Salisbury, N.C., Study Links Asphalt to Heightened Suicide Rate

Until yesterday, we had missed this news about research into the health hazards posed by asphalt plants. It's been slow to seep out, though the research was first presented at the 17th Annual U.S. Psychiatric and Mental Health Congress in San Diego back in December, and the Salisbury Post did run a long article on January 16, 2005. Otherwise, we've seen no mention of this explosive information anywhere in the state.

Dr. Richard H. Weisler, adjunct professor of psychiatry at the University of North Carolina at Chapel Hill School of Medicine and adjunct assistant professor of psychiatry at Duke University Medical Center, along with a team of researchers, investigated a statistically significant elevated suicide rate in two Salisbury, N.C., neighborhoods (Milford Hills and Meadowbrook) that are directly downwind of two asphalt plants on Jake Alexander Boulevard.

The two "census blocks" under investigation contain 1,561 people. In a population of that size, during a 10-year period, two deaths by suicide would be expected. In the Salisbury case study, between 1994 and 2003, six suicides occurred, three times the expected rate. And as the Salisbury Post article pointed out, the study did not include suicide attempts, including one last summer in which a man doused himself in gasoline and tried to ignite it.

The suspect ingredient in asphalt manufacture which might be causing the problem is hydrogen sulfide, a respiratory irritant that is known to affect brain neurochemistry. Dr. Weisler suggests that hydrogen sulfide might affect the brain's hypothalamic area, which is involved in the body's ability to deal with stress. Too much hydrogen sulfide equals a reduced ability to cope, Dr. Weisler hypothesizes.

The World Health Organization has a 10-minute exposure standard to hydrogen sulfide of 5 ppb (parts per billion). The California 1-hour standard is 30 ppb. Between 1994 and 2001, the N.C. Department of Environment and Natural Resources (NCDENR) had one of the weakest standards in the nation for regulating hydrogen sulfide emissions, officially allowing 1,500 ppb. In 2001, NCDENR estimated that the average maximum hydrogen sulfide level in a large part of the two Salisbury neighborhoods was 215 ppb, with several residences near the asphalt plants exposed to as much as 860 ppb. But the sad truth is that NCDENR can only estimate what it in fact rarely actually measures. In 2003 the state's Environmental Management Commission voted to set the acceptable level of hydrogen sulfide at 86 ppb, down considerably (!) from the previous 1,500 ppb, but so far the state isn't enforcing that standard because of political pressure.

And what's NCDENR's response to Dr. Weisler's study? They do not acknowledge an increased risk of suicide. But when you're in the business of permitting basically whatever emissions come out of asphalt production, what are you going to say? "Yes, we are exposing our citizens to harmful levels of hydrogen sulfide, not to mention deleterious levels of benzene, toluene, and other petroleum-based neurotoxic chemicals, but the paving lobby is just too powerful and politically well connected to do anything about it."

Incidentally, the same census blocks in Salisbury have already been under scrutiny for having high cancer rates, particularly primary brain tumors ... other research that NCDENR does not acknowledge has anything to do with the polluting industry they are permitting. NCDENR has rarely, if ever, turned down a permit for a proposed asphalt plant, including three different plants proposed in Watauga County since 1997, all defeated by zoning, with no help from the state agency which is supposed to be looking out for our collective well-being.