Daily intake of Se by adult population of Mumbai, India

The atmospheric Se levels in Mumbai varied between 0.02 and 1.92 ng m(-3) with a mean concentration of 0.21 ng m(-3). The daily intake of Se by the adult population of Mumbai is 61.9 microg day(-1). Differential pulse cathodic stripping voltammetry (DP-CSV) has been used for the determination of Se in air particulate and food samples. The detection limit of Se using DPCSV was found to be 0.05 ng ml(-1). The reliability of estimation was further assessed through the analysis of standard reference materials (SRMs), tuna fish, animal blood, milk powder and fish tissue obtained from IAEA. The frequency distribution of dietary intake levels of selenium for Mumbai adults showed that approximately 61% of the studied population have a dietary intake of 30-90 microg day(-1). Ingestion was found to be the main route of Se exposure for Mumbai adults. The turn over time of Se through blood is 17 days.     

Daily intake of aluminium by adult population of Mumbai,India

Electrothermal atomic absorption spectrophotometry (ET-AAS) has been used for the determination of Al in environmental and food samples with a detection limit of 0.3 ng ml(-1). The reliability of estimation is assessed through the analysis of Standard Reference Materials (IAEA SRMs) of Soil-7, SL-3, SD-M2/TM and Hay (V-10). The results indicate that the average concentration of aluminium in air particulate samples is 5.3 microg m(-3). The daily intake of Al by the adult population of Mumbai is 6.4 mg day(-1).     

Motor alterations associated with exposure to manganese in the environment in Mexico

Overexposure to manganese (Mn) causes neurotoxicity (a Parkinson-like syndrome) or psychiatric damage ("manganese madness"). Several studies have shown alterations to motor and neural behavior associated with exposure to Mn in the workplace. However, there are few studies on the effects of environmental exposure of whole populations. We studied the risk of motor alterations in people living in a mining district in Mexico. We studied 288 individual people (168 women and 120 men) from eight communities at various distances from manganese extraction or processing facilities in the district of Molango. We measured manganese concentrations in airborne particles, water, soil and crops and evaluated the possible routes of Mn exposure. We also took samples of people's blood and determined their concentrations of Mn and lead (Pb). We used "Esquema de Diagnóstico Neuropsicológico" Ardila and Ostrosky-Solís's neuropsychological battery to evaluate motor functions. Concentrations of Mn in drinking water and maize grain were less than detection limits at most sampling sites. Manganese extractable by DTPA in soils ranged between 6 and 280 mg kg(-1) and means were largest close to Mn extraction or processing facilities. Air Mn concentration ranged between 0.003 and 5.86 microg/m(3); the mean value was 0.42 microg/m(3) and median was 0.10 microg/m(3), the average value (geometric mean) resulted to be 0.13 microg/m(3). Mean blood manganese concentration was 10.16 microg/l, and geometric mean 9.44 microg/l, ranged between 5.0 and 31.0 mcrog/l. We found no association between concentrations of Mn in blood and motor tests. There was a statistically significant association between Mn concentrations in air and motor tests that assessed the coordination of two movements (OR 3.69; 95% CI 0.9, 15.13) and position changes in hand movements (OR 3.09; CI 95% 1.07, 8.92). An association with tests evaluating conflictive reactions (task that explores verbal regulations of movements) was also found (OR 2.30; CI 95% 1.00, 5.28). It seems from our results that people living close to the manganese mines and processing plants suffer from an incipient motor deficit, as a result of their inhaling manganese-rich dust.     

Daily intakes of copper, zinc and arsenic in drinking water by population of Shanghai, China

Daily intakes of metals in drinking water are of extreme importance in risk assessment to human health. Some papers focused on this topic, but most of them did not consider the effect of age, gender and work location on daily intakes of metals in drinking water. The objective of present paper is to estimate the levels of Cu, Zn and As ingestion in drinking water in Shanghai, China and the effect of age, gender and work location on daily intakes of these metals. It was also the first time that such a detailed investigation on daily intakes of metals in drinking water was carried out in China in recent years. Drink/Sample (D/S) method was used to estimate the daily intakes of Cu, Zn and As in drinking water. The mean concentrations of Cu, Zn and As in drinking water were 10.8 microg/l, 0.29 mg/l and 0.91 microg/l, which were lower than U.S. EPA's Drinking Water Equivalent Level (DWEL) and WHO guideline values. The average daily intakes of Cu, Zn and As in drinking water was 21.12 microg/d, 0.65 mg/d, and 1.83 microg/d, which were on average 0.01%, 1.1% and 1.5% of the provisional maximum tolerable daily intake (PMTDI) set by the Joint FAO/WHO Expert Committee. There was a significant difference in daily intake of Zn for different work locations (P=0.04). But no other significant differences in daily intakes of metals in drinking water were found according to age, gender and work location.     

