Lead Concentrations In Tissues Research Articles

Lead isotopes and lead shot ingestion in the globally threatened marbled teal (Marmaronetta angustirostris) and white-headed duck (Oxyura leucocephala)

Lead isotope ratios (206Pb/207Pb and 208Pb/207Pb) and concentrations in the livers and bones of marbled teal and white-headed duck found dead or moribund were determined in order to establish the main lead source in these waterfowl species. Lead concentrations in bone (dry weight) and liver (wet weight) were found to be very high in many of the white-headed ducks (bone: geometric mean=88.9 ppm, maximum=419 ppm; liver: geometric mean=16.8 ppm, maximum=57.0 ppm). Some of the marbled teal had high lead levels in the bones but liver lead levels were all low (bone: geometric mean=6.13 ppm, maximum=112 ppm; liver: geometric mean=0.581 ppm, maximum=4.77 ppm). Ingested lead shot were found in 71% of the white-headed duck and 20% of the marbled teal. The 206Pb/207Pb ratio in livers and bones of white-headed ducks and marbled teals showed no significant differences compared to the ratios obtained from lead shot. The 206Pb/207Pb ratio in bones of marbled teal ducklings with the highest lead concentrations tended to resemble the ratios of lead shot, which supports our hypothesis that the lead was derived from the hens. We also found that the lead ratios of lead shot and lead ratios described for soils in the area overlapped, but also that the isotopic ratio 206Pb/207Pb in lead shot used in Spain has a narrow range compared with those used in North America. The principal source of lead in many of these birds was, however, most likely lead shot, as supported by the similar isotopic ratios, high lead concentrations in tissues and evidence of ingested shot.

Effects of Lead-Contaminated Sediment on Rana sphenocephala Tadpoles

We exposed larval southern leopard frogs (Rana sphenocephala) to lead-contaminated sediments to determine the lethal and sublethal effects of this metal. Tadpoles were laboratory-raised from early free-swimming stage through metamorphosis at lead concentrations of 45, 75, 180, 540, 2360, 3940, 5520, and 7580 mg/kg dry weight in sediment. Corresponding pore water lead concentrations were 123, 227, 589, 1833, 8121, 13,579, 19,038, and 24,427 microg/L. Tadpoles exposed to lead concentrations in sediment of 3940 mg/kg or higher died within 2 to 5 days of exposure. At lower concentrations, mortality through metamorphosis ranged from 3.5% at 45 mg/kg lead to 37% at 2360 mg/kg lead in sediment. The LC50 value for lead in sediment was 3728 mg/kg (95% CI = 1315 to 72,847 mg/kg), which corresponded to 12,539 microg/L lead in pore water (95% CI = 4000 to 35,200 microg/L). Early growth and development were depressed at 2,360 mg/kg lead in sediment (8100 microg/L in pore water) but differences were not evident by the time of metamorphosis. The most obvious effect of lead was its pronounced influence on skeletal development. Whereas tadpoles at 45 mg/kg lead in sediment did not display permanent abnormalities, skeletal malformations increased in frequency and severity at all higher lead concentrations. By 2360 mg/kg, 100% of surviving metamorphs displayed severe spinal problems, reduced femur and humerus lengths, deformed digits, and other bone malformations. Lead concentrations in tissues correlated positively with sediment and pore water concentrations.

Morphometric analysis of brain lesions in rat fetuses prenatally exposed to low-level lead acetate: correlation with lipid peroxidation.

The effect of prenatal lead acetate exposure was studied microscopically together with the concentration of lead and lipid fluorescent products (LFP) in the brain of rat fetuses. Wistar rats were intoxicated with a lead solution containing either 160 or 320 ppm of lead acetate solution during 21 days through drinking water. The control group (ten rats) received deionized water for the same period. The rats were killed on gestation day 21 and fetuses were obtained; the placenta, umbilical cord and parietal cortex (Cx), striatum (St), thalamus (Th) and cerebellum (Ce) were collected for measuring tissue lead concentration, LFP as an index of lipid peroxidation and histopathologic examination. Lead contents were increased in placenta, umbilical cord, St, Th and Cx in both lead-exposed groups. Lead exposure increased (LFP) in placenta and umbilical cord, St, Th and Ce as compared to the control group. Histopathological examination showed severe vascular congestion in placenta, the Cx, St, Th and Ce with hyperchromatic and shrunken cells. Interstitial oedema was found in all regions studied of both lead exposed groups. The morphometric evaluation of the studied brain regions showed an absolute decrease in total cell number and increased number of damaged cells and interstitial oedema. Our results show that morphological changes in rat brain are correlated with increased lipid peroxidation, and the lead levels of the umbilical cord, however it is not clear whether oxidative stress is the cause or the consequence of these neurotoxic effects of lead.

