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At least 649 records · Page 36Linked to original sources
PubMed2003

Synthesis and estrogenic activity of bisphenol a mono- and di-beta-D-glucopyranosides, plant metabolites of bisphenol A.

The syntheses and characterization of bisphenol A mono- and di-beta-D-glucopyranosides were undertaken to confirm that these compounds are major plant metabolities of bisphenol A (BPA) and to allow an assessment of their estrogenicity. Synthesis involved the glucosidation of unprotected BPA with glucose penta-acetate with phosphorus oxychloride as catalyst. The estrogenic activity of BPA and its mono- and di-beta-D-glucopyranosides were measured with an enzyme-linked immunosorbent assay (ELISA)-based estrogen receptor competitive binding assay and with a yeast two-hybrid assay adapted to a chemiluminescent reporter gene (for beta-galactosidase). Both methods showed that the estrogenicity of BPA was eliminated by formation of the di-glucoside, but whereas the ELISA-based method indicated that reduced activity remained in the monoglucoside, the yeast two-hybrid method showed the monoglucoside to be inactive. Presumably these results reflect the more complex interactions of test compound and cellular components required to demonstrate estrogenicity in the yeast two-hybrid assay. As these processes parallel those in mammalian cells, the yeast two-hybrid method is likely to be the more realistic assay. The uptake and metabolism of BPA by plants offers the possibility of phytoremediation of contaminated water, but also provides an additional route for the compound to enter the human food chain.

Benzhydryl Compounds↗
PubMed2003

Ostreopsis sp., a possible origin of palytoxin (PTX) in parrotfish Scarus ovifrons.

A clone of toxic dinoflagellate Ostreopsis sp. and six specimens of a parrotfish Scarus ovifrons were collected in October 1997 at Tokushima Prefecture, Japan. Ostreopsis sp. was cultured in ESM medium for 16 days, and after rearing the cell pellet (about 4.0x10(5) cells) was extracted with 50% methanol, partitioned between an aqueous layer and 1-butanol layer, and biochemically tested. Similarly, the crude toxin from S. ovifrons was extracted, and tested. The mice injected with each 1-butanol layer from Ostreopsis sp. and S. ovifrons showed the common symptoms of convulsion, drowsiness and collapse, and died within 48 h. The lethal potency of Ostreopsis sp. was calculated to be 1.0x10(-4) MU/cell. All specimens of S. ovifrons were found to be toxic, where the highest potency was determined as 2 MU/g in muscle of one specimen. After being injected with toxins, the serum creatine phosphokinase levels of mice were found to be elevated. Toxins from Ostreopsis sp. and S. ovifrons showed delayed haemolytic activity with mouse and human erythrocytes, which was inhibited by an anti-palytoxin (PTX) antibody antibody and ouabain. Toxins from Ostreopsis sp. and S. ovifrons thus resembled each other, and strongly suggested to be PTX or its akin substance. Additionally, a considerable number of adherent Ostreopsis sp. was found in the gut contents of S. ovifrons during the heavy occurrence of Ostreopsis sp. in October 1997 at Tokushima Prefecture. From the above results, it can be strongly postulated that the dinoflagellate Ostreopsis sp. is the origin of PTX which is sequestered by the parrotfish S. ovifrons through food chain.

Acrylamides↗
PubMed2006

How was the French BSE epidemic underestimated?

In a previous study, we showed that estimates of the BSE epidemic in France were censored by cattle mortality and by a lack of diagnosis. Indeed, we estimated that 51 300 cattle were infected by the BSE agent between 1987 and 1997, whereas only 103 clinical BSE cases were detected by the passive surveillance system up to June 2000. The question thus arises as to the part played by each form of censorship in this underestimation. Here, using an updated cattle survival distribution, we estimated that 44 800 cattle were infected by the BSE agent between 1987 and 1997, and that 7100 of them showed clinical signs of BSE up to June 2000, showing the low efficiency of the surveillance system. Moreover, between 2087 and 5980 'infectious' cattle, with clinical or preclinical BSE, entered the human food chain before July 1996, the date of the ban on specified bovine offal.

Age Factors↗
PubMed2001

Factors controlling the bioaccumulation of mercury and methylmercury by the estuarine amphipod Leptocheirus plumulosus.

