Natural killer cell activity decreases in workers occupationally exposed to extremely low frequency magnetic fields exceeding 1 microT.

In a preliminary study a reduction in natural killer (NK) cell activity in peripheral blood lymphocytes (PBL) was observed in a group of workers exposed to levels of extremely low frequency-magnetic fields (ELF-MF) exceeding 1 microT. This study was performed to confirm the results. In 121 workers engaged in various occupational activities, individual ELF-MF exposure was monitored for 2 work shifts. Exposure levels were calculated as time-weighted average (TWA). Subjects were classified as Low exposure (TWA < or = 0.2 microT), Medium exposure (TWA 0.21-0.99 microT), or Higher exposure (TWA > or = 1 microT). In higher exposure workers NK activity proved significantly reduced compared to low exposure,(p<0.01). In medium exposure a reduction was also observed, but the difference was not significant. Multivariate analysis also confirmed the relation between exposure and NK activity. It has been suggested that ELF might affect tumour progression by inducing changes in the immune system: due to the role played by NK activity in host defence against cancer, the interference with the NK cell activity observed in this study is in agreement with this hypothesis. Furthermore, an increased risk for some neurodegenerative disorders has been reported in some epidemiological studies in ELF-MF-exposed workers: changes in NK function were also described in these diseases. Our results, showing the effect on NK activity of exposure exceeding 1 microT, suggest a possible mechanism for ELF-MF effects. This could open new horizons regarding the adverse long-term effects of these fields.

[Evaluation of the genotoxicity of the extremely low frequency-magnetic fields (ELF-MF) in workers exposed for professional reasons]. / Valutazione della genotossicità dei campi magnetici a frequenza estremamente bassa (ELF-MF) in lavoratori esposti per ragioni professionali.

Whether or not ELF-MF has genotoxic potential is a controversial issue. In the present study, we investigated the genotoxic effect using cytogenetic assays (CA - SCE - MN), in 109 workers exposed to ELF-MF. The mean value of occupational exposure in the whole group was 0.35 microT. According to the exposure level the workers were stratified in two different groups: low exposed (n. 39, TWA < or = 0.2 microT) and higher exposed (n. 70; TWA > 0.2 microT): the groups did not significantly differ for the examined variables. Due to these results we decided to re-evaluate the effect only considering the highest exposed workers: we selected 31 workers exposed to TWA levels exceeding 1 microT, and compared vs. the low exposed subjects: again, the difference in the groups examined were not significant. At multivariate regression analysis was also applied: no correlation was observed with cytogenetic biomarkers. The results of this study does not support the hypothesis of any direct genotoxic effect of ELF-MF, at least at the environmental levels currently found in an occupational settings.

[ELF-MF occupational exposure: repeated measures on workers]. / Campi magnetici ELF ed esposizione professionale: misure ripetute della esposizione individuale in lavoratori addetti a varie mansioni.

The aim of our study was to estimate occupational exposure to Extremely Low Frequency-Magnetic Fields (ELF-MF). Using personal dosimeters we evaluated occupational exposure in 543 workers employed in 9 occupational settings (about 150 jobs), representative of the main occupational activities in Emilia-Romagna region. In the whole sample, the median Time-Weighted Average (TWA) exposure resulted 0.14 microT (5 degrees - 95 degrees percentiles: 0.04 - 2.50 microT); Tile production presented the highest occupational setting TWA (0.46 +/- 1.83 microT), while the lower job TWA was Stock Clerk in Tile Production and Stock Clerk in Garment Production. After 6-9 months we repeated measurement in about 10% of the original sample (about 48 subjects) to verify the resulted obtained. At repeated measurement analysis with SPSS 12.0 no variation was found compared the previous monitoring. Individual occupational exposure to ELF-MF evaluated in a relatively large group of workers engaged in the main occupational activities proved low values compared to the proposed occupational limit.

[Personal exposure to ELF magnetic fields in workers engaged in various occupations]. / Esposizione personale a campi magnetici a frequenza estremamente bassa in lavoratori addetti a varie mansioni.

Using personal dosimeters worn during two complete work-shifts, we measured occupational exposure to Extremely Low Frequency-Magnetic Fields (ELF-MF) in 290 workers employed in 56 jobs, representative of the main occupational activities in the area of Modena and Reggio Emilia (Italy). Environmental nonoccupational exposure was also monitored. In the whole sample, the mean Time-Weighted Average (TWA) exposure during work resulted 0.59 microT (SD 3.2), while the median was 0.13 microT. Exposure was lower than 1 microT in more than 90% of the workers. In one job only exposure was greater than 1 microT (job-related median TWA); in other 8 exposure was between 1 and 0.4 microT, while about 84% of the jobs presented a median TWA lower than 0.4 microT. A high variability among workers engaged in the same job resulted in various occupational tasks. Non-occupational exposure was lower than 0.4 microT in more than 98% of the examined workers. Our results show a low to moderate occupational exposure to ELF-MF in the greatest part of the workers and working activities. Also the non-occupational exposure resulted low in the large majority of the subjects. The high variability observed among workers engaged in some occupations may represent a problem in exposure evaluation. Personal monitoring is particularly useful in such a situations.