Selenium status in Greenland Inuit

In Greenland, the human intake of selenium has always been relatively high and is closely connected to intake of the traditional food of marine origin. Analyses of historic and present day human and animal hair samples have indicated that the selenium level in the marine environment has been constant over time, while the levels in humans have declined corresponding to a decrease in intake of traditional food. The Inuit population in Greenland is in dietary transition where western-style food will increasingly dominate. As a consequence, the ample supply of selenium may not be sustained in the future. We report here the selenium status in three Greenlandic population groups, Ittoqqortoormiit and Tasiilaq on the east coast and Uummannaq on the west coast. Mean whole blood concentrations ranged from 178 microg/l in Tasiilaq men to 488 microg/l in Uummannaq men. Plasma concentrations ranged from 79 microg/l in Tasiilaq women to 113 microg/l in Uummannaq men. With increasing Se concentrations in whole blood, the plasma concentrations increased but tended to stabilise a level approximately 140 microg/l. Selenium blood levels were highly significantly correlated with long chain marine fatty acids. Dietary survey and food composition data from the west coast showed that whale skin, muktuk, is the main source of Se followed by birds, seal meat and organs, and fish. Terrestrial animals contributed only insignificantly to the selenium intake. In West Greenland, daily Se intake (235 microg/day) was estimated by dietary survey; it corresponded well with a calculated intake (220 microg/day) based on the mean blood concentration.     

Survey of arsenic and other heavy metals in food composites and drinking water and estimation of dietary intake by the villagers from an arsenic-affected area of West Bengal,India

An investigation of arsenic, copper, nickel, manganese, zinc and selenium concentration in foodstuffs and drinking water, collected from 34 families and estimation of the average daily dietary intake were carried out in the arsenic-affected areas of the Jalangi and Domkal blocks, Murshidabad district, West Bengal where arsenic-contaminated groundwater (mean: 0.11 mg/l, n=34) is the main source for drinking. The shallow large diameter tubewells, installed for agricultural irrigation contain an appreciable amount of arsenic (mean: 0.094 mg/l, n=10). So some arsenic can be expected in the food chain and food cultivated in this area. Most of the individual food composites contain a considerable amount of arsenic. The mean arsenic levels in food categories are vegetables (20.9 and 21.2 microg/kg), cereals and bakery goods (130 and 179 microg/kg) and spices (133 and 202 microg/kg) for the Jalangi and Domkal blocks, respectively. For all other heavy metals, the observed mean concentration values are mostly in good agreement with the reported values around the world (except higher zinc in cereals). The provisional tolerable daily intake value of inorganic arsenic microg/kg body wt./day) is: for adult males (11.8 and 9.4); adult females (13.9 and 11); and children (15.3 and 12) in the Jalangi and Domkal blocks, respectively (according to FAO/WHO report, the value is 2.1 microg/kg body wt./day). According to WHO, intake of 1.0 mg of inorganic arsenic per day may give rise to skin lesions within a few years. The average daily dietary intake of copper, nickel and manganese is high, whereas for zinc, the value is low (for adult males: 8.34 and 10.2 mg/day; adult females: 8.26 and 10.3 mg/day; and children: 4.59 and 5.66 mg/day) in the Jalangi and Domkal blocks, respectively, compared to the recommended dietary allowance of zinc for adult males, adult females and children (15, 12 and 10 mg/day, respectively). The average daily dietary intake of selenium microg/kg body wt./day) is on the lower side for the children (1.07 and 1.22), comparable for the adult males (0.81 and 0.95) and slightly on the higher side for the adult females (1.08 and 1.26), compared to the recommended value (1.7 and 0.9 microg/kg body wt./day for infants and adults, respectively).     

