The Times (London, UK)
January 17, 2006


Rachel's summary: Recent research suggests a connection between
household use of insect sprays, medicated shampoos, and mosquito
repellants -- and childhood leukemia. Before using such chemical
preparations, we can always ask, "What's the least-harmful way to achieve
my goal?"

By Sam Lister

Children frequently exposed to household insecticides used on plants,
lawns and in head lice shampoos appear to run double the risk of
developing childhood leukaemia, research suggests.

A study by French doctors, published today in the journal Occupational
and Environmental Medicine, supports concerns raised in recent years
about the use of toxic insecticides around the home and garden —
including plant sprays, medication shampoos and mosquito repellents —
and a possible correlation with increased rates of acute leukaemia in

The latest study by Inserm, France’s national institute for medical
research, was based on 280 children who had acute leukaemia, newly
diagnosed and 288 children matched for sex and age but disease free.

Detailed interviews were carried out with each mother. These included
questions about the employment history of both parents, the use of
insecticides in the home and garden and the use of insecticidal
shampoos against head lice.

It showed that the risk of developing acute leukaemia was almost twice
as likely in children whose mothers said that they had used
insecticides in the home while pregnant and long after the birth.

Exposure to garden insecticides and fungicides as a child was
associated with a more than doubling of disease occurrence. The use of
insecticidal shampoos for head lice was associated with almost twice
the risk.

Describing the links as “significant”, the authors said that
preventive action should be considered to ensure that the health risks
to children were as small as possible. A group of pesticides known as
carbamates, which are present in plant treatments, lice shampoos and
insect sprays, are most commonly linked to cases of leukaemia.

There are three main carbamates used in the UK — carbaryl, carbofuran
and carbosulfan.

Head lice products containing carbaryl are now restricted to
prescription after a report by a government committee that gave
warning of potential carcinogenic properties.

Florence Menegaux, the lead researcher based at the Paris
headquarters, and her fellow authors said that no one agent could be
singled out and a causal relation between insecticides and the
development of acute childhood leukaemia “remains questionable”. But
they said that the patterns revealed suggested that the results should
be acted on and “preventative action” considered.

Leukaemia is the term used to describe a number of cancers of the
blood cells. In children about 85 per cent of these are acute
lymphoblastic leukaemia, and acute myeloid leukaemia accounts for most
of the rest.

Leukaemia makes up about a third of all cancers in children and
currently kills more than any other disease in the UK. Of the 500
children under the age of 15 who have the disease diagnosed each year,
about 100 die. Research has shown that boys are 10 per cent more
likely than girls to suffer the disease.

In the late 1960s, the mortality rate for leukaemia among children was
about 26 deaths per million of the population in England and Wales.
This dropped to about 10 by the late 1990s. But the incidence rate
increased — from about 40 to 45 cases per million — over the same

The number of new cases being diagnosed has been rising for at least
40 years, particularly in the under-5s.

Scientists believe that the cancer starts in the womb, with a second
event triggering the disease’s development in childhood. Studies are
continuing to determine whether this trigger is genetic,
environmental, dietary or related to other factors.

The possible link to pesticides remains hotly debated, with many
scientists disputing the suggestion that it is a significant factor.
Some have drawn attention to a potential “cocktail effect”, when
apparently safe chemicals cause problems if combined with others.

Although products sold for use in homes and gardens are tested,
mixtures of pesticides are not generally tested because of the number
of permutations involved.