Each year, more than 39,000 women are diagnosed with breast cancer in the UK. It is estimated that one in nine will develop breast cancer in their lifetime.

The disease is now the most common form of cancer in women worldwide and while the exact cause is unknown, risk factors include age, diet, the Pill, HRT, obesity and family history.

According to Dr Charles Caulier, a toxicologist in Liege, Belgium, there is another risk factor to consider. His recent study found that women with breast cancer had higher pesticide residues in their bloodstream than healthy women.

In fact, women diagnosed with breast cancer were five times more likely to have DDT residues and nine times more likely to have residues of HCB (hexachlorobenzene) in their blood than a control group.

DDT is an organochlorine which, when broken down, mimics the female hormone oestrogen. Originally developed to control insects and protect crops, DDT was banned in 1972. However, it is still used to eradicate mosquitoes in developing countries.

DDT can remain active in tissues for up to 50 years and small quantities are still absorbed from the food chain.

HCB was used as a fungicide but banned in 1965. It is still found in the environment because of past usage and as a by-product of other chemicals.

The US Environmental Protection Agency ranks HCB in the top ten per cent of the most toxic chemicals. It is also classed as a probable human carcinogen.

Like DDT, it is called a "hormone disrupter" because it mimics the action of oestrogen in the body. Researchers suspect our exposure to increased levels of oestrogen or oestrogen-like compounds increases the risk of breast cancer.

"Foreign" oestrogens (also called xenoestrogens) accumulate in fatty tissue and, as women have a higher proportion of body fat than men, they are particularly vulnerable to the 400 or so pesticides routinely used in conventional farming.

Nobody knows what risks mixtures of such agents pose to the immune system.

By avoiding pesticides as much as possible, women can minimise exposure to potentially harmful agents.

Peel fruit and vegetables but be aware many chemicals remain within the plant. By eating organic food, you will not only reduce your intake of pesticides but improve your intake of nutrients and antioxidants.

The standards for organic food are laid down in European law and organic farms and food companies are regularly inspected.

Watch out for xenoestrogens in your immediate environment. Don't use synthetic chemicals in the garden and be aware some of the cleaning products or paints used in your home may be hormone disrupters.

Filter your water and avoid wrapping food in plastics.

Help block the action of harmful oestrogens by increasing your intake of phyto-oestrogens, found in fermented soy products (tempeh, miso), tofu, lentils, chickpeas and flax seed.

Eat cruciferous vegetables such as cabbage and broccoli. They contain compounds that help the body get rid of excess oestrogen more efficiently.

The soluble fibre in fruit and vegetables also binds to oestrogen and toxic wastes, preventing build-up.

Avoid alcohol and nicotine and exercise regularly.

In the fight against breast cancer, prevention remains the best weapon.