Mercury and methylmercury in population risk groups on the Atlantic coast of Southern Spain

The presence of methylmercury and total mercury in the hair of high risk groups residing in the highly industralized South Atlantic coastal area of Spain were studied. In fishermen, total mercury and methylmercury content showed slight non-statistically significant differences among groups from two different coastal areas (geometric means: 10.41 and 8.36 g/g for total mercury; 8.28 and 6.72 g/g methylmercury). Mercury content in both groups differed significantly from controls (geometric mean 2.5 g/g total mercury, 4.50 g/g for methylmercury; p<0.05). In pregnant women, statistically significant differences were found in the three groups (two coastal areas and controls). Geometric means were 2.40, 5.94, and 0.94 g/g for total mercury and 1.93, 4.78, and 0.82 g/g for methylmercury. Results were compared with those obtained in other European countries in the Mediterranean area. Simultaneously, the same compounds were analyzed in fish and molluscs from those most consumed by people in the above-mentioned groups. The following results were obtained: sword fish, 1.57±1.27 g/g and 1.20±0.94 g/g for total mercury and methylmercury respectively; Scrobicularia plana, 0.07±0.052 and 0.053±0.039 g/g; Tapes decussatus, 0.046±0.20 and 0.039±0.018 g/g.     

The inhibition of acetylcholinesterase activity in pink shrimp(Penaeus duorarum) by methyl parathion and its oxon

The inhibition of acetylcholinesterase, E.C.3.1.1.7, (AChE) activity in the ventral nerve cord of pink shrimp(Penaeus duorarum) by methyl parathion (MPT) and methyl paraoxon (MPO) was investigated. When the animals were exposed to these compounds in water(in vivo), AChE activity of the isolated nerve cord was significantly depressed by MPT only in moribund shrimp after exposure for six hr to 1.3g/L (96 hr LC50=1.9g/L). Methyl paraoxon (96 hr LC50=13.6g/L) did not depress AChE activity in surviving animals after exposure for 74 hr to 0.98g/L. Exposure of the excised ventral nerve cord directly(in vitro) resulted in inhibition of 100% after exposure for one hr to 60 mg/L MPT, 100% after exposure for one hr to 300g/L MPO. Implications with regard to the use of AChE activity as a monitor of water pollution by inhibitors of this enzyme are discussed.     

Subclinical effects of prenatal methylmercury exposure on cardiac autonomic function in Japanese children

Objectives: The subclinical effects of prenatal exposure to methylmercury from fish consumption on the cardiac autonomic function were assessed in 136 Japanese 7-year-old children recruited for this study. Methods: Samples of child’s hair and dry umbilical cord preserved were collected, and hair mercury and cord tissue methylmercury concentrations were determined as current and prenatal exposure biomarkers, respectively. Cardiac autonomic indicators of parasympathetic and sympathetic activities were calculated from the electrocardiographic RR intervals measured. Results: In the children, the cord tissue methylmercury (0.017–0.367, median 0.089 μg/g) was not significantly correlated with the hair mercury (0.43–6.32, median 1.66 μg/g). The cord tissue methylmercury was related negatively to parasympathetic components of cardiac autonomic indicators (P<0.05) and positively to sympathovagal indices (P<0.05), even after correction for possible confounders such as age and sex, although the hair mercury was not significantly correlated with any cardiac autonomic indicators. Conclusions: Despite the potential limitations involved in the retrospective study, these findings suggest that prenatal methylmercury exposure (median of estimated maternal hair mercury at parturition, 2.24 μg/g) may be associated with reduced parasympathetic activity and/or sympathovagal shift.     

Lead in deciduous teeth of children living in a non-ferrous smelter area and a rural area of the FRG

