The purpose of this paper is to clarify the temporary threshold shifts (TTS) of fingertip vibratory sensation produced by hand-transmitted vibration in an underwater work environment. The hand-transmitted vibration was applied with a pneumatic tool to the right hand of four experienced male SCUBA divers. The threshold of 125Hz vibratory sensation was measured at the tip of the right forefinger before and after vibration exposure in the atmosphere and underwater. Vibration exposure at a 4m depth produced greater TTS than in the atmosphere. The recovery time of TTS after vibration exposure in an underwater were affected by the underwater pressure.
The objectives of this study were to evaluate the health and safety conditions of 36 male and 27 female green tea workers who were aged 40-69 years and had worked for at least 5 years in green tea production procedures. The Mean ± SD of age was 57.1±5.8 years in males and 54.4±6.4 years in females. The mean working career was 26.1±9.5 years and 24.3±9.1 years, respectively. The most commonly subjective complaints developed while at work was pain in the lower back at a rate of 72.2% in males and 63.0% in females. Regarding persistent subjective complaints, female workers had significantly (P<0.05) higher prevalence rate for breath shortness (25.9%) compared to that of male workers (5.6%). It was observed that the male workers whose occupational career was equal to or more than 28 years had significantly higher prevalence rates for stiffness in the neck and pain in the arms, compared to those of male workers whose occupational career was less than 28 years. The prevalence of nasal allergy was 11.1% either in the male or female workers. The total rate of accidents during working hours in the male workers was 22.2%, and that in the female subjects was 18.5%. The mean frequency weighted vibration magnitude produced by using tealeaf plucker was in the range of 2.4-3.5m/s2. The mean equivalent A-weighted noise level while using the same equipment was 100.6±5.0dB(A). The need for occupational safety and health programs in these small farm settings are discussed.
The acute effects of carbon monoxide (CO) exposure on a steady-state operant behavior (bar-pressing under a VI 60-sec schedule of food reinforcement) were repeatedly measured in (a) rats exposed to various concentrations of CO (500, 1, 000, 1, 500 and 2, 000 ppm) for 1h and (b) rats exposed to 1, 500ppm for different periods (1, 2 and 4h). Measurements were made continuously before, during and after the exposure period. Abrupt cessation of the response was produced by exposure to 1, 000ppm or higher concentrations of CO. Recovery from the effects of CO exposure was observed as sudden resumption of responding during the post-exposure period. The duration of exposure required to produce response inhibition was closely correlated with the exposure concentration. The post-exposure interval required for response recovery was also correlated with the exposure concentration. This post-exposure response recovery interval, however, was constant and independent of the duration of exposure when the concentration was fixed at 1, 500ppm. In order to correlate these behavioral changes with an internal index of CO exposure, blood carboxyhemoglobin (HbCO) levels were determined under several exposure conditions corresponding to those of the behavioral observations. It was found that HbCO levels were within a certain range (33-43%) when response recovery occurred, suggesting the existence of a critical HbCO level (threshold) associated with the drastic behavioral change. Hence, these results support the view that blood HbCO is an important determinant of the acute behavioral effects of CO.
The influence of long and short fibre amosite on the generation of tumor necrosis factor (TNF) by rat alveolar macrophages was investigated in vitro. TNF rich supernatants were prepared from macrophages cultured in F10 medium +2% Bovine Serum Albumin (BSA). Spontaneously released TNF from unstimulated macrophages and TNF rich supernatants from macrophages exposed to Lipopolysaccharide (LPS) and fibres were stored at -70°C and then tested for their cytotoxicity towards L929 cells. Maximum spontaneously released TNF was obtained from 24 hour macrophage cultures. Short amosite fibres had no significant effect in stimulating alveolar macrophages to release TNF while the 50μg dose of long fibres resulted in significantly increased release of TNF. Co-treatment of alveolar macrophages with LPS and fibres further enhanced the TNF production and maximum production was obtained with LPS +50μg dose of long fibre resulted in significantly increased release of TNF. Co-treatment of alveolar macrophages with LPS and fibres further enhanced the TNF production and maximum production was obtained with LPS +50μg of long fibre amosite. The present study indicates that fibre dimension is a major factor in in vitro dust activity and TNF has a possible active role to play in dust induced inflammation in vivo.
Vitamin E (α-tocopherol), a well known naturally occurring chain breaking antioxidant and a free radical scavenger was found to exacerbate nickel (Ni) toxicity in mice. Vitamin E (Vit. E) mediated enhancement of nickel toxicity was demonstrated by (i) enhanced mortality in mice treated with Ni and Vit. E (ii) increased hepatic lipid peroxidation, (iii) increased rate of benzoate hydroxylation, and (iv) liposomal membrane damage.