We measured the concentrations of benzene, toluene, ethylbenzene, and xylenes (BTEX) in the ambient air of automobile repair garages in Montreal, Canada, using the direct atmospheric pressure chemical ionization-tandem mass spectrometry (APCI-MS/MS) method. Among all the air samples analyzed, toluene was the most abundant BTEX-species (127-1101 g/m3) followed by xylenes (50-323 g/m3), ethylbenzene (11-65 g/m3), and benzene (9.2-23 g/m3). BTEX levels where ventilation was controlled simultaneously by both mechanical and natural systems were significantly less than levels at garages where only natural ventilation was used. Results suggest that multiple sources contribute to the occupational exposure of automobile mechanics and painters to the BTEX. Owing to the toxic effects of these chemicals, both chronic non-cancer hazard and integrated lifetime cancer risk due to the exposure of this occupational group were assessed. The levels of the BTEX measured at all the garages were less than the established limits for occupational exposure; still, benzene levels pose a potential cancer risk for the workers. At the prevailing levels of BTEX, they may not cause any chronic non-cancer problems for the workers.

The impoundment of reservoirs temporarily increases the methylation of mercury bound to flooded soils and vegetation and the transfer of methylmercury (MeHg) to fish. MeHg levels in various fish species of hydroelectric reservoirs located in the James Bay territory increased by factors of 3 to 7, then gradually declined toward initial concentrations 10 to 20 years after flooding, depending on reservoir characteristics. The potential risk of increased MeHg exposure for recreational anglers who consume fish from these reservoirs had not been assessed previously. A less invasive method than systematic measurement of Hg levels in hair was developed to determine MeHg exposure of recreational anglers. A fish consumption questionnaire-based approach was combined with a toxicokinetic model to estimate tire corresponding hair MeHg concentrations. The results were compared,with actual analytical determinations of hair Hg levels for the 94 recreational anglers recruited for the study. The values predicted by the model based on self-reporting consumption overestimated actual hair Hg levels by an average factor greater than 6. The mean hair level predicted for the most recent period (September-October) was 23.3 mug.g(-1) compared to 3.6 mug.g(-1) for the measured value. Although the questionnaire protocol may certainly be improved to increase the precision of estimations, direct hair Hg measurement remains the more effective means to assess Hg exposure.

The increased use of Methylcyclopentadienyl manganese tricarbonyl (MMT) as a replacement for lead (Pb) in gasoline in Canada is suspected to lead to manganese (Mn) contamination, particularly in the urban ecosystems where traffic density is often high. This study has been conducted to assess the bioaccumulation and toxic effects of Mn in plants as they relate to the deposition of Mn3O4 resulting from a traffic volume of 150,000; 300,000 and 1,000,000 vehicles/day within 10 meters from the highway. Bean (Phaseolus vulgaris L.) and oat (Avena nova L.) plants were planted in organic soil in a controlled growth chamber. Each plant species was divided into four groups, one serving as the control group while the remaining three groups were exposed to three different quantities of Mn3O4 that compared to the theoretical deposition of Mn emitted by midsize vehicles from three different traffic volumes. The Mn concentration in the leaves of both plants and in oat roots were significantly higher (p <0.05) in the high exposed group compare to the control group. Significant differences in total and exchangeable Mn were found in the oat soil (p <0.05). Apparently, this increase in exchangeable Mn led to an increase in total Mn in oat leaves. There were no visible Mn toxicity symptoms for both species and the different parts of both plants did not exceed toxic threshold concentrations. The highest Mn concentration in bean leaves was 103 ppm and in the oat plants 41 ppm which are considered to be adequate for plants. Exposure level or traffic volume was significantly correlated with total Mn (p <0.05), exchangeable Mn (p <0.001) and pH (p <0.01) in the oat soil, The total Mn was significantly correlated with exchangeable Mn in the oat soil (p <0.01). These results suggest that Mn contamination from a traffic volume as high as one million vehicles per day, poses no significant problem in terms of bioaccumulation or effects on plants, even though Mn input caused an increase in exchangeable Mn in the soil where only oat plants were grown and in total Mn in the leaves of both plants.