Summary Lead concentrations were measured in the deciduous teeth (incisors) of 302 children living in a lead-smelter area in the FRG (Stolberg, Rheinland) and of 86 children living in a nonpolluted rural area (Gummersbach, Bergisches Land). Blood lead levels were determined in 83 of the children living in the lead smelter area. On average, tooth lead levels of children living in the smelter area (mean: 6.0 g/g; range: 1.49–38.5 g/g) were significantly higher than those of children living in the rural area (mean: 3.9 g/g; range: 1.6–9.4 g/g). Blood lead levels were 6.8–33.8 g/100 ml (mean: 14.3 g/100 ml). Children of lead workers had on average higher tooth lead and blood lead levels than children of people who were not lead-workers. Tooth lead levels increased with increasing duration of residence in the lead-smelter area and with the degree of local environmental pollution by lead, as indicated by the lead content of the atmospheric dust fall-out around the children's homes. The correlation coefficient of tooth lead vs blood lead was 0.47. The intra-individual variability of tooth lead levels was low (r=0.86), and tooth lead levels of brothers and sisters were similar (r=0.75), suggesting that tooth lead may be used as a representative and reliable indicator of long-term lead exposure.This study was carried out at the request and with support of the Ministerium für Arbeit, Gesundheit und Soziales NW, Düsseldorf     

Response of a freshwater bacterial community to mercury contamination (HgCl2 and CH3HgCl) in a controlled system

An experimental study was made on the effects of inorganic mercury (HgCl₂) and methylmercury (CH₃HgCl) on freshwater aerobic heterotrophic bacterial population. The experimental system was based on two-compartment biotopes: natural sediment, from the Garonne River, and dechlorinated tap water. The response of bacterial communities to mercury additions (to the water column) was monitored by determining total Hg in water and enumerating the total number of bacteria and the evolution of the mercury resistant community. Isolation was carried out by plate count method. Enumeration of mercury resistant strains was made with a general medium (Iron-Tryp-tone agar) amended with 10 g Hg/ml of HgCl₂. The response to 2 g Hg/L (HgCl₂) was fast approximately 50% of the maximum percentage of mercury resistant bacteria being reached after one hour (21.7% after 17 h exposure). Spikes of CH₃HgCl (2 g Hg/L) in the water column caused an initial inhibition of growth of Hg-resistant and sensitive bacteria followed by a complete recovery of the background microbial population after 84 h. Seven mercury resistant bacterial strains were isolated from the experimental systems and each of them was checked for HgCl₂ and CH₃HgCl transformation. All were able to volatilize HgCl₂ by producing elemental mercury, but none was able to degrade methylmercury. Additions of different concentrations of HgCl₂ (0.02 g Hg/L to 2 g Hg/L) to the water column caused a proportional increase in the percentage of mercury-resistant bacteria. Low concentrations (<0.6 g Hg/L) of CH₃HgCl also induced the Hg-resistant community, whereas 2 g Hg/L of CH₃HgCl inhibited the growth of both Hg-sensitive and Hg-resistant heterotrophic bacteria.     

Cytogenetic studies of herbicide interactions in vitro and in vivo using atrazine and linuron

The herbicides atrazine and linuron, found in Wisconsin's groundwater, were tested alone and in combination, both in vivo and in vitro, to determine their individual and combined genotoxic effects. Human lymphocytes exposed in vitro to either 1 g/ml linuron or 0.001 g/ml atrazine showed little chromosome damage, whereas significant chromosome damage was observed in lymphocytes simultaneously exposed to 0.5 g/ml linuron and 0.0005 g/ml atrazine, suggesting at least an additive model. In another experiment, mice were fed 20 g/ml atrazine, 10 g/ml linuron, or a combination of 10 g/ml atrazine and 5 g/ml linuron in their drinking water for 90 days, after which bone marrow cells and cultured splenocytes were examined for chromosomal damage. None of the treatment groups showed chromosome damage in bone marrow, whereas the cultured splenocytes demonstrated damage in all treatment groups. These experiments suggest that, prior to assessing the risk of a herbicide, it may be necessary to test it in combinations which mimic the mixtures which would occur under field conditions, such as in contaminated groundwater.     

