On October 20, 2014 EPA announced its preliminary positive regulatory determination for strontium. Strontium is a naturally occurring metallic element that is also found in fertilizers and pyrotechnics. It has been found frequently, but generally in very low concentrations, and below established health reference levels (HRLs), in drinking water. The positive determination is premised on concerns over the potential impact on children because it interferes with bone development by replacing calcium and reducing bone density during the bone development process.
Since publication of the positive determination, deeper evaluation of the analyses supporting the positive determination suggest that additional study is warranted before EPA moves forward on a final determination. In particular, the science underlying the assessment of the potential health effects in humans and the appropriate HRL to be used in analyses have been called into question. The relevant analyses on health effects are derived from animal studies, with high uncertainty in how those studies may translate to humans. Because of the relatively frequent occurrence of strontium in the environment, there appears to be ample opportunity to conduct more robust epidemiological studies to more accurately assess the potential health impacts to human subjects. This, in turn, would better inform the need/threshold for a strontium drinking water regulation.
The American Water Works Association (AWWA) has funded an exploratory study to look closer at the epidemiological association between strontium exposure and bone density to potentially inform EPA’s final regulatory determination. The Water Research Foundation and AWWA have also begun studying potential treatment options for low level strontium concentrations to better inform regulatory evaluations. Preliminary information from these studies that may inform EPA’s final regulatory determination is expected as early as this spring.