Several studies have shown increased rates of lung and brain cancer among workers with long-term exposure to asphalt emissions, the researchers said.
Weisler and his study team made a hypothetical link between hydrogen sulfide and suicides due to biological plausibility. They noted that hydrogen sulfide affects brain neurochemistry as a direct gaseous neuromodulator that potentially affects mood states and the psychological stress response. In animal studies, it has been shown to alter the neurotransmitters serotonin, norepinephrine, dopamine, aspartate and glutamate levels.
Hydrogen sulfide also affects the hypothalamic pituitary adrenal axis and corticotropin releasing factor in animal studies, the report said.
This is the part of the brain involved in the stress response, and we think its also involved in psychological resiliency, how people deal with stressors, Weisler said. Its frequently associated with mood disorders, and there are suggestions that resiliency is impaired when people are suicidal.
The study team reported that additional neurotoxic compounds such as benzene, chlorinated solvents and carbon disulfide, among others, were released in unknown quantities by the asphalt terminal and hot-mix asphalt plant. Carbon disulfide, also a neurotoxin, has been linked to personality changes, mood disorders and suicides in occupational settings, the researchers said.
In addition, Some research suggests that highway workers exposed to asphalt-solvent fumes show an increase of suicide rates and brain cancers.
A full characterization of the types of chemicals and the levels of releases at the liquid asphalt terminal is needed, said Weisler.
Also needed, he added, is the
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Contact: L.H. Lang
llang@med.unc.edu
919-843-9687
University of North Carolina School of Medicine
10-Dec-2004