Positive Health Online

Headlice are a frequent nuisance but cause no hazard to health beyond an itchy scalp. Yet they are treated with toxic pesticides, potentially capable of causing greater hazards to health and the environment than the lice themselves. Through the efforts of the pharmaceutical companies, chemical warfare against headlice is increasing and is the treatment recommended by many health authorities and health professionals. In 1991, 3 million treatments were sold in Britain at a cost of £8 million. By 1995, more than £14 million was spent[9]. However, the expense and the risks are unnecessary as a safe and effective non-chemical method of beth treatment and prevention is available.

The pesticides in headlice treatments are[3]: Malathion – an organophosphate in Derbac-M, Prioderm, Quellada-M, Suleo-M. Carbaryl – a carbamate in Carylderm, Clinicide, Derbac-C, Suleo-C, by prescription only until January 1998.

Pyrethroids – permethrin in Lyclear and phenothrin in Frill Marks. Lindane – an organochlorine, not sold in the UK but used in the USA. If the pesticides were effective, there would be some justification for their widespread use but according to one researcher, "the main problem in this therapeutic field which is riddled with ineffective products that are used in inadequate doses and in the wrong way is companies uncontested marketing and their recommendations for treatment that do not have a solid evidence base"[8].

Lack of effectiveness

A pesticide loses its effectiveness when the lice become resistant to it. Many health authorities have a policy of rotating from one pesticide to another every 3 years in order to prevent resistance[3]. But there is nothing to stop chemists from selling treatments not on the current rotation. Some treatments are not effective because the instructions are difficult to follow. Lotions must be left on about 10 hours and must cover the hair completely. Shampoos can be over-diluted or washed off before they have had time to act. Neither work unless repeated. Treatments are often ineffective if only some individuals with headlice are treated and the rest are untreated – left to reinfect those already treated.

Exposure

Exposure to the pesticides in headlice treatments is significantly higher than from eating food containing pesticide residues. Pesticides are toxic compounds and while they may well cause no hazard at the very low levels detected on food, frequent treatment can increase exposure to levels where there is a risk. Even if not high enough to cause any health risks to the individuals treated, the amount of pesticides washed down the drain to pollute water is of real concern to wildlife.

Health hazards

All of the pesticides used against headlice are toxic at high levels and there is concern about frequent exposure to lower levels. Malathion is a case in point – many health effects have been noted from malathion and its contaminants or breakdown products[2,7].

Heavy exposure brings on symptoms of dizziness, excessive salivation, urination, headaches, nausea, diarrhoea, convulsions, muscle weakness, incoordination, abdominal cramps, slowed heart beat, respiratory depression, paralysis, and coma. There are reports of deaths, poisoning, intestinal disorders, leukaemia, near sightedness and kidney damage after aerial spraying of malathion. From animal and in vitro tests, there is evidence of intestinal disorders, weakened immune system, lung damage, birth defects, chromosome damage, behavioural and reproductive effects. These are based on different amounts and kinds of exposure and may not be relevant to exposure in headlice treatments. However, there is one report of a severe birth defect in a baby born to a mother who had used malathion headlice treatment several times when she was 11 to 12 weeks pregnant[5].

The risk of cancer is a theoretical but unlikely possibility. There is uncertainty about malathion's ability to cause cancer 2. In 1995, the Ministry of Agriculture, Fisheries and Food took some steps to reduce exposure to carbaryl due to evidence of its carcinogenicity in animals [6]. However, the decision was taken not to restrict its use in headlice treatments because of the lack of alternatives. If carbaryl were not available and the lice became resistant to malathion and pyrethroids, there would be nothing left in the chemical armoury.

Environmental hazards

Malathion is extremely toxic to wildlife, capable of killing beneficial insects, snails, birds, fish, amphibians and soil microorganisms. There are reports of heart defects and damage to gills in fish, birth defects in turtles, mutations in tadpoles, impaired chemo-reception in shrimp, and liver and kidney damage in lizards at low levels of malathion and its breakdown products in the environment[7].

Safe alternative

There is an effective alternative against headlice which poses no risk to health or the environment and which shows the use of pesticides to be unjustified. This is the Bug Buster approach, promoted by Community Hygiene Concern[1] and available in Boots and other chemists for a one-off expense of £4.50. The hair is washed with regular shampoo and liberally conditioned with an ordinary conditioner. It is then combed thoroughly with a plastic Bug Buster comb every third or fourth day for two weeks. This approach is acknowledged by the Department of Health to be effective as long as the instructions are followed fully[4] and is the recommended treatment for headlice by many health authorities. The widespread adoption of the Bug Buster approach would go a long way towards reducing pesticide pollution and risks to health and the environment.

References

(1.) Community Hygiene Concern, 160 Inderwick Road, London N8 9JT, Phone 0181-341 7167. Produce teaching packs for schools, Bug Buster promotional days, full instructions on approach.
(2.) Brenner L, 1992, Malathion Fact Sheet, Journal of Pesticide Reform, Vol 12(4).
(3.) de Mont, 1993, Chemist & Druggist, 1 May, p iv-v.
(4.) DOH, 1997, Headlice Update, Department of Health Web Page – dorset.swest.nhs.uk/comm-dis/headlice.html
(5.) Lindhout D, 1987, Teratology, 36:7-9.
(6.) MAFF News Release, 1995,7 November, 389/95.
(7.) Sinclair, 1997, Malathion Medical Research, Web page – http://www.chemtox.com/malathion/malathion.htm.
(8.) Vander Stichele et al, 1996, BMJ, 13 January, 312:123.
(9.) Chemist & Druggist 22 July 1995, p124.