Sublethal effects of lead on northern leopard frog (Rana pipiens) tadpoles

Northern leopard frogs (Rana pipiens) were exposed to environmentally relevant concentrations of lead in water (3, 10, and 100 microg/L as lead nitrate) from the embryonic stage to metamorphosis. Survival, growth, deformity, swimming ability, metamorphosis, and lead tissue concentrations were evaluated. Tadpole growth was significantly slower in the early stages (Gosner stages 25-30) in 100 microg/L treatment. More than 90% of tadpoles in the 100 microg/L treatment developed lateral spinal curvature, whereas almost all the tadpoles in the other groups were morphologically normal. Spinal deformity was associated with abnormal swimming behavior. Maximum swimming speed of tadpoles in the 100 microg/L treatment was significantly lower than that in the other groups. No significant effect of lead exposure was found on percentage metamorphosis, snout-vent length, mortality, and sex ratio of metamorphs. Time to metamorphosis was delayed in 100 microg/L treatment. Lead tissue concentrations in the tadpoles ranged from 0.1 to 224.5 mg/kg dry mass, were positively related to lead concentrations in the water, and fell within the range of tissue concentrations of wild tadpoles found in previous studies. According to our results, the current U.S. Environmental Protection Agency freshwater-quality chronic criterion for lead (2.5 microg/L) is appropriate to protect northern leopard frog larvae.

Beneficial role of monoesters of meso-2,3-dimercaptosuccinic acid in the mobilization of lead and recovery of tissue oxidative injury in rats

We investigated the therapeutic efficacy of meso-2,3-dimercaptosuccinic acid (DMSA) and two of its analogues, monomethyl dimercaptosuccinic acid (MmDMSA) and mono-cyclohexyl dimercaptosuccinic acid (MchDMSA) in reducing lead concentration in blood and soft tissues, and in recovering lead induced oxidative stress in rats. Male wistar rats were exposed to lead acetate in drinking water for 20 weeks, followed by 5 days of oral treatment with DMSA (100 mg/kg, oral, once daily), MmDMSA or MchDMSA (50 and 100 mg/kg). Biochemical variables indicative of oxidative stress along with lead, zinc and copper concentration were evaluated in blood and other soft tissues. Exposure to lead caused a significant decrease in blood δ-aminolevulinic acid dehydratase (ALAD) activity and glutathione (GSH) level. These changes were accompanied by inhibition of kidney ALAD and an increase in δ-aminolevulinic acid synthatase (ALAS) activity in liver and kidneys. Also seen were a pronounced depletion of brain GSH, glutathione peroxidase (GPx), glutathione- S-transferase (GST) and decreased superoxide dismutase (SOD) activity and an increase in thiobarbituric acid reactive substances (TBARS) and reactive oxygen species (ROS) levels. These biochemical changes were correlated with an increased uptake of lead in blood and soft tissues. Blood and kidneys zinc concentration decreased significantly following lead exposure while, copper concentration remained unchanged. No effect of chelation on hepatic zinc concentration was noted, only liver copper concentration showed significant depletion on treatment with DMSA and MmDMSA (100 mg/kg). Treatment with DMSA, MmDMSA and MchDMSA provided significant recovery in altered biochemical variables and brain DNA damage besides significant depletion of tissue lead burden. Among the chelating agents used, MchDMSA and MmDMSA provided better recovery in altered biochemical variables and depletion of lead concentration in tissues compared to DMSA. The above results suggest DMSA monoesters to be a better treatment option than DMSA in eliciting recovery to the altered biochemical variables and in the depletion of body lead burden.

