Organotin compounds (as total Sn)

Sn-org, Organiska tennföreningar, som Sn

 Organotin compounds make up a large group of substances with different chemical and physical properties. They can be divided into four main groups: mono-, di-, tri- and tetra-organotin compounds.¹

Uses

Mono- and diorganotin compounds are used as additives (stabilizers) in plastic production. They can also occur in sealants, adhesives and lacquers as catalysts in the binder. In addition, diorganotin compounds in plastics provide protection to long-term exposure to sunlight. Dibutyltin dilaurate is used in veterinary medicine to combat worm infections in birds. The use of triorganotin compounds in antifouling paints is regulated. These substances have also been used for wood impregnation and as preservatives. Tetraorganotin compounds are used as feedstock in production of other organotin compounds and are not present in chemical products.², ³

Sources and transportation pathways

Despite the ban of organotin compounds in antifouling paints, these may still be present in high levels in for example sediment around marinas. Their use as protectant in timber and paper products result in soil pollution around wood processing plants, such as sawmills and paper mills. Presently, the primary transportation pathway of these substances is through diffuse emissions, for example emissions from contaminated sediment to water and through the use of goods and products containing organotin compounds.⁴, ⁵

Effects on environment and health

Dibutyl organotin compounds are more toxic than dioctyl organotin compounds. Repeated exposure to either of these types of compounds can affect the immune system. Dibutyl organotin compounds can be corrosive or irritating to the skin and eyes, have disruptive effects on the reproductive system as well as have mutagenic effects. Mono- and dibutyl organotin compounds and dioctyl organotin compounds are classified as environmentally hazardous.⁶ Tri organotin compounds have severe health and environmental effects. They are toxic to humans if ingested, inhaled or by skin contact. They are also very toxic to aquatic organisms, on which they have long-term impact.⁷

International agreements and regulations

Organotin compounds are regulated by the EU Industrial Emissions Directive (2010/75/EU) and the EU Water Framework Directive (2000/60/EC). The presence of organotin compounds in products is for example regulated by the EU REACH regulation (EC 1907/2006) and the EU Toy Safety Directive (2009/48/EC). The use of organotin compounds in antifoulant paints for ships registered in the EU is banned as of July 2003.⁸ In 2008, the International Maritime Organization (IMO) adopted a binding convention banning all use of organotin compounds in antifouling paints.⁹ The UN Rotterdam convention regulates international trade of tributyl tin. The UN Protocol on PRTRs and the EU E-PRTR regulation regulate how data on emissions of organotin compounds is made available.

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¹ https://www.kemi.se/prio-start/kemikalier-i-praktiken/kemikaliegrupper/tennorganiska-foreningar
² https://webapps.kemi.se/flodesanalyser/AmnesInfo.aspx?amne=dibutyltennd
³ https://www.kemi.se/prio-start/kemikalier-i-praktiken/kemikaliegrupper/tennorganiska-foreningar
⁴ https://www.havet.nu/dokument/Havet2007-tbt.pdf
⁵ https://www.kemi.se/prio-start
⁶ https://www.kemi.se/prio-start/kemikalier-i-praktiken/kemikaliegrupper/tennorganiska-foreningar 
⁷ https://rib.msb.se/
⁸ http://eur-lex.europa.eu/legal-content/SV/TXT/PDF/?uri=CELEX:32003R0782&from=SV
⁹ http://www.imo.org/en/OurWork/Environment/Anti-foulingSystems/Pages/Default.aspx