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Comparative sensitivity of children and adults to neurological effects of inhaled manganese
Citation:
Shaffer, R., Michael Wright, AND T. Bateson. Comparative sensitivity of children and adults to neurological effects of inhaled manganese. International Society for Environmental Epidemiology, New York, New York, August 23 - 26, 2021.
Impact/Purpose:
The U.S. EPA’s 1993 reference concentration (RfC) for inhaled Mn (per mg/m3) is based on neurological outcomes in adults. To understand whether this RfC, with a default intraspecies uncertainty factor (UFH), accounts for lifestage-based variations in susceptibility, we compared sensitivities to neurotoxicity in children and adults using Mn biomarker data.
Description:
To evaluated comparative susceptibility to neurological effects of Mn in children and adults, we identified paired studies based on concordant Mn source, biomarker, and outcome. Comparisons were made based on slope of the observed dose-response (children:adults).We identified five studies evaluating seven pairings of hair Mn and neurological outcomes in child and adult populations with environmental Mn inhalation exposure. Two Brazilian studies of children (ages 6-12) and one of adults reported effects on IQ; effects in both comparisons were stronger in children (203% and 121%). A paired study of children and adults in Ohio reported effects on five metrics of postural sway; children exhibited both stronger and weaker effects compared to adults (175% to 69%). Preliminary results suggest that a default UFH =10 is sufficient for considering variations in neurological effects by lifestage. This conclusion should be interpreted with caution, given the limited available paired studies