Features Production Research
Pesticides exposure linked to suicidal thoughts

October 29, 2009 — A new
study in China has found that people with higher levels of pesticide exposure
are more likely to have suicidal thoughts.

October 29, 2009 — A new
study in China has found that people with higher levels of pesticide exposure
are more likely to have suicidal thoughts.

The study was carried out
by Dr. Robert Stewart from the Institute of Psychiatry at King’s College London
together with scientists from Tongde Hospital Zhejiang Province.

The agricultural
pesticides commonly used in China are organophosphates, which are in wide use
in many lower income countries but have been banned in many Western nations. It
is well known that they are very dangerous if ingested as an overdose but there
is also biological evidence that chronic low-grade exposure to these chemicals,
which are very easily absorbed into the body through the skin and lungs, may
have adverse effects on mental health. This study is the first epidemiological
evidence to suggest possible effects on suicidal thoughts.

The study was carried out
in central/coastal China, a relatively wealthy area with a rapidly developing economy.
In a very large survey of mental health in rural community residents,
participants were also asked about how they stored pesticides. The study found
that people who stored pesticides at home, i.e. those with more exposure, were
more likely to report recent suicidal thoughts. Supporting this, the survey
also found suicidal thoughts to be associated with how easily accessible these
pesticides were in the home and that the geographic areas with highest home
storage of pesticides also had highest levels of suicidal thoughts in their
populations.

Given the high level of
pesticide exposure and the high suicide risk in rural China, clarification of
the causal mechanisms underlying this association and the development of
appropriate interventions should be priorities for public health and health
policy.

“Organophosphate
pesticides are widely used around the world although are banned in many
countries because of their risk to health,” said Dr. Stewart. “They are
particularly lethal chemicals when taken in overdose and are a cause of many
suicides worldwide. Our research findings that suggest that higher exposure to
these chemicals might actually increase the risk of suicidal thoughts provides
further support for calls for tighter international restrictions on
agricultural pesticide availability and use.”

“The findings of this
study suggested potential causal links and might partially account for the much
higher incidence of suicide in rural than urban areas of China,” added Dr.
Jianmin Zhang, associate chief psychiatrist at Tongde Hospital of Zhejiang
Province, and vice director of the Zhejiang Office of Mental Health in China.
“However, further studies particularly with more precisely defined and assessed
exposure are critically needed, as awareness of safer access to pesticides is
important both to policy-makers and pesticide users.”

The analysis involved data
from a survey of a representative sample of 9,811 rural residents in Zhejiang
province who had been asked about the storage of pesticides at home and about
whether or not they had considered suicide within the two years before the
interview.