Bioavailability, accumulation and effects of heavy metals in sediments with special reference to United Kingdom estuaries: a review

Nano-silver is used in an increasing number of products. Some of the applications have resulted in the concern of governments and the public, since little is known about the potential risks of nano-silver. In this review, an inventory is made to identify knowledge gaps that have to be filled before risks for both man and the environment can be assessed as reliable as for ‘non-nanosized’ chemicals. It is hypothesized that the toxic effects of nano-silver are due to a combination of the specific properties of silver nanoparticles and the generation of ions from them. The main topic for future research is validation of our ‘0-hypothesis’ that toxic effects of nano-silver are proportional to the activity of free silver ions released by the nanoparticles. Furthermore, it must be determined whether – or to what extent – nano-silver particles will enter the body. The outcomes of these tests will determine the requirements for further toxicity testing.

Nano-silver – a review of available data and knowledge gaps in human and environmental risk assessment

SUMMARY Available literature on the ecological and toxicological aspects of mercury (Hg) in the environment, with special reference to fish and wildlife resources, is reviewed and summarized. Subdivisions include sources, chemical properties, background concentrations, acute and chronic toxicity, sublethal effects, and proposed criteria to protect sensitive resources. Mercury has been used by man for at least 2,300 years, most recently as a fungicide in agriculture, in the manufacture of chlorine and sodium hydroxide, as a slime control agent in the pulp and paper industry, in the production of plastics and electrical apparatus, and in mining and smelting operations. Mercury burdens in some environmental compartments are estimated to have increased up to 5X precultural levels, primarily as a result of man's activities. The construction of artificial reservoirs, for example, which releases Hg from flooded soils, has contributed to the observed elevation of Hg concentrations in fish tissues from these localities. Elevated levels of Hg in living organisms in Hg-contaminated areas may persist for as long as 100 years after the source of pollution has been discontinued. One major consequence of increased mercury use, coupled with careless waste disposal practices, has been a sharp increase in the number of epidemics of fatal mercury poisonings in humans, wildlife, and aquatic organisms. Most authorities agree on six points: (1) mercury and its compounds have no known biological function, and the presence of the metal in the cells of living organisms is undesirable and potentially hazardous; (2) forms of mercury with relatively low toxicity can be transformed into forms of very high toxicity, such as methylmercury, through biological and other processes; (3) mercury can be bioconcentrated in organisms and biomagnified through food chains; (4) mercury is a mutagen, teratogen, and carcinogen, and causes embryocidal, cytochemical, and histopathological effects; (5) some species of fish and wildlife contain high concentrations of Hg that are not attributable to human activities; (6) anthropogenic use of Hg should be curtailed, as the difference between tolerable natural background levels of Hg and harmful effects in the environment is exceptionally small. Concentrations of total Hg lethal to sensitive, representative, nonhuman species range from 0.1 to 2.0 ug/l (ppb) of medium for aquatic organisms; from 2,200 to 31,000 ug/kg body weight (acute oral) and 4,000 to 40,000 ug/kg (dietary) for birds; and from 100 to 500 ug/kg body weight (daily dose) and 1,000 to 5,000 ug/kg diet for mammals. Organomercury compounds, especially methylmercury, …

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Mercury Hazards to Fish, Wildlife, and Invertebrates: A Synoptic Review

A eview of the literature revealed that bioaccumulation of silver in soil is rather low, even if the soil is amended with silver-containing sewage sludge. Plants grown on tailings of silver mines were found to have silver primarily in the root systems. In marine and freshwater systems, the highest reported bioconcentration factors (BCFs) were observed in algae (>105), probably because of adsorption of the dissolved silver (<0.45 μm fraction) to the cell surface. In herbivorous organisms (e.g., zooplankton and bivalves), the BCF was lower by about two orders of magnitude. Low amounts of silver were assimilated from food with no substantial biomagnification. In carnivores (e.g., fish), the BCF was also lower by one order of magnitude with no indication of biomagnification. Toxicity of silver occurs mainly in the aqueous phase and depends on the concentration of active, free Ag+ ions. Accordingly, many processes and water characteristics reduce silver toxicity by stopping the formation of free Ag+, binding Ag+, or preventing binding of Ag+ to the reactive surfaces of organisms. The solubility of a silver compound, and the presence of complexing agents (e.g., thiosulfate or chloride), dissolved organic carbon, and competing ions are important. In soil, sewage sludge, and sediments, in which silver sulfide predominates, the toxicity of silver, even at high total concentrations, is very low. The highly soluble silver thiosulfate complex has low toxicity, which can be attributed to the silver complexed by thiosulfate. Silver nitrate is one of the most toxic silver compounds. The toxic potential of silver chloride complexes in seawater is and will be an important issue for investigation. Aquatic chronic tests, long-term tests, and tests including sensitive life stages show lower toxicity thresholds (˜1 μg Ag+/L). The organisms viewed as most sensitive to silver are small aquatic invertebrates, particularly embryonic and larval stages.

