Dermal and inhalable cobalt exposure-Uptake of cobalt for workers at Swedish hard metal plants.

PURPOSE: Cobalt exposure is known to cause adverse effects on health. A major use of cobalt is in the manufacture of hard metal. Exposure can lead to asthma, hard metal lung disease, contact allergy and increased risk of cancer. Cobalt is mainly absorbed from the pulmonary tract, however penetration through skin may occur. The relationships between exposure to inhalable cobalt in air and on skin and the uptake in blood and urine will be investigated, as well as the association between dermal symptoms and dermal exposure. METHODS: Cobalt exposure in 71 workers in hard metal production facilities was measured as inhalable cobalt in the breathing zone and cobalt found on skin with acid wash. Uptake of cobalt was determined with concentrations in blood and urine. Correlations between exposure and uptake were analysed. RESULTS: Inhalable cobalt in air and cobalt in blood and urine showed rank correlations with coefficients 0.40 and 0.25. Cobalt on skin and uptake in blood and urine presented correlation coefficients of 0.36 and 0.17. Multiple linear regression of cobalt in air and on skin with cobalt in blood showed regression coefficients with cobalt in blood (ß = 203 p < 0.0010, and ß = 0.010, p = 0.0040) and with cobalt in urine (ß = 5779, p = 0.0010, and ß = 0.10, p = 0.60). CONCLUSIONS: Our data presents statistically significant correlations between exposure to cobalt in air with uptake of cobalt in blood and urine. Cobalt on skin was statistically significant with cobalt in blood but not with urine.

Behavioral type, in interaction with body size, affects the recapture rate of brown trout Salmo trutta juveniles in their nursery stream.

Movement activity levels of wild animals often differ consistently among individuals, reflecting different behavioral types. Previous studies have shown that laboratory-scored activity can predict several ecologically relevant characteristics. In an experiment on wild brown trout Salmo trutta, spanning from June to October, we investigated how spring swimming activity, measured in a standardized laboratory test, related to relative recapture probability in autumn. Based on laboratory activity scores, individuals clustered into 2 groups, which showed contrasting patterns in the size-dependency of their recapture probability. Size had a slightly positive effect on recapture probability for passive fish but a clear negative effect on active fish. Our results show that the population structure in a cohort, in terms of relative proportions of behavioral types in different size classes, can vary over time. The results of this study could depend on either selective mortality or migration. However, selective disappearance of individuals with specific phenotypes, regardless of the mechanism, will have implications for trout population management, such as stocking efficiency of hatchery fish with high growth rates or maintenance of fishways past migration barriers.