Exhumation examination to confirm suspicion of fatal lead poisoning

Acute poisonings with inorganic lead compounds are exceptionally rare. In all cases of diagnosis, there are two possible sources of error: failing to recognise lead poisoning when it is present, and mistaking other diseases for lead poisoning. If exposure history is carefully taken and proper laboratory techniques are employed, the diagnosis of lead poisoning should not be difficult. In the described case of the death of a 41-year-old-man, no enzymatic disturbances characteristic of congenital erythropoietic porphyria were ascertained, and furthermore, a considerable concentration of lead was found in antemortem material, 5 months before death (blood: 1584 μg/l, urine: 531 μg/24 h). Postmortem tissue lead content in the biological material, exhumed 6 months after death, were as follows: liver, 47.6 μg/g; kidney, 4.75 μg/g; bone, 103 μg/g of sacral vertebra, 20.4 μg/g of femoral bone, 112 μg/g of pelvis; hair, 30.2 μg/g of scalp hair, 33.7 μg/g of pubic hair; nails, 13.6 μg/g. The results indicated a case of acute lead poisoning (with lead(II) oxide, as it later turned out), which manifested as acute intermittent porphyria.

Lead Concentrations in Ruffed Grouse, Rock Ptarmigan, and Willow Ptarmiganin Québec

Between 1996 and 1998, ruffed grouse, spruce grouse, willow ptarmigan, and rock ptarmigan harvested by hunters in Québec were examined for lead contamination. On examination of the gizzards of these birds, lead shot was found only in ruffed grouse (1.2%). The probability of ingestion of lead shot by grouse and ptarmigans is low. Analyses of the lead concentrations in the wing bones of grouse and ptarmigans and in the muscle tissue of ptarmigans were conducted. Although differences were observed between individuals based on age and sex, the mean concentrations measured were in the range of those that occur naturally at background levels (<6 microg/g dw). Lead concentrations in muscle tissue were low, often at the limit of detection. However, the few high concentrations detected were probably related to a lead pellet or bullet fragment. Based on an analysis of the health risk associated with consumption of ptarmigan muscle, we conclude that the use of lead ammunition for hunting gallinaceous birds may pose an unnecessary risk of lead poisoning because of the possible ingestion of lead shot, bullets, fragments or embedded shot.

The ocean quahog Arctica islandica L.: a bioindicator for contaminated sediments

The use of benthic organisms as bioindicators in the aquatic environment is a suitable method for assessing the effects of contaminants in coastal waters. The accumulation of heavy metals in body tissues due to lifestyle and feeding mechanisms makes it possible to reveal contamination rates and recovery trends within polluted areas. Comparing a polluted historical dumping site in the inner Mecklenburg Bight (western Baltic Sea) with a less-contaminated reference site at the edge of the Mecklenburg Bight, representing the background contamination of the western Baltic Sea, the present study discusses the population structure and heavy metal exposure of the ocean quahog Arctica islandica L. (Mollusca, Bivalvia) and evaluates this organism as a bioindicator for contaminated sediments. The organism density was higher at the reference site in comparison to the dumping site. The absence of juvenile and adult individuals at the dumping site seems to be a sign that this ecological environment has not completely regenerated since the dumping event in the late 1950s to early 1960s. Heavy metal concentrations of copper, lead, and zinc in the soft body tissue of A. islandica were analysed using atomic absorption spectrometry (AAS). Shell measurements were carried out using laser ablation–inductively coupled plasma–mass spectrometry. Particularly the concentrations of copper and lead were significantly higher in the soft body tissue as well as in the shell from the dumping site than from the reference site. For pollutant biomonitoring research, the shells of the ocean quahog can be used as an indicator for heavy metal accumulation. They are more suitable for reflecting historical contamination events than the soft body tissue.

