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 Pesticides known as organophosphates were originally developed as
nerve gases and weapons of war, and today are used to control
insects at farms, golf courses, shopping malls and schools. People
can be exposed to these chemicals through the food they eat, the
water they drink and the air they breathe.
Restrictions on these chemicals have reduced but not eliminated
human exposure in recent years. The chemicals should be banned
outright because even at low levels currently allowed for
agricultural use, organophosphates have been linked to lasting brain
impairment in children, scientists argue in a policy statement
published in PLoS Medicine.
"Exposure to these organophosphate pesticides before birth is
associated with conditions that can persist into late childhood
and/or pre-adolescence, and may last a lifetime," lead author of the
statement Irva Hertz-Picciotto, director of the Environmental Health
Sciences Center at the University of California Davis School of
Medicine in California, told Reuters Health.
"Research on organophosphates now presents strong evidence that
includes behavioral outcomes such as problems with attention,
hyperactivity, full-blown ADHD, autistic symptoms or autism spectrum
disorder (ASD) or other behavioral issues," Hertz-Picciotto said in
an email.
Despite growing evidence of harm, many organophosphates remain in
widespread 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, Hertz-Picciotto said.
"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 said.
Once the organophosphates enter the lungs or the gut, they are
absorbed into the bloodstream, and can pass through the placenta to
babies developing in the womb. From there, the blood can carry these
chemicals to the developing brain.
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To prevent prenatal exposure to these chemicals, the products should
no longer be used for agricultural or other purposes, scientists
argue. Water should also be monitored for the presence of these
chemicals, and there should be a central system for reporting
pesticide use and illnesses linked to the products.
Absent a complete ban on these chemicals, doctors and nurses should
receive training to learn how to recognize and treat
neurodevelopmental disorders related to exposure and clinicians
should also educate patients on how to avoid or minimize exposure.
Eating organic foods may also help curb exposure to pesticides,
Hertz-Picciotto advised.
Pregnant women can also help prevent neurodevelopmental disorders in
children by taking prenatal vitamins with folic acid and iron.
"We have known for several decades that high exposure to
organophosphates can cause severe neurological impacts, and even
death; this isn't surprising, after all, because they were
originally designed as nerve agents in the period between the two
World Wars," said Dr. Joseph Allen, director of the Healthy
Buildings Program at the Harvard T.H. Chan School of Public Health
in Boston.
Since then, widespread use of these chemicals at lower levels in
pesticides was assumed to be harmless to humans, Allen, who wasn't
involved in the paper, said by email.
"This was shortsighted," Allen said. "The scientific evidence has
piled up and it shows that even low-level, prenatal exposure can
cause high-level, lifelong effects."
SOURCE: https://bit.ly/2PoyfCU PLoS Medicine, online October 24,
2018.
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