Is lead a concern in Canadian autistic children?

BACKGROUND

The Centers for Disease Control and Prevention (CDC) threshold for intervention for blood lead level (BLL) is greater than 0.48 μmol/L, but new research suggests that there are adverse effects at any level of exposure. Children with autism are at increased risk for lead exposure and intoxication, and have later and more prolonged exposures because of exploratory oral behaviours and pica.

OBJECTIVE

To estimate the mean BLL and prevalence of high BLL in a convenience sample of autistic children living in northern Alberta, based on the CDC threshold for intervention.

METHODS

Children with autism were recruited from the clinics at the Glenrose Rehabilitation Hospital in Edmonton, Alberta. A complete blood count and differential, serum ferritin and BLL were requested after consent was obtained. Summary statistics were reported. For dichotomous outcomes, proportions were presented. Continuous outcomes for the two groups with a BLL of 0.1 μmol/L or greater, or less than 0.1 μmol/L were compared.

RESULTS

None of the children tested had a BLL exceeding 0.48 μmol/L. Nine children (19%) had BLLs of 0.1 μmol/L or greater but less than 0.48 μmol/L, and 39 (81%) had BLLs of less than 0.1 μmol/L. Those with a BLL of 0.1 μmol/L or greater had significantly more pica or oral exploratory behaviours.

CONCLUSION

Children with autism in northern Alberta may not be at risk for elevated BLLs that exceed the CDC threshold for intervention. They should be screened for lead exposure risk factors and tested if there are risks, especially behaviours relating to pica and oral exploration of objects. Clinicians may need to further explore the reasons for low-level exposures to lead in the autistic population.