This 2020 rodent study from the labs of Dr. Michael Skinner at Washington State University examined how great-grandmothers’ insect repellent exposures produced diseases in their great-grand offspring:

“Permethrin and DEET are the pesticides and insect repellent most commonly used by humans. These pesticides have been shown to promote the epigenetic transgenerational inheritance of disease in rats.

Direct exposure impacts an individual and their germ line. If germline epigenetics are modified, offspring generated with the affected germ cell can have epigenetic impacts on health and physiology.

Negative health effects of pesticides exposure do not stop with the individuals directly exposed. Epigenetic transgenerational inheritance occurs when future generations without exposure also exhibit alterations and disease. Epigenetic alterations are more common among individuals with disease than specific genetic alterations or mutations.

Pathologies examined are relevant to human populations including prostate, testis and kidney disease, as well as multiple disease incidence. No common DMR [differential DNA methylation region] among the different transgenerational disease DMR biomarkers was identified.

Observations suggest a common set of epimutations is not present between different diseases to alter general disease susceptibility. Although suggestions of such general molecular impacts for disease susceptibility may exist, the current study suggests predominately disease specific epimutations.

DMRs are present for each individual disease on all chromosomes, except the Y chromosome and mitochondrial DNA. The multiple disease signatures are present on the Y chromosome, as well as all other chromosomes. These results support the idea that transgenerational epigenetic effects of ancestral pesticides exposure are genome-wide.

The current study used an epigenome-wide association analysis to identify an epigenetic signature of transgenerational disease present in sperm. Biomarkers identified herein may potentially be used to assess paternal transmission of disease susceptibilities to future generations.”

https://ehjournal.biomedcentral.com/articles/10.1186/s12940-020-00666-y “Epigenome-wide association study for pesticide (Permethrin and DEET) induced DNA methylation epimutation biomarkers for specific transgenerational disease”

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Don’t understand how studies on long-term effects of day-to-day human actions like applying insect repellent aren’t front page news. Everyone could benefit from this knowledge. When I explained this study to coworkers, they had a lot of questions and feedback.

An interesting side note was peer review exchanges. A human behavior indicator was pushback regarding repetition of key points among sections, which the researchers justified with:

“The reader does not have to skip back and forth between sections to understand the basic design and methods used.”

Behavioral aspects of epigenetic inheritance haven’t been investigated by this research group. Wouldn’t inherited conditions produce behavioral evidence of their consequences?

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