Since 1976, methylcyclopentadienyl manganese tricarbonyl (MMT), an organic derivative of Mn, has been used in Canada as an anti-knock agent in unleaded gasoline. In a preliminary evaluation of the contribution of MMT to urban air pollution, the CO and NOx emissions of 10 vehicles each having traveled less than 17 000 miles were sampled. Five of these vehicles were filled with MMT-free gasoline and the remaining five with MMT-added gasoline. The emissions were evaluated according to the Federal Test Procedure which simulates urban and highway driving cycles. As for the NOx and CO analysis, it was carried out by means of infrared spectrometry, while the concentration of Mn in the gasoline was determined through neutron activation. Overall, the amount of CO emitted by the vehicles using MMT-added gasoline was 1.48 g mile-1 ± 1.77. The amount emitted by the vehicles using clear (MMT-free) gasoline was 0.74 g mile-1 ± 0.88. As for the NOx emission level, it was 0.20 g mile-1 ± 0.15 for the vehicles using MMT-added gasoline vs 0.17 g mile-1 ± 0.18 for the vehicles using clear gasoline. However, probably due to the small sample size and the very high level of emission of one of the vehicles using MMT-added gasoline, these differences are not statistically significant. Further studies should take into account variables such as the driving history and the representativity of the fleet of vehicles tested.

Since 1990, methylcyclopentadienyl manganese tricarbonyl (MMT) has been added to all gasoline in Canada as an antiknock agent. The objective of this study is to determine the percentage of manganese emitted by different types of automobiles and to evaluate the size and chemical characteristics of the Mn-containing particles. Nine vehicles with different mileage and engine capacity were tested using standard procedures for urban and highway driving cycles. One ran on gasoline without MMT and served as a control. The particles were collected using two separate systems: a trapping device consisting of a water tank connected to the tailpipe and a pumping device linked to a cassette containing Teflon filters. Water samples were analyzed by neutron activation to determine the amount of Mn emitted at the tailpipe for each test. Teflon filters were analyzed by electron microscopy to determine the size and the chemical characteristics of the particles. The amount of manganese emitted from the tailpipe varied from 4 to 41% of the manganese consumed, depending on the driving cycle and the vehicle. For the urban cycle, the emission rate was positively correlated with previous mileage. Almost all particles found on teflon filters had a size less than 5 μm. They appeared to be mainly Mn oxides but other elements could be masked by the gold and paladium peaks.

Manganese tetroxide (Mn3O4) is a product from the combustion of methylcyclopentadienyl manganese tricarbonyl. Exposure to high levels of manganese can lead to serious health effects especially to the central nervous and respiratory systems. Very few studies on the effects of long-term low level exposure to Mn3O4have been reported. The present study was therefore conducted to examine the bioaccumulation and toxicity of manganese in various organs of feral pigeons (Columba livia) when exposed to low levels of Mn3O4via inhalation and hence to find any possible relationship between these two parameters. A total of 22 pigeons was exposed to 239 μg/m3of manganese for 7 h/day, 5 days/week for 5, 9, and 13 consecutive weeks. Manganese concentrations in various tissues, e.g., brain (mesencephalon), lung, liver, intestine, pancreas, kidney, muscle, bone, and whole blood, were measured by neutron activation analysis. Various biochemical parameters in blood, e.g., hematocrit, total proteins, glucose, uric acid, alanine aminotransferase, total iron, blood urea nitrogen and triglycerides, were also measured. Manganese concentrations in brain, lung, and bone were significantly higher in Mn3O4-exposed pigeons (0.59, 0.58, and 3.02 μg/g wet tissue, respectively) than in the control group (0.46, 0.19, 1.74 μg/g wet tissue, respectively). However, except for total proteins such exposure did not produce any changes in various biochemical parameters which were within the normal values. Thus these results have shown that, despite significant bioaccumulation of manganese in some tissues, no significant toxic effects could be seen.

Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic derivative of manganese (Mn) used as an additive in unleaded gasoline. The combustion of MMT leads to the formation of oxides of manganese. The objective of the present study is to predict the environmental levels of Mn and the human exposure in the St-Lawrence ecozone (fluvial section, Quebec, Canada) using an environmental fate/exposure model: GEOTOX. The results of our MMT research program on abiotic and biotic components of the ecosystem and on the human exposure were used to validate the model estimations. Air and surface soil were selected as source terms with an annual Mn input rate in each compartment of 0.083-0.113 mol km-2 d-1 and 0.44-0.87 mol km-2 d-1 respectively (Mn3O4 equivalent). The predicted air, soil, plant, surface water and sediment concentrations were similar (+/- 50%) to values measured in the Montreal region. As expected, the ingestion pathway was the main absorption route for adults (> 99%), with vegetables and fruits contributing almost 80% of the dietary intake of Mn. The multimedia exposure doses for adult men predicted by the model ranged between 0.04 and 0.08 mg kg-1 d-1 compared to 0.004 and 0.201 mg kg-1 d-1 (average = 0.05) for workers from the MMT study. Considering the landscape configuration and the source vectors (air and soil) included in the model, GEOTOX estimations were in good agreement with measured values.

Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organometallic compound used as an octane improver in unleaded gasoline. The combustion of MMT leads to the formation of manganese (Mn) oxides, mainly Mn3O4. The objective of this study is to assess the variations over time and space of respirable (MnR) and total (MnT) Mn in the urban atmosphere and to evaluate human exposure by inhalation. Two sampling sites were selected on the island of Montreal based on their local traffic density (municipal botanical garden, C- = 10,000-15,000 vehicles d-1; Montreal Waterworks, C+ = 100,000-130,000 vehicles d-1). Air samplings were made during the day at stations located 10 m from the road using portable pumps, some of which were equipped with a cyclone. MnR and MnT and other metals were measured on Teflon filters by neutron activation. Mn exposure doses by inhalation were calculated using Monte-Carlo simulations. MnR and MnT average concentrations were significantly higher at site C+ (MnR = 0.024 microgram m-3; MnT = 0.050 microgram m-3) than at site C- (MnR = 0.015 microgram m-3; MnT = 0.027 microgram m-3). Temporal profiles at sites C+ and site C- were similar, with a coefficient of correlation of 0.24 for MnR and 0.26 for MnT. Trend analyses (ARIMA) also showed that the period of the week (work days vs. off days) was significantly related to MnR and MnT variations at both sites. The average exposure dose by inhalation to MnR and MnT ranged from 0.001 to 0.030 microgram kg-1 day-1 and 0.001 to 0.05 microgram kg-1 day-1. MnR and MnT concentrations reflected a positive relationship with traffic density. However, it remains difficult to attribute these results directly to the combustion of MMT in unleaded gasoline. On average, the MnR and MnT inhalation doses were 2 to 15 times lower than the reference dose (RfC) proposed by the U.S. Environmental Protection Agency (EPA) for the general population.

This paper presents the results of a risk assessment study made using CalTOX, a multimedia, multiple pathway risk assessment model. The case study is based on the Polycyclic Aromatic Hydrocarbon (PAH) soil contamination resulting from the activities of a natural gas power station over a period of 70 years. It describes model characteristics and input parameters such as physico-chemical properties, landscape description, and human exposure factors. Model simulations and risk estimations corresponding to different remedial scenarios in an industrial zone are also presented. These estimations were based on soil contamination by 16 PAHs in the root-zone and vadose-zone layer. Results show that adult exposure (workers) to contaminated soil will lead to a potential health risk of carcinogenic effects, and to no potential risk of non-carcinogenic effects. On the other hand, the addition of 10 cm of clean soil over the contaminated soil (mitigated scenario) decreases the lifetime cancer risk to an acceptable level. The sensitivity analysis showed that the half-life of benzo[a]pyrene in the root-zone soil is the most sensitive parameter and that it contributes significantly to the variability of the cancer risk estimation. In addition, the cancer risk level of the workers exposed to this substance, as estimated by CalTOX (point estimate) in the mitigated and unmitigated scenario, corresponds approximately to the 95th percentile value obtained by means of Monte-Carlo simulations. Finally, CalTOX has proven to be a valuable tool to predict and elaborate scenarios for the risk management of sites contaminated as a result of industrial activities.

