Residue of organochlorine compounds and mercury in birds' eggs from the Niagara Peninsula,Ontario

Eggs (307) were collected in 1971 from twenty species of birds with a variety of feeding habits from the Niagara Peninsula. This area of Ontario is intensively developed for agriculture and heavy industry and has a large urban population. Representative species were obtained from both the terrestrial and aquatic food chains. Eggs were analyzed for organochlorine insecticides, polychlorinated biphenyls, and total mercury. Eggs from carnivorous species at the top of the aquatic food chain had the highest mean residues of DDT (7.6 to 22.4 ppm), PCB (3.5 to 74.0 ppm) and total mercury (0.64 to 0.83 ppm). Eggs from some terrestrial carnivores (red-tailed hawk and great horned owl) also had relatively high residues (2.5 to 3.9 ppm of DDT, 0.2 to 1.0 ppm of PCB, 0.06 to 0.09 ppm of mercury), however levels were much lower than those found in eggs from aquatic-feeding carnivores. Eggs from one red-shouldered hawk had residues comparable to the aquatic feeding carnivores. Eggs from herbivorous and insectivorous birds of both aquatic and terrestrial environments contained much lower residues. PCB residues were slightly lower in eggs among the terrestrial feeding species (0.05 to 2.0 ppm) than among the aquatic feeders (0.14 to 4.0 ppm) and tended to be lower in eggs from terrestrial species collected in rural than in city environs. Levels of DDT were similar in both groups with eggs from terrestrial feeders containing mean residues between 0.15 and 2.64 ppm and those from aquatic feeders between 0.33 and 2.79 ppm.     

Vector potential of culicine mosquitoes in Faiyum Governorate, Egypt

Culicine mosquito populations were studied for 1 year in 2 neighboring villages in Faiyum Governorate, Egypt. Dominant species in larval collections included Culex pipiens, Cx. univitattus, Cx. antennatus, Aedes caspius and Uranotaenia unguiculata; Culiseta longiareolata was less common. Culex pipiens accounted for 98% of 3,743 mosquitoes captured in human-biting collection (164 man-nights), 96% of 1,136 mosquitoes collected inside houses and animal sheds (396 inspections), and 98% of 15,000 mosquitoes from 22 donkey-baited traps. Adult Cx. univittatus, Cx. antennatus and Ae. caspius were infrequently captured by any of the collection techniques. Although larval collections identified 5 common species, only Cx. pipiens showed a significant association with the human population.     

Development and survival of Anopheles pharoensis and An. multicolor from Faiyum, Egypt.

Adults of Anopheles pharoensis and An. multicolor were held under cycling environmental conditions in the laboratory to examine the duration of the gonotrophic cycles, survival and life expectancy, and to examine the life table characteristics of F1 larvae. The first gonotrophic cycle took 6.14 and 7.37 days for An. pharoensis and An. multicolor, respectively. Subsequent gonotrophic cycles for the 2 species were shorter. Daily survival rates of An. pharoensis and An. multicolor in the laboratory were 0.95 and 0.93, respectively. The parity rate of field-collected females and estimates of the duration of the gonotrophic cycle yielded daily survivorship estimates of 0.89 and 0.80 for An. pharoensis and An. multicolor, respectively. Mean life expectancy at emergence was 19.0 days for An. pharoensis compared with 17.9 days for An. multicolor. Survivorship from egg eclosion to adult emergence and development time were similar for both species. Both the duration of gonotrophic cycles and mean life expectancies indicated that An. pharoensis had a greater potential to serve as a malaria vector than An. multicolor.     

Residue levels of organochlorine chemicals and polychlorinated biphenyls in fish from the Alexandria region,Egypt

Residues of polychlorinated biphenyls (PCBs) and organochlorine chemicals were analyzed by capillary gas chromatography in five fish species from Abu Qir Bay as well as in Tilapia species from Idku and Maryut lakes in Alexandria, Egypt. DDT and PCBs were the most predominant contaminants occurring in the muscle tissue of all fish samples. Remarkable variations in the concentrations of PCBs were noted among the species, and the concentrations of DDT were higher than that of PCBs in all fish species. Elevated PCB concentrations were observed in muscle tissue ofSargus vulgarius from Abu Qir Bay, and inTilapia zillii from Forn El-Gieraia, Maryut lake. Also, variations were found in the relative proportions ofp,p-DDT,p,p-DDD, andp,p-DDE in all fish samples. The results revealed an increase in chlorinated hydrocarbons with increase in body size and fat content. Neither -endosulfan nor -endosulfan was detected in fish from Abu Qir Bay; however, only -endosulfan was detected in trace amounts in Tilapia species from Idku and Maryut lakes. With the exception ofSargus vulgarius, mirex and methoxychlor occurred in low levels in all other fish species. Potential health hazards are discussed with the tolerance levels recommended.     

