Concentrations of Lead, Mercury, Arsenic, Cadmium, Manganese, and Aluminum in Blood of Romanian Children Suspected of Having Autism Spectrum Disorder

Background: Perinatal or postnatal environmental exposure to lead (Pb) has been associated with Autism Spectrum Disorder (ASD) in children. Higher concentrations of mercury (Hg), arsenic (As), cadmium (Cd), manganese (Mn), and aluminum (Al) in blood or urine of children have been associated with ASD. In collaboration with faculty at Carol Davila University of Medicine and Pharmacy in Romania, we conducted a pilot study to assess the feasibility for conducting epidemiologic research on gene-environment interactions in relation to ASD in Romania.

Objectives: To estimate blood concentrations of six metals (Pb, Hg, As, Cd, Mn, and Al) and identify their associated factors for children with ASD or suspected of having ASD in Romania.

Methods: From 2015-2107, sixty (60) children 2-8 years old who were suspected of having ASD were administered translated versions of ADOS and ADI-R in Romanian. Those who exceeded the threshold for ASD based on either ADOS or ADI-R were classified as “ASD or suspected of having ASD”. After assessment, 2-3 mL of blood was obtained from each child and analyzed for the concentrations of the six metals at the Michigan Department of Health and Human Services in Lansing, Michigan, USA. Concentrations below limits of detection (LoD) for each metal were replaced by 2^-1/2LoD. For all six metals, we calculated geometric and arithmetic means and standard deviations (SD) of concentrations. For metals that had no more than 30% of the concentrations below LoD, we assessed factors associated with concentrations by using the log of metal concentrations as a dependent variable in univariable and multivariable linear regression models.

Results: The mean age of children was 51.9 months and about 90% were male. More than half (65%) of the children were born in Bucharest; 45.5% of fathers and 71.7% of mothers had education beyond high school. The percentage of concentrations below LoD for Pb, Mn, Al, Hg, As, and Cd were 0%, 0%, 30%, 61.7%, 90%, and 95%, respectively. Geometric mean concentrations of Pb, Mn, Al, Hg, As, and Cd were 1.14 μg/dL, 10.84 μg/L, 14.44μg/L, 0.35μg/L, 0.99μg/L, and 0.10μg/L, respectively. Univariable linear regression analysis revealed that children who ate fresh shellfish (lobster, crab, crawfish) had significantly higher Mn level (P=0.05) compared to children who did not. Similarly, significantly higher Al concentrations were observed in children who ate melon (P=0.04), shrimp (P=0.03), and lamb (P=0.03), compared to children who did not. Multivariable linear regression analysis indicated that children who were female, had less educated parents, exhibited pica, and ate cold breakfast (e.g., cereal), watermelon, and lamb had significantly higher concentrations of Pb compared to their respective referent categories (all P <0.05 except for eating lamb, which was marginally significant, P=0.053).

Conclusions: This is the first study from Romania that provides information about concentrations of the six heavy metals in blood of Romanian children with ASD. The factors associated with higher levels of Pb, Mn, and Al also provide important information for designing future epidemiologic studies for investigating the role of these six metals in ASD in Romanian children.