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Objectives: Skin is such an important route of absorption of mercury compounds that the ACGIH has assigned them a skin notation. Soil has been recognised as a potential source of exposure to chemical contaminants. It therefore seems advisable to establish maximum daily exposure levels for mercury in soil. In the past, areas adjacent to certain industries and smelters were heavily contaminated by mercury. For example, on Monte Amiata in Tuscany, which was an important mercury mining and production centre in the past, several areas have been polluted. To understand the dermal uptake of chemicals bound to soil and dust, information on the pure substance is helpful but does not seem sufficient. Other factors must be accounted for, that can easily be reproduced and controlled in in vitro experiments., Methods: Using an in vitro diffusion cell system and human skin, we studied percutaneous penetration of mercury chloride (HgCl2) at different concentrations, with particular emphasis on skin absorption from soil. The test apparatus consisted of a flow-through diffusion cell system. Dermotomed human cadaver skin was used as the membrane, while the receiving liquid was a saline solution with 6% PEG-20 oleyl-ether and gentamycin sulphate. Mercury chloride was applied at two different concentrations using a buffered solution and soil as vehicles., Results and Conclusions: Increments of percentage of absorption at the different hours were found to be significantly lower in the cells where the higher concentration of mercury chloride was applied. In the receiving fluid of cells where soil was used as vehicle, the concentration of mercury was always below the detection limit. Skin contamination with soil containing inorganic mercury does not seem to be a dermal risk.

A number of studies on the health of occupational exposure to lead of workers from various industrial sectors are summarized. These studies document the disappearance of severe cases of saturnism, as seen in the past, and the occurrence nowadays, mainly of sub-clinical manifestations, such as alterations of blood levels of lead and protoporphyrin IX, in the large majority of cases. For the period 1984-95, a statistical analysis of the results obtained for these parameters is reported, together with other clinical data, for seven industrial sectors: crystal, ceramics, chemistry, metallurgy and mechanics, iron and steel, printing and painting. These results show a drop of the mean concentrations of blood lead levels in all sectors but the ceramic industry, especially since 1991, when the law, Decreto Legislativo 277/91--in accomplishment of European directives on protection of workers, including the directive 82/605/EEC--has been put into force.

The overall prevalence of occupational asthma is unknown. It has been estimated that 15% of all adult asthmatics suffer from asthma caused by occupational exposure. The prevalence of occupational asthma varies depending on the nature of the industrial agent, the concentration of exposure and working conditions. In Italy diisocyanates and flour dusts are the commonest causes (60%) of occupational asthma. The diagnosis of occupational asthma is made by confirming the diagnosis of bronchial asthma and by establishing a relationship between asthma and the work environment. History and measurement of non-specific bronchial hyperreactivity are useful to establish a clinical diagnosis, while skin (or serologic) tests with the appropriate extract may be useful in the identification of the responsible agent (high molecular weight compounds such as protein). With low molecular agents (e.g. diisocyanates, wood dust, colophony) the specific bronchial provocation test in hospital or the measurement of lung function tests at work ("stop-resume" test) are required. There are few follow-up studies of patients with occupational asthma; all of them show that only 40% (mean) of the patients completely recover after cessation of exposure. Atopy (one or more skin prick tests positive to common allergens) is not sufficiently discriminative for screening purposes when a person enters a new occupational environment where an occupational asthma agent is present. Preemployment screening is useful to define the higher risk workers: atopy may be used as an indication for more frequent or more strict monitoring in periodic medical surveillance.