Researchers are looking into how chemicals included in packaging and other common items increase the production of fatty tissues.
With rates of obesity increasing over the previous ten years and moving to younger ages, the worldwide obesity crisis is getting worse, particularly among children. Approximately 40% of high school students in the US were overweight when they started high school. Since the 1970s, the prevalence of obesity has tripled worldwide, and by 2030, one billion people are projected to be obese.
Since obesity is directly associated with high blood pressure, diabetes, heart disease, and other significant health issues, the implications are severe.
Despite the severity of the issue, scientists are unable to agree on a single explanation, even if they are aware of numerous possible causes, such as heredity, stress, viruses, and alterations in sleeping patterns. Of course, the widespread use of highly processed foods that are heavy in sugar, salt, and fat has also contributed, particularly in Western countries where individuals today consume on average more calories per day than they did fifty years ago. Yet, according to recent scientific analyses, a significant portion of the enormous increase in obesity that has occurred throughout the world in the last 40 years is still unknown.
The environment, especially the pervasive presence of chemicals that, even at very low doses, act to disturb the normal functioning of human metabolism and upend the body’s capacity to regulate its intake and expenditure of energy, is now thought by some scientists to be a significant underappreciated factor in obesity.
Some of these substances, referred to as “obesogens,” directly increase the synthesis of particular cell types and fatty tissues linked to obesity. Unfortunately, many of the most essential items of contemporary life, such as plastic packaging, clothing and furniture, cosmetics, food additives, herbicides, and pesticides, employ these compounds.
The theory of chemically produced obesity was somewhat of a fringe theory ten years ago, but not any longer.
Obesogens are certainly a contributing factor to the obesity epidemic, is what Bruce Blumberg, an expert on obesity and endocrine-disrupting chemicals from the University of California, Irvine, told me by email. The difficulty is determining what fraction of obesity is related to chemical exposure.
Importantly, current research shows that obesogens cause damage to individuals in ways that conventional chemical toxicity testing cannot. Particularly, the effects of chemical exposure can be transmitted through so-called epigenetic pathways to offspring even several generations removed, even if they do not manifest during the lifetime of the exposed organism. Tributyltin, sometimes known as TBT, is a common example. It is a chemical used, among other things, in wood treatments. Blumberg and his colleagues discovered noticeably more fat deposition in the following three generations in experiments in which mice were exposed to low and supposedly safe amounts of TBT.
TBT and other obesogens cause these effects by impairing the endocrine system’s natural biochemistry, which controls how much energy is stored and used as well as how people eat. This biochemistry is dependent on a range of hormones generated in the liver, pancreas, and gastrointestinal system, as well as brain chemicals that might affect hunger sensations. According to experiments, mice exposed to obesogenic substances before birth have dramatically altered appetites and are more likely to become obese as adults.
In tests on animals or people, around 1,000 obesogens with such effects have already been found.
They include phthalates, which are plasticizing chemicals used in paints, medications, and cosmetics, as well as the chemical bisphenol A, which is commonly used in plastics. Other ones include the fungicides known as organotins and parabens, which are employed as preservatives in food and paper products. Pesticides and herbicides, such as glyphosate, which a recent research found to be present in the urine of most Americans, are other obesogens.
An other hint that these chemicals may be the cause of obesity is the fact that studies have revealed that the obesity epidemic is also affecting cats, dogs, and other animals that live close to people. Even laboratory rodents and primates—animals grown under highly regulated circumstances of calorie intake and exercise—have shown a marked increase in obesity incidence.
According to researchers, these animals’ weight growth could only be caused by minute chemical changes in the meals they consume or in the materials used to construct their pens.
So it is feasible that we have unknowingly overloaded our living environment with chemicals altering some of the most fundamental biochemical feedbacks driving human growth and development. Unless we can find ways to remove such chemicals from the environment, or at least identify the most dangerous substances and significantly minimize human exposure to them, the obesity epidemic will probably continue or get worse.
At the very least, it will require a transformation in the way we test chemicals for their toxicity, especially the many compounds that are ubiquitous in our food, plastics, paints, cosmetics and other products. Discoveries in epigenetics have deeply changed basic biological science and medicine over the past 15 years but have not yet had much impact on prevailing practices for chemical safety testing. Scientists are pushing for changes, but it takes time.
Hopefully, appropriate test methods will be adopted within the next few years. If they aren’t, we may well struggle to make any appreciable dent in this pernicious epidemic.
It will at the very least necessitate a change in the way we assess the toxicity of chemicals, particularly the numerous substances that are widely used in our food, plastics, paints, cosmetics, and other items. Over the past 15 years, epigenetics discoveries have profoundly altered basic biological research and medicine, yet current procedures for chemical safety testing have not been significantly affected. Although it takes time, scientists are working to improve things.
Hopefully, appropriate test methods will be adopted within the next few years. If they aren’t, we may well struggle to make any appreciable dent in this pernicious epidemic.
