Researchers have for the first time found a connection between exposure to certain chemicals and insulin resistance, according to a study published in the online edition of Environmental Health Perspectives.

A group of European scientists examined whether exposure to persistent organic pollutants (POPs) contributed to insulin resistance, which has been increasing around the world. More than 25 percent of U.S. adults suffer from metabolic conditions stemming from insulin resistance that include fatigue, obesity and difficulty regulating blood levels of fat and sugar.

Researchers fed rats a high-fat diet of either crude or refined fish oil from farmed Atlantic salmon over 28 days. The crude fish oil contained average levels of POPs that people are exposed to through fish consumption, while the refined oil contained none. Both had equal fat levels.

They found that rats exposed to the crude fish oil developed belly fat and could not regulate fat properly. They had higher levels of cholesterol and several fatty acids in their livers. Those exposed to the refined fish oil experienced none of those symptoms.

Researchers said the findings provide "compelling evidence" of a causal relationship between POP exposure common in the food chain and insulin resistance, and highlight the need to understand the interactions of POPs and fat-containing foods such as fish, dairy products and meat.

How to deal with POPs is particularly challenging because they persist in the environment for long periods and can build up in animals' tissues.

The 2001 Stockholm Convention, which the United States has ratified but not signed, lists and bans numerous POPs from manufacture and use. The researchers say their evidence reinforces the need to have international agreements aimed at limiting the release of POPs into the environment in an effort to protect public health.

Reprinted from Greenwire with permission from Environment & Energy Publishing, LLC., 202-628-6500