Research suggests that chemicals found in tap water and pesticide-treated fruits and vegetables may weaken your immune system and increase your risk of food allergies.

Food allergies seem to be on the increase around the world, with recent studies confirming a significant rise in their incidence, particularly among children.

Allergies are caused when the body's immune system reacts to a substance that would normally be harmless, such as pollen or naturally occurring substances in foods.

In some people, the body identifies this substance as a threat and produces an exaggerated response to it, resulting in symptoms ranging from a mild rash to life-threatening anaphylaxis.

In the case of food allergies, one of the possible causes may be changes in our environment, with evidence showing that pollutants can exacerbate existing allergies, while the so-called 'hygiene hypothesis' suggests that modern-day children's lack of exposure to bacteria may hinder the development of their immune system.

Now, new research from the US suggests that another potential cause of food allergies may be the presence of pesticides in our tap water.

According to a study in the Annals of Allergy, Asthma and Immunology, the chemicals that are used to purify tap water may be partially to blame for rising rates of food allergies.

Scientists looked at data on 2,211 people who had taken part in the US National Health and Nutrition Examination Survey in 2005-06 and had measurements of chemicals called dichloriphenols taken from urine samples.

They found that high levels of dichlorophenols - which are used to chlorinate water - were associated with an elevated risk of food allergies.

Lead study author Dr Elina Jerschow, a fellow of the American College of Allergy, Asthma and Immunology, said that high levels of these chemicals in the body "can possibly weaken food tolerance in some people, causing food allergy".

She observed that both food allergies and environmental pollution are known to be increasing, and that the study results "suggest these two trends might be linked".

Dr Jerschow also noted that dichloriphenols are "commonly found in pesticides used by farmers and consumer insect and weed control products, as well as tap water".

This means that as well as coming out of our taps, we may be ingesting these potentially allergy-inducing chemicals whenever we eat fruits and vegetables that have not been grown using organic methods.

Taken together, the findings highlight the potential health harms caused by modern chemicals and underline the need to employ natural means to protect and bolster our immune system.