Aristeo Renzoni

What are the toxicological effects of mercury in Arctic biota

This review critically evaluates the available mercury (Hg) data in Arctic marine biota and the Inuit population against toxicity threshold values. In particular marine top predators exhibit concentrations of mercury in their tissues and organs that are believed to exceed thresholds for biological effects. Species whose concentrations exceed threshold values include the polar bears (Ursus maritimus), beluga whale (Delphinapterus leucas), pilot whale (Globicephala melas), hooded seal (Cystophora cristata), a few seabird species, and landlocked Arctic char (Salvelinus alpinus). Toothed whales appear to be one of the most vulnerable groups, with high concentrations of mercury recorded in brain tissue with associated signs of neurochemical effects. Evidence of increasing concentrations in mercury in some biota in Arctic Canada and Greenland is therefore a concern with respect to ecosystem health.

Delayed evoked potentials in children exposed to methylmercury from seafood.

Methylmercury poisoning may cause constriction of visual fields and deafness, especially if exposure occurs prenatally. However, the risks associated with exposure from contaminated seafood is unclear. We examined 149 children attending first grade in a Madeiran fishing community. As maternal dietary habits were relatively unchanged, current maternal hair concentrations were used as indicator of the childs prenatal exposure to methylmercury (geometric average, 9.64 microg/g [48.2 nmol/g]). After adjustment for age and sex, the mean (+/-SD) latency of peak III of the brainstem auditory evoked potentials at 40 Hz was increased by 0.128+/-0.047 ms when maternal hair-mercury concentrations exceeded 10 microg/g (50 nmol/g) (p for association, 0.002), and the increase of the N145 pattern-reversal visual evoked potential latency at 15 minutes of arc was 3.16+/-1.57 ms (p for association, 0.002). No such relationships were seen with the childs own hair-mercury concentration, and other clinical examinations revealed no mercury-associated deficits. Neurophysiological evidence of adverse effects on brain function are relatively independent of confounders, and should be considered in the risk assessment of this seafood pollutant.

Heavy metals in organisms from the Northern Tyrrhenian sea

The concentrations of zinc, manganese, copper, cadmium, lead and mercury have been determined in soft tissues of four marine organisms (Mytilus galloprovincialis Lmk., Nephrops norvegicus L., Mullus barbatus L., Engraulis encrasicolus L.) collected seasonally from the winter of 1976 to the spring of 1980 in various areas of the Tyrrhenian Sea (western Mediterranean). In all four species levels of all metals, except mercury in all areas are alike while mercury levels vary and, furthermore, are higher than in specimens from other areas of the Mediterranean and also from other seas. The possible natural origin of the mercury from cinnabar (HgS) ore as well as the suitability of the four species as bioindicators is discussed.

Review: Porphyrins as Biomarkers for Hazard Assessment of Bird Populations: Destructive and Non-destructive Use

In this review the biochemical, metabolic and toxicological significance of porphyrins in birds is examined, and their use as biomarkers of exposure to xenobiotics and heavy metals is explored. Laboratory studies pinpointing the main classes of compounds that alter porphyrin profiles are described, as well as those which defined the resulting porphyrin profiles and target organs. Field studies in which the biomarker was validated on natural populations of several species of birds are then reviewed. We finally illustrate their potential as a non-destructive biomarker suitable for situations in which destructive sampling of natural populations must be avoided, suggesting the implementation of this approach.

Toxicity of three oils to bivalve gametes and larvae

Abstract Water soluble extracts of three crude oils, Kuwait, Nigerian and Prudhoe Bay have been tested using the sperm and eggs of two marine bivalves. Fertilization is depressed and developmental abnormalities sometimes appear after exposure to these toxins. The spermatozoa, in particular, are very sensitive to the water-soluble fractions of these oils. Nigerian crude is particularly toxic.

Influence of crude oil, derivatives and dispersants on larvae

Abstract Crude oils, oil derivatives and especially mixtures of oil and dispersant are harmful to larvae of some marine bivalve molluscs, but high concentrations are needed to cause death. Such high concentrations are unlikely to be reached in the open sea but are possible inshore or in estuaries which are the site of commercial shell-fisheries. The fact that spermatozoa are particularly sensitive to these compounds may have important consequences for the breeding success of contaminated bivalve populations.

Trace elements and chlorinated hydrocarbons in eggs of Pelecanus crispus, a world endangered bird species nesting at Lake Mikri Prespa, North-western Greece

Eggs of the Dalmatian pelican, Pelecanus crispus, collected from 1984 to 1986 at Lake Mikri Prespa, north-western Greece, contained residues of trace elements and PCBs at low concentrations, and of DDE at rather high concentrations. DDE is negatively related to eggshell thickness. Eggshell thickness was reduced by 12-20% in comparison with the pre-1947 (before DDT use) eggshell thickness. However, this decrease did not affect the reproductive success of this species. The main fish species eaten by the Dalmatian pelican at Lake Mikri Prespa were analyzed for pollutants. All the fish contained low concentrations of residues. The contribution of the diet while the birds are on the wintering grounds is unknown. Recommendations for a monitoring programme of pollutants in eggs of the Dalmatian pelican, a world-endangered species, are proposed.

Contaminants in the Environment

Since the Industrial Revolution (1760-1840), there has been a fight for the balance of economic growth and environmental protection in the United States. As the economy and job market grew due to the expansion of industrial jobs, there was little governmental regulation on the byproducts leaving these factories and energy production plants. After environmental disasters like the Cuyahoga River fire in Illinois (1952) and the release of Rachel Carson’s book Silent Spring (1962), the United States began creating laws and regulatory agencies to protect its natural resources from misuse (Land and Water Conservation Act 1965, The Wilderness Act 1964, Clean Air Act 1970, Clean Water Act 1972). As technologies continue to improve through the 21st century, society has been able to reduce the number of contaminants that enter our environments to meet these governmental regulations.

The distribution of mercury in the surficial sediments of the northern Tyrrhenian sea

Abstract Marine sediments are the ultimate recipient of mercury introduced into aquatic ecosystem either by man or by weathering. In the surficial sediments of the northern Tyrrhenian sea high concentrations of this metal were found in an area close to the effluent of a chlor-alkali plant and in the bays of La Spezia and Leghorn, which receive wastes from numerous industries and from port activities. The sediments of a much larger marine area off the mouths of the Ombrone, Albegna and Fiora rivers also contain high levels of Hg, part of which derives from the weathering of the rich cinnabar deposits of Mount Amiata and part from mining and processing the cinnabar.

Recalcitrant organochlorine compounds in captive bottlenose dolphins (Tursiops truncatus): Biomagnification or bioaccumulation?

Organochlorine residues were measured in the diet, blood, faeces and exhaled air of captive bottlenose dolphins (Tursiops truncatus) to evaluate the absorption efficiency from food and the eliminatory potential via faeces and exhaled air. Differences between air-breathing and water-breathing animals feeding on similar prey are briefly discussed. It is concluded that high concentrations of recalcitrant organochlorines currently found in marine mammals feeding on fish are essentially due to the lack of branchial elimination and not to their predator status.