The bioaccumulation of inorganic mercury (HgI) and monomethylmercury (MMHg) by benthic organisms and subsequent trophic transfer couples the benthic and pelagic realms of aquatic systems and provides a mechanism for transfer of sedimentary contaminants to aquatic food chains. Experiments were performed to investigate the bioavailability and bioaccumulation of particle-associated HgI and MMHg by the estuarine amphipod Leptocheirus plumulosus to further understand the controls on bioaccumulation by benthic organisms. HgI and MMHg are particle reactive and have a strong affinity for organic matter, a potential food source for amphipods. Microcosm laboratory experiments were performed to determine the effects of organic matter on Hg bioaccumulation and to determine the major route of Hg uptake (i.e. sediment ingestion, uptake from water/porewater, or uptake from 'food'). Amphipods living in organic-rich sediment spiked with Hg accumulated less Hg than those living in sediments with a lower organic matter content. Feeding had a significant impact on the amount of HgI and MMHg accumulated. Similarly, amphipods living in water with little organic matter accumulated more Hg than those living in water with a greater percentage of organic matter. MMHg was more readily available for uptake than HgI. Experimental results, coupled with results from a bioaccumulation model, suggest that accumulation of HgI and MMHg from sediment cannot be accurately predicted based solely on the total Hg, or even the MMHg, concentration of the sediment, and sediment-based bioaccumulation factors. All routes of exposure need to be considered in determining the accumulation of HgI and MMHg from sediment to benthic invertebrates.

Animals↗
PubMed2006

Determination of carbendazim residues in the eggs, liver and pectoral muscle of Japanese quail (Coturnix coturnix japonica).

The effect of carbendazim, a widely applied cereal seed dressing agent, was studied in Japanese quail (Coturnix coturnix japonica) during an overall period of eight weeks, consisting of a four-week feeding phase and a subsequent four-week excretion period. Body mass and feed consumption of the birds were monitored and residues of the active ingredient were determined by an analytical chemical method. During the eight-week study period, changes (either decrease or increase) directly attributable to the toxic effects of carbendazim were not found either in body mass or in feed consumption. Active ingredient levels exceeding the limit of detection were found in the liver (average: 0.0262 mg/kg) and pectoral muscle (average: 0.0236 mg/kg) of the birds and also in the egg (0.0338 mg/kg) samples. From the results it can be concluded that through the consumption of cereal seeds dressed with carbendazim, this active ingredient can be incorporated into the tissues of animals. Via the food chain, carbendazim can also enter the human organism, where it may cause various pathological changes in interaction with other chemicals.

Animals↗
PubMed2004

Upward cascading effects of nutrients: shifts in a benthic microalgal community and a negative herbivore response.

We evaluated the effects of nutrient addition on interactions between the benthic microalgal community and a dominant herbivorous gastropod, Cerithidea californica (California horn snail), on tidal flats in Mugu Lagoon, southern California, USA. We crossed snail and nutrient (N and P) addition treatments in enclosures on two tidal flats varying from 71 to 92% sand content in a temporally replicated experiment (summer 2000, fall 2000, spring 2001). Diatom biomass increased slightly (approximately 30%) in response to nutrient treatments but was not affected by snails. Blooms of cyanobacteria (up to 200%) and purple sulfur bacteria (up to 400%) occurred in response to nutrient enrichment, particularly in the sandier site, but only cyanobacterial biomass decreased in response to snail grazing. Snail mortality was 2-5 times higher in response to nutrient addition, especially in the sandier site, corresponding to a relative increase in cyanobacterial biomass. Nutrient-related snail mortality occurred only in the spring and summer, when the snails were most actively feeding on the microalgal community. Inactive snails in the fall showed no response to nutrient-induced cyanobacterial growths. This study demonstrated strongly negative upward cascading effects of nutrient enrichment through the food chain. The strength of this upward cascade was closely linked to sediment type and microalgal community composition.

Animal Nutritional Physiological Phenomena↗
PubMed2005

Excess propagation and biological control of zooplanktonic Cyclops in drinking water sources.

