In March of last year, I wrote an article about the pervasiveness of plastic pollution in the environment. I was expressing a certain frustration at not being able to determine the verifiable impacts on human health of such widespread pollution by plastics, with the exception of a few known toxic compounds.
A year later, more and more observations on the prevalence of obesity around the world could provide a clue to the impact of plastic pollution on human health. Global obesity has tripled since 1975, and now more people on earth are obese or overweight than underweight.
Medically and socially, this situation is an enigma. The negative effects of obesity are now well known and there are many diets and treatments for obesity, but the number of obese people continues to increase every year. That does not make sense. More and more people are watching their caloric intake and/or eating healthier, but paradoxically they are still getting fat despite the availability of remedies for excessive weight gain.
The global obesity pandemic can be explained by a relatively new class of plastic-related compounds called obesogens. Technically, obesogens can be defined as “chemicals and compounds that disrupt the body’s normal homeostatic controls in such a way as to promote adipogenesis and lipid accumulation”.
Homeostasis refers to how the body maintains its metabolic balance, adipogenesis is the process by which fat cells grow and accumulate as adipose tissue, and lipid accumulation is the excessive retention of fat. excess fat cells in the liver, muscle tissue and other parts of the body. .
Three articles published in 2022 in the Biochemical pharmacology The review covered the results of around 1,400 studies on environmental factors that appear to affect obesity, with perhaps the most interesting article being “Drawing causal links between chemical exposures and obesity”. A curious finding was that in addition to fat accumulation, obesogens seem to promote the production and retention of white fat much more than brown fat.
White fat tends to stay in the body longer, primarily as storage tissue used for energy retention. Brown fat is burned and converted to heat much more easily, especially in cold weather, and is therefore considered the healthiest fat to have as it promotes energy expenditure. By the way, white fat can be converted into brown fat via a hormone called irisin, which is produced during heavy muscle exertion.
As already mentioned in my article last year, whatever compounds or chemicals are leached from environmental plastics, they are generally not extremely toxic. And since there are approximately 350,000 known chemicals and synthetic compounds swirling around in the environment, it is very difficult to determine which compounds or combinations of these chemicals affect our health and/or act as obesogens.
However, chemicals that are not extremely toxic do not mean they are safe, especially when humans are exposed to them for an extended period of time. By way of example, the known effects of obesogens are stated as follows:
• Proliferation of the number of fat cells (adipocytes)
• Expansion in adipocyte size, increased storage of fat or water per cell, or both
• Alteration of the endocrine pathways (hormone glands) responsible for controlling the development of adipose tissue (fat)
• Change in the basal metabolic rate (energy consumption of the body at rest)
• Modify the body’s energy management to promote calorie storage
• Changes in insulin sensitivity, fat metabolism and hormone production in organs such as the pancreas, adipose tissue, liver, gastrointestinal tract, brain and muscle.
• Altered balance of hormones that regulate appetite, satiety and food preferences
The effect of obesogens over time can lead to diseases such as diabetes, liver disease, eating disorders, thyroid disorders, faulty bowel functions, insulin tolerance and, of course, obesity with all the problems that come with it, such as cardiovascular disorders, strokes, etc.
Worryingly, the effects of obesogens can linger through generations of affected families. A 2021 study of families affected by dichlorodiphenyltrichloroethane (commonly known as DDT) found that grandmothers who had high levels of DDT in their blood were statistically more likely to have obese granddaughters.
Tests on laboratory rodents revealed that exposure to obesogens such as bisphenol-A (BPA), di-2-ethylhexyl phthalate (DEHP) and dibutyl phthalate (DBP) caused an increased incidence of obesity in their offspring. Curiously, tests using bisphenol-S (BPS) have successfully promoted excessive fat retention in four generations of rodents. BPA, DEHP, DBP and BPS are all plastic-based compounds and are extremely prevalent in our environment.
It is unclear exactly how such transgenerational inheritance of obesity occurs, but it is clear that obesogens somehow affect DNA structure in reproductive cells. This can happen through a process called epigenetic modification (or mutation).
An example of epigenetic mutation is the methylation of DNA by the addition of methyl groups (simple chemical structures consisting of a single carbon atom linked by 3 hydrogen atoms) on the DNA chain itself. These mutations can lead to a modification of the DNA transmitted during reproduction.
Another example of epigenetic mutation is histone modification, whereby the internal structures of cells are changed or damaged in some way. These structures are known as chromatin, which includes the chromosomes, proteins, RNA, and DNA of cells.
Such epigenetic mutations can also cause diseases such as cancers and are capable of significantly accelerating the aging process.
With hundreds of thousands of synthetic and chemical compounds in our environment, researchers have failed to define a complete map of the distribution of these compounds. Many of these compounds are found in the air we breathe, the water we drink, the food we eat, the things we touch, and even the clothes we wear. Every part of our planet has already been contaminated to some degree.
Thus, it may seem pointless to try to avoid such contaminants. But that wouldn’t be the right view. There are some compounds that are worth the effort to avoid, especially since the cost involved is usually minimal. And women should be diligent about avoiding obesogenic contaminants during pregnancy so as not to harm future generations.
A simple example would be to avoid eating or drinking hot food or drinks from plastic containers of any kind. Even with “safe” BPS containers, some compounds will often escape when heated and will be ingested with food.
Avoid eating take-out food delivered in polystyrene containers. If you have a plastic electric kettle, consider replacing it with a metal or ceramic one. Don’t breathe dirty air, so wear a good quality mask if the air quality is poor. At a minimum, wear a mask with a particulate filter 2.5 (PM2.5) if you walk in polluted air, especially due to traffic.
When using a microwave oven, always cook food in glass or ceramic containers. Do not use plastic lids to cover food when using microwave ovens.
Perhaps one of the best things you can do is to stop contributing to plastic pollution by limiting the disposal of plastic items such as containers, bags, wraps, bottles, etc.
Be aware that plastics never break down – they eventually degrade over centuries into microplastics that can absorb and concentrate toxins from other chemicals, becoming potentially more dangerous over time. Therefore, even a single discarded plastic bag will continue to pollute the planet forever.
We don’t control
A sobering article in 2022 in the journal, Environmental science and technologysuggested that chemical pollution had already recently exceeded a “planetary limit”, the limit being defined as the limit at which our planet’s environment becomes unstable (and potentially unlivable), after the environmental stability of the past 10,000 years.
Strikingly, the fact is that there has been a 50-fold increase in the production of chemicals and plastics since 1950, and this is expected to triple again by 2050. When it comes to plastics, the total mass of plastics now exceeds the total mass of all mammals on earth.
But either way, unless we all do something quickly, the end result is beyond doubt. However, there is still time for humans to move to a circular economy, which is an economy where materials and products are reused and not thrown away. Humanity really needs to apply its wits, wits and determination not to let the proliferation of synthetic compounds ruin our planet.
For more on plastics, please read last year’s article titled “A Diet of Plastics”.
The opinions expressed here are entirely those of the author.