Two new studies by international teams, including Egyptian scientists, have validated the link between autism and mercury.
In an article published in the journal Metabolic Brain Disease, a team of nine scientists from leading Egyptian universities and medical schools confirmed the causal role of mercury in the onset of autism.
The scientists determined the extent of mercury poisoning in children by measuring urinary excretion of organic compounds called porphyrins, which act as biomarkers for mercury toxicity. The researchers also measured blood levels of mercury and lead. The researchers found a strong relationship between mercury toxicity and the presence of autism and a direct correlation between levels of mercury toxicity and the severity of autism symptoms.
The scientists studied 100 children; 40 with autism spectrum disorder (ASD), 40 healthy individuals and 20 healthy siblings of ASD children. The results showed that the children with ASD had significantly higher mercury levels than healthy children and healthy siblings. Children with the highest mercury levels had the most severe autism symptoms.
At least six American studies have linked autism presence or severity to mercury exposure as determined by measuring urinary porphyrins. The first study, completed by Heyer et al. in 2012 (Autism Res 5:84) showed a correlation between the presence of autism and specific urinary porphyrins associated with mercury toxicity. This affirmed an earlier study by Kern et al. (2011, Pediatr Int 53:147) where specific porphyrins associated with mercury toxicity were significantly higher in ASD children as compared to non-autistic controls. Woods et al. (2010, Environ Health Perspect 118:1450) also saw disordered porphyrin metabolism in autistic kids which was not observed in non-autistic control children. This again suggested increased mercury toxicity associated with autism and autism spectrum disorder.