Effect of lead on the levels of some immunoregulatory cytokines in occupationally exposed workers.

Lead (Pb) may affect humoral and cellular immunity, acting on lymphocytes as well as on granulocytes and monocytes. Cytokines and nitric oxide (NO) play a central role in the immune balance. In this study, plasma levels of nitrites and nitrates (NOx), IL2, IL4, IL6, IL10, TNF-alpha and INF-gamma, were measured in healthy workers with very low (Pb-B=3.2-18.0 microg/dL) and low (Pb-B=9.1-46.0 microg/dL) Pb-exposure compared to non-exposed workers. Low Pb-exposed workers (Pb-B=9.1 -46.0 microg/ dL) were found to have significantly higher plasma IL-10 levels, and tendentially higher plasma TNF-alpha levels compared to non-exposed workers. This is the first report of a significant increase of plasma IL-10 levels in Pb-exposed workers. Plasma IL-10 increase was influenced by blood Pb levels even after correction for main confounding factors. No difference was found in plasma NOx levels between Pb-exposed and non-exposed workers, which is in agreement with previous findings exclusively regarding groups in the general population. Low Pb-exposure can induce an increase of pro-inflammatory cytokines, such as TNF-alpha, with a consequent increase of other cytokines, such as IL-10, considered a T cell cross-regulatory factor, suggesting possible interference of Pb in the system of immunophlogosis.

[Biological monitoring in oil refinery workers]. / Monitoraggio biologico per il benzene in lavoratori di una raffineria.

The effectiveness of t,t-muconic acid (t,t-MA) has been investigated as indicator of benzene exposure in workers of an oil refinery. 196 blue collar workers that operate in the field and 25 white collar workers who work in administration have been studied. Workers had not chronic diseases; all workers resulted fit to work. The environmental monitoring, effected with personal and fixed samplers (141 samplings), has shown that benzene air levels were lower than 170 mcg/m3. Biological monitoring was performed with measurements of blood benzene, urinary t,t-MA and urinary phenols. Each worker has been questioned regarding smoking habit, consumption of food containing sorbic acid and non-occupational exposure to benzene. Values of biological index were: t,t-MA 88 +/- 94.1 mcg/g cr, phenols 17.7 +/- 2.9 mg/g cr, blood benzene 25.4 +/- 4.3 ng/l. No significant differences were found between blue and white collars respect t,t-MA, phenols, blood benzene, non-occupational exposure to benzene, smoking habit, consumption of food containing sorbic acid. A meaningful correlation was found between the t,t-MA and the ingestion of the number of foods containing sorbic acid (r = 0.87). The results confirm that the t,t-MA seems incapable to distinguish occupationally exposed workers, at low levels of benzene exposure, from unexposed.