Over the past seven decades humans have experienced significant changes in diet, lifestyle and social practices, all of which may have profound effects on human health. According to researchers, environmental and lifestyle factors play a major role in human disease--accounting for perhaps 75 percent of most cancers.

It is suspected that environmental chemicals also play a role in these negative health effects, however researchers attempting to establish a link between environmental chemical exposures and health problems have found it to be a daunting task, as adverse effects may not show up until many years after exposure (for example, in adulthood after fetal exposure).

They suggest that exposure to chemicals may pose the greatest threat to pregnant women, which then may affect the health of the fetus later in life. They recommend that women reduce their use of cosmetics and body creams, which often contain chemicals, and seek to avoid other chemical exposures prior to becoming pregnant to lessen this risk.

Researchers offered the following points in their clinical review of the issue:

• Synthetic chemicals are pervasive in the environment, but understanding of their potential to cause harm is limited

• Several recent studies have shown associations between prenatal or postnatal exposure to certain pesticides or phthalates and reproductive disorders in humans

• Reproductive effects of environmental chemicals in (aquatic) wildlife are well established; these may provide sentinels for human effects, especially on the fetus

• Recent discoveries raise possibilities of effects of common environmental chemicals on endogenous hormones

The researchers also suggest six key recommendations to reduce the release of chemicals into the environment. These include:

• All chemicals "of concern" in current use (especially those not safety tested) should be sorted into "categories of concern" according to hazard assessment; the most hazardous to be selected for further investigation

• Chemicals found in unexpected environmental compartments or at unexpected concentrations, or associated with unusual biological phenomena, should be investigated

• Where synthetic chemicals are found in raised concentrations in biological fluids such as breast milk and in tissues of humans, marine mammals, or top predators, regulatory steps should be taken to remove them from the market immediately

New legislation should prohibit marketing of any chemical for which basic environmental safety data is not registered

British Medical Journal February 21, 2004;328:447-451 (Free Full-Text Article)