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Environmental toxicology

How environmental pollutants can threaten our health

Even low doses of environmental pollutants can threaten our health. The current epidemic of obesity and type 2 diabetes in western countries may be directly related to the effects of even small amounts of environmental pollutants on our bodies.

Photo:
Jerome Ruzzin

By Anders Goksøyr and Jérôme Ruzzin, translated by Elinor Bartle

Thanks to the industrial revolution, the standard of living has increased for most people around the world. What is less obvious is that the man-made chemicals that continue to drive our revolutionised society may be having a significant impact on our bodies and health. Our attention has been primarily focused on the advantages of industrial development and less on the potential negative effects.

However, we have been gradually becoming aware of the some of these negative consequences and a list of environmental pollutants requiring regulation is growing. Unfortunately these pollutants are part of our daily lives. They are in the food we eat and the air we breathe. Our skin is also exposed to them in the products we use for cleaning, skin care, etc.

Pollutants can be stored in our bodies

Many such chemicals do not break down easily and are therefore called Persistent Organic Pollutants (POPs). Starting even before we are born, POPs begin to be stored in our bodies, and this process continues over our entire lifetime. Other less persistent chemicals such as Bisphenol A (BPA) and phthalates (DEHP), which are commonly used in plastics, have invaded our environment. When such plastics come into contact with food, these compounds can leach into the food itself. BPA is one of the most commonly produced industrial compounds today. It is estimated that by 2015, 6 million tons will be produced on a global basis. Compounds such as BPA and POPs are now found in more than 80% of the population.

Concerns about fatty fish

Food products can contain various mixtures of environmental pollutants– but unfortunately little or no information is made available to consumers. In particular, some of the highest levels of POPs of any food product are found in fatty or oily fish – fish we are told are particularly healthy to eat. It is only now that research is showing that there are grounds for concern. Read more about this.

Fertility issues

Sex changes were first noticed in alligators in the early 1990’s, as well as in fish in a number of European rivers. In addition there were findings of poor sperm quality levels in men in a number of countries, including Denmark. Similar findings have been recently observed in France. The threat of decreased fertility quickly attracted attention to a group of environmental pollutants that can function as endocrine (hormone) disruptors, and in particular, environmental oestrogens.

Now, in the 21st Century, researchers are turning their attention to a new set of health issues that may be related to environmental pollutants: metabolic disorders. There is growing documentation supporting a direct link between some environmental pollutants and obesity and related diseases such as type 2 diabetes. This connection is leading researchers to postulate that the current obesity and type 2 diabetes “epidemic” in western countries may have a man-made chemical dimension.

More and more people are getting type 2 diabetes

Since 2006 an increasing number of studies have shown a positive relationship between the levels of environmental pollutants in the blood and the incidence of type 2 diabetes. Examples include an American study that showed that the risk for getting type 2 diabetes was 38 times higher in Americans with high levels of environmental pollutants.  A number of American studies are showing that the incidence of type 2 diabetes and obesity is strongly correlated with industrial chemical production over the past 50 years. A Finnish prospective study (a long-term study) showed a similar result. In this study, the main source of the environmental pollutants were oily fish such as salmon and herring caught in the Baltic Sea, where it is known that the levels of PCB and DDT are high. A recent Swedish report stated that organic environmental pollutants in the blood can give a higher risk for contracting type 2 diabetes in the elderly. Other chemicals, such as BPA, have been linked to metabolic disorders and overweight in both children and adults.

Studies in research animals and in vitro (laboratory) work with cell lines have given similar results. The in vitro work has shown that a number of compounds are able to affect the insulin sensitivity of cells, thereby affecting their glucose metabolism. In addition, the compounds can destroy pancreatic cells, which are responsible for insulin production.  Scientists are now classifying theseenvironmental chemicals as obesogens, i.e. chemicals able to affect a cell’s ability to produce and store fat. They may also be able to transform some kinds of cells into fat cells.

Cocktail effect

In Norway and the rest of Europe the European Food Safety Association (EFSA) sets the limits for safe levels of environmental pollutants in food. However, these levels may not efficiently protect consumers. Current food safety regulations do not take into account the potential effects of mixtures of environmental pollutants and the fact that it may be possible that lower levels of these pollutants in “cocktails” may still have harmful effects.

Differing food regulation standards

Another problem is that there is no consistency in food regulation standards across all foods. Things such as some aerosols, flame-retardants and components of PCB are regulated for many foods, but not for fish as yet. In addition, most regulations do not take into account the increased sensitivity levels of children to these chemicals as compared to adults.

As stated above, there are now many studies that are underlining the fact that exposure to some environmental pollutants increases the risk of getting a metabolic disease. Our exposure to these pollutants is almost certainly too high and safety regulators are not taking the latest research into account and setting levels that will better protect consumers.

Over-eating and insufficient exercise are still important risk factors for the current obesity-type 2 diabetes “epidemic”. However, these new research results are showing that exposure to environmental pollutants may be a new factor that definitely needs further study.

 

Original article in BT

Article from National Geographic about the same topic