Use of
organophosphates has lessened, but risks to early brain development still too
high
University of
California - Davis Health
Public health experts
have found there is sufficient evidence that prenatal exposure to widely used
insecticides known as organophosphates puts children at risk for
neurodevelopmental disorders.
In a scientific review
and call to action published in PLOS Medicine, the researchers call
for immediate government intervention to phase out all organophosphates.
"There is
compelling evidence that exposure of pregnant women to very low levels of
organophosphate pesticides is associated with lower IQs and difficulties with
learning, memory or attention in their children," said lead author Irva Hertz-Picciotto,
professor of public health sciences, director of the UC Davis Environmental
Health Sciences Center and researcher with the UC Davis MIND Institute.
"Although a single organophosphate -- chlorpyrifos -- has been in the national spotlight, our review implicates the entire class of these compounds," Hertz-Picciotto added.
Originally developed
as nerve gases and weapons of war, organophosphates today are used to control
insects at farms, golf courses, shopping malls and schools. They kill pests by
blocking nerve signaling.
People can come into
contact with these chemicals through the food they eat, the water they drink
and the air they breathe. As a result, organophosphate pesticides are detected
in the vast majority of U.S. residents, according to Hertz-Picciotto.
Elevated risks even
with low-level exposures
While existing limits
on organophosphates have reduced exposures, the review authors said this isn't
enough. Based on more than 30 epidemiologic studies and scores of experimental
studies in animals and cell cultures, they believe the evidence is clear:
Exposure to organophosphates before birth, even at levels currently considered
safe, is associated with poorer cognitive, behavioral and social development.
"It should be no
surprise that studies confirm that these chemicals alter brain development,
since they were originally designed to adversely affect the central nervous
system," Hertz-Picciotto said.
Despite growing evidence of harm and recommendations from scientific advisors to and scientists within the U.S. Environmental Protection Agency, many organophosphates remain in use. This may be in part because low-level, ongoing exposures typically don't cause visible, short-term clinical symptoms, leading to the incorrect assumption that these exposures are inconsequential, according to Hertz-Picciotto.
"Acute poisoning
is tragic, of course, however the studies we reviewed suggest that the effects
of chronic, low-level exposures on brain functioning persist through childhood
and into adolescence and may be lifelong, which also is tragic,"
Hertz-Picciotto explained.
Recommendations to
protect children
In addition to
conducting the scientific review, the authors offered recommendations for
substantially reducing organophosphate exposures, including:
- Removing organophosphates from agricultural and non-agricultural uses and products
- Proactively monitoring sources of drinking water for organophosphate levels
- Establishing a system for reporting pesticide use and illnesses
- Until a ban can occur, the reviewers recommend:
- Greater medical and nursing education on organophosphates to improve treatment for and patient education on avoiding exposures
- Training for agricultural workers in their languages on proper handling and application of organophosphate pesticides
- Increased use of less-toxic alternatives and a transition toward sustainable pest-control measures
