Mercury residues in tissues of dead and surviving birds fed methylmercury.

Concentrations of mercury in passerine birds fed diets containing 40 ppm methylmercury were similar in tissues of birds that died from mercury poisoning and in those that were sacrificed after half the group had died. Residues were higher in tissues of birds that died, but the differences were not statistically significant. Residue levels were highest in livers, followed by kidneys and brains. Levels of mercury were similar in breast muscle, carcass, and whole body. Mercury levels were highest in redwinged blackbirds, lowest in grackles, and intermediate in starlings and cowbirds. Mercury concentrations exceeded 20 ppm in all tissues of all species and were similar to levels reported in wild birds known to have died of mercury poisoning.     

Mercury accumulation in mallards fed methylmercury with or without added DDE

Adult female mallards (Anas platyrhynchos) were fed a control diet or diets containing 1 ppm methylmercury chloride, 5 ppm methylmercury chloride, 1 ppm methylmercury chloride plus 5 ppm DDE, or 5 ppm methylmercury chloride plus 5 ppm DDE. The presence of DDE in the diet did not affect retention of mercury in breast muscle or eggs. There was a good correlation between the levels of mercury in the breast muscle of females and their eggs, and this correlation was unaffected by the presence of DDE in the diet. This correlation suggests that one could predict mercury levels in female mallards in the field when only eggs have been collected and vice versa.     

Mercury and methylmercury exposure in the New Jersey pregnant population

Methylmercury is a known fetal developmental neurotoxicant. The only significant source of fetal exposure is maternal fish consumption; however, few recent data on exposure of the pregnant population are available. The authors undertook a study of methylmercury exposure in the New Jersey pregnant population to investigate the distribution of exposure and to identify predictors of elevated exposure. Mainly first-trimester pregnant women were recruited through six New Jersey obstetric practices. Hair and blood samples were analyzed for total mercury, and a subset was analyzed for methylmercury. A questionnaire on demographics, life style, and fish-consumption practices was also administered. Although 85-90% of the pregnant population had hair mercury levels that were less than 1.0 microg/gm, 1-2% had levels in a range of possible concern for adverse developmental effects (> 4.0 microg/gm). Regression analysis suggested that blacks and individuals with some college education experienced lower exposures to methylmercury.     

DDE in birds: Lethal residues and loss rates

Lethal brain residues of DDE² were determined experimentally in four species of wild birds given dietary dosage of 1,500 ppm DDE until one-half had died, then sacrificing the survivors, chemically analyzing the tissues, and comparing results in dead birds and survivors. In all species, residues of 300 to 400 ppm of DDE in the brain were considered to show increasing likelihood of death from DDE, confirming results of an earlier study with a single species. Body residues (ppm wet weight) were not diagnostic, overlapping grossly in dead birds and survivors, but averaging higher in survivors. Body residues (ppm lipid base), however, were higher in dead birds and did not overlap those in survivors.Loss rate was followed in grackles fed 1,500 ppm DDE for 7 days, then given untreated feed and sacrificed at intervals of 7, 28, 56, and 112 days. DDE was lost slowly from the bodies, at a rate of 0.30% per day (estimated half-life 229 days). DDE was lost more rapidly from brains, half of the initial concentration being reached in 25 days; concentrations in brains increased thereafter in close correlation with percentage of fat in the body.     

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.     

Induction of lipid peroxidation and change of fatty acid composition in rats fed methylmercury

Four groups of rats, with 5 animals in each, were fed a diet to which 1, 2, 4 or 8 ppm of methylmercury (MeHg) were added while another group of 5 rats was fed a diet containing no MeHg as a control. Moreover, each rat was daily supplied the same volume of these diets. During the experimental period of 40 days, body weights of the rats were daily checked individually. On day 40, expired air of the rats was collected to analyse for ethane and pentane production, and then the rats were sacrificed to obtain the liver, kidneys, brain and plasma. Thio-barbituric acid (TBA)-reactants in the selective organs and plasma were measured to investigate the effects of MeHg on lipid peroxidation. Further, gas-chromatographic analyses of fatty acids were carried out on the samples of the selective organs and plasma to examine the effects of MeHg on lipid metabolism. Results obtained were as follows: 1. The fifth day after the experiment started, the growth rates of the groups fed a diet containing MeHg (the MeHg groups) were higher than those of the control group. Moreover, the growth rates tended to increase with increases of MeHg concentrations in food from days 25 to 32 of the experimental period. Furthermore, the weights of the kidneys increased with increases in MeHg concentrations in food. 2. The amounts of expired ethane and pentane did not increase proportionally with increases in MeHg concentrations in food but those of expired ethane and pentane were higher in the MeHg groups than in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Distribution of cadmium in blood and tissues of wild birds

The principal aim of this study is to establish the kinetic behavior of cadmium by determining the concentrations of this element in the blood and in different tissues of wild birds exposed to environmental cadmium. We have studied a total of 118 birds living in the southeast of Spain, a zone with a Mediterranean climate and stopover point for important migratory species. The distribution pattern followed by the cadmium in our samples reveals that the kidney is the primary organ for accumulation, followed by the liver and, to lesser extent, the brain and bone. Low concentrations were found in the tissues and in the blood. The study of correlations between the different tissues and blood suggests a compartmental behavior of cadmium under these exposure conditions.     

Mercury in livers of wading birds (ciconiiformes) in southern Florida

Mercury was measured in livers from 144 wading birds representing seven species collected from four different areas in southern Flordia, including the Everglades National Park. Significant differences in hepatic mercury concentrations were identified between birds collected from different geographic locations, birds of different ages, dietary factors, and relative amounts of body fat. Birds collected from an area encompassing the central Everglades and eastern Florida Bay had significantly greater concentrations of hepatic mercury than did birds from other collection areas. Livers from fledgling and young adult birds contained approximately three times the concentration of mercury as livers from nestling birds. Bird species whose prey base consists of larger fish were found to have approximately four times the hepatic concentration of mercury as did those species which consume smaller fish or crustaceans. Birds with minimal to moderate amounts of body fat had two to three times the concentration of hepatic mercury as birds with relatively abundant body fat reserves. Four great blue herons collected from the central Everglades contained liver mercury at concentrations typically associated with overt neurologic signs (30 g/g). Between 30% and 80% of potential breeding-age birds collected from this area contained hepatic mercury at concentrations associated with reproductive impairment in ducks and pheasants. These data suggest that declining numbers of nesting ciconiiform birds in Florida may be due, in part, to mecury contamination of their food supply.