Plastics Pose Threat to Obesity

The global obesity epidemic is getting worse, especially among children, with rates of obesity rising over the past decade and shifting to earlier ages. In the US, approximately 40% of today’s secondary school students were overweight by the time they started high school. Globally, the incidence of obesity has tripled since the 1970s, with fully one billion people expected to be obese by 2030. The consequences are significant, as obesity correlates closely with high blood pressure, diabetes, heart disease and other serious health issues. Despite the magnitude of the problem, there is still no consensus or agreement on the cause.

An emerging view among scientists is that one major overlooked component in obesity is almost certainly our environment — in particular, the pervasive presence within it of chemicals which, even at very low doses, act to disturb the normal functioning of human metabolism, interfering the body’s ability to regulate its intake and expenditure of energy.

A study published in the journal Environmental Science and Technology in January this year found that there are over 55,000 different chemical components in plastic consumer products and identified 629 substances of which 11 are known to be metabolism-disrupting chemicals (MDCs) that trigger obesity.

According to recent research, obesogens have harmful effects on individuals that often go undetected by traditional tests of chemical toxicity.

Mr. Blumberg, an expert on obesity and endocrine-disrupting chemicals from the University of California, and his colleagues demonstrate this in studies using tributyltin (TBT), a chemical used in wood preservatives, among other things.

In their experiments, scientists found that exposing mice to low and supposedly safe levels of TBT significantly increased fat accumulation in the next three generations. TBT trigger such effects by interfering directly with the normal biochemistry of the endocrine system, which regulates the storage and use of energy, as well as human eating behavior. This biochemistry depends on a wide variety of hormones produced in organs such as the gastrointestinal tract, pancreas and liver, as well as chemicals in the brain capable of altering feelings of hunger. Experiments have shown that mice exposed to obesogenic chemicals before birth exhibit significantly altered appetites later in their lives, and a propensity to obesity.

In addition, around 1,000 obesogens with such effects have already been identified in studies with animals or humans, the Bloomberg report said.

This includes Bisphenol A, a chemical widely used in plastics, and phthalates, plasticising agents used in paints, medicine and cosmetics.

Others include parabens used as preservatives in food and paper products and chemicals called organotins used as fungicides.

Recent studies have also found that obesity affects cats, dogs and other animals living in proximity to people as well as in laboratory rodents and primates – animals raised under strictly controlled conditions of caloric intake and exercise.

In sum, it is possible that people have inadvertently saturated our living environment with chemicals affecting some of the most fundamental biochemical interaction controlling human growth and development. The obesity epidemic will likely continue, or get worse, unless we can find ways to eliminate such chemicals from the environment, or at least identify the most problematic substances and significantly reduce human exposure to them.

At the least, it will require a transformation in the way we test chemicals for their toxicity, especially the many compounds that are omnipresent in our food, plastics, paints, cosmetics and other products.