Small Doses of Harmful Chemicals May Have Large Impacts

  • Susan Phillips

The public health and environmental debate over fracking and gas drilling often relies on what, if any, exposures to toxins can have on a person’s health. And if residents and workers do come in contact with chemicals, what levels make them dangerous? The recent EPA release on toxins in water samples from Dimock, Pa. illustrate this perfectly. The EPA reported that none of the chemicals found in their first 11 samples posed any health risks. But these risks are based on levels of concentration determined by the EPA to be dangerous. And some of what the EPA found in the water, such as methane, do not have an official MCL, or maximum contaminant level for drinking water. In other words, either drinking lots of methane is fine, or, toxicologists are unsure what the impact could be if ingested. Scientists consulted by some of the residents had a different view of the health impacts. Water Defense, an environmental group that supports the Dimock residents who say drilling contaminated their water supplies, says the EPA has not yet established safe levels for a number of known carcinogens.
A study published recently raises new questions about these established levels of chemical exposure. Laura Vandenberg and a team of scientists published a paper in Endocrine Reviews that says small doses of certain chemicals that can impact the endocrine system may have more ill health effects than previously acknowledged. The report urges a complete revision of safety standards. Yale University’s environment360 has this to say about the study.

 Hormone-disrupting chemicals, the paper explains, challenge a fundamental tenet of toxicology — “the dose makes the poison” — which contends that the greater the dose, the greater the effect. Hormone-disrupting chemicals don’t necessarily behave like this. Significant health effects, the researchers say, sometimes occur at low rather than high doses.

One of the authors of the report, Theo Colburn, has been an outspoken critic the gas industry’s use of chemicals. But environment360 says not all toxicologists are on board with the report’s conclusions.

Some scientists in academia, industry, and the U.S. Environmental Protection Agency said there is not yet convincing proof that extremely low doses of endocrine-disrupting chemicals have ill health effects or consistently produce low-dose effects that are not predicted by their effects at higher doses.

Some of the chemicals referenced in the study include those used in plastics, pesticides, cosmetics, and soap.