Abstracts: ISEE 21st Annual Conference, Dublin, Ireland, August 25-29, 2009: Oral Presentations
University of California, Davis, Davis, CA, United States.
Abstracts published in Epidemiology have been reviewed by the organizations of Epidemiology. Affliate Societies at whose meetings the abstracts have been accepted for presentation. These abstracts have not undergone review by the Editorial Board of Epidemiology.
Background and Objective:
Because mercury is known to target the central nervous system, considerable interest has focused on this metal as a possible contributor to autism development. Nevertheless, little research has addressed total environmental mercury and much controversy surrounds the topic. In this study, we (1) addressed the relationship between sources of external mercury exposures and hair mercury levels in first baby haircuts and (2) determined if there is an association between baby hair mercury levels and autism development.
The Childhood Autism Risks from Genetics and the Environment (CHARGE) study is a comprehensive, population-based case-control study with participants sampled from three strata: children with autism, children with developmental delay but not autism, and typically developing children. Autism and ASD diagnoses were confirmed using established instruments, namely the ADI-R and ADOS. The child's first hair cut was collected from the mothers and mercury levels were determined using Laser Ablation coupled to ICP-MS (Inductively Coupled Plasma Mass Spectrometry). To predict hair mercury levels, we fit a multiple linear regression model including three levels of fish consumption and Rho D immunoglobulin. A multiple logistic regression model was fit to assess the relationship between log hair mercury levels and developmental outcome (autism versus typical development) in the presence of potential confounders including mother's fish consumption during the index period, duration of breastfeeding, and mother's education level.
Although none of the variables significantly predicted log hair mercury levels, there was a trend showing that increased levels of fish consumption predict higher hair mercury levels. The odds ratio for log hair mercury predicting developmental outcome was 0.98 (0.83, 1.16).
There does not appear to be a relationship between hair mercury levels in first baby haircuts and the development of autism, although further investigation of gene-environment interactions might identify vulnerable subsets.