Selenium in eggs and parental blood of a Dutch marine wader

On the basis of earlier reports on high selenium levels in organs of marine waders from the Dutch Wadden Sea, adverse effects in wader reproduction were anticipated. A local breeding population of the wader Haematopus ostralegus, oystercatcher, was examined for embryotoxicity and selenium levels in eggs and parental blood. Egg and/or blood samples from breeding oystercatchers were obtained also from two reference sites, a Dutch meadow nature reserve and a Norwegian Atlantic island. The blood selenium levels were high in the Dutch marine birds (red blood cells contained 21 mg/kg vs 0.1–1.2 mg/kg dry weight in man), but the highest red blood cell levels were recorded in the red cells of birds sampled at the Norwegian reference site (maximal value 42 mg/kg dry weight). Both the concentrations in eggs from the Wadden Sea and in eggs from inland pastures (about 2 mg/kg dry weight), were at background level and embryotoxicity was not observed. Considering the results, it was concluded that selenium is not a potential threat to the reproduction of waders from the Dutch Wadden Sea, despite the high selenium concentrations in the tissues of the waders foraging in this area. Selenium in egg white was about 1.6 times higher than in yolk. The first egg had a 10% higher egg white and a 19% higher yolk concentration compared to the subsequent eggs in the coastal clutches. Red blood cell levels were about 3.5 times higher in marine feeding birds than in inland feeding birds. Selenium concentrations in the plasma and red blood cells were positively correlated.     

Bioaccumulation of polychlorinated biphenyls and metals from contaminated sediment by freshwater prawns,Macrobrachium rosenbergii and clams,Corbicula fluminea

Freshwater prawns,Macrobrachium rosenbergii, and clams,Corbicula fluminea, were exposed for 48 or 50 days to three concentrations of a river sediment that contained environmental contaminants such as polychlorinated biphenyls (PCBs) and metals. Sediment was obtained twice during 1980 from the same location. Prawns were exposed to the first batch, sediment 5–80, which contained higher concentrations of some metals and PCBs compared to sediment 11–80, used with the clams. The highest concentration of sediment 5–80 was toxic to the prawns; sediment 11–80 was not toxic to the clams. Tissue analyses of prawns for PCBs, as Aroclors® 1242 and 1254, demonstrated bioaccumulation. Maximum concentration of 1242 in prawns was achieved by day 7 while 1254 continued to accumulate in prawn tissues during the initial 40 days of the exposure period. The PCB sediment bioaccumulation factors (BAF) for prawns ranged from 0.11 to 0.90 for 1242 and 0.20 to 2.40 for 1254, and were highest for animals exposed to 10% sediment. Exposed clams also accumulated PCBs (1242 + 1254) from the sediment. Sediment BAFs for clams were 0.54 to 12.52 and were highest for animals exposed to 10% sediment. Analyses of clams for metals showed lead (Pb) in exposed animals at higher concentrations compared with controls. Bioaccumulation of Pb differed from PCB in that the Pb concentrations did not increase over time and concentrations were higher among animals exposed to 10% sediment compared to animals exposed to 100% sediment. Sediment 11–80 contained 99 mg/kg of Pb while exposed animals, at 48 days, contained approximately 2.2 mg/kg Pb. Analysis of clams for cadmium (Cd) showed exposed animals contained less Cd than controls.     

Heavy Metal Levels in Marine Mollusks from Areas With,or Without,Mining Activities Along the Gulf of California,Mexico

To assess the safety for human consumption of commercially important bivalves harvested from areas with or without mining activities, we compared the levels of heavy metals in mollusks collected from different coastal environments along the Gulf of California. We sampled the mussel Mytilus edulis and the clams Laevicardium elatum and Megapitaria squalida (June 2004) and the clam Chione californiensis (November 2006). Concentrations of cadmium, lead, nickel, zinc, iron, copper, and manganese in the soft tissue of the mollusks were measured by atomic absorption spectrophotometry. Based on dry weight, the highest average concentrations of iron, copper, and cadmium were found in clams from Loreto (572, 181, and 4.66 mg/kg, respectively); that of nickel, in mussels from San Luquitas (12.2 mg/kg); that of zinc, both in mussels from San Luquitas and in clams from Golfo de Santa Clara (94.3 and 91.8 mg/kg, respectively); and those of lead and manganese in clams from the Golfo de Santa Clara (9.2 and 3.68 mg/kg, respectively). Although mollusks were taken from coastal areas of the Gulf of California, which are considered to be contaminated by mining activities, the heavy metals in the sediments apparently were in a chemical form that had low bioavailability for the bivalves feeding in those areas. The interplay of oceanographic conditions and the chemical composition of anthropogenic inputs into the environment is not well understood. Thus, these factors or their interaction could potentially result in increased concentration and bioavailability of such metals in areas without effluent generated by mining activities.     

