Exposure, health effects, immunological markers and biomarkers of susceptibility among Swedish rubber workers

Sammanfattning: Workers in the rubber industry have an increased risk of several diseases, such as airway disease, cancer and probably cardiovascular disease. The exposure is very complex; carbon disulfide (CS2) and polycyclic aromatic hydrocarbons (PAHs) being two of the contaminants. The general aim of this thesis was to find exposure-response relationships usable for risk assessments in the rubber industry. Urinary levels of TTCA and 1-HP, metabolites of CS2 and one PAH, was measured in 166 workers from eight rubber industries in southern Sweden and in 117 controls. Airways symptoms were recorded by structured interviews and immunological markers in blood analysed by routine analysis. Genotypes were established using molecular biology methods. Compared to controls, exposed workers had in average 420% higher urinary TTCA level and 200% higher urinary 1-HP level. The levels of TTCA and 1-HP differed between different rubber companies and their subdivisions, as well as between different vulcanisation methods. Exposed workers had, compared to controls, increased risk of itching, running or burning eyes, nose bleeds, throat burning and dryness, hoarseness, severe dry cough, nausea and headache. Only a few exposure-response relationships with either TTCA or 1-HP and symptoms were found, when the workers were divided into three equally sized groups according to their exposure. Increased levels of total IgG were observed among exposed workers compared to controls. No exposure-response relationship with neither TTCA nor 1-HP and immunological markers was found. Exposed workers with the GSTM1'O genotype had lower levels of TTCA compared to exposed workers with GSTM1'1 while the opposite were found for GSTT1. The effects of polymorphism in GSTA1-52 (G/A+A/A) on symptoms in exposed workers showed a consistent pattern of a protective effect. The results indicate that workers in the contemporary rubber industry develop symptoms and thus, the work environment should be further improved. Moreover, better markers of exposure should be established in order to obtain better exposure-response relationships. In addition, adding information of different genotypes may sharpen the risk assessments.