Neonicotinoids, a group of agricultural insecticides resembling nicotine, are currently the most widely used pesticides in the world and are well-known for their role in the rapidly declining bee populations.
In insects, neonicotinoids act on the nervous system, killing them by paralysis. However, very little research has been done on their effects on human health.
Now, new research published in the journal Environmental Health Perspectives reveals these pesticides may also be exerting a harmful effect on humans by disrupting our hormonal systems, particularly the production of estrogen.
The researchers have long been interested in the mechanisms of endocrine-disrupting chemicals and they wanted to determine whether neonicotinoids belong to this class of compounds.
“Endocrine disrupters are natural or synthetic molecules that can alter hormone function,” says Ph.D. student Élyse Caron-Beaudoin, the study’s main author. “They affect the synthesis, action, or elimination of natural hormones, which can lead to a wide variety of health effects.”
For the study, Caron-Beaudoin and Dr. Thomas Sanderson of INRS developed methods to evaluate the impact of neonicotinoids on the production of estrogens, essential hormones with several biological functions. The National Institute of Scientific Research (INRS) is a graduate university composed of four research and teaching centers in Quebec.
By targeting aromatase, an important enzyme in the synthesis of estrogens, the research team was able to test the effect of three neonicotinoids on breast cancer cells in culture after being exposed to neonicotinoid concentrations similar to those found in the environment in agricultural areas.
The findings reveal an increase in aromatase expression and a unique change in the pattern in which aromatase was expressed, similar to what is observed during the development of certain breast cancers.
“However, as these results were obtained in a cellular model of breast cancer, we cannot necessarily conclude that exposure to pesticides at concentrations similar to those in the human environment would cause or promote cancer,” Sanderson said. He indicates that more work must be done on the potential endocrine-disrupting effects of neonicotinoids.
The government of Quebec has recently decided to become more strict in their regulation of the use of certain pesticides, including neonicotinoids, which are widely used by Quebec farmers to control crop pests.
The current study is the first to show that neonicotinoids have an effect on aromatase gene expression and may potentially alter estrogen production. Hormonal disturbance by these insecticides will need to be confirmed in future research, but the new findings show that caution should be used in the management and use of neonicotinoids.