Sulfiding following acid exposure

Table 3-2 and Figure 3-2 describe the health effects observed in humans and experimental animals associated with dose and duration of oral exposure to selenium and selenium compounds (i.e., elemental selenium dust, selenium dioxide dissolved in water [selenious acid], sodium selenate, sodium selenite, potassium selenate, and dietary selenium compounds, which include selenoamino acids). All doses for these compounds are expressed in terms of total selenium. Table 3-3 and Figure 3-3 describe health effects observed in laboratory animals following oral exposure to selenium sulfides (SeS2 and SeS) at varying doses and exposure durations. All doses for selenium sulfide compounds are expressed in terms of the compound, because selenium sulfide preparations often exist as a variable mixture of the mono-and disulfide forms, precluding accurate expression of the dose in terms of total selenium. 

Concern for the dermal route of exposure to selenium compounds as a cause of adverse health effects in humans is extremely low except for the acid forms, which owe their dermal effects to their acidity more than to their selenium content. Selenium sulfide, an ingredient in some antidandruff shampoos, does not appear to be absorbed through the skin. Ingestion of large amounts of the compound, however, would be of concern because selenium sulfide has been shown to be carcinogenic in rats and mice following oral exposure. 

Several epidemiology studies have reported increased mortality among workers in viscose rayon plants who were occupationally exposed to carbon disulfide as well as other chemicals (Hemberg et al. 1970, 1973 Tolonen et al. 1975, 1979). Deaths have also been reported in a community in India following an accidental release of large amounts of carbon disulfide, hydrogen sulfide, and sulfuric acid from a viscose rayon plant (Kamat 1994). However, no definitive or consistent conclusions can be drawn from these studies because of concomitant exposure to other chemicals, uncertainty about exposure concentrations, and the likelihood of multiple routes of exposure. 

The primary target of carbon disulfide appears to be the nervous system. Neurophysiological and behavioral effects as well as pathomorphology of peripheral nervous system structures have been reported in humans as well as animals. Acute exposure to high concentrations of carbon disulfide can result in fainting and loss of consciousness. These effects were observed in 36-39% of 123 persons exposed to carbon disulfide following an accidental release of carbon disulfide, hydrogen sulfide, and sulfuric acid from a viscose rayon factory in India (Kamat 1994). 

---