Maternal serum concentrations of persistent organic pollutants and childhood acute lymphoblastic leukemia in the Finnish Maternity Cohort.

BACKGROUND/AIMS: Children are exposed to persistent organic pollutants (POPs) including polychlorinated biphenyls (PCBs) and organochlorine pesticides through in utero transfer from maternal serum. Few studies have evaluated the relationship between POPs and childhood leukemia risk.

METHODS

The Finnish Maternity Cohort is a population-based pregnancy cohort with banked serum and linkages to cancer registry and other databases. We measured first-trimester levels of 25 POPs in maternal sera collected in 1986-2010 for 388 childhood acute lymphoblastic leukemia (ALL) cases (<15 years) and 388 controls matched on sample date, gestational age (≥37 weeks; ± 1 week), birth order (first/second), mother's age, and child's sex. We analyzed lipid-adjusted POPs as continuous (log2-transformed) and categorical exposures and estimated odds ratios (OR) and 95% confidence intervals (CI) using conditional logistic regression with adjustment for correlated POPs (ρ = 0.3-<0.90) in multivariable models. We evaluated joint effects of POPs with >80% quantifications using quantile-based g-computation.

RESULTS

POPs detected in >80% of controls included trans-nonachlor (93%), p',p'-dichlorodiphenylethylene (p',p'-DDE; 100%), hexachlorobenzene (99%), β-hexachlorocyclohexane (β-HCH; 84%), and 10 PCBs (range: 84-100%). Increasing trans-nonachlor concentrations were associated with ALL (adjusted ORperlog2 = 1.48,CI = 1.11-1.97); risk was elevated among those in the 90th percentile (adjusted ORQ90vsQ1 = 2.32,CI = 0.98-5.45; p-trend = 0.05). PCB170, 180, 183, and total PCBs were associated with a 34-37% increased risk (e.g., PCB180 adjusted ORperlog2 1.37, CI = 1.05-1.78). β-HCH and p',p'-DDE were inversely associated with ALL. The mixture (hexachlorobenzene, β-HCH, trans-nonachlor, p,p'-DDE, total PCBs) was inversely associated with childhood ALL (ORperlog2 = 0.63, 95% CI 0.43-0.94).

CONCLUSION

Our findings suggest that trans-nonachlor and some PCBs may increase childhood leukemia risk with unexplained inverse associations for β-HCH and p',p'-DDE.