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Exposure to low levels of hydrogen sulfide and possibly other airborne chemicals from nearby asphalt plants may have contributed to an increased suicide rate in a North Carolina community, a study suggests for the first time. In 2003, the suicide rate in two Salisbury, N.C., neighborhoods was found to be 192 per 100,000 individuals a year, roughly 16 times the statewide average, as stated in community reports confirmed by death certificates for that year by the Blue Ridge Environmental Defense League (BREDL).
From Duke University:
Increased Suicide Rate is Possibly Linked to Chemicals Released from Nearby Asphalt Plants
Exposure to low levels of hydrogen sulfide and possibly other airborne chemicals from nearby asphalt plants may have contributed to an increased suicide rate in a North Carolina community, a study suggests for the first time.
In 2003, the suicide rate in two Salisbury, N.C., neighborhoods was found to be 192 per 100,000 individuals a year, roughly 16 times the statewide average, as stated in community reports confirmed by death certificates for that year by the Blue Ridge Environmental Defense League (BREDL).
The study's lead author is Dr. Richard H. Weisler, adjunct professor of psychiatry at the University of North Carolina at Chapel Hill School of Medicine, adjunct assistant professor of psychiatry at Duke University Medical Center and BREDL volunteer.
Other collaborators in this research were Dr. Jonathan R.T. Davidson, professor of psychiatry at Duke University Medical Center; Dr. Lynn Crosby, a toxicologist with BREDL; Lou Zeller, BREDL director; Hope Taylor-Guevera, director of Clean Water for North Carolina; Sheila Singleton, executive director of the N.C. Depression and Bipolar Support Alliance; and Melissa Fiffer and Stacy Tsougas, undergraduates at Duke University's Nicholas School of the Environment and BREDL summer interns.
The neighborhoods comprising two U.S. census tract block groups contained a total of 1,561 residents who were living immediately downwind from a liquid asphalt terminal; an asphalt hot-mix plant, which also contained a former N.C. Department of Transportation solvent-contaminated cleanup site where the DOT had previously dumped solvents used for testing asphalt; and a contaminated former petroleum tank farm.
Between 1994 and 2003, death certificate evaluations for the two Salisbury neighborhoods showed a 3.5-fold statistically significant increase in the suicide rate, the study found. Four deaths by suicide in adults were reported from the 687 residents in the census tract block group 1. Three deaths by suicide in adults were reported among the 874 residents of census tract block group 2. Only two deaths by suicide would be expected for this population over a 10-year period, but seven suicides were observed.
''For example, here in the block group 1 neighborhood in the mid-90s, we found one death by suicide for about every 230 people during the worst 12-month period, versus an average of one death by suicide for
''When we saw this data it gave us pause.''
Weisler said of hydrogen sulfide, ''The odor was frequently apparent when I lived there as a child and later when I visited my mother, who lived in the neighborhood from 1962 until her death in 2001.''
That year (2001), the N.C. Department of Environment and Natural Resources (NCDENR) estimated the average maximum hydrogen sulfide level in a large part of the affected area at 215 parts per billion (pbb), while some sections of the neighborhoods were reported as low as 30 ppb. Moreover, based on their own air modeling study, the NCDENR estimated that historical releases of hydrogen sulfide reached average maximum levels of 860 ppb in a few residences very near the asphalt facilities.
By comparison, the World Health Organization has a 10-minute exposure standard of five ppb. The California one-hour standard is 30 ppb. The newly revised, but not yet implemented, North Carolina 24-hour hydrogen sulfide standard is 86.2 ppb.
These exposures accompanied 574 formal complaints to the City of
Salisbury from March 11, 1999, to Oct. 15, 2004, for noxious odors and associated respiratory problems, which are still occurring
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