Aluminium content of drinking waters,fruit juices and soft drinks: contribution to dietary intake

Concentrations of aluminium in drinking waters (tap water, still mineral water and sparkling mineral water), fruit juices and soft drinks were determined using graphite furnace atomic absorption spectrometry (GFAAS) of samples processed with a HNO3-V205 acid digestion pre-treatment. In water samples, aluminium was determined directly. We verified the sensitivity, accuracy and precision of the method and ruled out matrix interferences. In analysed samples, aluminium values ranged from 4.2 to 165.3 microg/l in drinking water (n=41), from 49.3 to 1,144.6 microg/l in fruit juices (n=47), and from 44.6 to 1053.3 microg/l in soft drinks (n=88). According to the type of container (glass or can) statistically significant differences (P<0.01) have been demonstrated. Considering the mean daily individual consumption of these beverages in Spain, the daily dietary intake of Al supplied by this source is estimated as 156 microg/person/day. This study contributes new data on the Al content of a variety of foods and beverages in Spain and to estimate reliably the total dietary intake of aluminium.     

Pharmacokinetic model of daily selenium intake from contaminated seafood in Taiwan

Contaminated seafood has been reported as an important source of human exposure to metals in Taiwan. Seafood represents a non-negligible source of selenium in the human diet. This study was designed to determine the concentration of selenium in different types of seafood and predict the concentration of selenium in the blood of Taiwanese using a one-compartment steady-state pharmacokinetic (PK) model. Samples involved three subgroups, including fish, crustaceans and bivalve molluscs. Quantitative analysis for selenium was performed using an ICP-AES (Perkin Elmer) instrument. Selenium concentrations in seafood ranged from 0.63 to 2.01 microg/g wet wt. The highest selenium concentration found in fish was 2.01+/-0.36 microg/g wet wt in Salmo salar Linnaeus. In general, selenium concentration increased in the order of bivalve molluscs相似文献   

Oral manganese intake estimated with dietary records and with direct chemical analysis

The estimation of the daily oral intake of manganese (Mn) can vary significantly with the method used. This study aims to compare two different approaches: the use of dietary records along with tables of the Mn contents of different foods and the parallel collection of identical aliquots which are analyzed for Mn. Dietary samples and information were collected during a 3-day dietary assessment with five participants. The average daily oral intake of Mn estimated from the dietary records and tables of Mn contents was 3.52 mg/day (S.D. = 1.9), which corresponds to an exposure dose (ED) of 50.27 microg/kg body wt./day (S.D. = 26.2). With a parallel collection of identical aliquots and chemical analysis, the average intake was 2.88 mg/day (S.D. = 0.64) for an ED of 41.18 microg/kg body wt./day (S.D. = 8.9). Thus, the use of tables gives an estimated oral dose 22% higher than the more accurate direct chemical analysis.     

The toxicity of copper to crucian carp (Carassius carassius) in soft water

Crucian carp (Carassius carassius) were exposed to a Cu rich medium (pH 6.6, conductivity 25 microS/cm, 2.91 mg Ca(2+)/l, approximately 300 microg Cu(2+)/l). Untreated department water (pH 6.6, conductivity 25 microS/cm, 2.91 mg Ca(2+)/l) acted as control. Mortality in crucian carp was first observed after 13 days of exposure to the Cu rich medium. There were, however, significant changes in haematocrit, plasma chloride, plasma sodium and water content in muscle in fish exposed to the Cu rich medium after two days. After 14 days of exposure to copper, haematocrit increased to 52+/-2% (control: between 37 and 40%), plasma chloride decreased to 45+/-5 mmol/l (control: 99-106 mmol/l), plasma sodium decreased to 81+/-6 mmol/l (control: 116-137 mmol/l), and water content in muscle increased to 83.0+/-0.3% (control: 78.7-79.9%). No apparent changes in blood ethanol, and minor changes in plasma lactate were observed in copper exposed fish. Analyses of the gills revealed an increasing concentration of copper on the gills from fish exposed to Cu rich water. After 14 days, the concentration of copper accumulated in the gill was 12.8+/-4.1 microg Cu/g wet weight (control: 0.91-1.19 microg Cu/g wet weight). A reduction of the respiratory area in fish exposed to copper was observed, in terms of both lamellar and filamental fusion. The normoxic O(2) uptake did not change, but the critical oxygen tension was elevated to 6.12+/-1.04 mg O(2)/l after a 6 day exposure to copper (control: 1.03+/-0.05 mg O(2)/l). This study shows that crucian carp has a higher tolerance to copper compared to other freshwater fish species. Our results suggest that this tolerance is based on the ability of crucian carp to avoid becoming hypoxic as well as an extreme tolerance to severe loss of plasma ions.     

