| Summary: | 碩士 === 中臺科技大學 === 環境與安全衛生工程系碩士班 === 104 === Carbon black has been studied intensively by health scientists in recent decades. Although International Agency for Research on Cancer (IARC) classifies carbon black as a Group 2B carcinogen (possibly carcinogenic to humans) based on "sufficient evidence" in animals and "inadequate evidence" in humans, poorly soluble particles, such as carbon black particles, have been evaluated for their genotoxicity using both in vitro and in vivo assays, since the inhalation of these compounds by rats at high concentrations has been found to lead to tumor formation. Few recent studies have discussed the hazards of exposure to heavy metals of carbon black for workers in tire manufacturing workplaces, but a polycyclic aromatic hydrocarbon (PAH) and Dioxin have been identified as posing a health risk to workers in workplaces where carbon black is used. Each air sample for particle matter (PM) was collected for 24 h using a micro-orifice uniform deposited impactor (MOUDI II, MSP, Model 110R). Metallic particles were analyzed using an inductively coupled plasma with atomic emission spectroscopy (ICP-OES). The health risks of inhaling carbon black during work at tire manufacturing workplaces was evaluated by quantifying the risk of developing cancer using a probabilistic approach.
The ranges of thoracic and total particles concentrations were 143.88–998.56 µg/m3 and 188.4–1614.55 µg/m3, respectively. The mass ratios of thoracic PM to total PM were in the range 0.61–0.83, with a mean of 68% of thoracic particles’ passing into the lung below the larynx as a result of each worker’s breathing. The mean concentrations of total metals in the all fractions were 13.998.36 g/m3. The most abundant elements of all fractions were Zn (8.622±5.679 g/m3) and Al (3.11±2.02 g/m3). The next most abundant elements were Fe, Pb and Sr, ranging from 0.19 g/m3 to 1.52 g/m3. Most metal content contributed approximately 51.72 %84.95 % to the total PM content in submicron particles (PM1), except Al and Zn. The most abundant metal contents in PM1 on all sampling days were Cd.
Cancer risks of carcinogenic metals (Cd and Cr) in thoracic particles for carbon black feeding process workers at a tire manufacturing plant nevertheless exceeded 106. In particular, the assessment of health risk of inhaled Cd and Cr in UFP fractions exhibited to be higher than 106 indicating that a carcinogenic health effect existed in the tire manufacturing workplace.
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