[Field study of workers with longterm exposure to calcium cyanamide (author's transl)].

: Kalkstickstoff" (calcium cyanamide) is extensively used as a fertilizer and a herbicide and also as a chemical intermediate. Its main compounds are calcium cyanamide (CaCN2) (60%) and calcium oxide (15%). In earlier times cauterized damages of the skin and the mucous membranes caused by the content of calcium oxide were common. A certain effect of CaCN2 is the reaction of intolerance after alcohol intake, which expresses as a so-called burning, a flush with redness and feeling of heat of the head, the neck and the upper part of the body often combined with tachycardia and dyspnea. Further health impairments, sometimes with fatal end, were reported repeatedly in the older literature. Convincing evidences for the causal connections between the exposure to CaCN2 and these damages are missed. They exclusively concerned farmers but not workers in the production of CaCN2. Except of the damages of the skin also diseases of the respiratory and gastrointestinal tract, the kidneys, the nervous and circulatory system as well as favoring of infectious complications and goitrogenic effects are in discussion. Furthermore it was suggested that CaCN2 causes a lack of reduced glutathione in the organism. On the occasion of establishing a preliminary MAC-value for CaCN2 in the F.R.G. an occupationally medical field study was performed on 65 workers of a calcium cyanamide factory with long-term exposure to CaCN2. The maximal CaCN2 concentration measured at the working places was 8.3 mg/m3. No signs of diseases or health impairments, which are possibly caused by CaCN2, were found with the medical examination in the above mentioned organs and organ systems. There also was no decrease of the glutathione content of the total blood detectable. With an alcohol load of 22 voluntary workers 1 till 7 hours after the working shift in 6 cases modest and in 7 cases weak flush reactions were observed. As result of the study an elevation of the MAC-value from 1 to at least 2.5 mg/m3 is proposed.