Starting with the occurrence of Cyclops in drinking water sources and its danger to drinking water safety, we extensively investigated the nature of its excess propagation by analyzing the effect of living space and predator pressure in the food chain on its survival. Then we developed an ecological project using fish biomanipulation, different to the conventional fishery culture technique, to control excess propagation of Cyclops. The control effects on Cyclops of four species of fish were investigated experimentally at a stocking density of 30 g/m3 of water. Results showed that the food habit of the fish had a significant influence on the biological control of Cyclops. The propagation of Cyclops could be controlled effectively and also the water quality improved simultaneously by stocking filter-feeding fish, such as silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis). However, herbivorous Ctenopharyngodon idellus and omnivorous Cyprinus carpio had no obvious biological effects on controlling the growth of Cyclops and restoring water quality. The results further proved that under conditions of proper poly-culture densities of silver carp and bighead carp, the number of Cyclops might be controlled at very low levels and eutrophication might be abated by removing nutrients from the water body.

Animals↗
PubMed2005

Effects of tungsten on environmental systems.

Tungsten is a metal with many industrial and military applications, including manufacturing of commercial and military ammunition. Despite its widespread use, the potential environmental effects of tungsten are essentially unknown. This study addresses environmental effects of particulate and soluble forms of tungsten, and to a minor extent certain tungsten alloy components, present in some munitions formulations. Dissolution of tungsten powder significantly acidifies soils. Tungsten powder mixed with soils at rates higher than 1% on a mass basis, trigger changes in soil microbial communities resulting in the death of a substantial portion of the bacterial component and an increase of the fungal biomass. It also induces the death of red worms and plants. These effects appear to be related with the soil acidification occurring during tungsten dissolution. Dissolved tungsten species significantly decrease microbial yields by as much as 38% for a tungsten media concentration of 89 mg l(-1). Soluble tungsten concentrations as low as 10(-5) mg l(-1), cause a decrease in biomass production by 8% which is possibly related to production of stress proteins. Plants and worms take up tungsten ions from soil in significant amounts while an enrichment of tungsten in the plant rhizosphere is observed. These results provide an indication that tungsten compounds may be introduced into the food chain and suggest the possibility of development of phytoremediation-based technologies for the cleanup of tungsten contaminated sites.

Animals↗
PubMed2002

Studies on the accumulation and transformation of arsenic in freshwater organisms II. Accumulation and transformation of arsenic compounds by Tilapia mossambica.

Bioaccumulation and biotransformation of arsenic (As) compounds in freshwater Tilapia mossambica was investigated. The direct accumulation of As by T mossambica was proportional to the concentration of arsenicals in water. Small amounts of accumulated As were transformed to methylated As, including trimethylarsenic (TMA) species. Accumulation and transformation of As(III) by T. mossambica via freshwater food chain results in the transformation of As(III) to As(V) with little biomethylation of accumulated As. Approximately 90% of accumulated As was depurated to water.

Animals↗
PubMed2003

Biotransfer of selenium: effects on an insect predator, Podisus maculiventris.

The effects of selenium (Se) accumulation in phytophagous insects on predators in the next trophic level were investigated. The generalist predator Podisus maculiventris Say (Hemiptera: Pentatomidae) was fed an herbivore Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) larvae from control diet and diets at two Se levels (0, 109, and 135 microg/g sodium selenate dry weight added). Predators reared on larvae grown on diets with sodium selenate took longer to complete each developmental stage and had significantly higher mortality rates. Predators achieving the adult stage on Se-containing hosts weighed 20% less than those feeding on control larvae. Reduced adult weight of insects has been associated with reduced fitness (longevity, egg production, etc.), which would have long-term negative impacts on population dynamics. These developmental and mortality effects resulted from biotransfer of Se, not biomagnification since the trophic transfer factor was less than 1.0 (approximately 0.85). Host larvae in Se-treatments contained significantly more total Se (9.76 and 13.0 microg/g Se dry weight host larvae) than their predators (8.34 and 11 microg/g Se dry weight predatory bugs, respectively). Host larvae and predators in the control groups did not differ in their Se content. These data demonstrate that Se in the food chain may have detrimental population level effects on insects even in the absence of biomagnification, given the host contains significantly elevated concentrations of selenium.

Animals↗
PubMed1999

[Small handbook of dioxin et alias].

Dioxin is the common name for a series of 75 dibenzodioxins, 135 dibenzofurans and 209 PCBs. Among these chemicals, less than 30 prove to be toxic. Those molecules can act as hormone disrupters, suppress the immune system, alter the physiology of the sebaceus follicle and participate in the carcinogenesis of sacromas, lymphomas and some carcinomas. They may be responsible for some birth defects. In some regions of the world, dioxins and dioxin-like chemicals are present in the environment, the food chain and body tissues at doses at or near at the level supposed to cause harm to public health.