Assessment of trace elements in canned fishes (mackerel, tuna, salmon, sardines and herrings) marketed in Georgia and Alabama (United States of America)

The concentrations of mercury and 13 other trace metals in 104 canned fish samples purchased within the states of Georgia and Alabama (United States of America) were determined using the direct mercury analyzer (DMA) and the inductively coupled plasma-optical emission spectrometer (ICP-OES). The ranges obtained for the elements analyzed in mg/kg (wet weight) are as follows: Hg (0.02–0.74), Ag (0.0–0.20), As (0.0–1.72), Cd (0.0–0.05), Cr (0.0–0.30), Fe (0.01–88.4), Pb (0.0–0.03), Mn (0.01–2.55), Ni (0.0–0.78), Co (0.0–0.10), Cu (0.01–5.33), Sn (0.04–28.7), V (0.0–0.31) and Zn (0.14–97.8). Three tuna samples had Hg level above the European dietary limit of 0.5 mg Hg/kg. The mean Hg concentrations in the tuna (285 μg/kg) and sardine (107 μg/kg) brands were higher than the averages posted by the pink salmon (36.1 μg/kg), red salmon (32.8 μg/kg) and mackerel (36.4 μg/kg) brands. Two tuna samples and a sardine sample exceeded the Australian permissible limit of 1 μg/g inorganic arsenic (wet weight). Two samples (brand 15: herring) had zinc levels exceeding the Food and Agriculture Organization (FAO) recommended limit of 40 mg/kg and two pink salmons also exceeded the Brazilian regulatory limit of 0.1 mg Cr/kg. One tuna sample had a cadmium level slightly exceeding the Codex Committee on Food Additives and Contaminants draft guideline of 0.50 mg Cd/kg. However, the concentrations of lead, cadmium and copper were below the corresponding MAFF guidelines of 2.0, 1.0 and 30 mg/kg, respectively. Also, based on the United States Environmental Protection Agency (US EPA) health criteria for carcinogens, there are no health risks with respect to Pb, Cr, Cu and Zn concentrations in canned fishes analyzed. The result of the one-way analysis of variance (ANOVA) conducted on the data suggested that significant variations (P<0.05) existed in the concentrations of Hg, As, Co, Cr, Cu, Fe, Mn, Sn, V, and Zn across the various fish species and canned fish brands analyzed. The estimated weekly intakes of Hg, As, Cd, Pb, Sn, Fe, Cu and Zn for a 60 kg adult consuming 350 g of fish/week were below the respective provisional tolerable weekly intakes (PTWI) in μg/kg body weight for: Hg: 5; As: 15; Cd: 7; Pb: 25; Sn: 14000; Fe: 5600; Cu: 3500; and Zn: 7000.     

Changes in intracellular free amino acids in tissues of the caged mussel,Elliptio complanata,exposed to contaminated environments

Intracellular tissue concentrations of free amino acids (FAA) were monitored in caged mussels (Elliptio complanata) exposedin situ for 27–29 days and 77–79 days in the Yamaska River watershed (Quebec, Canada). Total concentrations of FAA (nmol/mg wet weight) increased in both mantle and adductor muscle tissue at several sites impacted by agricultural runoff and urban effluent from municipal sewage and light industries when compared to levels in mussels located at a site with little anthropogenic impact. Consistent changes in the per cent composition of individual FAA to the total FAA pool included decreases in serine, threonine, glycine and valine as well as increases in glutamic acid and glutamine at 27–29 days but results were not consistent with longer exposure and varied amongst sites. Few changes in total or individual FAA were observed in gill tissue. The results suggest that increases and/or decreases in total FAA in some tissues of freshwater bivalves may be indicative of generalized stress induced by a variety of environmental factors and may be useful as anin situ biochemical index of toxicity.     

