Journal of School of Public Health and

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The use of biological safety cabinets (BSCs) in laboratories has greatly increased over the last few decades. BSCs are used in laboratories to protect both the scientists and the experiments from contamination by biological hazards during tissue culture procedures. The function of BSCs depends upon the HEPA filtration, the fan performance and the airflow patterns in the cabinet. To ensure BSCs proper functioning, regular performance evaluation tests are necessary. Failure to observe this may lead to direct and indirect losses. The objective of this study which was conducted at a biological research center was to evaluate the performance of seven present BSCs used in different laboratories. Based on BS 5726 (1992), two sets of measurements were performed: a) Determination bioaerosol concentration in the cabinet and b) inflow and downflow velocity measurements at the cabinet. The results revealed that the lowest and the highest bioaerosol concentrations were 0.2 cfu/m3 and 1.33 cfu/m3, respectively. The lowest inflow mean velocity was found to be 0.33 m/s which was far less than the recommended value in BS 5726 (0.7 m/s). The highest inflow velocity was 1.1 m/s. The lowest downflow velocity equaled to 0.09 m/s which was below the recommended value (0.25- 0.5 m/s). The highest downflow measured was 0.55 m/s. As a conclusion, in general, none of the BSCs evaluated in this study provided sterile atmosphere at the cabinets. In no case, airflow patterns met the recommended values proposed in BS 5726.

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Background and Aim: Exposure to hexavalent chromium in plating operations is associated with skin ulceration, contact dermatitis, respiratory tract irritation, cancer, and kidney damage. We investigated the possibility of using biological monitoring to assess exposure to hexavalent chromium in chrome-plating workers. We compared mean Cr6 concentrations in the breathing zone plus urine chromium, β2 microglobulin (B2M), and N-acetyl-B-D- glucosaminidase (NAG) at the end of the working shift. Then we assessed the correlation between exposure to hexavalent chromium and biological indicators.

Materials and Methods: This study involved 45 chrome platers (Cases) and 40 zinc platers (Controls) in Isfahan. Air and urine samples were collected at the end of the work shift. Measurement of Cr6 concentrations in the workers' breathing zone was performed using the NIOSH Methods 7600. Urine Cr levels were determined by atomic absorption spectrophotometry, with a graphite furnace (Shimadsu, AA680). B2M and NAG were measured by Kits.

Results: Overall, geometric mean of hexavalent chromium concentrations in the breathing zone was significantly higher among chrome platers (14.577 μg/m3) compared to zinc platers (0.862 μg/m3, p<0.001). Moreover, the mean urine Cr concentrations were higher in chrome platers (9.198 vs. 1.811 μg / g creatinine, p<0.001). Similarly, there were significant differences between mean NAG in chrome platers (12.608IU/gr creatinine) and zinc platers (6.824 IU/g creatinine, p<0.001). Differences in B2M concentrations were not significant (p>0.05). A significant correlation was found between Cr6 concentrations in the chrome platers' breathing zone and their urinary chromium levels (r= 0.838, p<0.001). A similar association was found between concentrations of Cr6 and NAG in the breathing zone (r= 0.304, p<0.05).

Conclusion: As urinary B2M concentration did not change significantly, it may not be a sensitive indicator in evaluating exposure to hexavalent chromium. There were significant differences between mean urinary Cr and NAG concentrations in the two groups. The significant correlations between Cr and NAG concentrations indicate that these markers may be suitable indicators of exposure to hexavalent chromium. Our results indicate that NAG is an early indicator of renal dysfunction in chrome platers.

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Background and Aim: Lead is a toxic metal used in different industries and occupational and environmental exposure to it is quite likely to occur. Because of its high potential toxicity, serious damages to those exposed to it are common. Since the ceramic industry, in which lead is used, is considered a domestic industry in Iran, in this study occupational exposure of glaze workers to lead was assessed in a ceramic industry.

Materials and Methods: A total of 55 glaze workers (39 tillers and 16 potters) were selected as the case group. Association of lead concentration with several variables, including work shift, work type, ventilation system, and the number of extra work hours during the previous month, was determined. A sampling pump (SKC Co.) and ester cellulose filters with a pore size of 0.8 µm, 37 mm in diameter, were used for sampling. The flow-rate was adjusted at 2 l/min based on the NIOSH 7300 method. After sampling, filters were transferred to the laboratory and digested in a mixture of nitric acid and per chlorate solution (4:1) and analyzed by ICP-AES. To minimize probable errors and pollution during sampling and sample handling, samples were also taken from employees in the administration department to serve as control. Spiro metric tests were performed on both the case and the control groups.

Results: The lead concentrations were higher than the threshold limit value (TLV) (0.17 mg/m). Independent t-test showed that there was a significant relation between concentration of the lead present in the breathing zone air and 2 independent variables, including shifts work (morning and afternoon) and the ventilation system among tillers. Also, based on the one-way ANOVA, there was a significant relation between concentration of the lead present in the breathing zone and the number of extra working hours over the shift.

Conclusion: The mean lead concentration in the breathing zone was higher than the respective TLV. Considering the hazardous nature of lead, protective measures─ personal, occupational and environmental─ should be taken. Moreover, clinical examination of job applicants at the time of employment, as well as periodic examinations and Spiro metric tests on the workers, are also strongly recommended.