Dioxins↗
PubMed1999

Human health implications of environmental contaminants in Arctic Canada: a review.

This paper assesses the impact on human health of exposure to current levels of environmental contaminants in the Canadian Arctic, and identifies the data gaps that need to be filled by future human health research and monitoring. The concept of health in indigenous groups of the Arctic includes social, cultural, and spiritual dimensions. The harvesting, sharing and consumption of traditional foods are an integral component to good health among Aboriginal people influencing both physical health and social well-being. Traditional foods are also an economic necessity in many communities. Consequently, the contamination of country food raises problems which go far beyond the usual confines of public health and cannot be resolved by health advisories or food substitutions alone. The primary exposure pathway for the contaminants considered in this paper is through the traditional northern diet. For the Inuit, the OCs of primary concern at this time from the point of view of exposure are chlordane, toxaphene, and PCBs. Exposures are higher in the eastern than in the western region of the North. For Dene/Metis, exposure to OCs is in general below a level of concern. However, estimated intake of chlordane and toxaphene has been found to be elevated for certain groups and is a cause for concern if exposures are elevated on a regular basis. The developing foetus and breast-fed infant are likely to be more sensitive to the effects of OCs and metals than individual adults and are the age groups at greatest risk in the Arctic. Extensive sampling of human tissues in the Canadian north indicate that a significant proportion of Dene, Cree and Inuit had mean maternal hair mercury levels within the 5% risk-range proposed by the WHO for neonatal neurological damage. Based on current levels, lead does not appear to pose a health threat while cadmium is likely only a major risk factor for heavy smokers or consumers of large amounts of organ meats. Consumers of traditional foods are exposed to an approximately seven-fold higher radiation dose than non-consumers of traditional foods due predominantly to the bioaccumulation of natural radionuclides in the food chain. Risk determination for contaminants in country food involves a consideration of the type and amounts of food consumed and the sociocultural, nutritional, economic, and spiritual benefits associated with country foods. Risk management options that minimize the extent to which nutritional and sociocultural aspects of Aboriginal societies are compromised must always be considered.

Adult↗
PubMed1997

Environmental oestrogens--present understanding.

Three years ago it was hypothesized that the reported adverse changes in male reproductive health could be explained by exposure to compounds with oestrogenic (or other hormone disruptive) activity. Although this issue has been highly publicized, there has been little progress towards a realistic assessment of whether environmental oestrogens pose a health risk to humans. This article attempts to give a brief overview of the current status of knowledge concerning environmental oestrogens and highlights some of the difficulties associated with risk assessment. Compounds within several major groups of chemicals, including organochlorine pesticides, polychlorinated biphenyls, phenolic compounds and phthalate esters, have been identified as being weakly oestrogenic by in vitro and in vivo screening methods. Many of these compounds are widespread and persistent in the environment. They are likely to be present in the food chain, drinking water, plastics, household products and food packaging, although which is the most important route of human exposure is unclear. In addition to exposure to man-made chemicals, the consumption of plant-derived oestrogens in foodstuffs poses a potential risk to human health as phytoestrogens are more potent oestrogens and their intake by some infants is likely to be considerable.

Animals↗
PubMed2003

[Microbial risks--from animal farming to the food].

Microorganisms by far are representing the most important cause for food safety risks. Sources of food contamination are given along the whole food chain. The most frequent causative agents of food infections, Salmonella and Campylobacter, mostly can be found in the animals herds. A real improvement of the situation can only be reached by a strong inclusion of the agricultural area in the programs for repressing the pathogens. Problems in animal health and premortal stress of the slaughter animals cause considerable bacterial translocation processes and increase the consumer risks. Only few publications exist on the influence of the animal farming systems on the development of microbial food risks. The consumer accepts only animal management systems, which meet the demands for animal welfare, economical efficiency and especially the demand for product safety.

Animal Husbandry↗
PubMed2006

Transfer and metabolism of paralytic shellfish poisoning from scallop (Chlamys nobilis) to spiny lobster (Panulirus stimpsoni).