https://setac.onlinelibrary.wiley.com/doi/epdf/10.1002/etc.5620180112

Bioaccumulation and toxicity of silver compounds: A review

Estuaries exhibit a wide array of human impacts that can compromise their ecological integrity, because of rapid population growth and uncontrolled development in many coastal regions worldwide. Long-term environmental problems plaguing estuaries require remedial actions to improve the viability and health of these valuable coastal systems. Detailed examination of the effects of pollution inputs, the loss and alteration of estuarine habitat, and the role of other anthropogenic stress indicates that water quality in estuaries, particularly urbanized systems, is often compromised by the overloading of nutrients and organic matter, the influx of pathogens, and the accumulation of chemical contaminants. In addition, the destruction of fringing wetlands and the loss and alteration of estuarine habitats usually degrade biotic communities. Estuaries are characterized by high population densities of microbes, plankton, benthic flora and fauna, and nekton; however, these organisms tend to be highly vulnerable to human activities in coastal watersheds and adjoining embayments. Trends suggest that by 2025 estuaries will be most significantly impacted by habitat loss and alteration associated with a burgeoning coastal population, which is expected to approach six billion people. Habitat destruction has far reaching ecological consequences, modifying the structure, function, and controls of estuarine ecosystems and contributing to the decline of biodiversity. Other anticipated high priority problems are excessive nutrient and sewage inputs to estuaries, principally from land-based sources. These inputs will lead to the greater incidence of eutrophication as well as hypoxia and anoxia. During the next 25 years, overfishing is expected to become a more pervasive and significant anthropogenic factor, also capable of mediating global-scale change to estuaries. Chemical contaminants, notably synthetic organic compounds, will remain a serious problem, especially in heavily industrialized areas. Freshwater diversions appear to be an emerging global problem as the expanding coastal population places greater demands on limited freshwater supplies for agricultural, domestic, and industrial needs. Altered freshwater flows could significantly affect nutrient loads, biotic community structure, and the trophodynamics of estuarine systems. Ecological impacts that will be less threatening, but still damaging, are those caused by introduced species, sea level rise, coastal subsidence, and debris/litter. Although all of these disturbances can alter habitats and contribute to shifts in the composition of estuarine biotic communities, the overall effect will be partial changes to these ecosystem components. Several strategies may mitigate future impacts.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0376892902000061

Environmental threats and environmental future of estuaries

: Selective review and synthesis of the technical literature on copper and copper salts in the environment and their effects primarily on fishes, birds, mammals, terrestrial and aquatic invertebrates, and other natural resources. The subtopics include copper sources and uses; chemical and biochemical properties; concentrations of copper in field collections of abiotic materials and living organisms; effects of copper deficiency; lethal and sublethal effects on terrestrial plants and invertebrates, aquzatic organisms, birds, and mammals, including effects on survival, growth, reproduction, behavior, metabolism, carcinogenicity, mutagenicity, and teratogenicity; proposed criteria for the protection of human health and sensitive natural resources; and recommendations for additional research.

Copper Hazards to Fish, Wildlife, and Invertebrates : A Synoptic Review

: Interest in the toxicity of tin compounds dates to the early 1800's when investigators demonstrated that inorganic tin compounds produced muscular weakness, loss of pain sensation, and immobility in dogs (Reiter and Ruppert 1984; Idemudia and McMillan 198Gb). In man, organotins can be assimilated by inhalation, absorption through the skin, and from food and drinking water (Zuckerman et al. 1978). The first documented case of organotin poisoning of humans was in 1880 when workers complained of headaches, general weakness, nausea, and diarrhea after exposure to triethyltin acetate vapors (Reiter and Ruppert 1984). Renewed interest in the toxicity of organotin compounds resulted from a medical tragedy in France in 1954. Stalinon, a proprietary compound of diethyltin diiodide plus linoic acid used to treat furuncles and other skin infections, caused 217 poisonings and 111 deaths (Piver 1973; Duncan 1980; Idemudia and McMillan 198Gb). The identified toxic components in Stalinon were triethyltin contaminants; victims received a total dose of 3 grams over a 6- to 8-week period. Symptoms included constant severe headache, rapid weight loss, vomiting, urine retention, vertigo, hypothermia, abdominal pain, and visual and psychic disturbances. Some of the more severely affected patients had convulsions. Death usually occurred in coma or from respiratory or cardiac failure. In survivors, headaches and diminished visual acuity remained for at least 4 years.

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Tin Hazards to Fish, Wildlife, and Invertebrates: A Synoptic Review.

VOLUME 1 - Metals Cadmium Chromium Copper Lead Mercury Nickel Silver Tin Zinc VOLUME 2 - Organics Acrolein Atrazine Carbofluran Chlordane Chlorpyrifos Cyanide Diazinon Diflubenzuron Dioxins Famphur Fenvalerate Mirex Paraquat Pentachlorophenol Polychlorinated Biphenyls Polycyclic Aromatic Hydrocarbons Sodium Monofluoroacetate Toxaphane VOLUME 3 - Metaloids, Radiation, Index Arsenic Boron Molybdenum Selenium Radiation Index

Handbook of chemical risk assessment : health hazards to humans, plants, and animals

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Ronald Eisler

Papers

Mercury Hazards to Fish, Wildlife, and Invertebrates: A Synoptic Review

Copper Hazards to Fish, Wildlife, and Invertebrates : A Synoptic Review

Tin Hazards to Fish, Wildlife, and Invertebrates: A Synoptic Review.

Handbook of chemical risk assessment : health hazards to humans, plants, and animals

Arsenic Hazards to Fish, Wildlife, and Invertebrates: A Synoptic Review