THE PIGEON (COLUMBA-LIVIA) AS A MONITOR FOR MANGANESE CONTAMINATION FROM MOTOR-VEHICLES

Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic deriv ative of manganese (Mn) used in unleaded gasoline in Canada since 1977 . It has been suggested that the production of Mn3O4 resulting from th e combustion of MMT may become one of the principal sources of mangane se contamination in the urban environment. This research evaluates the feral pigeon (Columba livia) as a monitor of Mn contamination in rura l (Lachute) and urban (Montreal) environments. Atmospheric Mn concentr ations were measured over a 6-month period in the rural and urban area s. Twenty pigeons were captured in each area and the Mn concentrations of several tissues (liver, kidney, lung, pancreas, intestine, brain, down feathers, feces, whole blood, and blood serum) were measured by n eutron activation. Biochemical profiles of the blood samples (total pr otein, aspartate aminotransferase, hematocrit, glucose, and uric acid) were also measured. Air particulate data showed significantly higher Mn levels (p < 0.05) in the urban area (0.036 mu g/m(3)) relative to t he rural area (0.026 mu g/m(3)). Mn concentrations were similar (p > 0 .05) in the two groups of pigeons for all the tissues except liver (La chute = 2.42 ppm; Montreal = 3.13 ppm) and feces (Lachute = 32.2 ppm; Montreal = 46.8 ppm); the urban pigeons had about 35% more Mn than the rural pigeons. Aspartate aminotransferase (AST) was also significantl y different in the two groups. These results show the importance of th e entero-hepatic cycle in the homeostasis of Mn in blood and other tis sues. Since the excess of Mn in the feces and liver of the urban pigeo ns relative to the rural pigeons was similar to the excess Mn in urban air over rural air, pigeon feces and liver appear to be good biomarke rs of Mn contamination. Although it is premature to associate this exc ess Mn with the combustion of MMT, these results nevertheless lead us to consider the pigeon as an interesting indicator of the potential ri sk to the ecosystem and to human health.