Variations of heavy metals and arsenic in fish and other organisms from the Calcasieu River and Lake,Louisiana

The edible parts of several species of fish and other marine organisms inhabiting the Calcasieu River/Lake, Louisiana were analyzed for Cd, Cr, Cu, Pb, Hg, Ag, Zn, and As. Concentrations of all metals measured in both intra and interspecies showed no significant variation with sample location. Differences in elemental concentrations were related to organism mobility and not to site-specific variations in metal loadings. Different species of finfish contained only trace amounts of Cd (0.02-0.08), Ag (<0.01–0.3), Pb (<0.2–0.5), and As (<0.1–0.3) mg kg^–1. Concentrations of Cu and Cr were highly variable, in contrast to Zn, which was present in relatively constant amounts across all species (28 ± 7 mg kg^–1). Sessile organisms such as oysters had the highest concentrations of heavy metals, including Cd. Periphyton and Zooplankton were the only groups that showed differences in metal concentrations with sampling location.     

Using feathers to assess risk of mercury and selenium to bald eagle reproduction in the Great Lakes region

Mercury (Hg) and selenium (Se) concentrations were determined in feathers of nestling and adult bald eagles (Haliaeetus leucocephalus) in the Great Lakes region, 1985–1989. Relationships between concentrations and two measures of reproduction, productivity and nesting success, were examined. Hg and Se were detected in all feathers analyzed. A maximum concentration of 66 mg/kg Hg was found in adult feathers in the upper peninsula of Michigan. The geometric means of Hg in adult feathers for sample areas were: interior lower peninsula of Michigan, 21 mg/kg; interior upper peninsula of Michigan, 21 mg/kg; Lake Superior, 22 mg/kg; Lakes Michigan and Huron, 20 mg/kg; and Lake Erie, 13 mg/kg. The geometric means of Hg in nestling feathers for sample areas were: interior lower peninsula of Michigan, 8.8 mg/kg; interior upper peninsula of Michigan, 8.1 mg/kg; Lake Superior, 8.7 mg/kg; Lakes Michigan and Huron, 8.0 mg/kg; Lake Erie, 3.7 mg/kg; and Voyageurs National Park, 20 mg/kg. Se concentrations were not significantly different across regions or between adult and nestling feathers, and Se concentrations ranged from 0.8 to 3.2 mg/kg.No significant relationships between adult or nestling feather concentrations and either measure of reproduction, productivity or nesting success, was found for either Hg or Se. It was concluded that neither Hg nor Se concentrations are currently affecting bald eagle reproduction in the Great Lakes region.     

Comparative acute toxicity and bioconcentration of selenium by the midge Chironomus decorus exposed to selenate,selenite, and seleno-DL-methionine

The increased flux of selenium into aquatic ecosystems due to anthropogenic activities has resulted in the degradation of several systems. Initial experiments examined the comparative acute toxicity of waterborne selenate, selenite, and seleno-DL-methionine to fourth instar Chironomus decorus larvae resulting in 48-h LC₅₀ concentrations of 23.7, 48.2, and 194 mg Se/L, respectively. The relative toxicities of the selenium forms are reversed compared to previous studies on other species and demonstrate that relative waterborne selenium toxicity is species specific. Studies examining the kinetics of selenate and selenite (the dominant waterborne forms) accumulation by C. decorus larvae exposed to the 48-h LC₅₀ selenium concentrations showed initial rapid uptake and subsequent plateauing with maximum concentrations attained by 16 h. The final whole body selenium levels were approximately 63 mg Se/kg for selenate and 85 mg Se/kg for selenite. Comparative bioconcentration experiments demonstrated that after 48 h selenium accumulation was greater in larval C. decorus exposed to 25 mg Se/L as seleno-DL-methionine than in those exposed to 25 mg Se/L as selenate and selenite.     

Evaluation of Some Minerals and Toxicants in Some Nigerian Soup Meals

Some antinutrients (hydrocyanic acid, oxalate, and phytate) and some mineral elements (calcium, copper, iron, magnesium, zinc, and phosphorus) were analyzed in five popular Nigerian soup meals, afang (Gnetum africana), atama (Heinsia crinata), editan (Lasianthera africana), edikang ikong (Telfaria occidentalis), and okro (Hibiscus esculentus). The concentrations of antinutrients in these soup meals were 0.17–0.42, 1.50–10.40, and 484–745 mg/100 g dry wt for hydrocyanate, oxalate, and phytate, respectively. The mineral contents (mg/100 g dry wt) were Ca (1430–3930), Cu (1.6–3), Fe (130–470), Mg (490–910), Zn (12.7–40), and P (490–580). The computed [calcium]/[phytate] [phytate]/[zinc], [calcium] [phytate]/[zinc] and [phytate]/[P] millimolar ratios/kg, Dwt ranged from 45 to 98, 2 to 5, 117 to 650, and 4 to 6, respectively. The results showed that the concentrations of antinutrients were below toxic levels and these levels may not affect bioavailability of the minerals.     

