ESTABLISHMENT OF THE IN VITRO DOSE-RESPONSE CALIBRATION CURVE FOR X-RAY-INDUCED MICRONUCLEI IN HUMAN LYMPHOCYTES.

The cytokinesis-block micronucleus assay has proven to be a reliable technique for biological dosimetry. This study aimed to establish the dose-response curve for X-ray-induced micronucleus. Peripheral blood samples from three healthy donors were irradiated with various doses and scoring criteria by the micronuclei (MN) in binucleated cells. The results showed that the frequency of MN increased with the elevation of radiation dose. CABAS and Dose Estimate software were used to fit the MN and dose into a linear quadratic model, and the results were compared. The linear and quadratic coefficients obtained by the two software were basically the same and were comparable with published curves of similar radiation quality and dose rates by other studies. The dose-response curve established in this study can be used as an alternative method for in vitro dose reconstruction and provides a reliable tool for biological dosimetry in accidental or occupational radiation exposures.

Assessment of personal noise exposure of overhead-traveling crane drivers in steel-rolling mills.

BACKGROUND: Noise is widespread occupational hazard in iron and steel industry. Overhead-traveling cranes are widely used in this industry, but few studies characterized the overhead-traveling crane drivers' noise exposure level so far. In this study, we assessed and characterized personal noise exposure levels of overhead-traveling crane drivers in two steel-rolling mills. METHODS: One hundred and twenty-four overhead-traveling crane drivers, 76 in the cold steel-rolling mill and 48 in the hot steel-rolling mill, were enrolled in the study. Personal noise dosimeters (AIHUA Instruments Model AWA5610e, Hangzhou, China) were used to collect full-shift noise exposure data from all the participants. Crane drivers carried dosimeters with microphones placed near their collars during the work shifts. Work logs had been taken by the drivers simultaneously. Personal noise exposure data were divided into segments based on lines in which they worked. All statistical analyses were done using SPSS 13.0. RESULTS: The average personal noise exposure (L(Aeq.8h)) of overhead-traveling crane drivers in the hot steel-rolling mills ((85.03 +/- 2.25) dB (A)) was higher than that in the cold one ((83.05 +/- 2.93) dB (A), P < 0.001). There were 17 overhead traveling cranes in the hot steel-rolling mill and 24 cranes in the cold one, of which carrying capacities varied from 15 tons to 100 tons. The average noise exposure level based on different lines in the hot and cold steel-rolling mills were (85.2 +/- 2.61) dB (A) and (83.3 +/- 3.10) dB (A) respectively (P = 0.001), which were similar to the average personal noise exposure in both mills. The noise exposure levels were different among different lines (P = 0.021). CONCLUSION: Noise exposure levels, depending upon background noise levels and the noise levels on the ground, are inconstant. As the noise exposure levels are above the 85 dB (A) criteria, these drivers should be involved in the Hearing Conservation Program to protect their hearing.

[Measurement of personal noise exposure in a cold rolling mill].

OBJECTIVE: To measure and evaluate the personal noise exposure of cold rolling mill workers by using noise dosimeter. METHODS: According to job category and work type, all workers were divided into 11 groups. 3 to 5 day shift (8:00 to 16:00) workers from each group were selected as subjects for personal noise exposure measurement. SH-126 dosimeters were worn by each subject and collect noise data by a phone fix at collar. All subjects were asked to take notes about their working activities when they were wearing SH-126 dosimeters. Each worker's L(A)(eq) of 8 hours, geometric mean and range of each group were computed. RESULTS: There were many noise sources in the workshop. Recorded data showed that noise exposure of cold rolling mill was unstable. The varieties of personal noise levels were quite large. Among 53 workers, the highest noise exposure level was 100.0 dB (A), the lowest was 81.2 dB (A); the highest work type was of the foreside welders [94.20 dB (A)], and the lowest was of the straight-cutters [89.02 dB (A)]; quality checkers had the biggest rang [16.3 dB (A)], and primary rolling workers had the lest [2.3 dB (A)]. CONCLUSION: Noise exposure of all the 11 groups were more than 85 dB (A). Noise protection of these workers should be improved. It suggested that measuring personal noise exposure individually with dosimeters might obtain the noise exposure level more integrally in the complicated environment.