NCPA - National Center for Policy Analysis

Low-Level Chemical Exposure Unlikely to Effect Endocrine System

June 3, 2002

The glands in the endocrine system and the hormones they release regulate our mood, growth, development, reproduction, metabolism and tissue function. Endocrine system disruption has been shown to occur in humans exposed to high-levels of certain chemicals -- but those levels are exponentially greater than typical daily exposure.

But according to a new study by the Reason Public Policy Institute, there is no substantiated correlation between low-level chemical exposure and damage to the endocrine system, rates of cancer, decreased sperm counts, or other disorders. For example,

  • Chemical exposure has been blamed for a reported 40 percent decline in human sperm counts; but this claim is based on a study of human sperm donors, who are not representative of the general population.
  • Data from farm animals equally exposed to chemicals show no long-term change in sperm counts over the last 70 years.
  • Some scientists have proposed that estrogenic chemicals in the environment -- specifically pesticides -- might increase risk of breast cancer; but studies analyzing the relationship between DDT and breast cancer are inconclusive -- most show no direct effect.
  • Some researchers have claimed a link in children between exposure to low-levels of PCBs (used as a hardener in plastics) and retarded intellectual and neurological development; but similar studies have yielded inconsistent data, with some effects appearing and reappearing among the same children at different ages.

A reanalysis of 49 studies of low-dose chemical exposure by the Environmental Protection Agency found that scientists had been unable to duplicate most of the data from experiments that found positive correlations between exposure and effects. When scientists were able to duplicate effects, they were similar to natural variations in diet, stress and other factors.

Source: Joel Schwartz, "Hormonally Active Chemicals in the Environment." Plain English Guide No. 5, April 2002, Reason Public Policy Institute, 3415 South Sepulveda Boulevard, Suite 400, Los Angeles, Calif. 90034, (310) 291-2245.


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