Poisoning from lead gunshot: still a threat to wild waterbirds in Britain

Lead is a highly toxic metal known to be an important cause of morbidity and mortality in waterbirds and terrestrial birds worldwide. The risk to birds of poisoning from lead has resulted in the introduction of legislation in many countries, such as UK restrictions on the use of lead in angling weights and lead gunshot. In this study, we examined data on current and historical trends in lead poisoning in British waterbirds and related these to the introduction of legislation restricting the use of lead. Our results indicate that lead poisoning has continued to affect a wide range of British waterbirds long after legal restrictions were introduced. Elevated levels of lead (i.e. >20.0 μg/dL) were found in the blood of 34 % (n?=?285) of waterbirds tested at four sites in Britain during the 2010/2011 winter and accounted for the deaths of at least 10.6 % (n?=?2,365) of waterbirds recovered across Britain between 1971 and 2010 and 8.1 % (n?=?1,051) between 2000 and 2010, with lead gunshot being the most likely source of poisoning. The proportion of birds dying from lead poisoning in England did not vary significantly after the introduction of legislation, accounting for 13.7 % of non-infectious causes of death between 1971 and 1987 (n?=?204), 20.8 % (n?=?360) between 1988 and 1999 and 11.8 % (n?=?423) between 2000 and 2010, despite a significant change in lead-related mortality in mute swans found during the same time period, 25 % (n?=?12) between 1971 and 1987, 4.6 % (n?=?65) between 1988 and 1999 and 2 % (n?=?100) between 2000 and 2010. Existing legislation needs review and extension to ensure the delivery of international commitments and a broad-scale transition to the use of non-toxic shot and angling materials in all environments.     

The multidisciplinary approach to safety and toxicity assessment of microalgae-based food supplements following clinical cases of poisoning

Commercially available food supplements based on microalgae such as Spirulina (Cyanobacteria) or Chlorella (Chlorophyta) are becoming increasingly popular. Both are considered as non-toxic per se but the quality and safety of the final product depends on culturing and manufacturing conditions. This study presents two cases of human poisoning following the simultaneous use of Spirulina and Chlorella food products and a multidisciplinary approach to their evaluation: cytotoxic tests using human whole-blood in vitro and a suite of analytical screenings of over 30 elements, arsenic species and cyanotoxins: cylindrospermopsin (CYN), anatoxin-a (ANA) and three microcystin (MC) analogues. To compare metal content the Food Supplement Metal Index and Toxic Elements Contamination Index were also introduced. In all performed analyses two other commercial products were also investigated. Reported clinical symptoms of poisoning included the spreading of atopic dermatitis, nausea, dizziness, headache and fatigue. Extracts of supplements obtained from affected subjects were found to act pro-necrotically in human neutrophils, while tablets contained higher levels of several metals including Cd, Pb and Hg. All analyzed food supplements contained a significant content of Al. Neither CYN, ANA nor MC were present in any examined product. The quality of both Spirulina-based and Chlorella-based food supplements was very doubtful. The contamination problem of some commercially available microalgae-based supplements appears to be pleiotropic. The present study clearly indicates that such products should be subject to strict and routine monitoring before being registered and distributed as some of them may pose a distinct threat to human health.     

Epithelial transport parameters: an analysis of experimental strategies

A set of experiments was simulated on a computer version of the Koefoed-Johnsen & Ussing model for high-resistance epithelia. The results obtained were analysed according to procedures commonly applied to the analyses of experimental data and interpreted in terms of the model parameters. Although the computer model encodes a stoichiometry of 3:2 for Na-K exchange through the Na pump, the simulation of published experimental procedures yields different figures in almost every case. We show that ENa as originally defined by Ussing & Zerahn (Acta physiol. scand. 23, 110-127 (1951)) and as obtained from flux-ratio experiments has different values under different experimental conditions with unchanged system parameters and that it is distinct from ENa measured by other methods. We also show that unless the pump is saturated with internal Na an increase in the rate of pumping cannot cause a substantial increase in the rate of transepithelial Na transport.