Environmentally acquired lead,cadmium, and manganese in the cattle egret,Bubulcus ibis,and the laughing gull,Larus atricilla

The concentrations of lead, cadmium, and manganese in the tissues of cattle egrets (Bubulcus ibis) and laughing gulls (Larus atricilla) gathered from the Galveston Bay region of Texas were compared, to determine if different patterns of accumulation exist. Their levels in these species were within the range reported for other bird species. Lead levels in bone were comparable, but gulls had more lead in brain, kidney and liver tissues than the egrets, which suggested a higher rate of accumulation or exposure. Due to their high abundance and comparable positions in the estuarine and terrestrial food webs, it is suggested thatBubulcus ibis andLarus atricilla may serve as convenient biological indicators to monitor potentially toxic substances in these ecosystems.     

Gender differences in the effects of organochlorines, mercury, and lead on thyroid hormone levels in lakeside communities of Quebec (Canada)

Environmental chemicals can disrupt endocrine balance and in particular thyroid hormone (TH) homeostasis. However, studies differ with respect to thyroid profile changes and gender differences are rarely examined. This study investigated the THs, triodothyronine (T3), thyroxine (T4), and thyroid stimulating hormone (TSH), in relation to serum organochlorines (OCs), bioindicators of mercury (Hg) and blood lead (Pb) in 211 freshwater fish consumers (124 men and 87 women) from two communities in Canada. Thyroid hormones were within the normal range and the bioindicators of exposure were low compared to other reports on fish consumers. Stratified analysis showed that for women, serum T3 concentrations were negatively related to serum concentrations of PCB 138, PCB 153, the non-coplanar congeners, Arochlor 1260, and ΣPCB, as well as p,p′-DDE. No relations were observed between T4 and any of the chemicals measured, but TSH was negatively related to blood Pb. For men, serum T4 was inversely related to PCB 138, non-ortho-substituted (dioxin-like) PCBs and ΣPCB. A significant positive relationship was observed between serum TSH and different PCB congeners (PCB 138, PCB 180, non-coplanar congeners, mono-ortho coplanar congeners, dioxin-like PCBs), as well as ΣPCB. Serum TSH increased with hair and blood Hg concentrations and was highest among those in the highest 50th percentile for both Hg and dioxin-like PCB congeners compared to the others. No associations were observed for T3 in men. These findings suggest that even at low concentrations, these environmental contaminants can interfere with thyroid status and effects may differ by gender.     

Lead, mercury, cadmium, chromium, and arsenic levels in eggs, feathers, and tissues of Canada geese of the New Jersey Meadowlands

The New Jersey Meadowlands are located within the heavily urbanized New York/New Jersey Harbor Estuary and have been subject to contamination due to effluent and runoff from industry, traffic, and homes along the Hackensack River and nearby waterways. These extensive wetlands, though heavily impacted by development and pollution, support a wide array of bird and other wildlife species. Persistent contaminants may pose threats to birds in these habitats, affecting reproduction, egg hatchability, nestling survival, and neurobehavioral development. Metals of concern in the Meadowlands include arsenic, cadmium, chromium, lead, and mercury. These metals were analyzed in eggs, feathers, muscle, and liver of Canada geese (Branta canadensis) breeding in four wetland sites. We sampled geese collected during control culling (n=26) and collected eggs from goose nests (n=34). Levels of arsenic were below the minimum quantification level (MQL) in most samples, and cadmium and mercury were low in all tissues sampled. Chromium levels were high in feather samples. Mercury levels in eggs of Canada geese, an almost exclusively herbivorous species, were lower (mean ±SE 4.29±0.30 μg/g wet weight) than in eggs of omnivorous mallards (Anas platyrhynchos), and insectivorous red-winged blackbirds (Agelaius phoeniceus) and marsh wrens (Cistothorus palustris) from the Meadowlands, consistent with trophic level differences. However, lead levels were higher in the goose eggs (161±36.7 ng/g) than in the other species. Geese also had higher levels of lead in feathers (1910±386 ng/g) than those seen in Meadowlands passerines. By contrast, muscle and liver lead levels were within the range reported in waterfowl elsewhere, possibly a reflection of metal sequestration in eggs and feathers. Elevated lead levels may be the result of sediment ingestion or ingestion of lead shot and sinkers. Finally, lead levels in goose liver (249±44.7 ng/g) and eggs (161±36.7 ng/g) may pose a risk if consumed frequently by humans. Mill Creek, the site with the most documented prior contamination, had significantly elevated cadmium, chromium, mercury, and lead in goose tissues.     