A comparative study of manganese and lead levels in human umbilical cords and maternal blood from two urban centers exposed to different gasoline additives

Manganese (Mn) and lead (Pb) are two neurotoxic chemicals and experimental evidence suggests that they can cross the placental barrier. Tetraethyl lead was still in use as an antiknock agent in Paris during the sampling period of the study, while it has been replaced by methylcyclopentadienyl manganese tricarbonyl (MMT) in Canada since 1977. By 1990, MMT was in 100% of gasoline in Canada. In a study of 160 pairs of mothers-neonates in Montreal and 206 pairs in Paris, we compared levels of Mn and Pb in the umbilical cord and in maternal blood. Neonates and mothers had significantly higher Pb levels in Paris where lead additives were still used in gasoline. Geometric mean maternal blood Pb levels were 5.4 microg/dl compared to 2.1 microg/dl in Montreal and cord blood Pb levels were 3.2 microg/dl in Parisian mothers compared to 1.7 microg/dl in Montreal. The prevalence of Paris Pb values superior to the 95th percentile of the Montreal distribution was highly elevated in all media studied. The prevalence of high Mn levels in umbilical cord blood was also significantly higher in Montreal. 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 high Mn values between Montreal and Paris cannot, at this time, be attributed to MMT in Montreal's gasoline. Further studies are needed to infer an association between Mn emissions from MMT and prenatal exposure to Mn.     

The influence of the abandoned Kalecik Hg mine on water and stream sediments (Karaburun,Izmir, Turkey)

This study covers the geochemical investigations on water and stream sediments to evaluate the influence from the abandoned Kalecik Hg mine. The groundwater samples (S5, S8, S9, WW10) are neutral, slightly alkaline waters which have pH values varying between 7.3 and 7.5. Electrical conductivity (EC) values of groundwaters for spring samples are low (250-300 microS/cm). However, groundwater obtained from a deep well has a higher EC value of 950 microS/cm. Hg concentrations of groundwater samples vary between 0.01 and 0.13 microg/l. Hg concentrations of other water samples taken from mining area from surface waters and adits are between 0.10 and 0.99 microg/l. Adit water (A4) collected at the mine has the highest Hg content of 0.99 microg/l and a pH of 4.4. Trace element concentrations of mine water samples show variable values. As is observed only in MW1 (310 microg/l). A4 was enriched in Cd, Co and Cr and exceed the Turkish drinking water standards (Türk Standartlari Enstitüsü, 1997). Cu concentrations vary between 6.0 and 150 microg/l and are below the Turkish water standards. Mn concentrations in mine waters are between 0.02 and 4.9 mg/l. Only for sample A4 Mn value (4.9 mg/l) exceeds the standard level. Ni was enriched for all of the mine water samples and exceeds the safe standard level (20 microg/l) for drinking water. Of the major ions SO(4) shows a notable increase in this group reaching 650 mg/l that exceeds the drinking water standards. Stream sediment samples have abnormally high values for especially Hg and As, Sb, Ni, Cr metals. With the exception of sample Ss6 of which Hg concentration is 92 mg/kg, all the other samples have Hg contents of higher than 100 mg/kg. Pollution index values are significantly high and vary between 69 and 82 for stream sediment samples.     

Assessment of daily intake of trace elements due to consumption of foodstuffs by adult inhabitants of Rio de Janeiro city

