A COMPARATIVE STUDY OF MANGANESE AND LEAD LEVELS IN HUMAN UMBILICAL CORDS AND

MATERNAL BLOOD FROM TWO URBAN CENTERS EXPOSED TO DIFFERENT GASOLINE ADDITIVES

Smargiassi Audrey* (CINBIOSE, University of Quebec in Montreal, C.P. 8888,

succ. Centre Ville, Montreal, Quebec H3C 3P8), Huel Guy, Hellier Georgette

(INSERM, Research in Epidemiology, Villejuif, France), Masse André, Sergerie

Martin (CHUM, St. Luc Hospital, Montreal, Quebec), Mergler Donna

(CINBIOSE, University of Quebec in Montreal)

Manganese (Mn) and lead (Pb) are two neurotoxic chemicals. While experimental

studies clearly indicate that Pb can cross the placental barrier, little is

known about Mn placental transport. Mn is however known to increase during

pregnancy. Tetraethyl lead is still in use as an antiknocking agent in Paris,

while methylcyclopentadienyl manganese tricarbonyl (MMT) has replaced its use

in Canada. In a matched study of 100 pairs of mother-neonates in Montreal and

Paris, we compared levels of Mn and Pb in cord and maternal blood. Neonates

and mothers have significantly higher Pb levels in Paris where lead additives

are still used in gasoline. Median maternal blood Pb levels were 5.8 ug/dl in

Paris compared to 2.5 ug/dl in Montreal, while cord blood Pb levels were 3.7

and 2.0 respectively (paired t-test, p<0.01). The prevalence in Paris of Pb

values superior to the 95th percentile of the Montreal distribution was highly

elevated in all media studied (Mc Nemar, p<0.01). While mean manganese maternal

and cord blood levels were similar in Montreal and Paris, the distribution of

manganese cord blood levels differed. The prevalence in Montreal of Mn cord

blood values superior to the 95th percentile of the Paris distribution was

significantly higher than the expected 5% prevalence of abnormal values in

Paris (McNemar, p=0.04). Surveillance programs are important to limit Pb

overexposure and associated neurological effects in neonates where tetraethyl

Pb is still in use as a gasoline additive. Since Mn is an essential element and

dietary Mn intake may differ between Montreal and Paris, the difference observed

with regard to abnormal Mn values, between Montreal and Paris cannot, at this

time, be necessarily attributed to MMT in Montreal's gasoline. Further studies

are needed to confirm the association beetween Mn emissions from MMT and

prenatal exposure to Mn.