Posidonia oceanica as a Historical Monitor Device of Lead Concentration in Marine Environment

We show that Posidonia oceanica is able to reliably monitor the variability of environmental lead (Pb). We analyze lead concentration measured in the scales and rhizomes of Posidonia oceanica collected in seven sites along the coasts of the Sicily island and subsequently fractioned them according to a lepidochronological analysis. We measure lead concentration in Posidonia oceanica tissues by using the flame atomic absorption spectrophotometry technique. We compare the measured lead concentration with the estimated lead emission in air due to the gasoline sold and used for combustion in car engines in Sicily. By computation of the Pearson cross-correlation coefficient, we show that lead concentration, which is measured in the scales of Posidonia oceanica, is statistically correlated to lead emission in air and reflects the level of lead pollution in the coastal marine environment.

Heavy Metal Concentrations in Human Eyes

To measure the concentration of toxic heavy metals in the fluids and tissues of human eyes. Laboratory investigation. Thirty autopsy eyes of 16 subjects were dissected to obtain the aqueous, vitreous, lens, ciliary body, retina, and retinal pigment epithelium/choroid. Concentrations of lead, cadmium, mercury, and thallium in ocular tissues, ocular fluids, and blood were determined using an inductively coupled plasma-mass spectrometer and expressed as ng/g. Heavy metal concentrations in ocular tissues were compared using a paired t test. Lead and cadmium were found in all of the pigmented ocular tissues studied, concentrating to the greatest extent in the retinal pigment epithelium/choroid (mean, 432 +/- 485 ng/g and 2,358 +/- 1,522 ng/g). Cadmium was found in the retina in all eyes (mean, 1,072 +/- 489 ng/g) whereas lead was found in the retina in 9 (30%) of 30 eyes (mean, 53 +/- 54 ng/g). Trace concentrations of lead and cadmium were detected in the vitreous (mean, 0.5 +/- 1.0 ng/dl and 19 +/- 29 ng/dl), lens (mean, 13 +/- 18 ng/g and 20 +/- 18 ng/g), and blood (mean, 0.5 +/- 1.2 mug/dl and 3.1 +/- 4.1 mug/l) but were not detected in the aqueous. Mercury and thallium were not detected in any ocular tissues or fluids or in the blood. Lead and cadmium accumulate in human ocular tissues, particularly in the retinal pigment epithelium and choroid. The potential ocular toxicity of these heavy metals and their possible role in eye disease requires further study.

Effect of Arjuna (Terminalia arjuna.) Extract on Tissue Lead Levels in Rats

The prophylactic efficacy of arjuna (Terminalia arjuna. L.) extract to reduce tissue lead (-Pb) concentration was evaluated experimentally in rats. Thirty female rats were divided into five groups, with group A as the control. Rats of groups B, C, D, and E received lead acetate orally at the rate of 5 mg per kg body weight daily for 6 weeks. The arjuna extract was tried in three doses, viz., 50 mg (low), 100 mg (medium), and 200 mg (high) per kg body weight orally and given simultaneously with Pb salt to the rats of groups C, D, and E, respectively. Mean blood Pb concentration in Pb-exposed rats ranged between 0.13 ± 0.02 and 0.96 ± 0.06 µg/ml, whereas in arjuna-treated rats, the range was between 0.15 ± 0.02 and 0.94 ± 0.06, 0.17 ± 0.01 and 0.77 ± 0.06, and 0.13 ± 0.1 and 0.51 ± 0.07 µg/ml in low-, medium-, and high-dose groups, respectively. The mean Pb concentration in liver, kidneys, brain, and bone of Pb-exposed rats was 2.289 ± 0.206, 4.748 ± 0.609, 1.019 ± 0.10, and 44.075 ± 2.60 µg/g, respectively. Concomitant use of arjuna bark extract at three different doses was found to reduce Pb concentration considerably in these vital organs indicating the potential therapeutic activity of arjuna against lead toxicity.

Lead Uptake and the Effects of EDTA on Lead-Tissue Concentrations in the Desert Species Mesquite (Prosopis spp.)

