Is Lead a Concern in Autistic Children?

Background:

Lead is a known environmental toxin that affects the nervous system. Little research on prevalence of blood lead levels in developmentally affected children is available. Currently, there are no Canadian programs that offer surveillance of blood lead levels in young children or in “at risk” developmentally delayed groups although they are identified as being at risk for potential exposures.  Although the Centre for Disease Control (CDC) and Health Canada report regulatory levels of lead as 10 ug/dL or 0.48mmol/L, new research suggests levels of greater than 2 μg/dL or 0.1 mmol/L may affect IQ and behavior in young children.

Objectives:

To compare the blood lead levels in a sample of autistic children living in Northern Alberta with standards provided by the CDC guidelines.

Methods:

Children with a diagnosis of Autism were recruited from the Preschool Assessment Service and Autism follow-up clinics at the Glenrose Rehabilitation Hospital in Edmonton, Alberta. A CBC & differential, ferritin and blood lead were requested after consent was obtained. Summary statistics were reported as means with standard deviation as well as medians with ranges. For dichotomous outcomes rates were presented.

Results:

Table 1: Summary of blood work findings of Autistic cohort

Outcome [Unit]	Number (n)	Mean (SD)	Median (Range)
Age [years]	48	5.4 (2.1)	5.0 (3.0-10.8)
Blood Lead [umol/L]	48	0.082 (0.082)	0.05 (0.02-0.42 )
Hemoglobin [g/L]	42	130.94 (8.3)	131.5 (111-150)
MCV [fL]	42	82.2 (4.5)	83 (61-88)
Ferritin [ug/L]	40	29.8 (17.7)	25 (7-86)

None of the children had levels exceeding the current limits set by the CDC related to unsafe levels of blood lead. Nine (19%) had levels greater or equal to 0.1 umol/L but less than 0.48 umol/L. 39 children (81%) had blood levels less than 0.1 umol/L .

Conclusions:

Autistic children in Northern Alberta may not have a concern with elevated blood lead levels that exceed current CDC guidelines. Clinicians may need to explore the reasons for low level exposures to lead further and provide primary prevention for all children at risk.