Mercury Biomagnification in a Tropical Black Water,Rio Negro,Brazil

The population living along the riverbanks of the Amazon basin depends heavily on fish for nutritional support. Mono-methyl-mercury (MMHg) concentrates in fish, which can contaminate humans, the risk depending not only on fish MMHg concentration but also on the amount of fish consumed. We sampled nine locations of the Rio Negro basin, differing in water pH, Hg concentrations, and dissolved organic carbon (DOC), and determined total Hg from 951 fish samples of species representative of the food web: herbivorous, detritivorous, omnivorous, and piscivorous. Mercury concentrations varied widely in all species but showed a trend that depended on fish feeding strategies. The highest mean concentration was found in the piscivorous species (688.90 ng/g^–1), followed by omnivorous (190.30 ng/g^–1), detritivorous (136.04 ng/g^–1), and herbivorous (70.39 ng/g^–1). Fish Hg concentrations exceeding current safe limits (500 ng/g^–1) for human consumption were found mainly in the piscivorous species (60%). Significant positive correlation between fish weight and Hg concentration was seen for the piscivorous Serrasalmus spp. (n = 326; r = 0.3977; p < 0.0001), Cichla spp. (n = 125; r = 0.4600; p < 0.0001), and Pimelodus spp. (n = 12; r = 0.8299; p = 0.0008), known locally as Piranha, Tucunaré, and Mandi, respectively. However, a negative correlation was seen for nonpiscivorous Potamorhina latior (n = 30; r –0.3763; p = 0.0404) and Leporinus spp. (n = 44; r = –3987; p = 0.0073), known as Branquinha (detritivorous) and Aracu (omnivorous). Fish-Hg concentrations in the acidic waters (pH range, 4.09–6.31) of the Rio Negro habitat, with its wide gradient of Hg concentrations (3.4–11.9 g/L^–1) and DOC (1.85–15.3 mg/L^–1)—but no history of gold mining activity—are comparable to other Amazonian rivers. Opportunity fish catches in the Rio Negro habitat show high muscle-Hg derived from natural sources, but no systematic association with site-dependent geochemistry.     

Bioaccumulation of Atrazine in Freshwater Bivalves Anodontites trapesialis (Lamarck, 1819) and Corbicula fluminea (Müller, 1774)

The bioaccumulation of atrazine in bivalves is expected due to its wide use in agriculture and its moderate water solubility (33 mg/l). To assess the capacity of bioaccumulation, we performed a laboratory study in which two bivalves species (Anodontites trapesialis and Corbicula fluminea) were exposed to atrazine (concentrations of 0.06 to 0.34 μg/ml) during 48 h. The results showed that both bivalve species were able to bioaccumulate atrazine in their tissues. In another experiment, groups of bivalves from the specie A. trapesialis were exposed to atrazine at the concentration of 1 μg/ml and different organs of these animals were analyzed. The visceral mass, foot and mantle plus siphon showed the highest values of atrazine bioaccumulation.     

Transfer of lead from shotgun pellets to humus and three plant species in a finnish shooting range

A study of lead transfer from shotgun pellets to humus and plants in a shooting range in Helsinki, Southern Finland, revealed that pellet lead is mobilized into the humus layer. Concentrations of total lead (shotgun pellets excluded) in the shooting range varied between 4,700 mg/kg and 54,000 mg/kg, whereas concentration in the reference area was 240 mg/kg. Of the total lead, 90% was in EDTA-extractable form. Concentration of lead in the humus layer did not correlate with the content of lead in leaves ofBetula pendula, Tussilago farfara andEquisetum sylvaticum. The content of plant leaves was approximately one thousandth of that in humus. Species, however, differed significantly in their content of lead. Lead in leaves ofBetula pendula was the highest (14–70 mg/kg (DW), mean 44 mg/kg), that ofEquisetum sylvaticum the lowest (12–31 mg/kg (DW), mean 20 mg/kg), whereas that ofTussilago farfara (29–50 mg/kg (DW), mean 38 mg/kg) was intermediate. Lingonberries of the area had a lead content of 0.3 mg/kg, and were inedible according to the Finnish food safety regulations.     

