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Environment
Pesticides have an effect on male fertility
Men exposed to dioxin father more girls, according to
a Russian study of workers exposed to pesticides containing
dioxin: the herbicide 2, 4 5-T and a biocide, chlorophenol.
The workers were exposed to these chemicals in the organochlorine
family at an agricultural chemical plant that operated
between 1961 and 1988 in the city of Ufa. While 106 boys
were born for every 100 girls in the areas's population,
the ratio fell to 54 boys for 100 girls among descendents
of plant workers. “These data are similar to data from
Seveso, Italy, where a lower birth rate for boys compared
to girls was observed among individuals who were badly
contaminated with dioxins and furans during accidental
exposure in July 1976,” notes Professor Gaétan Carrier,
whose work was published recently in the journal Environmental
Health .
From the Saint-Basile-le-Grand PCB fire to a study of
emissions from the Des Carrières incinerator, from
lead contamination to the effects of electromagnetic fields,
Mr. Carrier has been involved in all the hot environmental
issues in Québec in the past 20 years. When he proposed
a mathematical risk analysis model in his doctoral thesis,
he paved the way for a review of government environmental
health protection norms. Using this mathematical model,
he was able to evaluate the relationship between dioxin
and furan exposure and the ratio of male/female children
fathered by Ufa workers, even many years after the fact.
Working with researchers Zarema Amirova of the Ufa Environmental
Centre and John Jake Ryan of Health Canada, the holder
of the Chair in Human Health Toxicological Risk Analysis
at Université de Montréal studied the effect
of various types of dioxins on health by analyzing 84 samples
of blood from two cohorts of exposed workers, including
150 men and 48 women. The results showed a 30 times higher
average chemical concentration in these workers than among
the rest of the region's population. The ratio of male/female
births (40% boys/60% girls) was well below the ratio in
the city of Ufa and other urban areas around the world. “Normally,
we expect to see 51% and 49% respectively,” the researcher
notes.
But even more curious is the result he found based on
the sex of the parent who was exposed to the contaminant. “We
observed a reduction in the number of boys born to exposed
fathers, but no change for exposed mothers.” As in the
Seveso incident, exposure to high levels of dioxins is
associated with the more female births, but only where
the father was exposed. Actually, this “estrogenization” of
progeny associated with exposure to organochlorines is
not specific to humans. In an ecosystem such as Rivière
des Prairies, north of Montréal, biologists have
noted up to 70% more females in the mollusc and fish populations.
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