ABSTRACT Experimental results have shown that the desert plant species mesquite (Prosopis spp.) is capable of accumulating high levels of lead in the roots, translocating it to the aerial portion of the plant. One-week-old mesquite seedlings were treated for 7 d in a hydroponic culture using a modified Hoagland solution. Six treatments were used; three treatments contained only Pb [as Pb(NO3)2]at 25-, 50-, and 75-mg L−1 levels and three treatments contained the same levels of Pb, but with equimolar concentrations of disodium ethylenediamine tetraacetic acid (EDTA). Our results showed that the plants exposed to 25-, 50-, and 75-mg Pb L−1 treatments without EDTA concentrated in stems 524, 3726, and 1417 mg kg−1, respectively. However, the plants treated with Pb-EDTA concentrated in stems 480-, 607-, and 1247-mg Pb kg−1 for the 25-, 50-, and 75-mg Pb L−1 treatments, respectively. Results for the roots followed a similar trend; without EDTA the Pb levels ranged from 16,055, 89,935, and 63,396 for the 25-, 50-, and 75-mg Pb L−1 treatments, respectively, and with EDTA these levels were 9,562, 49,902, and 39,181 mg kg−1 for the three treatments. However, the addition of EDTA increased lead movement to the leaves. The levels of Pb without EDTA were 20, 35, and 51 mg kg−1 for the 25-, 50-, and 75-mg Pb L−1 levels, respectively. Treatments with EDTA showed uptake levels of 105, 124, and 313 for the 25-, 50-, and 75-mg Pb L−1 treatments. Further, the percent Pb in dry leaf tissues for all EDTA treatments were greater than 0.1%. However, only the 25-mg Pb L−1 treatment was greater than 0.1%, compared to 0.04 and 0.08% for the 50- and 75-mg Pb L−1 treatments, respectively. Preliminary transmission and scanning electron microscopy corroborate the presence of lead.

Phytoremediation of lead using Indian mustard ( Brassica juncea) with EDTA and electrodics

The use of plants to remove toxic metals from soil (phytoremediation) is emerging as a cost-effective alternative to conventional methods. Because contaminants such as lead have limited bioavailability in the soil, methods to facilitate its transport to the shoots and roots of plants are required to the success of phytoremediation. Indian mustard ( Brassica juncea) has been shown to be effective at accumulating high tissue concentrations of lead when grown in contaminated soil with the addition of a chelating agent, such as EDTA. The addition of an electric field around the plants is an alternative approach to increase the uptake of lead. In this work, bench scale studies illustrated the application of electrodic phytoremediation with EDTA for lead using Indian mustard. The effects of a range of parameters such as operating current/voltage with different concentrations, application time of EDTA and electric potential, and daily application time of electric potential were studied. The accumulation of lead in the shoots using 0.5 mmol/kg EDTA with electric potential increased by two- to four-fold compared to the use of EDTA only. The maximum lead accumulation in the shoots was obtained with the application of electric field 1 h per day for 9 days with EDTA.

Lead accumulation in woodchucks (Marmota monax) at small arms and skeet ranges

Increasing concern regarding the stewardship of US Army lands requires a proactive program to evaluate sites of potential risk. Small arms and upland skeet ranges are a potentially significant source of lead exposure for burrowing mammals. Woodchucks (Marmota monax) were evaluated for lead exposure in a previously used upland skeet range and a small arms range, respective to animals collected at two nearby reference locations. Soil lead concentrations collected at burrow entrances on the firing ranges were compared with blood, bone, kidney, liver, and fecal concentrations of woodchucks collected from the reference areas. No statistical differences were found in the lead concentrations in tissue between woodchucks in reference and firing ranges; concentrations of lead in liver and kidney were below detection limits. Levels in bone, blood, and feces suggest the bioavailability of lead at these various sites, although other factors (e.g., differences in foraging areas, age structure, habitat preferences, and environmental conditions) were also likely to influence exposure. Blood levels were below that which suggests toxicity. Further analysis of other ranges with higher lead concentrations and of small mammal species with smaller home ranges is recommended to further elucidate trends that could be extrapolated to other sites.