HCH and DDT Residues in Bivalves <Emphasis Type="Italic">Anodonta woodiana</Emphasis> from the Taihu Lake,China

The present article attempts to use freshwater bivalves Anodonta woodiana for monitoring the pollution of hexachlorocyclohexane isomers (α-, β-, γ-, δ-HCH), dichlorodiphenyltrichloroethanes (o, p′, p, p′-DDT) and metabolites (p, p′-DDE, p, p′-DDD) in the Taihu Lake, China. A total of 36 bivalves were sampled from 4 sites of Huzhou city, Dapu of Yixing city, Xueyan of Changzhou city, and Wulihu of Wuxi city around the lake in August–October 2004. The organochlorines were detected in all bivalves, and the mean concentration of ΣDDTs (7.07 ng/g wet weight) was significantly higher than that of ΣHCHs (2.37 ng/g wet weight). Overall, ΣHCHs are at the highest concentrations in the bivalves from the Dapu and Huzhou site, whereas ΣDDTs are at highest concentrations in the bivalves from the Wulihu site. Compositions of ΣHCHs were predominated by α- and γ-HCH isomers in the bivalves from all four study sites. Among these sampling sites, p, p′-DDT exhibited the highest percentage in the bivalves from Huzhou site. Furthermore, significant regional variations in compositions of both ΣDDTs and ΣHCHs had been identified. The residue levels of ΣDDTs and ΣHCHs in the bivalves of the present study were much lower than the corresponding residue limits for aquatic products of Ministry of Agriculture of China, FDA, and FAO/WHO. These findings suggest that Anodonta woodiana could serve as a unique bioindicator to monitor the HCH and DDT pollutions in the freshwater environment.     

Mercury Contamination in Idaho Bald Eagles, <Emphasis Type="Italic">Haliaeetus leucocephalus</Emphasis>

Because mercury contamination is potentially threatening to bald eagle (Haliaeetus leucocephalus) populations, we collected molted feathers at nests to determine the level of contamination in bald eagles in the state of Idaho, USA. Eagle feathers contained measurable amounts of cadmium (Cd), chromium (Cr), selenium (Se), lead (Pb), as well as mercury (Hg). Cadmium, Cr, Se, and Pb levels averaged 0.17, 4.68, 2.02, and 1.29 mg/kg dry weight, respectively, and were at or below concentrations indicated as causing reproductive failure in bald eagles. Mercury contamination was found to be the highest averaging 18.74 mg/kg dry weight. Although a concentration of only 7.5 mg/kg dry weight Hg in bird feathers can cause reduced productivity and even sterility, all of the eagles we sampled bred successfully and the population of bald eagles continues to grow annually throughout the state.     

Total and Methyl Mercury Contents and Distribution Characteristics in Cicada, Cryptotympana atrata (Fabricius)

Total and methyl mercury concentrations of cicada bodies, wings, and exuviae were investigated to study the mercury distribution characteristics. Results indicated that total and methyl mercury concentrations of cicada bodies were 2.64 mg/kg and 123.93 ng/g on average, respectively. In cicada tissues, total mercury concentrations were found to increase in the order of exuviae (0.50 mg/kg on average) < wings (0.98 mg/kg on average) < cicada bodies (2.64 mg/kg on average) and methyl mercury concentrations of cicada bodies were 123.93 ng/g on average and were the highest. Methyl mercury concentrations accounted for about 4.69% of total mercury in cicada bodies and most mercury was in inorganic forms in cicada. Sex differences of total mercury concentrations were significantly great (F = 8.433, p < 0.01) and total mercury concentrations of the males, which were 3.38 mg/kg on average, were much higher. Correlation analysis showed that neither total nor methyl mercury concentrations of cicada bodies was significantly related to the corresponding contents of soil (r = 0.0598, p > 0.05).     

