To protect public health, the European Commission established maximum levels of certain contaminants permitted in foodstuffs. The maximum amount of lead allowed in bivalve mollusc is 1.5 µg g−1 wet weight. In the Galician Rías, which are important areas of shellfish production in Spain, high levels of lead have been detected in the commercial bivalve Dosinia exoleta (Veneridae). Given the environmental and socio-economical problems this could represent, Pb concentration was tested in D. exoleta from two Rías, and the relation of lead accumulation with body size studied in detail. Implications for fisheries management are also discussed in this paper. Results showed a strong dependence of Pb accumulation on body size, with lead concentrations increasing exponentially with shell length. Larger animals presented a 5-fold increase in lead concentrations above the maximum permitted level. The size limit (length beyond which D. exoleta should not be extracted for commercial purposes) was initially established at 40 mm; but a more comprehensive geographical study of Pb concentrations in individuals from 35 to 40 mm long revealed that this size limit was not protective enough, and 35 mm is proposed as a safer limit.

Exposure of Chlorella vulgaris to elevated concentrations of copper, chromium, nickel and zinc led to intracellular accumulation of high concentrations of these metals. Concomitantly, accumulation of free proline occurred, depending on the concentration of metals in the external medium or in the cell. The greater the toxicity or accumulation of a metal, the greater the amount of intracellular proline in algal cells. However, higher concentrations of copper and chromium were inhibitory to proline accumulation by the test organism. The accumulation of proline was triggered within a few hours of metal treatment. Test metals also induced lipid peroxidation; copper was the most efficient inducer whereas zinc was the least. Pretreatment of C. vulgaris with proline counteracted metal-induced lipid peroxidation and potassium ion efflux. Thus the present work shows a protective effect of proline on metal toxicity through inhibition of lipid peroxidation.