There were increased scores for anger, depression, tension, confusion, fatigue and vigor.
The automatic (subconscious) parts of the neuro-axis were impaired. Impaired performance was accompanied by reduced perceptual motor speed. The exposure to reduced-sulfur gases, predominantly hydrogen sulfide, was considered the most plausible explanation of the neurotoxic effects in this study.
Gaitonde UB, Sellar RH and O’Hare AE. Long-term exposure to hydrogen sulphide producing sub acute encephalopathy in a child. British Medical Journal. Vol 294, pp. 614, 1989.
This is a report on a 20-month-old infant exposed for a year to 0.6 ppm hydrogen sulfide downwind from a burning tip gas ignition point for a colliery. The child had subacute necrotizing encephalopathy in the basal ganglia and white matter.
Chronic Reference Dose (RfD). Based upon animal studies and the child reported by Gaitonde et al, the U.S. EPA has recommended a RfD of 0.8 micrograms per cubic meter of air for both subchronic and chronic human inhalation exposure. The RfD is that concentration at which no adverse health effects should occur. Concentrations above the RfD may result in adverse health effects, including neurotoxicity.
Chronic and subchronic exposure to low concentrations of hydrogen sulfide and other organosulfur compounds (reduced sulfur compounds) do cause long-term health problems in humans. These problems appear as various symptoms of the upper and lower respiratory tract, central nervous system, skin and eyes. The central nervous system symptoms are associated with permanent neurophysiological deficits. Injury to the central nervous system includes damage to the basal ganglia and white matter.
Some Other References
Cooper CE, Brown GC (2008) The inhibition of mitochondrial cytochrome oxidase by the gases carbon monoxide, nitric oxide, hydrogen cyanide and hydrogen sulfide: chemical mechanism and physiological significance. J Bioenerg Biomembr 40(5):533.
Haahatela T, et al (1992) The South Karelia air pollution study: Acute health effects of malodorous sulfur air pollutants released by a pulp mill. Amer J Pub Health 83:603-5.
Hooper DG et al (2010) Isolation of sulfur reducing bacteria and oxidizing bacteria found in contaminated drywall. Int. J. Mol Sci 11:647.
Kilburn KH (1999) Evaluating health effects from exposure to hydrogen sulfide: Central Nervous System Dysfunction. Environ Epidemiol Toxicol, 1:207.
Kilburn KH, Thrasher JD, Gray MR (2010) Low level hydrogen sulfide and central nervous system dysfunction. Toxicol Indust Health.
Kilburn KH, Warshaw RH (1995) Hydrogen sulfide and reduced-sulfur gases adversely affect neurophysiological functions. Toxicol Indust Health, 11:185-97.
Legator MS, et al (2001) Health effects from chronic low level exposure to hydrogen sulfide. Arch Environ Health 2001; 56:123.
Tvedt B, et al (1991) Brain damage caused by hydrogen sulfide: a follow-up study of six patients. Am J Ind Med 20:91.
Saadat M, Bahaoddini A (2004) Hematological changes due to chronic exposure to natural gas leakage in polluted areas of Masjidi-i-Sulaiman (Khozestan province, Iran). Ecotoxicol Environ Saf, 2004;58:273-6.
Savokainen H, et al (1980) Cumulative biochemical effects of repeated subclinical hydrogen sulfide intoxication in mouse brain. Int Arch Occup Environ Health.46:87
Solnyshkova TB, et al (2002) Ultrastructure of the cerebral cortex to gas containing hydrogen sulfide. Morfologia 122:11.
Truong DH, et al (2006) Molecular mechanisms of hydrogen sulfide toxicity. Drug Merg Rev, 36:733-44.
NOTE: The odor threshold varies from one individual to another. Therefore, the disparate values of odor detections comes from various sources in the literature. Also, olfactory fatigue and sinus disease also have a role in odor detection.