Concentrations of Al, Cd, Cr, Cu, Mn, Ni, Pb, U and Zn were determined in vegetables (leafy vegetables, fruit, root, grain and cereal), derived products (sugar, coffee, manioc flour, wheat flour, corn flour, and pasta) and animal products (meat, fish, milk) most frequently consumed by adult inhabitants of Rio de Janeiro city. A total of 90 samples were analyzed using inductively coupled plasma mass spectrometry (ICPMS) as the principal method following sample dissolution by dry and wet ashing. Generally, highest contributions for the intake of micronutrients (Cu, Mn, Ni and Zn) arise from bean, rice and wheat flour consumption. Meat, cow milk and the flours, wheat and manioc, are major sources of Al, Cd, Pb and U intake. The daily intake of nine elements via foodstuffs was estimated as: 3.4x10(-4) mg of U, 1.8x10(-3) mg of Cd, 2.8x10(-2) mg of Pb, 2.3x10(-2) mg of Cr, 8.9x10(-2) mg of Ni, 1.12 mg of Cu, 2.5 mg of Mn, 3.5 mg of Al and 4.8 mg of Zn. The intake of toxic elements ranged between 2.7% (Cd) and 30% (U) of the provisional tolerable daily intake and reference dose values indicating that food consumption is, at present, no critical factor for the uptake of these toxic metals, in the population studied here. Concerning micronutrients, the recommended values of daily intake of Cu and Mn are conveniently supplied by the diet; however, for Cr and Zn they are lower than the recommend daily allowance. Due to high metal concentrations and consumption rates, black bean is the foodstuff that provided the highest ingestion rates of Cu, Mn, Ni and Zn (36-60% of the reference dose), being therefore a very important source of micronutrient supply.     

Dietary intake of cadmium by children and adults from Germany using duplicate portion sampling

The dietary intake of cadmium was studied among children and adults from Germany. The study area comprised the highly industrialized Ruhr district as well as the North Sea island Amrum. A total of 229 duplicate samples were collected from 49 individuals between December 1994 and May 1995. The sampling period for each participant was either 3 or 7 days. Cadmium concentrations in duplicate samples were measured by atomic absorption spectrometry. The daily cadmium intakes (geometric mean) for 4 different groups of individuals distributed as follows: for small children (mean age: 1.8 years) from the Ruhr district 0.17 microg/(kg(bw) x day) [range: 0.02-1.62 microg/(kg(bw) x day)], for children (mean age: 3.8 years) from the Ruhr district 0.49 microg/(kg(bw) x day) [range: 0.11-2.06 microg/(kg(bw) x day)], for children (mean age: 3.9 years) living on the North Sea island Amrum 0.35 microg/(kg(bw)-day) [range: 0.09-1.13 microg/ (kg(bw) x day)] and for adults (mean age: 40.9 years) from the Ruhr district 0.37 microg/(kg(bw) x day) [range: 0.05-1.32 microg/(kg(bw) x day)]. Compared to the provisional tolerable weekly intake (PTWI) of 7 microg/(kg(bw) x week) proposed by the WHO the dietary intake of cadmium was rather high. The geometric mean and maximum intake values for the different groups ranged between 24.3-55.7% and 62.7-120.7 respectively of the PTWI. We therefore conclude, that the cadmium exposure of the population needs to be reduced in order to minimize the risk of adverse health effects related to this metal.     

Serum sample levels of selenium and copper in healthy volunteers living in Rio de Janeiro city

The objective of this study was to analyze the serum sample levels of selenium and copper in healthy volunteers living in the city Rio de Janeiro. Thirty individuals were submitted for nutritional assessment, electrocardiogram, echocardiogram, and serum selenium and copper analysis through hydride generation and flame atomic absorption spectrometry, respectively. The accuracy and precision of these methods were evaluated using certified reference materials. None of the studied individuals was undernourished; 53% were overweight and 13.3% were slightly obese. The mean serum selenium level was 73.18+/-9.9 microg/l (56.50-94.50 microg/l). Among women it was 76.28+/-8.7 microg/l and in men 72.23+/-10.24 microg/l (P=0.35). Among non-white individuals the mean was 73.12+/-12.57 microg/l and in the white individuals it was 73.20+/-9.11 microg/l (P=0.98). The mean serum level of copper was 1.09+/-0.39 mg/l (0.56-1.80 mg/l). The mean found in women was 0.99+/-0.22 mg/l and in the men 1.13+/-0.43 mg/l (P=0.42). In non-white individuals it was 1.36+/-0.48 mg/l and in white individuals was 1.00+/-0.31 mg/l (P=0.02). The authors concluded that selenium and copper serum levels observed in this study were similar to those found in other cities.     

