The World Health Organization has increased its drinking water quality guideline for atrazine from 2 parts per billion to 100 ppb — a far less stringent level than EPA’s current drinking water standard of 3 ppb.
Atrazine proponents say the new guideline reaffirms the safety of atrazine, which EPA is currently re-evaluating. But a long time critic of the herbicide says WHO failed to take into account infants and young children’s special vulnerability and higher exposure per body weight than adults.
The new 100 ppb guideline will be included in the 4th edition of WHO’s Guidelines for Drinking-water Quality, to be published in 2011. The purpose of the guidelines is to assist regulators and policymakers in the development of national standards.
“The WHO has no regulatory force at all, and the drinking water guidelines are merely recommendations,” Jennifer Sass, senior scientist at the Natural Resources Defense Council, tells Pesticide & Toxic Chemical News via e-mail. “They are often adopted by countries that do not have the resources to conduct their own assessments.”
Sass says while both WHO and EPA rely on the same study to achieve their guideline and standard, respectively, EPA has attempted to address the vulnerability of infants and children, “albeit not to our satisfaction,” by applying the 10X Food Quality Protection Act safety factor.
Furthermore, to arrive at its drinking water guideline, WHO assumes a 60kg adult drinking two liters of water a day, with 20% of total daily intake of atrazine coming from drinking water. But kids drink more water per body weight than adults, Sass says, noting EPA has a default water intake rate of one liter of water per day for a 10kg child.
However, others say EPA should take a page out of WHO’s scientific playbook.
“Here in the U.S., activists, insisting that atrazine levels at or even below 3 parts per billion are dangerous, have led EPA and the American taxpayer on an expensive wild goose chase,” says Triazine Network Chairman Jere White, referring to what he believes is a politically motivated atrazine re-evaluation. “The U.S. EPA should follow the lead of the World Health Organization and continue to rely on sound science to evaluate atrazine,” White adds in an Oct. 5 statement.
James Lamb, director and principal scientist at consulting firm Exponent’s Center for Toxicology and Mechanistic Biology, says EPA’s current drinking water standard for atrazine appears to be too severe.
“These new findings from WHO suggest that the EPA should re-evaluate the current 3 parts per billion standard in order to bring it into line with the latest scientific data,” he says in the statement.