Nasopharyngeal carcinoma in Malaysian Chinese: occupational exposures to particles, formaldehyde and heat

Background During 1990-1992, 282 Chinese residents of Selangor and the Fede ral Territory, Malaysia with histologically confirmed nasopharyngeal carcin oma (NPC) were interviewed about occupational history, diet, alcohol consum ption, and tobacco use, as were an equal number of Malaysian Chinese popula tion controls, pair-matched to cases by age and sex. Methods Exposures to 20 kinds of workplace substances, solar and industrial heat, and cigarette smoke, were analysed by univariate and multivariate me thods. Results Nasopharyngeal carcinoma was associated with occupational exposures to construction, metal and wood dusts; motor fuel and oil; paints and varn ishes: certain other chemicals; industrial heat; solar heat from outdoor oc cupations; certain smokes; cigarette smoking; and childhood exposure to par ental smoking. After adjustment for risk from diet and cigarette smoke, onl y wood dust (OR = 2.36; 95% CI : 1.33-4.19), and industrial heat (OR = 2.21 ; 95% CI : 1.12-4.33) remained clearly associated. Wood dust remained stati stically significant after further adjustment for social class. No signific ant crude or adjusted association was found between NPC and formaldehyde (a djusted OR = 0.71; 95% CI:0.34-1.43). Conclusions This study supports previous findings that some occupational in halants are risk factors for NPC. The statistical effect of wood dust remai ned substantial after adjustment for diet, cigarette smoke, and social clas s. Intense industrial heat emerged as a previously unreported risk factor, statistically significant even after adjustment for diet and cigarette smok e. No association was found between NPC and formaldehyde.