Associations of heavy metal levels with environmental and behavioral factors in children with autism spectrum disorder

Abstract Background The etiologies of autism spectrum disorder (ASD) are yet unclear. Previous studies suggested that ASD is associated with environmental heavy metals. Thus, the present study analyzed the levels of 41 heavy metals and the associated environmental factors in children with ASD. Methods The 25 children diagnosed with ASD were included in the case group (ASD group), while the 18 age- and gender-matched healthy children who came for routine care were included in the typical development group (TD group). The levels of heavy metal in the blood were measured in both groups. The questionnaire survey collected the demographic information, socioeconomic information, and risk factors of potential heavy metal sources for the analysis of risk factors. Results A total of 25 children were included in the ASD group and 18 in the TD group. The blood manganese (Mn) level was significantly higher in the ASD group than the TD group . The father’s educational level was significantly higher in the ASD group than the TD group. The living status was mainly scattered for the ASD children and daycare for the TD group. The frequency of book-reading, washing hand with sanitizer/soap, and the folic acid intake by the mother before pregnancy was significantly lower in the ASD group than the TD group, while the percentage of birth disorder history was significantly higher in the ASD group than the TD group. Binary logistic regression analysis showed that the folic acid intake by the mother before pregnancy and father’s education level beyond junior college were protective factors for ASD. Also, the frequencies of washing hands with sanitizer every time, sometimes, and hardly acted as protective factors for ASD. Conclusion Blood Mn level was significantly higher in ASD than TD, suggesting that environmental Mn exposure could be a risk factor of ASD in children. Folic acid intake by the mother before pregnancy and father’s education levels are protective factors for ASD. Concentrated heavy metal in the blood in prenatal or early life exposures which suggested ASD is needed in the future study.