14 DAY TRIAL // For decades, mercury pollution has been linked to many diseases. This heavy metal is known to attack the nervous system. With all that, a new study published in the Health & Place journal connects industrial mercury pollution to higher risk of autism and, for the first time ever, reveals a link between autism risk and the physical distance from a mercury source.
"This is not a definitive study, but just one more that furthers the association between environmental mercury and autism," said lead author Dr. Raymond F. Palmer, associate professor of family and community medicine at the UT Health Science Center San Antonio.
The researchers discovered that community autism prevalence became lower by 1-2% with each 10 miles (16 km) away from the mercury source. "This study was not designed to understand which individuals in the population are at risk due to mercury exposure. However, it does suggest generally that there is greater autism risk closer to the polluting source. The effects of persistent, low-dose exposure to mercury pollution, in addition to fish consumption, deserve attention. Ultimately, we will want to know who in the general population is at greatest risk based on genetic susceptibilities such as subtle deficits in the ability to detoxify heavy metals," said Palmer.
Other researches detected higher mercury amounts in plants, animals and humans situated closer to the source of mercury pollution. "We suspect low-dose exposures to various environmental toxicants, including mercury, that occur during critical windows of neural development among genetically susceptible children may increase the risk for developmental disorders such as autism," the authors wrote.
The team investigated mercury-release data from 39 coal-fired power plants and 56 industrial facilities in Texas and, at the same time, autism rates from 1,040 Texas school districts. Each batch of 1,000 pounds (440 kg) of mercury expelled by industries in Texas in 1998 was linked to a 2.6% rise in autism rates in the school districts of the same area, that only became obvious in 2002. The same amount of mercury released by Texas power plants that year caused a rise by 3.7% in 2002 autism rates in the already mentioned school districts.
"We need to be concerned about global mercury emissions since a substantial proportion of mercury releases are spread around the world by long-range air and ocean currents," Palmer warned.
The US annual environmental mercury releases were of about 158 million tons by late 1990s, 33% of that number coming from coal-fired utility plants, 29% from municipal/medical waste incinerators and 18% from commercial/industrial boilers. Cement plants also contaminate with mercury. On the bright side, current legislation has led to a slight decline in mercury contamination.
Palmer warned that the research did not show the true community prevalence rates of autism, as children not of school age were not taken into account. That's why the 1:500 autism rate in the research is actually below the rate of 1:150, as made public in recent official reports.