Common pollutant might raise
suicide risk, researchers say
link to child neglect, abuse also hinted
March 30, 2005
Special to World Science
A common chemical pollutant with a familiar rotten-egg smell may raise suicide risk,
two studies have tentatively found.
The researchers also said there are hints that the substance, and related pollutants,
might increase child neglect and abuse rates in exposed neighborhoods.
If borne out, the findings would be the first evidence that pollutants in the environment raise suicide risk.
But “It’s still speculation—a lot more work need to be done,” said Richard H. Weisler, a psychiatrist at the University of North Carolina School of Medicine and volunteer with an environmental group, who led the studies.
He added that it remains unclear whether the chemical, hydrogen sulfide, is itself the culprit. Other substances that polluted the same areas at the same time periods covered in his studies may have caused the increased suicide rates, he said.
On the other hand, he added, hydrogen sulfide is known to
chemically affect the brain in animal studies.
In the latest study, Weisler and colleagues linked higher suicide rates to hydrogen sulfide and other airborne chemicals from a paper mill and possibly other industrial sites in Haywood County, N.C.
The mill’s owners said the allegations had no scientific basis.
The findings were presented Nov. 7 at the annual U.S. Psychiatric and Mental Health Congress in Las Vegas.
Weisler’s previous study suggested a possible link between an increased suicide rate in Salisbury, N.C. and hydrogen sulfide and other chemicals from nearby asphalt plants and oil remediation sites.
The new study found Haywood County’s suicide rate nearly doubled to about 21.1 per 100,000 residents for 1997-2002, when taking the residents’ age into account. Haywood ranked 46th out of North Carolina’s 100 counties for average age-adjusted suicide rate for 1979-1996, but the county was ranked third for 1999-2002, the authors added.
“There have been increases in suicides during this time period when there were also operational changes at the paper mill” that increased hydrogen sulfide emissions, said Weisler, who also volunteers with the Blue Ridge Environmental Defense League.
Hydrogen sulfide is a toxin that alters levels of several brain chemicals in animals, Weisler added. People exposed to it in their workplace have been found to exhibit increased rates of nervousness, mania, dementia and violence, he added.
But he added that hydrogen sulfide may merely serve as a “marker” for other possibly neurotoxic compounds that were released in the mountain valley area that his study covered. Other chemical releases reported by the paper mill include carbon disulfide, dimethyl disulfide, dimethyl sulfide and methyl mercaptan, he said.
Weisler said Haywood County also saw a jump in child neglect and abuse cases at about the same time as the rise in suicide. In the future, he said, he plans to study whether this trend is also linked to pollutants. It might also have been a result of greater vigilance by child-protection authorities, he noted.
Hydrogen sulfide is a common emission from a wide range of industries, Weisler said, including fertilizer plants, coke ovens, farms, fisheries, iron smelters, mines, natural gas plants, oil drilling operations, pesticide plants, rayon plants, petroleum refineries, asphalt, rubber, sugar beet processing and tanneries. Volcanoes also release hydrogen sulfide.
Bob Williams, director of regulatory affairs for Blue Ridge Paper Products—the company that owns Canton Mill, the paper plant fingered in Weisler’s study—called the study “fishy.”
He said Weisler, “in his own comments, stated there was no direct correlation” between pollution and suicides. Despite that lack of evidence, “he proceeded to draw conclusions not based on any data… That calls into question in my mind the motivations of those associated with the study.”
Williams added that Weisler hasn’t sought out the company’s viewpoint. “He’s never asked for a tour, and we do these things on a regular basis… If there was an interest in getting to the bottom of the allegations, he would at least engage us in that kind of communication.” The mill actually slashed hydrogen sulfide emissions by 95 percent in the mid-1990s, according to Williams.
Study co-author Jonathan R.T. Davidson, a psychiatrist at Duke University Medical Center, said the key point people should remember is that suicidal depression is treatable.
“People who are experiencing persistent symptoms of depression should contact their health-care provider for a professional evaluation,” he said.*
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