The Mn contamination arising from the combustion of MMT (methylcyclopentadienyl manganese tricarbonyl) in unleaded gasoline was assessed using snow collected at different distances 15, 25, 125 and 150 m from an expressway (Montreal, Canada) in February 1993. The snow samples were analyzed by atomic absorption and by neutron activation for total Mn, Mg, Cu, V, Al, Zn, Fe, Na, and Ca concentrations in the soluble (<0.4 μm) and particulate fractions. ANOVA with ranked values was performed to compare element concentrations and soluble/particulate ratios among receptor sites and depths. Principal component analysis was used to describe the spatiotemporal variations of the deposition rates and the influence of meteorological factors. The average concentration of all trace elements, except Mg, Cu, and V, decreased significantly (p < 0.05) from receptor sites near the road (15–25 m) to those farther away (125–150 m). The deposition rates of all metals and ions, except Cu, were highly positively correlated (τ = 0.5–0.9) with each other and inversely correlated with snowfalls. Wind frequency showed no correlation with deposition rate. The spatial trend was similar for all these elements making it difficult to distinguish Mn arising from the combustion of MMT from that due to other sources, such as road dust. Only the soluble/particulate ratio calculated for Mn seemed higher than that for the other metals, which might be explained by the particle size of Mn from MMT (0.2–0.4 μm). The present study only indicates a direct contamination of the snow by road activities and substantial deposition of trace elements near the roadway; no clear link can be established between motor vehicle emissions and the concentration of Mn in snow.

This research measured the exposure of two groups of workers to respirable and total manganese (Mn) and characterized the Mn particles emitted from an automobile tailpipe. The exposure of 20 office workers and 9 taxi drivers in Toronto to total airborne Mn and respirable Mn was measured over a 7-day period, 24 hours per day. Subjects were asked to wear two pumps (one included a size-selective cyclone that collected the respirable particles), and two battery chargers were supplied to each person so that the pump batteries could be recharged overnight while sampling continued. All filters were analyzed by neutron activation. In addition, Mn particles emitted from a car were collected directly at the exhaust. Particles were observed using secondary electron images in a scanning electron microscope (SEM), and their elemental composition was determined by energy dispersive x-ray spectrometry. The Mn concentrations obtained for the group of office workers ranged from 0.001 to 0.034 microgram/m3 for respirable Mn and from 0.002 to 0.044 microgram/m3 for total Mn. For the taxi drivers the Mn concentrations ranged from 0.007 to 0.032 microgram/m3 for respirable Mn and from 0.008 to 0.073 microgram/m3 for total Mn. There was a significant difference (p < 0.05) between the two groups for both respirable and total Mn. SEM analysis showed that the particles were mostly heterogeneous agglomerates varying from 1 to 100 microns. Even if the specific exposure to Mn from automobiles has not been directly established, these results suggest that the related increase of exposure may be limited.

Inhalation exposure to manganese (Mn) was measured for a group of garage mechanics and a control group of nonautomotive workers. The airborne Mn exposure of 35 garage mechanics suspected of being relatively highly exposed to Mn from MMT was measured at the workplace over one-week period. It also was measured for 30 nonautomotive workers at the University of Montreal. The environmental exposure also was measured for the two groups, as was the exposure to three other metals, aluminum (Al), iron (Fe), and zinc (Zn). At work the mechanics were exposed to Mn concentrations varying from 0.010 to 6.673 micrograms m-3 with a mean of 0.45 microgram m-5, while the control group was exposed to concentrations varying from 0.011 to 1.862 microgram m-3 with a mean of 0.04 microgram m-3. The mean environmental exposure for the two groups was similar to the Mn concentrations gathered in Montreal in 1992. Workplace concentrations of Al, Fe, and Zn also were higher for the garage mechanics. The results suggest that less than 10% of the Mn exposure of the garage mechanics was due to MMT. The levels of the metals measured were below the established limits for industrial and even environmental exposure.

Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic additive used in Canada since 1976 as an anti-knock agent in unleaded gasoline. Its combustion leads to the emission of Mn oxides, especially Mn3O4. Since no study has assessed the potential risk of chronic exposure to low concentrations resulting from these emissions, the present investigation was undertaken to assess the level of environmental and occupational exposure of the human population. The multimedia exposure of two groups of workers (garage mechanics and blue-collar workers) potentially exposed to different levels of Mn from the combustion of MMT was assessed using personal air samplers, a dietary compilation, water samples at their places of residence, an epidemiological questionnaire and blood and hair samples. Results show that garage mechanics were exposed on average to higher atmospheric Mn at work (0.42 µg/m3) than the blue-collar workers (0.04 µg/m3). However, the contribution of atmospheric Mn to the total absorbed dose was less than 1%, and well below the standards estabished for occupational or environmental exposure; food contributes more than 95% of the multimedia dose. The average whole blood Mn concentrations were similar for the two groups (0.67–0.76 µg/100 ml) and fall within the normal adult range. The average hair Mn concentrations were significantly higher for the garage mechanics (0.66 µg/g) than for the blue-collar workers (0.39 µg/g). The contribution of exogenous Mn versus endogenous Mn is questioned. As judged by the governmental standards or criteria for occupational and non-occupational environments, the current Mn levels in food, water and air may not cause any problems for the workers.

Since 1976, methylcyclopentadienyl manganese tricarbonyl (MMT) has been used in Canada as an antiknock agent in gasoline and it completely replaced lead in 1990. The combustion of MMT leads to the formation of Mn oxides, especially Mn3O4. This paper calculates the contribution of Mn from MMT source to the total atmospheric Mn concentration using two dispersion models (CALINE4, ISCLT). The results are compared to CO estimates since CO is often used as a surrogate for Mn human exposure assessment. The study area is located near a major highway (117,585 cars per day) in the city of Montreal. Model estimates were validated using results from two sampling stations located 25 and 250 m from the road centerline. Both models gave similar Mn estimates for distances over 250 m with values ranging from 1 to 3 ng m(-3). These predicted values underestimate by a factor of ten the measured values 250 m from the road. The Mn contribution from MMT may be masked by other sources such as Mn enriched road dust or naturally occurring crustal material. On the other hand, CO estimates and measured values are almost identical. This may be explained by the fact that the mobile source Mn contribution to total atmospheric emissions is less than 20%, whereas for CO it may reach 75%. The total uncertainty in the model predictions was estimated at 50%.

Methylcyclopentadienyl manganese tricarbonyl (MMT) has been used in Canada since 1976 as an additive in unleaded gasoline. The combustion of MMT leads to the emission of Mn oxides to the environment and may represent a potential risk to public health. It therefore seems important to assess the associated Mn exposure. The present study is part of a broader research program on total human exposure to Mn and aims specifically at assessing the level of exposure to Mn and other metals via drinking water. A comparative study was performed between two groups of workers (garage mechanics and blue collar workers of the University of Montreal) differentiated by their exposure to inhaled Mn. For Pb, Cu and Zn in residential tap water, significant differences were observed between the first sample and the one taken after one minute of flow. A significant difference was also found between the two groups of workers (combined flow time) for Mn, Cu and Ca. The Mn contribution from water is estimated to be 1% of the total dose from ingested food. This low exposure may become important (17%) for persons drinking well water, especially if we consider interactions between metals following multimedia exposure.

Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic derivative of manganese (Mn) used in unleaded gasoline in Canada since 1977. It has been suggested that the production of Mn3O4 resulting from the combustion of MMT may become one of the principal sources of manganese contamination in the urban environment. This research evaluates the feral pigeon (Columba livia) as a monitor of Mn contamination in rural (Lachute) and urban (Montreal) environments. Atmospheric Mn concentrations were measured over a 6-month period in the rural and urban areas. 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 neutron activation. Biochemical profiles of the blood samples (total protein, 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 μg/m3) relative to the rural area (0.026 μg/m3). Mn concentrations were similar (P>0.05) in the two groups of pigeons for all the tissues except liver (Lachute=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 significantly different in the two groups. These results show the importance of the entero-hepatic cycle in the homeostasis of Mn in blood and other tissues. Since the excess of Mn in the feces and liver of the urban pigeons 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 biomarkers of Mn contamination. Although it is premature to associate this excess Mn with the combustion of MMT, these results nevertheless lead us to consider the pigeon as an interesting indicator of the potential risk to the ecosystem and to human health.

