Specific relationship between blood lead and air lead in the crystal industry

Objectives: The main objective of the study was to establish the consequences of exposure to crystal dust on blood lead level in workers employed in hand-finishing and grinding crystal pieces. The second objective was to research a relationship between ambient air lead and blood lead. Methods: A study conducted in eastern France on 131 subjects occupationally exposed to an aerosol containing crystal particles involved personal measurements of atmospheric exposure to lead, determination of blood lead and, by questionnaire, collection of personal data on exposure characteristics, state of health and level of hygiene of survey volunteers. Results: Initial analysis showed that differences in exposure at the workplace corresponded to differences in blood lead in the operators. There was definitely a potential risk of overexposure to lead, but the existence of this risk was not confirmed by level of blood lead concentrations and, moreover, no clinical signs of lead poisoning in the employees exposed were revealed. The existence of a relationship between personal air (PbA) and blood lead (PbB) levels in grinders and polishers was demonstrated. This relationship, of the form log PbB=2.064+0.181×log PbA, turns out to be different from those provided by previously published models, which were developed from studies conducted in lead–acid battery manufacturing plants and form the basis of national regulations. Thus, chronic exposure at 100 µg/m3 of lead at a crystal-grinding workshop corresponds to a mean PbB level of 270 µg/l, whereas the recognized models estimate 350 to 500 µg/l. Conclusions: This study revealed a specific risk for these categories of exposed individuals. The origin of the descriptive model obtained for the lead exposure/ PbB level relationship raises, through the example of lead, the more general problem of the need to take into account differentiation of chemical substances containing the same element in biological monitoring.