A pilot study of lead and cadmium exposure in young children in Stockholm,Sweden: Methodological considerations using capillary blood microsampling

A capillary blood microsampling technique was tested among urban young children in Stockholm. Blood lead (BPb) and hemoglobin (Hb) concentrations were determined in capillary blood obtained by fingerstick from 41 children, 13–20 months old, and the accompanying parent. The quality control included control for lead (Pb) and cadmium (Cd) contamination of material and equipment used for blood sampling, washing procedures for the hands and fingers to be punctured, comparisons of Pb and Cd concentrations in blood obtained by fingerstick and by brachial vein puncture from the same individuals, analysis of external quality control samples for Pb and Cd in blood together with the collected samples, and evaluation of the analytical performance using linear regression analysis.The results showed that blood sampling material may contaminate the blood samples with amounts of Pb and Cd that would seriously influence the monitoring results in the low concentration range (<100 g Pb/L and <1 g Cd/L). However, it is possible to obtain reliable BPb concentrations (>10 g Pb/L), but not BCd concentrations (<1 g Cd/L), with the capillary blood microsampling technique tested provided that a strict quality control is applied. The sampling procedure tested was well accepted by the children and their parents. The children's median BPb concentration (27 g/L; range 9–73 g/L) was similar to the median BPb concentration of their parents (27 g/L; range 7–74 g/L). However, the correlation between child and parent BPb concentrations was poor (R²=0.20), which may indicate different sources to Pb exposure in children and parents.     

Size-dependence of mercury (II) accumulation kinetics in the mosquitofish,Gambusia affinis (Baird and Girard)

Size-dependence of mercury (II) accumulation from water by the mosquitofish,Gambusia affinis was assessed under controlled laboratory conditions. Uptake rates were higher for smaller fish than for larger fish. Mean (±S.D.) uptake rate for mosquitofish exposed to 0.24 g/L of Hg was 0.32 ± 0.15 g/g dry wt/day. Uptake rate constants were similar for the Hg (II) and Hg° as reported elsewhere. Both inorganic species (Hg (II) and Hg°) were accumulated faster than methylmercury. Elimination rate constants averaged 0.530.14 per day (mean ± 1 S.D.). No significant size effects on elimination rate constants were detected. Elimination constants were similar to those reported elsewhere for Hg° elimination but larger than those for methylmercury elimination.     

Mercury levels in seabirds from the Azores,Mid-North Atlantic Ocean

Levels of total mercury were determined in body feathers of 257 seabirds belonging to seven species from the Azores Archipelago, Mid-North Atlantic Ocean. Mercury levels in adult birds showed highly significant inter-specific variations. Median levels were higher in small petrels (Madeiran storm petrel=12.5 g/g; Bulwer's petrel=22.1 g/g) than in shearwaters (Little shearwater=2.1 g/g; Cory's shearwater=6.0 g/g) and terns (Roseate tern=2.0 g/g; Common tern=2.3 g/g). Such inter-specific variability is discussed in relation to biological factors that may influence mercury dynamics in birds. Intra-specific variations in mercury levels were also found. Mercury levels were significantly lower in chicks than in adults of Cory's shearwater, Roseate tern and Common tern. The levels in chick feathers were 60–70% of those in adult feathers. In Cory's shearwater and the terns (Roseate and Common combined), mercury levels decreased significantly with increasing age of chicks. Mercury levels in adult Madeiran storm petrel showed pronounced seasonal variation, being about 50% lower in Spring breeders than in Autumn breeders. Mercury levels are compared with levels reported for seabird populations of the same or related species, from a variety of regions. The use of bird feathers to monitor mercury in the marine environment is briefly discussed.     

The effects of poly chlorinated biphenyls and methylmercury,singly and in combination,on Mink. I: Uptake and toxic responses

Ranch-bred mink (Mustela vison) were maintained in outdoor cages and fed experimental diets containing either polychlorinated biphenyls (Aroclor^® 1254) and/or MeHg (methylmercury) for eight months. Unexpected mortality of some mink was attributed to a combination of cold stress and exposure to 1.0 g/g MeHg. Mortality was lower in the group exposed to a combination of 1.0 g/g MeHg plus PCB. There were no observed treatment effects on the thyroid, pituitary, adrenal glands or serum T4 or T3 levels of adult mink. There was evidence of significant placental transfer of MeHg to the fetus, and transfer of PCB to growing kits via the mother's milk.     

