This paper proposes to study the extent of hearing loss in an occupationally exposed group to lead and arsenic, in contrast with the same loss in workers: a) non-exposed, and b) exposed only to lead. In all work places of the copper industry in Transilvania area the occupational exposure of workers to lead exceeded by 3–28 times the maximal admissible concentration (MAC = 0.1 mg/m3), and by 1.7–4.2 times the MAC for arsenic (0.1 mg/m 3). The studied group included 71 workers from a copper foundry exposed concomitantly to lead and arsenic. The control group consisted 70 non-exposed workers. A third group comprised 72 workers exposed only to lead, from a lead foundry. The subjects with a hearing history were excluded from the study. The workers from all groups were 20–55 year old. All the groups were tested by air and bone conducted audiometry in a sound proof chamber. The blood lead level and urinary arsenic level were used as exposure indicators. The biochemical tests performed in the lead and arsenic exposed subjects reveled a blood lead level between 10–48 µg/dl, and an urinary arsenic level between 3.7–96 µg/g creatinine. In the group exposed only to lead the blood lead level was between 15–54 µg/dl. The blood lead levels and urinary arsenic level of the reference group were under 14 µg/dl and 17 µg/g creatininc respectively. The results have shown a statistically significant increase of the differences (12, 17, 20 and 21 dB for 4, 6, 8 and 10 kHz frequencies) on hearing threshold level (HTL), in the lead and arsenic exposed group as compared to the non-exposed one. In the sample exposed only to lead, some lesser decreases of HTL (7, 15, 14 and 12 dB for 4, 6, 8 and 10 kHz frequencies) were observed as compared to the non-exposed one. In order to establish a possible relation between the HTL and blood lead and urinary arsenic values, correlation coefficients were calculated for each frequency. The results show a significant correlation between the two mentioned biological parameters and HTL. The values of the coefficients for the higher frequencies (above 4 kHz) suggest a close correlation between the blood lead level and HTL for both exposed groups. In the same way smaller but significant correlation was calculated between urinary arsenic level and HTL, in lead and arsenic exposed workers. In conclusion hearing loss may be used as an effect indicator of exposure to lead and arsenic.
Institute Of Public Health Cluj-Napoca, Romania.