Occupational exposure to trihalomethanes in indoor swimming pools

The study evaluated occupational exposure to trihalomethanes (THMs) in indoor swimming pools. Thirty-two subjects, representing the whole workforce employed in the five public indoor swimming pools in the city of Modena (Northern Italy) were enrolled. Both environmental and biological monitoring of THMs exposure were performed. Environmental concentrations of THMs in different areas inside the swimming pools (at the poolside, in the reception area and in the engine-room) were measured as external exposure index, while individual exposure of swimming pool employees was estimated by THMs concentration in alveolar air. The levels of THMs observed in swimming pool water ranged from 17.8 to 70.8 microg/l; the mean levels of THMs in ambient air were 25.6+/-24.5 microg/m3 in the engine room, 26.1+/-24.3 microg/m3 in the reception area and 58.0+/-22.1 microg/m3 at the poolside. Among THMs, only chloroform and bromodichloromethane were always measured in ambient air, while dibromochloromethane was detected in ambient air rarely and bromoform only once. Biological monitoring results showed a THMs mean value of 20.9+/-15.6 microg/m3. Statistically significant differences were observed according to the main job activity: in pool attendants, THMs alveolar air were approximately double those observed in employees working in other areas of the swimming pools (25.1+/-16.5 microg/m3 vs. 14.8+/-12.3 microg/m3, P < 0.01). THMs in alveolar air samples were significantly correlated with THMs concentrations in ambient air (r = 0.57; P < 0.001). Indoor swimming pool employees are exposed to THMs at ambient air levels higher than the general population. The different environmental exposure inside the swimming pool can induce a different internal dose in exposed workers. The correlation found between ambient and alveolar air samples confirms that breath analysis is a good biological index of occupational exposure to these substances at low environmental levels.     

A Pb isotope and trace element study of rainwater from the Massif Central (France)

Lead isotope ratios and Zn, Pb, Cu, Cd, Sb and Rb contents were measured in samples of rainwater collected over a period of 15 months from the Massif Central (France). Each sample, collected automatically at monthly intervals, represents a series of rainfall events. Rainwater chemistry was interpreted in terms of the chemical contributions from wet deposition and from different source regions for dust in the centre of France. Trace element concentrations in rainwater samples showed a wide range, particularly for Pb (1.30-465 microg/l), with variations decreasing for Cd (0.07-1.70 microg/l), Zn (1.00-54.00 microg/l), Cu (0.20-25.00 microg/l), Sb (approximately 0-0.33 microg/l) and Ni (approximately 0-15.00 microg/l). Trace element contents do not correlate with rainfall amount and no inter-element correlations are evident in the data. Lead is the most common trace metal found in the rainwater (mean value = 996 microg/m2/y) while Sb is the least common element measured (mean value = 1.12 microg/m2/y). The composition of rainwater collected from the Massif Central shows a range in Pb isotope ratios from 17.935 to 19.22 (206Pb/204Pb), 15.578 to 15.73 (207Pb/204Pb) and 37.559 to 38.606 (208Pb/204Pb). A five-component mixing model involving contributions from the natural background, gasoline inputs from industrial and agricultural activity and a source resulting from mining waste may be used to explain both the Pb isotope signature and the fluctuations in trace metal contents of Massif Central rainwater.     

Total suspended particulate manganese in ambient air in Montreal 1981-2000

Our research group previously established the time variation of atmospheric Mn in Montreal for the period 1981-1992. The results indicated stable Mn concentrations between 1981 and 1990 followed by a decrease of almost 50% attributed to the closing of a ferromanganese plant located approximately 25 km from Montreal. The aim of this study is to assess the atmospheric concentrations of Mn in Montreal between 1993 and 2000, to compare these data to those for the period 1981-1992, and to evaluate the presence of any trend. Three sampling stations belonging to the Montreal Urban Community (MUC) air quality surveillance network were selected. Filters from 1993 to 2000 were obtained from the MUC archives. The first sample of each month was selected and chemical analysis was performed by neutron activation analysis. The mean annual atmospheric Mn concentrations in Montreal from 1993 to 2000 were found to be very stable. The mean Mn concentration calculated for this time period was 0.01 microg/m(3) for station 99 (characterized by a low traffic density), which was significantly different (P<0.05) from the mean of 0.03 microg/m(3) for stations 13 and 68 which had higher traffic densities. Even though Mn represented a small percentage of the TSP (varying between 0.02% and 0.14%), the comparison between Mn and TSP is interesting since the stable temporal profile of Mn since 1993 contrasts with the continuously decreasing atmospheric TSP concentrations. This observation suggests that the combustion of MMT used in gasoline could be contributing to maintaining stable atmospheric Mn levels.     