The effects of poly chlorinated biphenyls and methylmercury,singly and in combination on mink. II: Reproduction and kit development

Adult ranch-bred mink (Mustela vison) were fed diets containing either 0, 1.0 g/g polychlorinated biphenyls (PCB) (Aroclor^® 1254), 1.0 g/g methylmercury (MeHg), a combination of 1.0 g/g PCB plus 1.0 g/g MeHg, or 0.5 g/g PCB plus 0.5 g/g MeHg. Fertility of adult male mink, percentage of females whelped or number of kits born per female were not affected by the treatments. However, growth rate of kits nursed by mothers exposed to 1.0 g/g PCB was significantly reduced. There was a synergistic effect of PCB and MeHg which reduced kit survival in groups receiving both chemicals simultaneously. Kit survival to weaning in the control, 0.5 g/g PCB/MeHg, and 1.0 g/g PCB/MeHg groups was 72.0%, 62.7% and 35.8%, respectively. The results suggest that growth and survival of mink kits are adversely affected at dietary levels of PCB and MeHg currently present in some environments.     

Historical and Other Patterns of Monomethyl and Inorganic Mercury in the Florida Panther (<Emphasis Type="Italic">Puma concolor coryi</Emphasis>)

Since the late 1980s, elevated levels of mercury have been reported in the tissues of the Florida panther (Puma concolor coryi) from the Florida Everglades. The extent, degree, and length of time of mercury contamination in the Florida panther are unknown. The objective of this study was to determine the historical and other patterns of monomethyl and inorganic mercury in the Florida panther by analysis of mercury in panther hair from museum collections. In addition, this study evaluated the effects of preservation of skins on mercury concentrations in hair and the representativeness of museum collections for evaluating historical trends of contamination in the Florida panther. Hair from 42 Florida panther specimens collected from 1896 to 1995 was analyzed for both monomethyl and inorganic mercury. Monomethyl mercury (MMHg) and inorganic mercury (IHg) were found in all specimens. Monomethyl mercury in hair from untanned skins was significantly higher than MMHg in hair from tanned skins. For untanned specimens, the mean MMHg concentration in hair was 1.62±1.87 g/g (range 0.11 to 6.68 g/g, n=16). Monomethyl mercury accounted for 88% of the total mercury in untanned Florida panther hair. No sexual or geographical differences were found. Although MMHg is generally stable in hair, the tanning process appears to reduce the amount of MMHg in hair. In addition, exogenous IHg contamination of the panther hair was found in museum specimens, especially in older specimens. The implication of these and other factors in interpreting results of museum studies is discussed. The presence of MMHg in panther hair since the 1890s indicates long-term and widespread exposure of the Florida panther to mercury. Levels of MMHg are significantly greater in the 1990s than the 1890s. When combined with field studies of mercury in the Florida panther, considerable individual variability is observed, reflecting short-term changes in exposure of individual panthers to mercury. Although museum specimens showed a significant increase in MMHg over the last 100 years, they did not show the magnitude of increase that field populations of Florida panthers did. A number of Florida panthers appeared to be at risk from mercury over their lifetimes, especially individuals from the early 1990s.     

Effects of mercury,selenium, and organochlorine contaminants on reproduction of Forster's terns and black skimmers nesting in a contaminated Texas Bay

Mean mercury (0.40 g/g), and geometric mean DDE (1.6 g/g) and polychlorinated biphenyl (PCB) (2.3 g/g) concentrations in Forster's tern (Sterna forsteri) eggs from Lavaca Bay were higher than those in tern eggs from a reference area in San Antonio Bay, but residues were not correlated with hatching success. Nest success was similar between bays. Selenium levels in Lavaca Bay tern eggs (0.71 g/g) were also comparable to those in eggs from the reference area (0.68 g/g).Clutch size (3.1 to 3.4) of Lavaca Bay black skimmers (Rynchops niger) was no different than that (3.4) at a reference colony near Laguna Vista. Nest success was similar among three Lavaca Bay colonies, but success was lower at one Lavaca Bay colony (40%) than at Laguna Vista (65%). Mean mercury (0.46 g/g) and selenium (0.75 g/g) concentrations in skimmer eggs from Lavaca Bay were higher than those (0.19, 0.33 g/g) from Laguna Vista; however, concentrations of neither contaminant were related to hatching success. DDE concentrations in Lavaca Bay skimmer eggs (3.4 g/g) were similar to those from Laguna Vista (3.2 g/g) and DDE was negatively correlated with hatching success. PCBs were higher in eggs from Lavaca Bay (1.3 g/g) than Laguna Vista (0.8 g/g). Organochlorine and metal contaminants in most eggs were below embryotoxic levels. Eggshell thinning in Forster's terns (7%) and black skimmers (5%) was below that associated with lowered reproduction.DDE and PCBs were detected in 9 Caspian tern (S. caspia) eggs; maximum concentrations were 4.7 and 5.4 g/g. Caspian tern and least tern (S. albifrons) eggs contained low (0.9 g/g) concentrations of mercury and selenium.     

