Man made chemicals may be contribute significantly to the increase in rates of diseases in Western nations. Evidence suggests that chemicals belonging to the organochlorine and organophosphate group of synthetic chemicals, used extensively in agriculture, may be damaging to the health. In particular, exposure to the organophosphate chemicals has been shown to be particularly damaging to the nervous system. In this regard exposure to high concentrations of organophosphate compounds acutely, or lower concentrations chronically, may lead to neurological problems. Exposure to various organophosphate compounds for example has been shown to increase the risk of dementia significantly. In addition, the organochlorine molecules such as DDT (dichlorodiphenyltrichloroethane), PCB (polychlorinated biphenyl), lindane and dioxins may be hormone disrupting chemicals through their ability to interact with various hormone receptors. The DDT metabolite DDE for example is a known anti-androgen.
Some organochlorine molecules have been banned because of their known damaging effect, including DDT. However, many of the banned organochlorine chemicals remain in the environment as they do not readily biodegrade and can also bioaccumulate in animals due to their fat soluble nature. These chemicals tend to concentrate as they pass up the food chain, and high concentrations have been detected in those animals at the top of the food chain such as birds of prey, where they disrupt the ability of the birds to produce healthy eggs. This effect is suspected as responsible for the decline in the populations of birds of prey in some areas. As humans are at the top of the food chain, it is not surprising that high levels of DDT have also been found in human adipose tissue, despite the chemical being banned in the countries where the human subjects were tested. It is unclear how long it will take for DDT to be removed from the food chain, but this is likely to take decades.
However, of more concern are the plasticisers. These include the nonylphenols such as alkylphenols, the octaphenols, as well as the bisphenols which include the notorious bisphenol A. The plasticisers are of more nutritional importance than the organochlorine and organophosphate molecules because plastic food packaging used for example in fruit juices, milk, bottled drink and the plastic lining of canned foods all contain plasticisers that can leach into the foods they contain. These chemicals are still widely produced and evidence suggests that they bioaccumulate in humans fat tissue, are released to the blood, and then have oestrogen-like effects. The plasticisers are thought to be at least partly responsible for the increase in the rates of hormone dependent cancers in humans that are particularly prevalent in Western nations. Evidence suggest that the chemicals may have synergistic effects and so the large variation in plasticisers may produce additive effects on hormonal disruption.
It is virtually impossible to eliminate the organophosphate, organochlorine and plasticiser from the diet. This is because they are now so widespread and used in so many products that modern life exposes even the most careful avoider to quite considerable concentrations of these chemicals. Minimising exposure is therefore highly important. Many pesticides belonging to the organochlorine and organophosphate groups can be avoided by eating organic meat and animal produce. These chemicals are not allowed to be used in organic farming by law and so the concentration in organic meat is much lower, although they are still present in some organic foods due to environmental contamination. Avoiding food in plastic containers, particularly milk and other fat containing foods is also effective at reducing exposure. Fatty foods tend to accumulate more plasticisers because the chemicals are fat soluble. Exposure of plastic containers to heat and light may also increase the release of the chemicals to the foods, and plastic containers for food should not be exposed to these conditions.