7. Conclusions
Tributyltins are harmful to many aquatic organisms at low concentrations. They are present in the environment primarily from human activity. They have been shown to impose male sexual characteristics on females of some marine gastropods and appear to have the potential to induce sex reversal in some marine fish. Estimated and measured concentrations of tributyltins in some locations in Canada are high enough to cause adverse effects in sensitive organisms. Furthermore, tributyltins meet the criteria for persistence and bioaccumulation according to the Persistence and Bioaccumulation Regulations of CEPA 1999. Tributyltins are present as a contaminant in commercial tetrabutyltin formulations and probably at much lower levels in dibutyltin formulations.
Tetrabutyltin can be harmful to sensitive aquatic organisms at low concentrations. There is further concern for this substance because it can break down to tributyltin by dealkylation and because commercial formulations of tetrabutyltin contain substantial amounts of tributyltin.
Monomethyltins, dimethyltins, monobutyltins, dibutyltins, monooctyltins and dioctyltins have the potential to harm aquatic organisms, and commercial formulations of monobutyltin and dibutyltin may contain tributyltin as a contaminant. However, it is believed that harmful concentrations of these substances would not be reached with industry-wide stewardship practices in place to limit their environmental releases. Releases from other uses of these substances as catalysts or in glass coatings are not expected to be significant, based on the much smaller quantities currently used in these industries.
Triphenyltins can be harmful to sensitive aquatic organisms at low concentrations, and they meet the criteria for persistence and bioaccumulation according to the Persistence and Bioaccumulation Regulations of CEPA 1999 (Government of Canada, 2000). They are present in the environment primarily from human activity. It is believed that these substances are no longer in use in Canada.
Tetraphenyltin has the potential to break down to the more hazardous triphenyltins. Commercial formulations of tetraphenyltin likely contain triphenyltin as a contaminant. It is believed that this substance is no longer in use in Canada.