The use of feathers in monitoring bioaccumulation of metals and metalloids in the South African endangered African grass-owl (Tyto capensis).

Few studies have quantified metals in South African species and no published data on residues specifically in South African owl feathers exist. Tyto capensis is listed as vulnerable within South Africa, making it preferable to use a non-invasive technique to determine metal bioaccumulation for this species. Comparisons are made with the cosmopolitan T. alba to determine whether this species could be used as a surrogate. Concentrations of various metals were thus determined in feathers of the two species and compared with liver and muscle samples. Samples were taken from 119 owls collected as road kill along a national road. A comparison of concentrations in feathers revealed similarly higher concentrations of aluminium, antimony, lead, nickel, and strontium, whereas concentrations of chromium, copper, iron, manganese, selenium, titanium and zinc were similarly higher in internal tissues for both species. Metal concentrations of owls were comparable to those reported in literature and below toxic levels, suggesting that these metals were not likely to impact the owls. Further regressions between feathers and corresponding livers were examined to determine if feathers were indicative of internal metal burdens. Significant positive relationships were found for aluminium, copper, lead, nickel and vanadium in T. alba and nickel, manganese and vanadium in T. capensis. Preliminary results support the feasibility of using feathers as non-destructive indicators of environmental contamination in T. capensis although caution needs to be taken when interpreting the results.

Human risk assessment of heavy metals: principles and applications.

Humans are exposed to a number of "heavy metals" such as cadmium, mercury and its organic form methylmercury, uranium, lead, and other metals as wel as metalloids, such as arsenic, in the environment, workplace, food, and water supply. Exposure to these metals may result in adverse health effects, and national and international health agencies have methodologies to set health-based guidance values with the aim to protect the human population. This chapter introduces the general principles of chemical risk assessment, the common four steps of chemical risk assessment: hazard identification, hazard characterization, exposure assessment, risk characterization, and toxicokinetic and toxicity aspects. Finally, the risk assessments performed by international health agencies such as the World Health Organisation, the Environmental Protection Agency of the United States, and the European Food Safety Authority are reviewed for cadmium, lead, mercury, uranium, and arsenic.