Quantifying histopathological alterations in the hepatopancreas of the woodlouse Porcellio laevis (Isopoda) as a biomarker of cadmium exposure

The aims of this study were to determine and quantify the effects of cadmium sulfate on the histological structure of the hepatopancreas of Porcellio laevis, to determine the extent of the changes due to cadmium exposure, and to assess whether these effects could serve as biomarkers of cadmium exposure. For this purpose, different batches of P. laevis were exposed for 6 weeks to shredded leaves contaminated with a range of different concentrations of cadmium sulfate. Histological sections of different parts of the hepatopancreases revealed that the exposure changed the structure of the hepatopancreas. Quantification of this change in hepatopancreas structure (expressed as the percentage cellular area or PCA) showed that there was a dose-related change in certain areas of the hepatopancreas of woodlice exposed to cadmium sulfate in comparison to those areas of unexposed controls. This change was evident despite the fact that PCA also varied over the length of the hepatopancreas in the control specimens. This study showed that PCA can be a useful measure of change in the hepatopancreas resulting from toxic stress. Although it may not be practical for regular monitoring, it could serve as a useful research tool and general biomarker in studies of toxic stress in woodlice.