Monitoring lead workers

Ong CN, Chua LH andTERAMOTO K (1990) Biological monitoring of workers exposed to lead stearate. J Appl Toxicol 10 65-68. 

PbU has some interpretive features shared with other biomarkers of Pb exposure, especially PbB and PbP. Notably, single PbU measurements done in isolation do not offer helpful data on the nature of Pb exposures or their sources. Serial measurements are considerably more useful. Such an apphca-tion would be more of an advantage in occupational exposure monitoring for lead workers than in monitoring short-term or even chronic exposures in the very young. 

So far only acute adverse effects which could be readily associated with excessive lead exposure have been considered. However, studies on lead workers have elicited symptoms of lassitude, anorexia, abdominal discomfort, constipation, insomnia, irritability, pallor and anaemia - complaints which are common in the general population. The recent development of environmental and biological monitoring procedures, and of epidemiological methodology, now enables us to investigate non-specific and subclinical effects in relation to lead exposure with greater precision. 

For the periodic monitoring of workers exposed to lead, the Commission of the European Communities now recommends PbB level as a measure of internal dose and erythrocyte protoporphyrin (see Mushak, this volume) as an indicator of effect. It is further recommended that in male workers PbB levels should not exceed 60/ig/dl, and in women workers of childbearing age PbB should be no higher than 40 lig/dl because of a potential adverse effect on the fetus (Alessio and Foa, 1983). 

In addition to limits on airborne lead, an OSHA regulation provides for biological monitoring and places limits on blood lead levels in workers of... 

Information on occupational exposure to lead is obtained primarily from the National Occupational Exposure Survey (NOES) and industry surveys of workers. While occupational exposure is widespread, environmental monitoring data on levels of exposure in many occupations are not available. OSHA has established a permissible exposure limit (PEL) for lead of 50 pg/m3 for workplace air (OSHA 1991). NIOSH has estimated that more than 1 million American workers were occupationally exposed to inorganic lead in more than 100 occupations (NIOSH 1977a, 1978a). According to NOES, conducted by NIOSH between 1980 and 1983, an estimated 25,169 employees were exposed to tetraethyl lead (not used in gasoline since December 31, 1995) approximately 57,000 employees were exposed to various lead oxides mostly in non-ferrous foundries, lead smelters, and battery plants 3,902 employees were exposed to lead chloride and 576,579 employees were exposed to some other form of lead in the workplace in 1980 (NIOSH 1990). Workers who operate and maintain solid waste incinerators are also exposed to air lead levels as high as 2,500 pg/m3 (Malkin 1992). 

Tabuchi T, Okayama A, Ogawa Y, et al. 1989. A new HPLC fluorimetric method to monitor urinary delta-aminolevulinic acid (ALA-U) levels in workers exposed to lead. Int Arch Occup Environ Health 61 297-302. 

VuralN, Duydu Y. 1995. Biological, monitoring of lead in workers exposed to tetraethyllead. Sci Total Environ 171 183-187. 

Because the molar volume of an unfolded protein is less than that of the native state, increasing pressure leads to denaturation (Gross and Jaenicke, 1994). Royer and co-workers have employed high-pressure SAXS to monitor the pressure-induced unfolding of Snase. They find that the unfolded ensemble achieves a pressure-independent Rg of... 

Unless the coverage of adsorbate is monitored simultaneously using spectroscopic methods with the electrochemical kinetics, the results will always be subject to uncertainties of interpretation. A second difficulty is that oxidation of methanol generates not just C02 but small quantities of other products. The measured current will show contributions from all these reactions but they are likely to go by different pathways and the primary interest is that pathway that leads only to C02. These difficulties were addressed in a recent paper by Christensen and co-workers (1993) who used in situ FT1R both to monitor CO coverage and simultaneously to measure the rate of C02 formation. Within the reflection mode of the IR technique used in this paper this is not a straightforward undertaking and the effects of diffusion had to be taken into account in order to help quantify the data obtained. 

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