(Beyond Pesticides, April 4, 2017) Exposure to commonly used pyrethroid insecticides results in the early onset of puberty in boys, according to a study presented at the 99th meeting of the Endocrine Society in Orlando, Florida this week. Pyrethroids, which exhibit endocrine disrupting properties, have the ability to interfere with the proper regulation of the human body’s hormonal system. This research is the first to investigate not only the association between pyrethroids and accelerated puberty, but also the causal mechanisms involved in the physiological changes taking place within the human body.
For the study, Jing Liu, PhD, and colleagues from Zhejuang University in China, analyzed the urine in 463 Chinese boys aged 9 to 16 for the presence of metabolites from the pyrethroid insecticide cypermethrin. Results show that a 10% increase in the metabolite 3-PBA is associated with a roughly 4% increase in luteinizing and follicle-stimulating hormones, which facilitate puberty and sperm production. The author’s note that, “Boys with increased urinary levels of 3-PBA have a significantly increased risk of earlier pubertal onset, in which the odds of being in an advanced pubertal stage are increase by 73% to 110%.”
The study, acknowledging the limitation in determining causality, further investigates the mechanism which gives rise to this development in laboratory studies using test tubes and rodents. Dr. Liu and his team found that the same process held up in rodent models, with cypermethrin accelerating puberty through hormonal release. Rather than a response from the hyperthalamus, which controls the release of pituitary luteinizing and follicle-stimulating hormones, scientists found that cypermethrin acts directly on cells within the testis and pituitary glands.
“This is the first study to provide evidence that environmental exposure to pyrethroids. . .is associated with measurable effects on male pubertal development. Given the growing use of pyrethroid insecticides, we must prudently assess these chemicals for their risks to children’s health,” Dr. Liu indicated in a statement to Medscape.
Given recent data on the rise in use of these chemicals for household pest control, both researchers and advocates are concerned about the range of implications these chemicals could be having on young children in the U.S. and abroad. Previous research finds these chemicals are associated with behavioral problems in children, including externalizing and internalizing disorders, ADHD, and delayed cognitive and motor development. Proximity to heavy use of these chemicals in agriculture is associated with an 87% increased risk of a child developing autism when applied during pregnant mother’s third trimester.
Pyrethroids have also been linked to cancer in young children. Exposure to permethrin in utero is linked to increased risk of infant leukemia diagnosed before age two. In an interview with Medscape, Julie Ann Sosa, MD, a surgical oncologist and endocrine surgeon at Duke University Medical Center, said, “We need to understand that ‘progress’ potentially comes with a cost. If we understand the cons, we can start to work on alternatives [that are safer].”
Beyond Pesticides continues to encourage alternatives to the use of toxic, endocrine disrupting pyrethroid chemicals for use in pest management. To manage home and garden pests, refer to the ManageSafe tool, where you’ll find strategies to fight the causes of a pest outbreak, rather than focus on the symptoms. For alternatives in controlling nuisance and public health mosquito outbreaks, see the Mosquito Management and Insect-Borne Diseases webpage. And for agriculture, learn about why organic, which prohibits synthetic pyrethroids, is the right choice for you and your family when you shop. Lastly, to facilitate a community level conversion to safer practices, Beyond Pesticides has the Tools for Change needed to institute lasting protections.
All unattributed positions and opinions in this piece are those of Beyond Pesticides