The effect of adding cadmium and lead alone or in combination to the diet of pigs on their growth, carcase composition and reproduction

AbstractLimits for cadmium and lead concentrations in food animal products have been established independently, whereas these two toxic metals often co‐exist in polluted regions. Weaned pigs (60) were allocated to ten treatments: control; low (0.5 mg kg−1), medium (1 mg kg−1) or high cadmium (2.5 mg kg−1) in feed; low (5 mg kg−1) medium (10 mg kg−1) or high (25 mg kg−1) lead in feed; and low, medium and high cadmium plus lead in feed. Growth rates and concentrations of cadmium and lead in body tissues (kidney, liver, spleen, lungs, heart, testicle, ribs, hair and teeth) were measured after 137 days. There was a similar reduction in weight gain for pigs in the cadmium and lead treatments, compared with the control, and a greater reduction for the pigs in the cadmium plus lead treatments. The reduction increased with the level of metal included. There was an increase in cadmium concentration of all tissues and blood with increasing feed cadmium concentration, which was usually less when lead was also included in the feed. There was also an increase in tissue lead concentration with increasing dietary lead, and this was in most cases increased when cadmium was also included in the feed. The most sensitive tissues for cadmium and lead exposure were the kidney, liver, hair and teeth, and regression equations were developed for the accumulation rates in these tissues. Tissue and blood cadmium concentrations increased gradually with increasing dietary lead, whereas tissue lead concentration was not sensitive to dietary cadmium, except in the ribs and heart. In a second experiment, 10 sows were allocated to a control diet or the same diet but with a supplement of cadmium and lead. The birth weight of piglets was decreased by the supplement and their mortality increased. Lead accumulated most in the ovary and oviduct of the sows, and there were increases in the lead and, to a lesser extent, cadmium concentrations of tissues of the piglets from these sows. Copyright © 2003 Society of Chemical Industry

Lead Contamination of Chicken Eggs and Tissues from a Small Farm Flock

Twenty mixed-breed adult laying hens from a small farm flock in Iowa were clinically normal but had been exposed to chips of lead-based paint in their environment. These chickens were brought to the Iowa State University Veterinary Diagnostic Laboratory, Ames, Iowa, where the concentration of lead in blood, eggs (yolk, albumen, and shell), and tissues (liver, kidney, muscle, and ovary) from 5 selected chickens was determined over a period of 9 days. Blood lead levels ranged from less than 50 to 760 ppb. Lead contamination of the yolks varied from less than 20 to 400 ppb, and shells were found to contain up to 450 ppb lead. Albumen contained no detectable amount. Lead content of the egg yolks strongly correlated with blood lead levels. Deposition of lead in the shells did not correlate well with blood lead levels. Mean tissue lead accumulation was highest in kidneys (1,360 ppb), with livers ranking second (500 ppb) and ovarian tissue third (320 ppb). Muscle contained the lowest level of lead (280 ppb). Lead contamination of egg yolks and edible chicken tissues represents a potential public health hazard, especially to children repeatedly consuming eggs from contaminated family-owned flocks.

Lead accumulation in feathers of nestling black‐crowned night herons (Nycticorax nycticorax) experimentally treated in the field

Although lead can attain high concentrations in feathers, interpretation of the biological significance of this phenomenon is difficult. As part of an effort to develop and validate noninvasive methods to monitor contaminant exposure in free-ranging birds, lead uptake by feathers of nestling black-crowned night herons (Nycticorax nycticorax) was evaluated in a controlled exposure study. Four- to 6-d-old heron nestlings (one/nest) at Chincoteague Bay, Virginia (USA), received a single intraperitoneal injection of dosing vehicle (control, n = 7) or a dose of lead nitrate in water (0.01, 0.05, or 0.25 mg Pb/g body wt of nestling; n = 6 or 7/dose) chosen to yield feather lead concentrations found at low- to moderately polluted sites. Nestlings were euthanized at 15 d of age. Lead accumulation in feathers was associated with concentrations in bone, kidney, and liver (r = 0.32-0.74, p < 0.02) but exhibited only modest dose dependence. Blood delta-aminolevulinic acid dehydratase activity was inhibited by lead, although effects on other biochemical endpoints were marginal. Tarsus growth rate was inversely related to feather lead concentration. Culmen growth rate was depressed in nestlings treated with the highest dose of lead but not correlated with feather lead concentration. These findings provide evidence that feathers of nestling herons are a sensitive indicator of lead exposure and have potential application for the extrapolation of lead concentrations in other tissues and the estimation of environmental lead exposure in birds.