Aquatic hazard assessment of the organophosphate insecticide fonofos

This study determined the acute and chronic toxicity of the organophosphate insecticide fonofos to standard freshwater aquatic organisms under laboratory conditions. Fonofos was acutely toxic to bluegill (Lepomis macrochirus), Daphnia (D. magna), and midge (Chironomous riparius) at 5.3, 2.7, and 39 g/L, respectively. Three fonofos formulations (technical, 94.8% A.I.; 20G, field granular 20% A.I.; and 4E, field liquid 4#/gal A.I.) exhibited similar acute toxicities to bluegill. Exposure to fonofos delayed reproduction and decreased the intrinsic rate of increase of Daphnia during 21-d chronic exposure at the lowest tested concentration (0.08 g/L). The no observable effect concentration (NOEC) for Daphnia survival was 0.42 g/L; 0% survival occurred at the lowest observable effect concentration (LOEC) of 1.45 g/L. The NOEC for midge emergence was 3.42 g/L; only 34% emergence occurred at the LOEC of 8.24 g/L. Chronic 30-d exposure of juvenile bluegills decreased growth and survival at 5.65 g/L (LOEC), but no effects occurred at 2.33 g/L (NOEC). The relative hazard of fonofos to aquatic life is similar to other carbamate and organophosphate corn insecticides.     

Mercury concentrations in hair from populations in Wau-Bulolo area, Papua New Guinea

Total mercury (Hg) concentrations were determined in scalp hair from the populations in the Wau-Bulolo area, eastern Papua New Guinea (PNG), where humans are exposed to large quantities of Hg through gold-mining activities by Hg amalgamation processes. Humans living upstream and not engaged in gold mining had a mean hair Hg concentration of 0.55 g g^–1 (range: 0.19–1.1 g g^–1) (n=80), which was recognized as the background level in this area. In contrast, the populations involved in gold-mining activities had a significantly higher level of hair Hg (mean: 1.2 g g^–1, range: 0.39–3.0 g g^–1) (n=86) than the background level, indicating direct or indirect exposure to Hg from gold mining. The hair Hg level in populations downstream of the gold-mining area was significantly higher than the background level, due to the consumption of Hg-contaminated fish. Mercury concentrations were significantly higher in males than in females, regardless of location properties.     

Susceptibility of clinical isolates of campylobacter pylori to 24 antimicrobial and anti-ulcer agents

Forty-nine isolates of Campylobacter pylori were tested for their susceptibility to twenty antibiotics and four anti-ulcer agents by an agar dilution technique. Penicillin and amoxycillin were the most active drugs (MIC₉₀, 0.06 /ml); erythromycin, cefazolin, minocycline, ciprofloxacin, ofloxacin and gentamicin were sligthtly less active (MIC₉₀, 1 g/ml). Moderate activity was found for doxycyclin, rifampin, nitrofurantoin, norfloxacin, pefloxacin, enoxacin, paromomycin, metronidazole and tinidazole. All strains were resistant to trimethoprim (MIC > 512 g/ml). Nalidixic acid (MIC₉₀, > 256 g/ml) and colistin (MIC₉₀, > 64 gg/m1) had little to no activity. Of four anti-ulcer drugs, only bismuth subcitrate showed activity (MIC₉₀, 64 g./ml).Strains resistant to all 4-quinolones were found in patients who had previously received ofloxacin as part of a clinical trial aimed at eradication of C. pylori. These isolates remained susceptible to amoxycillin, tetracyclines and to other classes of antibiotics.Corresponding author.     

