Pregnancy, maternal exposure to hair dyes and hair straightening cosmetics, and early age leukemia.

OBJECTIVE: To investigate the association between maternal exposure to hair dyes and hair straightening cosmetics (HDSC) during pregnancy and leukemia at an early age (<2yr., EAL).

METHODS: A multicenter hospital-based case-control study was carried out in 13 states in Brazil between 1999 and 2007. Mothers of 176 ALL (acute lymphocytic leukemia) and 55 AML (acute myeloid leukemia) cases and 419 controls were enrolled and interviewed. Data on maternal exposure to HDSC occurring 3months before pregnancy, during pregnancy and during breastfeeding were obtained. Data were also gathered on paternal exposure to HDSC before pregnancy. Unconditional logistic regression was performed and odds ratios (OR) on the association between HDSC use and EAL were obtained after adjustment for hormonal intake during pregnancy, maternal age, education, birth weight, and the child skin color.

RESULTS: An adjusted OR of 1.78 (95% C.I. 1.13-2.81) was observed between maternal exposure to HDSC in the first trimester of pregnancy and ALL. Regarding AML, an adjusted OR of 2.43 (95% C.I. 1.13-5.22) was found for maternal exposure to HDSC during breastfeeding. No association between maternal exposure to HDSC during pregnancy and ALL or AML was observed in children with MLL (Mixed Lineage Leukemia) gene rearrangement.

CONCLUSIONS: Results in this study seem to support the hypothesis that maternal exposure to HDSC during pregnancy may be involved in the etiology of leukemia in children under 2years of age.