Wednesday, February 29, 2012

Common toxic exposures can affect future generations/PLOS

This story was reported today in Science News, and the scientific publication from which the story was derived also came out today in PLOS. The concept is troubling:  toxic materials we encounter in everyday life may seriously scar our progeny generations later.  Although this research was performed for the Army, using toxics encountered by military personnel, the toxic exposures were also those faced by civilians.  Exposures to incinerator fumes (dioxins), the linings of tin cans (bis-phenol-A) and insect repellents all affected rat offspring.

Back in 2009, I wrote about birth defect rates after anthrax vaccine, and noted that the rate of major birth defects was about 3.0% in the US population overall.  But the rate is higher in the military:  in  offspring of military women who did not receive anthrax vaccine prior to pregnancy, the birth defect rate is 3.85--4.0%.  In female military servicemembers  who received anthrax vaccine before or during their pregnancies, the birth defect rate rises to 4.5--4.7%.

Why is the birth defect rate higher for offspring of military mothers who did not receive anthrax vaccine than for civlian moms?  This report hints at an answer.  Exposure to toxic materials is widespread in the military and almost impossible to avoid, although less than in years past.
Pollutants long gone, but disease carries on
Certain chemicals cause epigenetic changes that foster illness in rats’ offspring
Exposure to certain pollutants early in a rat’s pregnancy can foster disease in her offspring during their adulthood as well as in subsequent generations, a new study shows. A wide range of pollutants elicited such lasting effects, despite future generations never encountering the triggering pollutant.
Some chemicals tested led to premature puberty among great-granddaughters, with an increased risk of disease in reproductive tissues. In some tests, the chemicals disrupted ovarian function, something that in humans could lead to infertility or premature menopause. And another chemical exposure caused premature death of sperm-forming cells in the great-grandsons, researchers report online February 28 in PLoS ONE.
Rather than altering genes, the tested pollutants altered chemical switches that regulate genes, reports Michael Skinner and his colleagues at Washington State University in Pullman. These epigenetic switches can lock a gene on or off...

In the new work, Skinner worked with the Army, which funded the study, to identify pollutants to which troops would probably be exposed. They settled on dioxins (spewed by burning materials or the defoliant Agent Orange); the insect deterrents DEET and permethrin; the plastic ingredients bisphenol A and phthalates; and jet fuel (often sprayed onto dirt for dust control). “I tried to pick classes of compounds that were across the whole [pollutant] spectrum — everything from hydrocarbons down to an endocrine disruptor like bisphenol A,” Skinner says.
The exposures used were relatively high, but not high enough to cause fetal deaths or signs of toxicity in either exposed rat moms or their pups. Yet “all promoted epigenetic transgenerational changes,” Skinner says. This suggests that epigenetic changes that get passed down through the generations are not some unique quirk of any one chemical, he says; he now suspects most pollutants have the potential to do this...


Anonymous said...

I am a concerned mother/grandmother wondering if you have any new findings on birth defects amongst military women and Anthrax vaccine? My daughter is an OEF veteran. Her son was conceived after deployment, but had severe genetic birth defects and died 3 days after he was born. He had VACTERL H and an omphalacele. She has had one miscarriage after his death. She is now 5 weeks pregnant. I am very concerned for the future of my third grandchild. On the base she was stationed at there were a few other mothers who gave birth to babies with birth defects. One baby was born without a brain. Any info would be helpful. Thank you.

Meryl Nass, M.D. said...

I have heard from a number of women who had children with birth defects or had miscarriages. It is likely that anthrax vaccinations are related to APLA syndrome, which causes miscarriages but can be treated.

Please see this post about anthrax vaccine and birth defects.