A prospective cohort study among new Chinese coal miners: the early pattern of lung function change.

AIMS: To investigate the early pattern of longitudinal change in forced expiratory volume in 1 second (FEV1) among new Chinese coal miners, and the relation between coal mine dust exposure and the decline of lung function. METHODS: The early pattern of lung function changes in 317 newly hired Chinese underground coal miners was compared to 132 referents. This three year prospective cohort study involved a pre-employment and 15 follow up health surveys, including a questionnaire and spirometry tests. Twice a month, total and respirable dust area sampling was done. The authors used a two stage analysis and a linear mixed effects model approach to analyse the longitudinal spirometry data, and to investigate the changes in FEV1 over time, controlling for age, height, pack years of smoking, mean respirable dust concentration, the room temperature during testing, and the groupxtime interaction terms. RESULTS: FEV1 change over time in new miners is non-linear. New miners experience initial rapid FEV1 declines, primarily during the first year of mining, little change during the second year, and partial recovery during the third year. Both linear and quadratic time trends in FEV1 change are highly significant. Smoking miners lost more FEV1 than non-smokers. Referents, all age less than 20 years, showed continued lung growth, whereas the miners who were under age 20 exhibited a decline in FEV1. CONCLUSION: Dust and smoking affect lung function in young, newly hired Chinese coal miners. FEV1 change over the first three years of employment is non-linear. The findings have implications for both methods and interpretation of medical screening in coal mining and other dusty work: during the first several years of employment more frequent testing may be desirable, and caution is required in interpreting early FEV1 declines.

A comparison of pneumoconiosis interpretation between Chinese and American readers and classifications.

As a preliminary step in joint Sino-American pneumoconiosis research efforts, a formal chest X-ray pneumoconiosis reading trial was conducted among Chinese and American radiologists. Twelve Chinese readers from different institutions located in south central China used the 1986 Chinese Roentgenodiagnostic Criteria of Pneumoconioses. Three American radiologists, centified as NIOSH "B" readers, used the International Labour Office Classification of Pneumoconioses. The chest X-ray study set consisted of 150 posterior-anterior films. One-half were Chinese X-rays of silica-exposed workers, and the other half were American films of variously exposed workers but primarily coal miners. All readings were done independently. The results showed that the inter-reader variability among the Chinese was similar to that of the American readers, both being in an acceptable range. In addition, there was general agreement between the Chinese and American interpretations. For small opacity profusion, the Chinese readers tended to read slightly more diseases than their American counterparts, although there was exact agreement as to the major category in two-thirds of the films. Agreement for film quality, and pleural disease was less, but was not different from reported variation among American "B" readers. Overall, the results suggest that despite the use of two different classification systems, a valid correspondence exists between the Chinese and American Interpretations, which is suitable for use in epidemiologic research.

Fire fighters' exposure to carbon monoxide during Australian bushfires.

Fatal entrapments of Australian bushfire fighters have led to suggestions that carbon monoxide (CO) poisoning could have contributed to these accidents by impairing the fire fighters' judgement. Carboxyhemoglobin saturation (COHb%) levels were assessed from alveolar CO levels in 24 fire fighters working with handtools and in 12 accompanying scientific observers, before and after fire fighting (duration 37-187 min) on 15 experimental bushfires. Carboxyhemoglobin levels increased on average by 0.7% per hour in the fire fighters and by 0.3% per hour in the observers. Nonsmoking fire fighters had lower COHb% after fires than the smokers had before fires. Estimates of environmental CO concentrations (including cigarette smoke) during the fires averaged 31 parts per million (ppm) for the smokers, 17 ppm for the nonsmoking crew members, and 11 ppm for the observers, none of whom smoked. The highest estimates of environmental CO arising solely from bushfire smoke were 40 to 50 ppm. Smokers were exposed to as much CO from their cigarettes as from bushfire smoke. Carboxyhemoglobin levels at the end of 8-hr fire fighting shifts, predicted from these levels of environmental CO, averaged about 5% (maximum 11%) in smokers and about 3% (maximum 7%) in nonsmokers. Acute levels of COHb% of this degree are not considered to have significant effects on health or performance. These results indicate that bushfire fighters are generally unlikely to experience hazardous levels of CO exposure.

Antifertility treating with long term gossypol.

PIP: In the 1974-86 period, gossypol acetate was taken as an antifertility measure by 16 men. The initial dose was 20 mg/day, with a maintenance dose of 40 mg/week. Antifertility efficacy was obtained in all 16 cases. Azoospermia persisted in 1 case where the gossypol had been taken for 8 years and discontinued for the past 2 1/2 years. Symptoms experienced in the first 2 weeks of gossypol acetate administration included dizziness, anorexia, nausea, fatigue, and stomach discomfort. Results of examinations of blood and urine; functions of the heart, liver, lung, and liver; electrolytes; external genitalia; and sexual performance were all in the normal range. Measurements of semen, plasma biochemistry, and endocrine changes also were within normal limits. However, in the 9 cases in which the average value of plasma testosterone was near the lower limit of normal, the average value of follicle-stimulating hormone was higher than normal and the testosterone/luteinizing hormone ratio was unusually low. Testis biopsy indicated that long-term gossypol treatment affected both germ cells and Sertoli cells. Leydig cells also demonstrated some damage. Gossypol acetate is, in general, considered an ideal male contraceptive because of its long-term effectiveness, reversibility, and lack of severe toxic side effects.^ieng