07
Mar
Bee-Toxic Neonicotinoid Insecticide Exposure Linked to Hormone-Dependent Breast Cancer
(Beyond Pesticides, March 7, 2019) A publication in the journal Environmental Health Perspectives highlights findings from a recent study showing that environmental concentrations of the neonicotinoid insecticides thiacloprid and imidacloprid increase expression of a gene linked to hormone-dependent breast cancer. Authors of the featured study uncovered a pathway through which neonicotinoids stimulate excess estrogen production, known to occur during the development of progressive hormone-dependent breast cancer. In the words of the authors, “Our findings highlight the need for further research to assess the potential impacts of low-dose and chronic exposure to neonicotinoids on endocrine processes affecting women’s health.”
The study, published in Environmental Health Perspectives in April 2018 by researchers at the University of Quebec, is not the first to point to a potential link between neonicotinoid exposure and breast cancer. A 2015 study by the same research group revealed that the neonicotinoids thiacloprid and thiamethoxam, along with the herbicide atrazine, induce similar effects in breast cancer cells. In both studies, exposure to neonicotinoids alter promoter activity to induce heightened production of the enzyme aromatase, which is known to stimulate estrogen production and thereby cancer cell proliferation.
The recently published study, authored by Silke Schmidt, PhD, brings greater urgency to the group’s findings, quoting first author Elyse Caron-Beaudoin as stating, “This provides in vitro evidence that neonicotinoids can be endocrine disruptors and that aromatase may be one of their targets. Importantly, the promoter switch occurs at concentrations that are highly relevant to humans.” Indeed, authors were careful to test concentrations of thiacloprid and imidacloprid “similar to those found in urine samples of farmers and women from the general population in Japan (Nomura et al. 2013; Ueyama et al. 2015).”
These findings add to a growing body of scientific evidence suggesting that neonicotinoids cause unreasonable harm to the environment and human health. Neonicotinoids are infamously known for their central role in pollinator decline, but as more and more studies reveal, that is just the tip of the iceberg. Because these chemicals are broad-spectrum insecticides, beneficial soil dwelling insects, benthic aquatic insects, grain-eating vertebrates, along with pollinators are also victims of these systemic chemicals. Even slight deviations in exposure levels take a heavy toll on vulnerable wildlife. University researchers have found that tiny amounts of neonicotinoids are enough to cause migrating songbirds to lose their sense of direction and become emaciated.
The newfound evidence suggesting neonicotinoids as potential endocrine disruptors is of particular concern given that these insecticides are ubiquitous in the environment, found across land types and waterbodies, regardless of individual management decisions and practices. A recent study in Switzerland found neonicotinoids in sparrow feathers sampled from all 47 farms studied, including a range of organic, integrated-production and conventional farms. A 2018 study by U.S. Geological Survey (USGS) researchers found neonics widespread in the Great Lakes at levels that harm aquatic insects—the foundation of healthy aquatic ecosystems.
Unsurprisingly, human exposure to neonicotinoids is also on the rise. A recent study by researchers at the U.S. Geological Survey (USGS) and the University of Iowa found two metabolites of imidacloprid in drinking water that have never been detected previously, nor evaluated for their potential risks to human and environmental health. Experts warn that these metabolites may morph further into new forms of chlorinated disinfection byproducts (DBPs) during routine water treatment processes, with potential for high toxicity to humans due to loss of insect-specificity. The authors warn, “Because of their pervasiveness in source waters and persistence through treatment systems, neonicotinoids are likely present in other drinking water systems across the United States.”
With significance at known exposure levels, the newest findings linking neonicotinoids to endocrine disruption and breast cancer highlight yet another unacceptable hazard wrought by pesticide use. Beyond Pesticides holds the position that nothing short of a complete transformation to organic, least-toxic practices can begin to reverse the damage wrought by decades of unchecked poisoning. Stay abreast of new public health findings by reading Beyond Pesticides’ Daily News Blog and Pesticide-Induced Diseases Database. Join the movement to end destructive pesticide use by engaging at the local, state and federal levels to transform our agricultural system.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Sources: Environmental Health Perspectives
