Lots of recent research on neonicotinoid pesticides has focused on their deadly effects on honeybees and hives, but few have studied their possible effects on human health.
Now, a Quebec research team has made some disturbing findings, including how the pest killers might affect unborn babies during pregnancy, and how they play a role in fuelling breast cancer.
Elyse Caron-Beaudoin, a postdoctoral fellow at the University of Montreal's School of Public Health, says while neonic pesticides have passed tests related to their toxicity in order to be approved for use in Canada, no one has looked at the long-term effects of these chemicals on human hormone production.
鈥淎nd so that鈥檚 what we decided to investigate,鈥� Caron-Beaudoin told 麻豆影视 Channel from Montreal Thursday.
She and her team decided to focus on estrogen production in two contexts: during pregnancy and during the development of breast cancer.
Since it would have been unethical to experiment on actual pregnant women or breast cancer patients, she and her team tried to mimic some of those physiological processes in the lab.
In the pregnancy model, they used a 鈥渃o-culture鈥� of two different cells placed put together to mimic the interaction between the fetus and the placenta.
鈥淲e exposed that model to neonic insecticides at concentrations that we would find in the environment, and what we found was there was an alteration of estrogen production,鈥� she explained.
While it鈥檚 unclear what effects that estrogen disruption might have on real humans, Caron-Beaudoin notes that previous research has shown varying hormone levels in pregnancy can harm the baby.
鈥淲e know that alteration of estrogen production during pregnancy is associated with some negative birth outcomes, like low birth weight and smaller heads,鈥� she said.
For their second round of experiments on the effects of neonics on breast cancer, Caron-Beaudoin鈥檚 team used a cancer cell line derived from breast cancer patients.
She explained that in hormone-dependent breast cancer -- which comprises the majority of breast cancer -- the growth and proliferation of cancer cells is driven by high concentrations of estrogen.
鈥淪o we exposed those cells to concentrations of neonics that we would commonly find in the environment, and we saw there was an increased activity of a protein, of an enzyme that is responsible (for) estrogen production. So again, we saw that neonics could potentially be endocrine disruptors ,鈥� she said.
That enzyme is called aromatase, which turns the hormone androgen into small amounts of estrogen in the body. One of the key treatments for hormone-dependent breast cancer is aromatase inhibitors, which help block the production of estrogen.
The full results of Caron-Beaudoin鈥檚 research will appear in an upcoming issue of Environmental Health Perspectives.
Neonicotinoids remain the most commonly used insecticides in Canada, and are used on the majority of cornfields in Ontario and Quebec and fruit orchards to keep them free from aphids, spider mites and stink bugs.
Quebec announced last month new restrictions on three neonic pesticides, a move applauded by the The Suzuki Foundation and beekeepers, but one that was met with criticism from the Quebec Grain Producers.
Ontario limited the use of neonics for corn and soybeans in 2014, while the cities of Vancouver and Montreal have banned their use entirely within city limits.
