Herbicides Linked to Infant Health
ProblemsThe herbicides atrazine, cyanazine and metolachlor may be linked to a range
of adverse health effects, including respiratory distress, cerebral palsy and
impaired development. According to a recent study of drinking water
contamination in Iowa, these three herbicides were each associated with higher
community levels of intrauterine growth retardation (slow fetal growth resulting
in low birth weight) among newborns. The researchers said that slow fetal growth
is a predictor of increased infant mortality and is the second leading known
cause of fetal death.
The researchers pointed out that this study is based on data at the community
level rather than on data collected from individuals, and stressed that their
findings should be considered preliminary until more detailed epidemiological
studies on individual exposure levels are carried out.
However, they stated that previous studies have indicated herbicides can
cause adverse effects on growth and development in laboratory animals and that
atrazine has been linked to endocrine disruption. These studies suggest that the
reported link in Iowa between herbicide consumption and slow fetal growth is
biologically plausible.
The study examined 13 communities in southern Iowa served by the Rathbun
Regional Water Association, a water system that supplies drinking water
exclusively from the Rathbun reservoir. It compared levels of contaminants in
the Rathbun communities' water with drinking water from other communities in
southern Iowa. The communities were similar in population size, education level,
income and other demographic variables.
Between 1984-1990, drinking water in the Rathbun system had more positive
detection's of alachlor, atrazine, cyanazine, metolachlor and 2,4-D than
drinking water in other communities surveyed. The mean level of atrazine in
Rathbun was 2.2 micrograms/liter during this period compared to 0.8
micrograms/liter for other surface water supplies examined.
For cyanazine, the difference was 1.4 micrograms/liter in Rathbun compared
to 0.7 micrograms/liter in other surface waters.
The study also compared birth records of babies born to mothers living in
communities served by the Rathbun reservoir with babies whose mothers lived in
the other southern Iowa communities. Researchers found that communities in
southern Iowa served by the Rathbun reservoir had a higher rate of slow fetal
growth than the other communities included in the study. During 1984 to 1990,
the percentage of live births with slow fetal growth was 11.2% in the Rathbun
communities compared to a range of 6.4%-6.9% in the other communities.
Statistical analyses revealed that atrazine, matolachlor and cyanazine were
each significant predictors of community rates of slow fetal growth. The
researchers stated that a strong causal relationship cannot be inferred,
however, owing to limitations in the study design.
Atrazine, cyanazine and metolachlor are widely used herbicides in the U.S.
According to a recent review of pesticide use in the North American Great Lakes
Basin, metolachlor, atrazine and cyanazine are, respectively, the first, second
and seventh most used pesticides by weight in the region. Due to concerns that
atrazine and cyanazine pose serious health and environmental risks, the U.S.
Environmental Protection Agency (EPA) put them in Special Review to examine
their hazards and benefits in 1994.
Cyanazine was subsequently removed from Special Review because it is being
phased out -- DuPont, its manufacturer, is withdrawing all uses in the U.S. by
the end of 2002. EPA expects to complete atrazine's Special Review by 1999. EPA
considers atrazine, cyanazine and metolachlor to be "possible human
carcinogens."
