A review of health effects of carbon disulfide in viscose industry and a proposal for an occupational exposure limit.

Occupational exposure limits (OELs) for carbon disulfide vary between 1 and 10 ppm worldwide. They are generally based on health effects observed in viscose industry. Publications after the mid-1970s are reviewed to determine whether there is a scientific justification for an OEL below 10 ppm. The exposure situation in viscose industry is governed by long exposure durations, high exposures in past decades, high peak exposures, former analytical procedures underestimating exposure, and shift work. Three approaches were used to define an OEL based on workplace data: (1) Division of a cumulative exposure index by lifetime exposure duration. This approach ignores the possible existence of a threshold and fails to differentiate between brief high and sustained low exposures. (2) Defining the NOEL/LOEL by mean exposure levels. With a wide range of exposures, effects observed at the mean are driven by high exposures underestimating the true NOEL. (3) Assessment of effects observed at workplaces complying with a predefined exposure limit. Without adverse effects at such a limit this should be the starting point to define the OEL. The most important health effects for carbon disulfide are coronary heart disease, coronary risk factors, retinal angiopathy, color discrimination, effects on peripheral nerves, psychophysiological effects, morphological and other central nervous system (CNS) effects, and fertility and hormonal effects. The data generally support an OEL of 10 ppm. Some uncertainties exist for effects on electrocardiogram (ECG), heart rate, retinal microaneurysms (in Japanese workers), peripheral nerve conduction velocities, some psychophysiological parameters, brain magnetic resonance imaging (MRI; hyperintensive spots), and hearing function. Further investigations on workers under defined long-term exposure conditions might help to come to a final conclusion. Finally, the reproductive capacity of female workers may not be adequately protected at exposures around 10 ppm.