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Don’t imagine that the UK is safe from this; levels in some of our houses were just as bad. Inside aeroplanes they found high levels too. And it became clear that human blood levels corresponded to the levels inside their houses — but that children had around ten times the blood levels of adults. Well, they do crawl around and put their hands in their mouths a lot. So this tells us that “feeding your child a bit of dirt” is no longer an option — but also, more worryingly, that they are already taking in significant amounts of toxins that way. I don’t have to tell you that they, we, are also exposed to potentially harmful levels of pesticides from food, water and air. Three cheers to Georgina Downs, by the way, for her victory over the government in her court case about crop-spraying and the amount of pesticides that country-dwellers are exposed to; go to her site at http://www.pesticidescampaign.co.uk/ and tell her we love her, and she’s a hero. But how much does all this have to do with allergies? The answer is emerging right now from the new science of genomics. My medical society is the British Society for Ecological Medicine (http://www.ecomed.or.uk); our by-line has always been “Allergy, Environment, Nutrition”, as these are the tools we use to help patients. |
But now we have to factor in genomics, the study of relatively minor changes in our DNA, and the health risks that they influence. The data is still patchy — we have a vast amount to learn — but there is one study that demonstrates the link between pollution, genomics and allergy, and it’s worth looking at carefully. There are several enzymatic pathways in the liver by which the body detoxes and removes chemicals. The single most important one is a bunch of closely-related enzymes called Glutathione-S-Transferases. In 2006 researchers in Californis studied people who have genomic variations in these (known as polymorphisms, from the Greek for many shapes); they took people who had known pollen allergies (hay fever), and exposed them to the pollen, but just before that they exposed them sometimes to second-hand tobacco smoke or to exhaust fumes. One group had these polymorphisms, the other didn’t. When exposed to pollen only, they all produced about the same amount of IgE (the major antibody in classical allergies such as hay fever and asthma). But when exposed to tobacco fumes before the pollen, the subjects with normal GSTM1 genes, who produced healthy enzymes, made 6 times as much IgE, but those with the “null” genes, who didn’t produce any functioning enzyme, made 15 times as much IgE (see Table 1). In other words, if your body can’t detox well, pollution can make your allergy a lot worse. |