"... Millions of Americans will be at risk of exposure to dangerous levels of this toxic chemical in their drinking water. Fetuses and infants are especially vulnerable to harm from perchlorate. EPA has more than tripled the amount of perchlorate it now recommends allowing in water. Scientists recommend a limit that is 10 to more than 50 times lower than what the agency is proposing ...”
EPA is proposing a standard of 56 parts per billion [ppb] — more than 3 times its own previous limit of 15 ppb. State standards based on scientists’ recommendations set the limit dramatically lower — 2 ppb (Massachusetts) and 6 ppb (California). Perchlorate impairs hormone production critical to brain development. It has been widely used by the military and defense industries ... It is highly soluble in water, and can move quickly into ground and surface water when it contaminates soil. The EPA has revised drinking water standards since the 1996 amendments to the Safe Drinking Water Act, but this is the first new standard the agency is putting forward for an unregulated contaminant in more than 23 years.
Anne Hawke
NRDC
May 23, 2019
Agency Abandons Peer-Review
Process at Behest of Big Water
EPA’s scientists developed a sophisticated model that considers the impact of perchlorate on the development of the fetal brain in the first trimester when the fetus is particularly vulnerable to the chemical’s disruption of the proper function of the maternal thyroid gland ... In April, a consulting firm published a study critiquing EPA’s model. The authors acknowledged the model as a valuable research tool but did not think it is sufficient to use in regulatory decision-making due to uncertainties. Therefore, the authors concluded that EPA should discard the peer-reviewed model and rely on a 14-year old calculation of a “safe dose” that does not consider the latest scientific evidence and has even greater uncertainties ... In 2016, EPA developed a Biologically-Based Dose Response Model (BBDR) that focused on the third trimester and breast-fed infants. A peer review panel, convened by the agency, provided positive feedback but challenged the agency to focus on the first trimester when the fetus is most vulnerable to hypothyroxinemia.
In 2017, EPA rose to the challenge and refined the BBDR model for the first trimester after conducting a rigorous review of the science. It also drew on five distinct children studies showing a quantitative relationship between perchlorate exposure, low [levels of a thyroid hormone known as "free T4" or] fT4 and harm to the developing brain ... In March 2018, the panel gave what amounts to high praise coming from independent scientists convened to be critical of the agency’s work ... The American Water Works Association, a 501c(3) technical and education organization representing drinking water professionals and utilities that would be affected by the rule, funded a consulting firm, Ramboll, to evaluate EPA’s model.
The authors of the report ... proposed ignoring new, compelling evidence that perchlorate exposure during pregnancy harms the developing brain. Instead, they called for EPA to use an RfD [reference dose] developed in 2005 that was estimated using a study of healthy non-pregnant adults ... The authors’ conclusion is at direct odds with those made by EPA’s independent peer-review panel through a multi-year transparent public process, which acknowledged the uncertainties but deemed them adequately addressed by the agency’s model. The recommendations appear to be an unrealistic demand for perfection. EPA’s model represents the “best-available, peer reviewed science,” which the Safe Drinking Water Act requires EPA to base its decisions upon ... Therefore, based on our calculations, the RfD should be 0.03 µg/kg-bw/day – about 20 times more protective than the current reference dose.
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