Evaluation of the critical body burden concept based on inorganic and organic mercury toxicity to rainbow trout (Oncorhynchus mykiss)

Subadult rainbow trout (Oncorhynchus mykiss) were exposed to four waterborne concentrations each of 64–426 g/L mercuric chloride (HgCl₂) and 4–34 g/L methylmercury chloride (CH₃HgCl) until death to evaluate the critical body burden concept. Mean days to death for fish exposed to the highest and lowest concentrations of HgCl₂ were 1 and 58 d, and 2 and >100 d for fish exposed to CH₃HgCl. Time to death was an important factor that influenced Hg tissue concentration, and was most evident among fish that died within a few days of exposure. Critical body burdens for Hg could be difficult to establish at the tissue level because no threshold concentrations were clearly indicated among the liver, kidney, spleen, brain, muscle, and gill that were monitored in this study. A critical burden for Hg was derived on a whole body basis for Hg in its organic form. An evaluation of this and other studies suggests whole body concentrations of 10–20 mg/kg Hg could be lethal to fish. Extrapolation from other studies indicate whole body concentrations of 1–5 mg/kg Hg could have chronic effects on fish and possibly other aquatic organisms. This concept could be used to assess the toxicological significance of chemical concentrations that are monitored in feral aquatic organisms. This tissue-based approach appears to have some advantages over current assessment protocols that focus on waterborne concentrations.     

Toxicity and removal of heavy metals (cadmium, copper, and zinc) by Lemna gibba

Effects of cadmium, copper, and zinc on the aquatic plant Lemna gibba were determined under controlled conditions; in parallel their removal from the growth medium was followed. The results showed that the three heavy metals affected growth, a physiological stress index defined as the ratio of Chlorophyll to phaeophytin (D665/D665a), and the contents of proline. After 4 days, 10⁻³–10⁻¹ mg/L Cd inhibited growth by 25–100%, reduced D665/D665a by 35–89%, and increased proline content by 44–567%. Under the same conditions, 10⁻⁴–10⁻¹ μg/L Cu inhibited growth by 36–75%, reduced D665/D665a by 19–81%, and increased proline content by 67–288%. Comparable concentrations of Zn had little effect. However, higher concentrations (4, 30, and 50 mg/L) inhibited growth by 50–79%. Also, 0.1 and 30 mg/L induced a small reduction of D665/D665a (−3.8% and −22%) and an increase in proline contents (+144% and +177%). When it was observed, proline accumulation was always transient and the maximum was reached after 4 days. Monitoring metal concentration in the medium showed that L. gibba was able to remove metals from the medium. Zn and Cu removal was biphasic, it was rapid during the first 2 days (> 60% reduction) and slow (10–20%) during the following 8 days. For Cd, removal was linear and depended on the initial concentration. It reached approximately 90% after 6 or 8 days for initial concentrations of 10⁻¹ and 10⁻³ mg/L, respectively.     

Patterns, trends, and toxicological significance of chlorinated hydrocarbon and mercury contaminants in bald eagle eggs from the pacific coast of Canada, 1990–1994

Bald eagle (Haliaeetus leucocephalus) eggs were collected during incubation, 1990–1992, from 16 nests near three bleached-kraft pulp mills, from six nests in the Fraser River estuary and from seven nests at a reference site on the Pacific coast of Canada. Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were present in all eggs in a qualitatively similar pattern among sites. Mean concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) were significantly higher in eggs collected from near three kraft pulp mill sites in the Strait of Georgia (44, 45, 84 ng/kg) than from the reference area in Johnstone Strait (15 ng/kg). There were few differences among sites in mean organochlorine pesticide levels, indicating the diffuse distribution of those chemicals and the domination of atmospheric inputs. Mean concentrations of total polychlorinated biphenyls (PCBs) were highest in eggs from the Strait of Georgia (4.86 mg/kg) and the PCB congener pattern was significantly different between that area and both the lower Fraser valley and Johnstone Strait. Mean mercury concentrations, which were mainly methyl-mercury, were significantly higher in eggs collected from the lower Fraser Valley (0.258 mg/kg) and Johnstone Strait (0.294 mg/kg) compared to the Strait of Georgia (0.188 mg/kg). Individual and regional variation in concentrations of organochlorine pesticides, PCBs and mercury in eagle eggs were thought to be influenced mainly by dietary differences. Toxicologically, in 1990, mean TCDD-toxic equivalents (TEQs) in bald eagle eggs were about two-fold greater than a lowest-observed-effect level, suggested elsewhere for this species, of 210 ng/kg TEQs. In the Strait of Georgia, PCCDs and PCDFs made a greater contribution to TEQs than non-ortho and mono-ortho PCBs, whereas the reverse was true for eggs outside the strait. Mean eggshell thickness was less than the pre-1947 value at all sites, although there was no significant relationship between eggshell thickness and DDE concentrations. Levels of other organochlorine pesticides and mercury were below those considered to be toxic.     