Placental transfer of lead,mercury and cadmium in women living in a rural area

Summary The influence of the lead content of drinking water on the transplacental transfer of lead was investigated in 70 pregnant women living in a rural area of Belgium. The mothers were divided into 2 groups: group A: morning water lead below 50 g/liter; group B: morning water lead above this value. In group A, the mean lead content of water was 11.8 g/liter and in group B it amounted to 247.4 g/liter.The difference in the mean lead concentration between the two groups were for maternal blood: 3.2 g/100 ml, for umbilical cord blood: 3.3 g/100 ml, and for placenta: 3.6 g/100 g. These differences are statistically significant.There were significant correlations between water lead and lead concentration in blood (mother, newborn) or placenta. An increment of water lead concentration from 50 to 500 g/liter increases blood lead concentration in mother and in newborn by about 3 g/100 ml and in placenta by about 2.5 g/100 g (wet weight).     

Effects of dieldrin in food on growth and bioaccumulation in mallard ducklings

The effects of dieldrin in food organisms and commercial feed on growth and bioaccumulation were determined in mallard ducklings (Anas platyrhynchos). Dieldrin-fed crickets, mealworms and annelid worms, and dieldrin-spiked commercial feed, were fed to mallard ducklings for 8 days. Mean measured food concentrations (animals plus feed) of <0.2, 2.6, 26.2, and 49.3 g/g dieldrin did not affect growth after 14 days. Tissue dieldrin concentrations (g/g wet wt) increased rapidly: up to 80.7 (lipid), 30.1 (skin), 4.1 (liver), 1.8 (muscle), and 1.6 (brain) g/g. Dieldrin concentrations in tissues were up to 3.7 times greater than in the test diets.     

Mercury vapor as an atmospheric contaminant of dental offices

Airborne mercury from dental offices was selectively trapped by silver gauze elements in borosilicate glass absorbers, followed by heat-desorption and spectrophotometric measurement at 2537A. As little as 0.4 ng of Hg could be accurately determined, which is equivalent to 49 ppt in a one-L air sample on a v/v basis. Over 860 air samples were taken over a range of locations and working conditions at 88 different dental offices, and at the Dental Training Clinic of the University of Manitoba. The Hg vapor concentrations at the dental facilities ranged from 0.45 to 742g/m³ of air; 29% of the samples were within 0.45 to 5g; 37.8 were within 5.1 to 25g; and 33.2% were above 25g. Mercury concentrations varied during the working day, depending on the time of sampling, the number of amalgams placed, and the interval between placements. The lowest concentrations were obtained in the morning. Disturbance of residual mercury droplets on floors or working areas by sweeping or dusting, or immediately after attempted clean-up of a mercury spill, sharply increased the amount of airborne mercury.     

The toxicity of selenium in experimental freshwater ponds

Flue Gas Desulphurization equipment installed in coal-fired power stations to reduce sulphur dioxide emissions produces effluent containing several contaminants, including selenium. To assess the effects that this might have on fish reproduction and biological community richness, selenate and selenite were added to freshwater pond systems to achieve duplicated nominal concentrations of 0 (control), 2, 10 and 25 g Se/L. Perch (Perca fluviatilis), grass carp (Ctenopharyngodon idella Val.) and stickleback (Gasterosteus aculeatus) were placed in each pond in the early summer and left relatively undisturbed until the following spring. A spawning tray was then placed in each pond and monitored regularly for the appearance of perch egg ropes. When ropes were found, they were removed to the laboratory and either placed in uncontaminated well water or exposed to selenium. Almost half the perch exposed to 25 g Se/L died during the pond experiment, but there were no observed deaths at the lower concentrations. No grass carp were recovered from the 25 g Se/L ponds but all were recovered from the other ponds. Stickleback were missing from all treatments, presumably due to predation by the perch. Perch egg ropes were found in seven of the eight ponds, and all but one rope showed signs of successful fertilisation. Hatching success in the laboratory was highly variable for eggs obtained from the 0, 2, and 10 g Se/L ponds, but was always above zero. No eggs hatched from ropes obtained from the 25 g Se/L ponds. Effects of selenium on plants, macroinvertebrates and zooplankton in the ponds were generally limited. Accumulation of selenium in fish was dose-related and comparable with results reported from other contaminated systems. The results from this experiment suggest that mean environmental concentrations of approximately 25 g Se/L may seriously affect the reproductive capacity of perch, but no clear effects on reproduction are evident at mean concentrations of 10 g Se/L and below. Selenium-induced effects occur during gametogenesis, but only become evident between fertilization and hatching.