Q:Last month my daughter caught head lice at school and I had to go to the chemist to get some shampoo for her. After she had the treatment, I was horrified to read in the papers that some brands of this special treatment caused cancer in animals an

A:As you rightly say, parents everywhere were in a panic last month when the British government withdrew as an over-the-counter drug all brands of treatments for head lice containing carbaryl (such as Suleo-C and Derbac-C). These treatments are still allowed on prescription, but you can no longer walk into your chemist and buy them. The government announced that it had done so as a result of animal studies demonstrating that a cancer risk existed. Chemists pooh-poohed the move as hysteria, as the pesticide was used in lotions or shampoos that were used once or possibly repeated.

The government has given the all-clear for head lice treatments containing malathion or other substances, such as Derback M, Prioderm, Full Marks and Lyclear.......

Nevertheless, according to the Breakspear Hospital, the special centre for allergies and chemical sensitivities, malthion is an organophosphate pesticide of the general type used in sheep-dip. Both malthion and carbaryl work by blocking a bodily enzyme called cholinesterase. In humans this can cause such side effects as headache, nausea, paralysis, chest pain, muscular twitch, blurred vision, cramps, giddiness, impaired memory and disorientation, dizziness, tremulousness and hallucinations.

Recently, this variety of organophosphate has also been shown to cause certain long-term effects, such as disturbances in visual memory, dexterity and reaction, and verbal and visual attention.

Most serious long-term reactions tend to happen in patients who have been exposed to these pesticides over the long-term, such as farmers.

Although the likelihood of your child suffering these long-term effects is not high, given that he or she would be exposed once or maybe twice at a time to these substances, no one can say exactly what short-term exposure could do.

In response to patients' concerns, the Breakspear (run by our panellist Dr Jean Monro) offers up a non-toxic treatment of head lice.

This treatment combines shampooing, soaking and combing with a fine-toothed comb to remove the eggs (also called nits). It may be laborious, but you can rest easy in the knowledge that you won't be exposing your child to something the government might be issuing yet another warning about in the near future.

First, thoroughly wet your child's head with warm water and apply a coconut based shampoo or bar soap which contains dodecyl alcohol. This substance kills adult lice.

You could also use a shampoo which lists sodium lauryl sulphate on the label-a substance based on coconut oil. Work the shampoo into a lather and cover the entire hair area.

Rinse the shampoo and repeat the process, leaving the suds in the hair. Wrap your child's suds covered head in a towel for 30 minutes.

When the time is up, remove the towel and comb your child's hair with an ordinary comb to remove tangles. Then comb it again using a nit removing comb on one-inch sections of hair (the comb's manufacturers will describe exactly how to use it in an accompanying instruction sheet).

If the hair dries during this painstaking process, re-dampen it with water. But be prepared for nit-combing to take up to three hours, depending on how long and how curly your child's hair is.

Once all lice and nits are removed, wash the hair again with the same shampoo, rinse and dry. Thumb through the hair to check for any lice that may have been missed and remove them with the comb.

In a week to 10 days, check if any nits were missed and have since hatched. If they have, repeat the entire process again, including checking another week later for any rogue lice.

It's important to remember that if one member of your household has headlice, every one else in the family must be treated. Otherwise the infestation can be passed back and forth indefinitely.

Also, although it can be a real pain, make sure to have everyone comb their hair daily, to check for any lice. It's also wise to change your clothes and bed linen and towels every day and to vacuum all soft furnishings daily.

You also need to put pillow, blankets and duvets in your tumble drier to kill any lice that may be lurking there.