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Pesticide chemicals linked to food allergies

4th December 2012

Researchers in the United States say that chemicals found in chlorinated tap water have been linked to higher incidence of food allergies.


People who had high levels of dichlorophenols in their urine were found to be more susceptible to food allergies.

According to Elina Jerschow, assistant professor of allergy and immunology at the Albert Einstein College of Medicine in New York, high levels of pesticides containing dichlorophenols can weaken food tolerance.

For some people, this will mean they become allergic to more foods.

Jerschow said dichlorophenols can be found in chlorinated tap water, as well as in insect and weed control products and pesticides used in agriculture.

Jerschow and fellow researchers studied a group of 2,211 participants in the US National Health and Nutrition Examination Survey, looking for the incidence of food allergies.

In a study published in the journal Annals of Allergy, Asthma and Immunology, they looked particularly closely at the 25% of study subjects who had the highest levels of dichlorophenols in their urine samples.

This group was found to be 80% more likely to be allergic to foods than the rest of the participants.

Typical food allergies can include eggs, peanuts, milk or shellfish.

The 550-strong group was also 61% more likely than the rest of the participants to have an allergy to something in the environment; pollen, for example.

The team concluded that there was a consistent association between dichlorophenol exposure and the level of food allergies.

According to Jerschow, previous studies have shown that both food allergies and environmental pollution - which includes pesticide residues in food and water - are on the rise in the United States.

She said that the two trends could be linked, and that increased use of pesticides could be behind the boom in food allergies.

However, further research will be needed to confirm this hypothesis.

Even if the link is proven, simply avoiding tap water is unlikely to make much difference.

Jerschow said that dichlorophenols, which are formed as a by-product when water is chlorinated, are also widely found in fruit and vegetables which have been treated by pesticides.

The Geneva-based World Health Organisation says it only has limited data on the toxicity of the compounds, which are formed when phenols from plants react with chlorine.

The number of US citizens with food allergies grew by 18% from 1997-2007.

Many of these were allergies to milk, eggs, peanuts, wheat, tree nuts, soy, fish, and shellfish.

A similar rise has been noted in the UK, where experts suggest there may be more behind it than greater awareness in the general population.

One in 20 children living on the Isle of Wight was found to have a food allergy, confirmed by clinical testing.

Not everyone who thinks they have a food allergy actually does.

More than a third of people believe they are allergic to at least one type of food, but only one in 10 actually are, according to a study carried out by the UK's National Institute for Health and Clinical Excellence in 2010.

One water company in the UK said their water was chlorinated only after it had been purified, which meant there should be no organic matter, or phenols, for the chlorine to react with.

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