Parental exposures and risk for childhood acute lymphoblastic leukemia, Colombia, 2000-2005

Objective: The objective of this paper is to determine the risk factors for childhood acute lymphoblastic leukemia (ALL) and, in particular, the role of the parental occupational exposure to carcinogenic and probably carcinogenic hydrocarbons before the child's conception. Methods: We conducted a neighborhood-based matched case-control study in six Colombian hospitals. Cases were children (0-14 years) who were newly diagnosed with ALL between January, 2000 and March, 2005. An interview with both parents of 170 children (85 cases and 85 individually matched neighborhood controls) gathered information about parental demographic and occupational characteristics, medical history, habits, pregnancy and birth history and child's exposures. A job-exposure matrix was used. Conditional odds ratios (OR) and 95% confidence intervals (95%CI) were calculated by period of exposure (preconception, pregnancy and childhood). Results: The risk of childhood ALL was linked to: a. parental occupational exposure to hydrocarbons before conception: neither parent exposed (reference); father only (OR=1.66; 95%CI: 0.64-4.28); mother only (OR=6.33; 95%CI: 1.41-28.31); both exposed (OR=13.47; 95%CI: 3.31-54.71); b. paternal and/or maternal smoking before conception (OR=2.63; 95%CI: 1.24-5.56); c. maternal low socioeconomic status during pregnancy (OR=3.53; 95%CI: 1.22-10.21) and; d. advanced maternal age at birth (35+: OR=3.72; 95%CI: 1.13-12.29). Conclusions: These findings suggest an association between childhood ALL and the parental occupational exposure to carcinogenic and probably carcinogenic hydrocarbons before conception showing differences depending on the parent exposed, however, in further studies, the additive or multiplicative role of other environmental sources of hydrocarbons should also be investigated.