Heavy-Metal Levels in Feathers of Cattle Egret and Their Surrounding Environment: A Case of the Punjab Province, Pakistan

Levels of 10 heavy metals in cattle egret chick feathers, prey, and surrounding soils from three heronries in Punjab Province, Pakistan, were assessed by atomic absorption spectrophotometry. Mean levels of cadmium (Cd), iron (Fe), chromium (Cr), and lithium (Li) in feathers, manganese (Mn), cobalt (Co), and nickel (Ni) in prey, and lead (Pb), iron (Fe), chromium (Cr), zinc (Zn), cobalt (Co), and lithium (Li) in soils were significantly different among Trimun Headworks, Shorkot, and Mailsi heroneries. Mean levels of Pb (43.10 μg/g), Cr (35.77 μg/g), Co (18.34 μg/g), Cu (0.20 μg/g), and Ni (0.22 μg/g) in feathers were significantly greater at Mailsi, and Mn (3.07 μg/g), Zn (18.83 μg/g), and Li (1.5 μg/g) levels were significantly greater at Shorkot. Multivariate analysis identified that some metals, such as Fe, Zn, and Li, in feathers were either associated with natural sources or with human-related activities, whereas Ni, Cr, Pb, Cd, Cu, Co, and Mn were correlated mainly with anthropogenic processes. Alarming levels were recorded for Cr, Pb, and Cd in feathers that were above threshold levels that may affect cattle egret flighting capacity and reproduction, thus leading to their population decline in Punjab Province. The results of this study provide evidence for the potential of feathers of cattle egret to be used as a biomonitor for the local heavy-metal contamination.     

Joint toxicity of mercury and selenium in salmonid eggs

Toxic interactions between mercury and selenium in fertilized eggs of rainbow trout (Salmo gairdneri) and lake trout (Salvelinus namaycush) were investigated and compared to the pronounced synergistic effect previously reported in carp (Cyprinus carpio) eggs. Mercury produced concentration-dependent decreases in median survival times and caused decreases in median hatch times. Selenium, at concentrations up to 10 mg Se/L, had no effect on hatching times, and did not produce mortality, and had no effect on mercury toxicity. At concentrations of 100 mg Se/L and higher, an apparent protective effect of selenium on mercury toxicity was observed in lake trout eggs. Requirements for additional research are discussed with emphasis on predictions of region-wide damage to freshwater fish populations due to atmospheric deposition of these chemical elements.     

Mercury, cadmium and lead levels in Bagrus bayad fish from the river Nile, Delta Region, Egypt

A total of 50 random samples of Bagrus bayad were collected from various localities of River Nile at lower Egypt and were analyzed for determination of Hg, Cd and Pb concentrations by AAS. The obtained results revealed that the concentrations of Hg, Cd and Pb in fish muscles were ranged from 0.026 to 0.391, 0.028 to 0.053 and 0.022 to 0.654 with mean +/- SE values of 0.190 +/- 0.017, 0.048 +/- 0.003 and 0.215 +/- 0.047 microg/g wet weight, respectively. 24% and 6% of the examined fish samples exceeded the maximal permissible limit set by FAO/WHO (1992) for Cd and Pb, respectively. Whereas none of the examined samples exceeded the maximal limit for Hg. The possible health hazards of heavy metals as well as the suggestive measures for minimizing the pollution of fish and water had been discussed.     

Relation of mercury exposure to elemental mercury levels in the urine and blood

The levels of elemental and inorganic mercury were measured in urine and blood samples from workers in thermometer manufacturing factories. The inorganic mercury levels in the urine did not correlate with the levels of mercury exposure for each worker. However, a significant correlation was noted between elemental mercury levels in the urine and the levels of individual exposure. A significant correlation was also found between elemental mercury levels in the urine and mercury levels in the blood. These findings suggest that the determination of elemental mercury in urine may serve as a useful indicator for assessing levels of recent exposure to mercury vapor, as well as the level of inorganic mercury in the blood.     

Hair mercury levels, fish consumption, and cognitive development in preschool children from Granada, Spain ,

The main source of human exposure to mercury is the consumption of fish contaminated with methylmercury, which may adversely affect early neurodevelopment. This study assessed mercury levels in hair of preschoolers in Spain, where fish consumption is elevated, with the aim of investigating the influence of their fish intake and other factors on mercury exposure, and evaluating their association with cognitive development. A population-based birth cohort from Granada (Spain) was studied at the age of 4 yr. Total mercury (T-Hg) levels were determined in children's hair, and daily fish intake was assessed by a food frequency questionnaire. The McCarthy Scales of Children's Abilities (MSCA) were used to assess children's motor and cognitive abilities. Complete data were gathered on 72 children, and multivariate analyses were performed to evaluate the influence of mercury exposure and fish intake on MSCA outcomes. Mean concentration of T-Hg in hair was 0.96 μg/g (95% confidence interval=0.76; 1.20 μg/g). T-Hg levels were associated with higher frequency of oily fish consumption, place of residence, maternal age, and passive smoking. After adjustment for fish intake, T-Hg levels ≥1 μg/g were associated with decrements in the general cognitive (−6.6 points), memory (−8.4 points), and verbal (−7.5 points) MSCA scores. Higher mercury exposure in children from this Mediterranean area was associated with cognitive development delay. Studies on the putative benefits of fish intake during early development should consider mercury exposure from different fish species.