rule established that the 0.01 mg/L (10 μg/L) MCL becomes enforceable on January 23, 2006, and that the clarifications to compliance and new source contaminants monitoring regulations become enforceable on January 22, 2004 (40 CFR 141.6(j) & (k)).

Because of the importance of the Arsenic Rule and the national debate surrounding it related to science and costs, EPA's Administrator publicly announced on March 20, 2001, that the Agency  would take additional steps to reassess the scientific and cost issues associated with this Rule. EPA requested that the National Academy of Sciences (NAS) convene a panel of scientific experts to review the Agency's interpretation and application of arsenic research, worked with its National Drinking Water Advisory Council (NDWAC) to review the assumptions and methodologies underlying the Agency's estimate of arsenic compliance costs, and asked its Science Advisory Board (SAB) to look at the benefits associated with the Rule. On October 31, 2001, the EPA Administrator announced that the 10 ppb (0.010 mg/L) standard for arsenic would remain stating that, "the 10 ppb protects public health based on the best available science and ensures that the cost of the standard is achievable."

On January 22, 2001 EPA adopted a new standard for arsenic in drinking water at 10 parts per billion (ppb), replacing the old standard of 50 ppb.  The rule became effective on February 22, 2002.  The date by which systems must comply with the new 10 ppb standard is January 23, 2006.