Occupational and environmental exposure to airborne manganese has been measured for two groups of workers in Montreal, taxi drivers and garage mechanics. In Canada methylcyclopentadienyl manganese tricarbonyl (MMT) has replaced lead as an anti-knock agent in gasoline and represents a potentially important source of manganese contamination for the population in general and for the two chosen groups of workers in particular. Twenty workers (10 taxi drivers and 10 garage mechanics) wore a personal air sampler for five consecutive working days and two off-work periods. The amount of total Mn on each filter was determined by neutron activation analysis and then converted to atmospheric Mn concentrations. The values obtained varied from 0.004 microgram m-3 to 2.067 micrograms m-3. At work the garage mechanics were exposed to an average of 0.250 microgram m-3 and the taxi drivers to 0.024 microgram m-3. Off-work, the two groups were exposed respectively to an average of 0.007 microgram m-3 and 0.011 microgram m-3. In the garages there was twice as much Mn in the air on days when the doors were closed compared to days when they were left opened (0.314 micrograms m-3/0.152 microgram m-3). The levels found in this study remain well below the established limits for occupational and environmental airborne exposure. These results will lead to further studies to positively identify the source of Mn as MMT and to explore other pathways leading to the contamination of the general population.

This study on the bioaccumulation of manganese (Mn) by plants was motivated by the increased use of Methylcyclopentadienyl manganese tricarbonyl (MMT) as a replacement for lead in gasoline. Oats and beans were grown in sandy and organic soils at a control site (Eo) and at two other sites weakly (E+) and highly exposed (E++) to Mn contamination, potentially from a MMT source. Total Mn, Ca, Mg, Fe, Zn and Al were measured in the soils and in the plants (roots, stems/leaves and fruits). Exchangeable Mn was measured in the soils at the beginning and at the end of the exposure period. The pH of the organic and sandy silty soils were found to be lower outdoors (E+ and E++) than in the greenhouse (Eo) and exchangeable Mn was found to be significantly higher in the organic soil at E++ (1.03–1.36 ppm). Higher Mn accumulation was also found in the fruits and stems of oats grown in the organic and sandy soils at E++. This Mn accumulation is often associated with increased Fe and Al in the plant. These results suggest that the addition of MMT to gasoline may result in an increase in exchangeable Mn in organic soils. However, it has not been proven that the source of the increased Mn accumulation is indeed MMT in gasoline.

Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic derivative of manganese (Mn) used as an additive in unleaded gasoline. Its use in Canada has increased since 1976 until it completely replaced lead (Pb) in gasoline in 1990. Canada is the only country in the world to have authorized the replacement of Pb in gasoline by MMT. The aim of this study is to compare the concentrations of Mn, Pb and suspended particulates (TSP) in Montreal air from 1981 to 1992, as well as the emission rates of Mn and Pb from mobile sources from the same period. The atmospheric concentrations of Mn, Pb and TSP were measured by the Montreal Urban Community at three sampling stations located in areas of low and high traffic density. The data on emission rates were obtained from Environment Canada and from the Canadian Petroleum Products Institute. Multiple regression and non-parametric correlation analysis were used to predict and to compare the evolution of the chosen variables. Discriminant analysis was used to determine the variables which best distinguish low and high traffic density areas. The results indicate stable Mn concentrations between 1981 and 1990 followed by a substantial decrease, in spite of annual increases of about 10% in Mn emissions from the combustion of MMT since 1981. The decrease observed since 1991 is attributed to the closing of a ferromanganese plant near Montreal. The decrease in atmospheric Pb concentrations observed since 1981 corresponds to the decrease of about 30% per year of emissions from mobile sources over the same period. A definitive evaluation of the environmental contamination and exposure due to Mn from MMT will require an improved estimation of the dispersion of particulates near motorways using dispersion models, as well as receptor modeling based on the physicochemical analysis of particulates using electron microscopy.