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PESTICIDE residues may be affecting the reproductive systems of children in
developing countries, say researchers in Belgium.

A team led by Jean-Pierre Bourguignon from the University of Liège has
found that children who had immigrated from countries such as India and Colombia
are 80 times more likely to start puberty unusually young. The researchers
suspect that DDT may be to blame.

Three-quarters of these immigrant children with “precocious puberty” had high
levels of a chemical derivative of DDT in their blood. This chemical, called
DDE, mimics the effects of the hormone oestrogen, which is important in
controlling sexual development.

Children with precocious puberty start sexual development several years
earlier than normal. The girls in Bourguignon’s study started developing breasts
before the age of eight, and started their periods before they were 10.

Youngsters emigrating to other European countries also have an increased
tendency to begin puberty early. This effect was thought to be because children
who were undernourished in their home countries gain weight rapidly upon
reaching the West. But the Belgian researchers found that this theory couldn’t
explain what they saw. “Some foreign children were not retarded for weight or
growth when they arrived,” says Bourguignon. And there was no particular home
country affected, suggesting genetic factors weren’t responsible either.

The team tested the children for a range of pesticides and found that 21 out
of 26 immigrant children with precocious puberty had high levels of DDE in their
blood. The chemical was only detectable in 2 out of 15 native-born Belgian
children.

“The results certainly suggest an environmental factor,” says endocrinologist
Stuart Milligan of King’s College London. But he says more studies are needed to
confirm a link with pesticides. “What’s dangerous is to create a scare story
from something that’s not proven,” he says.

DDT has been banned in the European Union and the US for decades, but it is
still commonly used in many developing countries, mainly to control malaria.

Bourguignon and his team now plan to check whether immigrant children with
early puberty have higher levels of pesticide than those who don’t. They’re also
studying the effects of DDE in the lab. Preliminary results suggest that in rats
DDE causes the brain to send out the biochemical signals that stimulate puberty.
“It may have a priming effect,” Bourguignon says.

He suggests that children in developing countries don’t normally suffer from
early puberty because they tend to be undernourished, and this slows their
development down. But even if the effect on puberty is masked, their
reproductive systems could still be harmed. “There is concern about other
pesticide effects, for example hormone-sensitive cancers such as breast cancer,”
says Bourguignon.