Leached from various sources, all the organotin compounds have an impact on natural aquatic
environments. In both freshwater and seawater ecosystems, they are dangerous in that they can have deleterious
effects on biocenoses already at low concentrations. All these compounds are known to be toxic at relatively low
levels, not only for aquatic invertebrates, but also for fish and laboratory mammals. Moving easily along the
trophic chains, organotins are also rapidly bioaccumulated in the tissues of non-target organisms living in the
water-sediment interface, causing severe, long-term toxic effects on local epifauna, with repercussions on
biodiversity and human health. Among toxic effects, genotoxicity and immunotoxicity are the most important
affecting the capacity for survival of animals. Genotoxicity appearing in the form of chromosomal aberrations,
increasing in frequency of micronuclei and induction of cytogenetic damage has recently been reported in
mammals, fish and aquatic invertebrates. Organotins interfere selectively with the immune system of vertebrates,
causing atrophy of the thymic cortex and lymphoid tissues with a consequent leucopoenia. Short-term in vitro
exposures of haemocytes of various vertebrate and invertebrate organisms reveal inhibition of phagocytosis,
cytolysis and/or apoptosis of leucocytes after inhibition of chemotaxis and respiratory burst, with resulting
depression of cell-mediated immune responses. These immunosuppressive effects are dose- and time-dependent,
and vary according to the number and type of organic moiety present. Both Ca2+-dependent and Ca2+-independent
mechanisms of action have been proposed. They are linked and synergistic in triggering the cascade of secondary
events that lead to toxic action.
Keywords: Genotoxicity - mutagenicity - immunotoxicity - lymphoid organ atrophy - apoptosis - calciumdependent
and calcium-independent immunosuppression - organotins.