Labile aluminium chemistry downstream a limestone treated lake and an acid tributary: effects of warm winters and extreme rainstorms

The outlet from the limestone treated Lake Terjevann consisted mainly of well-mixed lake water (mean pH 6.1) during the ice-free seasons including the unusually warm winters of 1992 and 1993. However, during the ice-covered period acidic water (mean pH 4.8, mean inorganic aluminium (Al(i)) about 160 microg/l) from the catchment draining under the lake ice dominated. A downstream tributary was generally acid and rich in aluminium (mean pH 4.6, Al(i) about 230 microg/l). After an extreme rainstorm loaded with sea-salts cation exchange in the soil resulted in more than a doubling of the Al(i) concentration (reaching about 500 microg/l). It took 3-4 months until the Al(i) concentration returned to pre-event levels. During the ice-covered period, the acidic outlet and tributary waters resulted in acidic conditions below the confluence (pH<4.8, Al(i) about 150 microg/l) while during the ice-free periods the more neutral outlet water resulted in higher pH and lower Al(i) concentrations (pH>5.2, Al(i) about 95 microg/l). However, during the latter climatic conditions the water was most probably more harmful to fish due to hydrolysing and polymerizing aluminium. After the sea-salt event, the increased Al(i) concentration in the tributary made the zone below the confluence potentially more toxic (pH approximately 5, Al(i) approximately 250 microg/l). Expected global warming resulting in winter mean temperatures above 0 degrees C may eliminate the seasonal acidification of the outlet from limestone-treated lakes creating permanent toxic mixing zones in the confluence below acidic aluminium-rich tributaries. Besides, more frequent rainstorms as a consequence of global warming may increase the frequency of sea-salt events and the Al(i) concentrations in the mixing zones.     

Assessing remedial effectiveness through the blood lead:soil/dust lead relationship at the Bunker Hill Superfund Site in the Silver Valley of Idaho

The 21 square mile Bunker Hill Superfund Site in northern Idaho includes several thousand acres of contaminated hillsides and floodplain, a 365-acre abandoned lead/zinc smelter and is home to more than 7000 people in 5 residential communities. Childhood lead poisoning was epidemic in the 1970s with >75% of children exceeding 40 microg/dl blood lead. Health response activities have been ongoing for three decades. In 1991, a blood lead goal of 95% of children with levels less than 10 microg/dl was adopted. The cleanup strategy, based on biokinetic pathways models, was to reduce house dust lead exposure through elimination of soil-borne sources. An interim health intervention program, that included monitoring blood lead and exposures levels, was instituted to reduce exposures through parental education during the cleanup. In 1989 and 2001, 56% and 3% of children, respectively, exceeded the blood lead criteria. More than 4000 paired blood lead/environmental exposure observations were collected during this period. Several analyses of these data were accomplished. Slope factors derived for the relationship between blood lead, soil and dust concentrations are age-dependent and similar to literature reported values. Repeat measures analysis assessing year to year changes found that the remediation effort (without intervention) had approximately a 7.5 microg/dl effect in reducing a 2-year-old child's mean blood lead level over the course of the last ten years. Those receiving intervention had an additional 2-15 microg/dl decrease. Structural equations models indicate that from 40 to 50% of the blood lead absorbed from soils and dusts is through house dust with approximately 30% directly from community-wide soils and 30% from the home yard and immediate neighborhood. Both mean blood lead levels and percent of children to exceed 10 microg/dl have paralleled soil/dust lead intake rates estimated from the pathways model. Application of the IEUBK model for lead indicates that recommended USEPA default parameters overestimate mean blood lead levels, although the magnitude of over-prediction is diminished in recent years. Application of the site-specific model, using the soil and dust partitions suggested in the pathways model and an effective bioavailability of 18%, accurately predicts mean blood lead levels and percent of children to exceed 10 microg/dl throughout the 11-year cleanup period. This reduced response rate application of the IEUBK is consistent with the analysis used to originally develop the cleanup criteria and indicates the blood lead goal will be achieved.