RE: OEHHA Fails to Provide Legitimate Scientific Rationale for a New Perchlorate Public Health Goal

California’s Office of Environmental Health Hazard Assessment (OEHHA) has failed to provide scientific evidence that the state’s perchlorate public health goal (PHG) needs to be reduced from the current, highly conservative level, and continues to rely on questionable science that is inconsistent with 60 years of research.

This new decision also creates new impediments to access to reliable water supplies, contrary to the Governor’s plans for statewide drought relief, without valid scientific rationale.

Despite repeated efforts by numerous stakeholders to compel OEHHA and Cal/EPA to address the weaknesses in the new PHG, the regulators have ignored comments and pushed a proposal that is indefensible against the preponderance of scientific evidence, relies on highly questionable assumptions and cannot withstand objective scrutiny and is in conflict with state law.

Highlights among the many concerns with OEHHA’s new perchlorate PHG:

  • OEHHA has failed to provide any evidence that the current PHG is not protective, nor has it defined any public health benefits that would come from lowering the PHG from the current 6 parts per billion (ppb).
  • Several authoritative bodies, including the National Academy of Sciences and the US EPA Office of The Inspector General have concluded that even levels as high as 24.5 ppb—four times higher than California’s current PHG—have no effect on human health.
  • State law (HSC Section 116356(c)(1)(D) states that where there is adequate scientific evidence demonstrating a safe dose response threshold, as there clearly is with perchlorate, OEHHA should set the PHG at that threshold.
  • OEHHA relies on untested and unsupportable assumptions and methodologies to support its position. As one example, the agency assumes a 95th percentile one-month-old infant would consume 280% of their blood volume in drinking water every day. This is the equivalent of the average adult consuming nearly four gallons of tap water daily.
  • The PHG document misrepresents the weight-of-evidence for perchlorate health to support its conclusions. OEHHA uses five studies as the foundation of its assessment, four of which are presented with calculations by OEHHA, not the actual study authors. In contrast, several peer-reviewed studies that do not support OEHHA’s conclusions are noticeably excluded by OEHHA.

By lowering the PHG, OEHHA sends the message that water supplies considered safe yesterday are no longer safe today – a message that is completely at odds with the preponderance of scientific evidence. As a precautionary measure, water purveyors are likely to take wells offline that currently meet the state standard of 6 ppb, but may have perchlorate levels higher than the new PHG. 

At a time when state resources—including its water supply—are scarce, we cannot afford to have regulatory decisions based on anything other than the best available science. To do otherwise puts water supplies at unnecessary risk without offering any public health benefit.


Additional background:

  • 1 ppb is roughly equal to a half teaspoon of material diluted in an Olympic-sized pool
  • Adverse effects of perchlorate exposure have not been demonstrated in humans, even at levels as high as 14,000 ppb, assuming an average adult drinking 2 liters of tap water daily.
  • Claims that perchlorate has been linked to thyroid problems, birth defects or other serious health problems are inaccurate – no published research exists in more than 60 years of scientific study to support these claims. More…
  • According to OEHHA’s Guide to Public Health Goals for Chemicals in Drinking Water, a PHG  “is not a boundary line between a ‘safe’ and ‘dangerous’ level of a contaminant, and drinking water can still be considered acceptable for public consumption even if it contains contaminants at levels exceeding the PHG.” 

Please visit for factual information on perchlorate, or contact Bill Romanelli at 916-448-3152 or 916-212-1446 (cell).