DNA stability and lipid peroxidation in vitamin E–deficient rats in vivo and colon cells in vitro

Summary Background Fruit and vegetable consumption protects against cancer. This is attributed in part to antioxidants such as vitamin E combating oxidative DNA damage. Anthocyanins are found in significant concentrations in the human diet. However, it remains to be established whether they are bioactive in vivo. Aim To investigate the consequence both of vitamin E deficiency on oxidative damage to DNA and lipids and the cytoprotective effect of nutritionally relevant levels of cyanidin–3–glycoside both in vivo in rats and in vitro in human colonocytes. Methods Male Rowett Hooded Lister rats were fed a diet containing less than 0.5 mg/kg vitamin E or a vitamin E supplemented control diet containing 100 mg d–tocopherol acetate/kg. Half of the controls and vitamin E–deficient rats received cyanidin–3–glycoside (100 mg/kg). After 12 weeks endogenous DNA stability in rat lymphocytes (strand breaks and oxidised bases) and response to oxidative stress ex vivo (H₂O₂; 200 µM) was measured by single cell gel electrophoresis (SCGE). Tissue levels of 8–oxo–7,8–dihydro–2–deoxyguanosine (8–Oxo–dG) were measured by HPLC with EC detection. D–tocopherol and lipid peroxidation products (thiobarbituric acid reactive substances; TBARS) were measured by HPLC. Rat plasma pyruvate kinase and the production of reactive oxygen by phagocytes were detected spectrophotometrically and by flow cytometry respectively. Immortalised human colon epithelial cells (HCEC) were preincubated in vitro with the anthocyanins cyanidin and cyanidin–3–glycoside and the flavonol quercetin (all 50 µM) before exposure to H₂O₂ (200 µM). DNA damage was measured by SCGE as above. Results Plasma and liver d–tocopherol declined progressively over 12 weeks in rats made vitamin E deficient. Lipid peroxidation was increased significantly in plasma, liver and red cells. Reactive oxygen levels in phagocytes and plasma pyruvate kinase were increased. Vitamin E deficiency did not affect DNA stability in rat lymphocytes, liver or colon. Cyanidin–3–glycoside did not alter lipid peroxidation or DNA damage in rats. However, it was chemoprotective against DNA damage in human colonocytes.DNA strand breakage was decreased 38.8 ± 2.2 % after pretreatment with anthocyanin. Conclusion while it is accepted that vitamin E alters lipid oxidation in vivo, its role in maintaining DNA stability remains unclear. Moreover, whereas cyanidin–3–glycoside protects against oxidative DNA damage in vitro, at nutritionally relevant concentrations it is ineffective against oxidative stress in vivo.     

Effects of Light on Microalgae Concentrations and Selenium Uptake in Bivalves Exposed to Selenium-Amended Sediments

The purpose of the current study was to evaluate the role of visible light during trophic transfer of the essential metalloid, selenium (Se) from sediments by way of the microalgae Phaeodactylum tricornutum to bivalves. Initial experiments compared uptake of Se with algal cell number after deposit-feeding (Tellina deltoidalis) and filter-feeding (Soletellina alba) bivalves were exposed for 12 days under 16:8 h light:dark and 24-hour dark regimes to sediments amended with Se (17 mg/kg dry weight). Comparisons of filter-feeding with deposit-feeding organisms indicated >2-fold higher body burdens in the deposit-feeding organisms after 12 days. Darkness failed to significantly and consistently diminish algal cell densities. However, general trends indicated a decrease of pelagic algal numbers in +Se/dark treatments during the 12-day exposure. To determine whether time-dependent patterns were present in the uptake of Se by the deposit-feeding species, a second experiment was conducted using Se-laden sediments under light and dark conditions. Algal cell counts were measured and Se concentrations determined in animals sampled at days 0, 3, 6, 9, and 12. Deposit-feeding animals maintained in the dark accumulated, Se more rapidly than animals on light to dark cycles until 12 days at which time no significant differences were observed between treatments. Concentrations of Se in tissues of deposit-feeding bivalves were not directly related to algal cell density in lighted or dark chambers. These results indicate that pelagic microalgae may only play a key role in Se uptake during early hours of exposure, and feeding behavior may be a more important factor in deposite-feeding bivalves.