The transfer and transformation of paralytic shellfish poisoning (PSP) from scallop Chlamys nobilis to spiny lobster Panulirus stimpsoni were investigated in the present study. The results demonstrate that transfer and transformation of PSP toxins occurred when Panulirus stimpsoni were fed with toxic viscera of Chlamys nobilis, but depurated with non-toxic squids. Additionally, only the lobster hepatopancreas were found to contain PSP, and the toxin profiles were the same with those in the viscera of the scallop, including carbamate toxins (GTX(1-3)), N-sulfocarbamoyl toxins (C(1+2) and B(1)) and decarbamoyl toxins (dcGTX(2+3)). Unlike the lobster, the scallop contained more alpha than beta toxins. After being fed with toxic Chlamys nobili for 6 d, Panulirus stimpsoni selectively accumulated N-sulfocarbamoyl toxins with low toxicity. However, when they were depurated with non-toxic squid, N-sulfocarbamoyl toxins tended to transform into carbamate toxins with higher toxicity. The concentration of dcGTX(2+3) in Panulirus stimpsoni decreased significantly and wasn't detectable after depuration for 6 d, which was likely due to their initial low accumulation of toxins. These results reveal that PSP could be transferred and transformed in Crustaceans along the given food chain under the conditions of laboratory, but there are many questions remained to be solved, and the further studies should be carried out.

Animals↗
PubMed2002

The use of spatial modeling in an aquatic food web to estimate exposure and risk.

This paper quantitatively evaluates interactions among foraging behavior, habitat preferences, site characteristics and the spatial distribution of contaminants in estimating PCB exposure concentrations for winter flounder at a hypothetical open water dredged material disposal site in the coastal waters of New York and New Jersey (NY-NJ). The models implemented in this study include a spatial submodel to account for spatial and temporal characteristics of fish exposure and a probabilistic adaptation of the Gobas bioaccumulation model to account for temporal variation in concentrations of polychlorinated biphenyls (PCBs) in sediment and water. We estimated the geographic distribution of an offshore winter flounder subpopulation based on species biology, including such variables as foraging area, habitat size, disposal site size and migration characteristics. We incorporated these variables together with an estimate of differential attraction to a management site within a spatially explicit model to assess the range of expected PCB exposures to a winter flounder population. The output of this modeling effort, flounder PCB tissue concentrations, provides exposure point concentrations for estimates of human health risk through ingestion of locally caught flounder. The risks obtained for the spatially non-explicit case are as much as one order of magnitude higher than those obtained after incorporating spatial and temporal characteristics of winter flounder foraging and seasonal migration. Incorporating spatial and temporal variables in food chain models can help support sediment management decisions by providing a quantitative expression of the confidence in risk estimates.

Animals↗
PubMed2003

Assessment and analysis of industrial liquid waste and sludge disposal at unlined landfill sites in arid climate.

Municipal solid waste disposal sites in arid countries such as Kuwait receive various types of waste materials like sewage sludge, chemical waste and other debris. Large amounts of leachate are expected to be generated due to the improper disposal of industrial wastewater, sewage sludge and chemical wastes with municipal solid waste at landfill sites even though the rainwater is scarce. Almost 95% of all solid waste generated in Kuwait during the last 10 years was dumped in five unlined landfills. The sites accepting liquid waste consist of old sand quarries that do not follow any specific engineering guidelines. With the current practice, contamination of the ground water table is possible due to the close location of the water table beneath the bottom of the waste disposal sites. This study determined the percentage of industrial liquid waste and sludge of the total waste dumped at the landfill sites, analyzed the chemical characteristics of liquid waste stream and contaminated water at disposal sites, and finally evaluated the possible risk posed by the continuous dumping of such wastes at the unlined landfills. Statistical analysis has been performed on the disposal and characterization of industrial wastewater and sludge at five active landfill sites. The chemical analysis shows that all the industrial wastes and sludge have high concentrations of COD, suspended solids, and heavy metals. Results show that from 1993 to 2000, 5.14+/-1.13 million t of total wastes were disposed per year in all active landfill sites in Kuwait. The share of industrial liquid and sludge waste was 1.85+/-0.19 million t representing 37.22+/-6.85% of total waste disposed in all landfill sites. Such wastes contribute to landfill leachate which pollutes groundwater and may enter the food chain causing adverse health effects. Lined evaporation ponds are suggested as an economical and safe solution for industrial wastewater and sludge disposal in the arid climate of Kuwait.

Animals↗