Soot, as Found in Occupational Exposure of Chimney Sweeps

For hundreds of years, chimneys have been swept with long steel brushes inserted manually into the chimney from the top and from the bottom. Chimney sweeps are exposed to soot, with concurrent exposure to sulfur dioxide and arsenic (Bagchi & Zimmerman, 1980). Soot is black particulate matter that is formed as a by-product of combustion or pyrolysis of organic (carbon-containing) materials, such as coal, wood, fuel oil, waste oil, paper, plastics and household refuse. The chemical composition and properties of soots are highly variable and depend on the type of starting material and the conditions of combustion. Soots vary considerably with respect to their relative content of carbon, their particle type, size and shape, and the types of organic and inorganic compounds adsorbed onto the particles. In general, soots have a total carbon content of up to 60%, a high content of inorganic material, and a soluble organic fraction. The latter is extractable with organic solvents and consists largely of PAHs and their derivatives. Inorganic constituents may include oxides, salts, metals, sulfur and nitrogen compounds, water, and other adsorbed liquids and gases (IARC, 1985; Watson & Valberg, 2001). Table 1.1 summarizes several recent studies that investigated exposure of chimney sweeps to PAHs. Knecht et al. (1989) assessed exposures in the breathing zone of chimney sweeps during so-called ‘dirty’ or ‘black work’ on 11 working days. Samples were taken per ‘job category’, based on the type of fuel fired: oil fuel, oil/solid or solid fuels. Twenty PAHs were quantified in a total of 115 samples. Higher concentrations were seen in soots that originated from burning of solid fuels. A bio-monitoring study carried out in Germany (n = 93) and Poland (n = 7) in 1995 reported 1-hydroxypyrene concentrations in the urine ranging from below the detection limit (0.1 μg/L) up to 12.8 μg/L (Letzel et al., 1999). Urinary concentrations in the samples from Poland were on average five times higher, most probably due to the fact that coal and wood are used more often as fuels in Poland. The concentrations in urine samples from workers in Germany were relatively low. The use of personal protective devices among this group of 100 chimney sweeps was not mentioned. In an Italian study, Pavanello et al. (2000) analysed the urine of 27 chimney SOOT, AS FOUND IN OCCUPATIONAL EXPOSURE OF CHIMNEY SWEEPS