Lead poisoning combined with cadmium in sheep and horses in the vicinity of non-ferrous metal smelters

The diagnosis of lead poisoning combined with cadmium in sheep and horses living on farmland in the vicinity of non-ferrous metal smelters in Baiyin of Gansu province in China was based on laboratory findings as well as clinical signs. The concentrations of lead, cadmium, copper and zinc in soils, water, forages, feed and blood, hair and tissues of affected sheep and horses were determined in the surroundings of the smelters in Baiyin and controls. Haematological values were also measured. The concentrations of these elements in soils, forages, water and feed were significantly higher than those in the control area ( P<0.01). The contents of lead and cadmium were 9.3 and 690 times in forages, respectively, 10 and 35.6 times in feed. The concentrations of lead and cadmium in blood, hair and tissues of the affected sheep and horses were significantly higher than reference values and control animals ( P<0.01). The occurrence of anaemia in affected animals belonged to a hypochromic and microcytic pattern. Lead and cadmium intake levels, estimated according to the ingestion rates of forages, illustrates that the apported lead and cadmium through the ingestion of vegetation growing in the closest sites to the smelters were approximately 6.0 mg Pb/kg body wt./day and 1.1 mg Cd/kg body wt./day in horses, 21.4 mg Pb/kg body wt./day and 4.0 mg Cd/kg body wt./day in sheep, surpassing the fatal dosages for horses of 1.7 mg Pb/kg body wt./day and for sheep of 4.4 mg Pb/kg body wt./day and 1.0 mg Cd/kg body wt./day. It is, therefore, suggested that the disease of sheep and horses in this region is caused by lead poisoning combined with cadmium, mainly due to environment heavy metal pollution by industrial activity. Meanwhile, as such levels of contamination in animal food and grain pose a significant potential risk to human health, these results have formed the basis for subsequent research on levels of metal contamination in human tissues from affected populations. Thus, it can be seen that knowledge of lead and cadmium concentrations in livestock in this region is important for assessing the effects of pollutants on domestic animals themselves and contaminant intakes by humans.

Lead poisoning in upland-foraging birds of prey in Canada.

We examined the degree of lead exposure, based on tissue-lead concentrations, in 184 raptors of 16 species found dead across Canada. The most prevalent species available for examination were Red-tailed hawks, Great horned owls, and Golden eagles (n = 131). The majority of individuals examined had very low lead accumulation, however 3-4% of total mortality in these 3 most commonly encountered species was attributed to lead poisoning. In addition, 1 of 9 Bald Eagles found dead far from aquatic environments was lead poisoned; and a single Turkey Vulture had a highly elevated bone-lead concentration (58 microg/g dry weight). Evidence from our study, along with other published research, indicates that upland-foraging birds of prey and scavengers that typically include game birds and mammals in their diets, are at risk for lead poisoning from the ingestion of lead projectiles from ammunition used in upland hunting. The use of non-lead ammunition for hunting upland game would effectively remove the only serious source of high lead exposure and lead poisoning for upland-foraging raptors.

Experimental lead poisoning in turkey vultures (Cathartes aura).

Lead-induced mortality appears to have been a major factor in the decline of the California condor (Gymnogyps californianus). We orally dosed turkey vultures (Cathartes aura) with BB-sized lead shot from January 1988 through July 1988 to determine physiologic response (delta-aminolevulinic acid dehydratase inhibition, erythrocyte protoporphyrin levels, anemia), diagnostic tissue lead concentrations (blood, liver, and kidney), and comparative sensitivity of this species. Two turkey vultures died and two became so intoxicated they were euthanized. Overall, responses of measured parameters were comparable to other species exposed to lead although there was considerable individual variation. Survival time (143-211 days), even with the large numbers of shot and constant redosing, was much longer than reported for other species of birds, suggesting considerable tolerance by turkey vultures to the deleterious effects of lead ingestion. Based on these observations, turkey vultures appear to be poor models for assessing the risk of lead poisoning to California condors or predicting their physiologic response.