12/04/2008 05:12 am ET Updated Nov 17, 2011

Rain, Autism, and Mercury

A new study out of Cornell University says that children growing up in the rainiest or snowiest areas of the country seem to have a higher risk for autism than children living in drier climates.

The authors estimated that removing precipitation as a factor in autism would slice the prevalence of the disorder by 33% to 43%.

Among the possible explanations given were: A lack of vitamin D from a sun-deprived life under the clouds, an increased amount of time spent indoors amid toxic household chemicals, or the presence of dangerous neurotoxins in the precipitation itself, which in turn might trigger a genetic predisposition to ASD.

One of the most omnipresent, growing (and obvious) air-borne neurotoxins in the world to consider, of course, is mercury.

For a number of years, I have questioned whether rising levels of mercury from coal-fired power plants and other sources might be contributing to the overall body burden of heavy metals in pregnant women and infants in North America and elsewhere.

This "background" mercury, combined with mercury from maternal seafood consumption, dental amalgams, the vaccine preservative thimerosal, and other sources, might combine and accumulate in the systems of genetically susceptible infants and fetuses, resulting in autism, I have speculated.

It is not clear how mercury fallout onto land and surface water can cause higher levels of inorganic mercury in the bloodstreams of humans. But a recent study of federal data showed that the percentage of Americans with detectable levels of inorganic mercury in their blood increased eightfold between 2000 and 2004.

These are the same years that we see burgeoning levels of mercury being spewed into the atmosphere from industrializing areas of the world, particularly in China and other Asian countries.

The US Government has detected "mercury plumes" that carry the dangerous neurotoxin in great quantities across the Pacific and, within five days, found them hovering just offshore of San Diego, California. (See Map HERE)

At a recent vaccine forum at Hackensack University Medical Center, in New Jersey, I made this observation, and mentioned that the mercury carried aloft through the atmosphere will come down in the form of rain along the west coast or, during drier periods, continue eastward until it finds wetter, rainier parts of the country, where it is washed to the ground. (Mercury deposition maps HERE and HERE)

The evidence to show that rainy weather leads to increased mercury deposition on the ground is ample. In fact, scientists use rainfall as a measure to estimate mercury deposition in the environment.

One study from the University of Central Florida, showed that 80% of the atmospheric mercury fallout in Florida occurs during the rainy season. In fact, the average amount of mercury deposited on the ground per square meter, per week, was three times higher in the wet season (600 nanograms) than the dry season (200 nanograms).

There is likewise evidence to suggest that higher levels of background mercury are linked to a greater risk of autism. Two peer-reviewed studies from the University of Texas have suggested an increased risk of autism associated with physical proximity to mercury-emitting coal-fired powered plants and other industrial facilities.

A third study, funded by the CDC and published in the NIH journal Environmental Health Perspectives, showed that children born in the most polluted tracts of the San Francisco Bay Area (heavy metals like mercury carried the highest risk) were 50% more likely to develop autism.

"Our results suggest a potential association between autism and estimated metal concentrations in ambient air around the birth residence," concluded the government-sponsored study, (which was essentially ignored by the media).

Suddenly, the "Mercury Rain" hypothesis starts to make a little more sense. Not that coal from China could cause autism directly, but prenatal mercury exposures might make children more susceptible to other environmental triggers, including vaccine ingredients.

Richard Lathe, an autism expert from Pieta Research in Edinburgh, Scotland, told the Washington Post that the new study's findings almost certainly implicate rainfall, at the least.

"Statistical correlations do not necessarily imply causality," he said, but added, "the authors demonstrate, with better than 99 percent certainty, that the correlation is not by chance."

Lathe believes the most likely explanation, "is that rain carries chemicals in the atmosphere to the ground." He said that, "Emissions from manufacturing industries, power plants (ie, coal), and from domestic waste incineration generally rise to the troposphere to be diluted into the large volume of the atmosphere. Precipitation can dump this load back on the land, to be absorbed by plants and animals in the food chain."

And, Lathe noted, "There has been a suggestion that maternal exposure to environmental toxins might contribute to autism in children," he said.

I am not the only one to suggest that ALL mercury exposures - both environmental and vaccine-related - must be taken into account when trying to asses the risk of mercury and autism.

In my book, Evidence of Harm, I noted that Dr. Neal Halsey, director of the Vaccine Safety Institute at Johns Hopkins University School of Medicine, and a vaccine authority, said in 1999 that, "Mercury accumulated in women is transferred to their children prenatally and in breast milk." Subsequent exposures from other sources, "including biologic products, (ie, vaccines), are presumed to be additive to their baseline body loads."

And in 2006, a special panel of the NIH wrote that background mercury exposures must be taken into account when assessing the risk of autism and thimerosal.

"Panel members expressed a concern that thimerosal dose, administered through a series of vaccinations, may provide a poor surrogate measure of the cumulative exposure of a child to organic mercurials. Exposures through diet or other environmental sources would not be documented reliably," the NIH panel wrote.

Can rain cause autism? Of course not. But could it pull mercury down from the skies - mercury carried aloft from far away countries across the seas - and affect unborn and newborn children to the point of making them more vulnerable to autistic regression? Perhaps.

This new study makes one thing fairly clear to me: Autism is not a purely genetic disorder. Our changing, endangered, dirty environment is playing a role.