Toxicological effect of endocrine disrupting insecticide (deltamethrin) on enzymatical, haematological and histopathological changes in the freshwater iridescent shark, Pangasius hypothalamus

Pyrethroids are synthetic derivatives of natural pyrethrins extracted from Chrysanthemum cinerariaefolium. They are 2250 times more toxic to insects than to vertebrates due to insects’ smaller size, lower body temperature and more sensitive sodium channels. In particular, three pyrethroid compounds, namely deltamethrin, permethrin, and alpha-cypermethrin, are commonly used as insecticides and are recommended for in-home insect control because they are considered to be relatively non-toxic to humans in all stages of life. However, recent data show that they are not completely harmless to human health as they may enter the body through skin contact, by inhalation and food or water, and absorption level depending on the type of food. Permethrin seems to have an adverse effect on fertility, the immune system, cardiovascular and hepatic metabolism as well as enzymatic activity. Deltamethrin induces inflammation, nephro- and hepatotoxicity and influences the activity of antioxidant enzymes in tissues. Alpha-cypermethrin may impair immunity and act to increase glucose and lipid levels in blood. The aim of the review is to provide comprehensive information on potential hazards associated to human exposure to deltamethrin, permethrin and alpha-cypermethrin. The results of presented studies prove that the insecticides must be used with great caution.

Histological changes in gills, kidney and liver were used to evaluate the health of the Neotropical fish species Prochilodus lineatus, subjected to in situ tests for 7 days in a disturbed urban stream and in a reference site, during winter and summer. In fish caged in the urban stream the most common lesions were epithelial lifting, hyperplasia and hypertrophy of the respiratory epithelium, lamellar fusion, and aneurysms in the gills; enlargement of the glomerulus, reduction of Bowman's space, occlusion of the tubular lumen, cloudy swelling and hyaline droplet degeneration in the kidneys; hepatocytes with hypertrophy, cytoplasmic and nuclear degeneration, melanomacrophage aggregates, bile stagnation and one case of focal necrosis in the liver. The lesions were comparatively most severe in the liver. Histopathology showed to be a very suitable biomarker for use in conjugation with the in situ test, because the seasonal variation did not interfere in the results and it was possible to differentiate the sites in the urban stream from the reference site.