Environmental and Biological Assessment of Exposure to Benzene in Petroleum Workers

Occupational exposure to benzene was measured in two gasoline marketing terminals and five major refineries in Singapore. A total of 280 workers were monitored over two years. This assessment was carried out with two primary objectives: (1) To find out the extent of occupational exposure to benzene in the petroleum industry in Singapore, (2) To identify suitable biomarkers for monitoring of low levels of benzene exposure. The exposure was measured in five different categories of petroleum and petrochemical workers, i.e., truck drivers, despatch assistant, process operators, oil movements operators and laboratory technicians. The results revealed wide variations in exposure, from 0.01 to 13.6 ppm for personal time weighted average (TWA) exposure over the whole workshift. The exposure of truck drivers appeared to be the highest, with geometric mean (GM) of 1.98 ppm (ranged from 0.25 to 13.6 ppm). The average benzene exposure for process operators was relative low with a GM of 0.04 ppm. Lowest benzene exposure was found in the laboratory technicians, with a GM of 0.02 ppm. As cigarette smoking is known to affect metabolism of benzene, data analyses on the relationships with environmental exposure were conducted only on the 190 nonsmokers. The results showed that urinary trans, trans-muconic acid (ttMA), unmetabolized benzene in urine (UBZ) and benzene in blood (BBZ) were better biomarkers for low level benzene exposure as compared to urinary phenolic metabolites in urine, such as hydroquinone, phenol and catechol.     

The incidence of fungi and mycotoxins in South African barley and barley products

Barley is grown as a crop in South Africa, mainly for use in the barley beer (lager) industry, particularly in the production of barley malt. This investigation was done to find out what fungal infection and mycotoxin contamination this barley and the malt contained. The survey, done in 2005, not only covered barley and malt but also the final product in the form of several brands of beer purchased from retail outlets. Analysis was done using a range of methodologies including chromatography, immunoaffinity/fluorimetry and cytotoxicity testing. The results show that barley, which also includes barley sold directly to the public, and malt, contain various fungi, sometimes at high incidence and also a range of mycotoxins which persisted through, although at low levels, to beer. The malt showed a different pattern of micro flora, as compared to the barley, which indicates infection during the malting process, which is not uncommon. Interestingly, fumonisin B1 was found in some of the samples, as well as the beer, although in the latter case these were at very low levels. Recent studies have shown that the immunoaffinity/fluorimetry method can give false positives for the fumonisins, so these results were confirmed by high performance liquid chromatography. As is the case with other cereals grown in South Africa, there is the concern that the public is exposed to mycotoxins on a regular basis through the consumption of products made from them.