Triphenyltin compounds

What type of substance is it?

Triphenyltin compounds are man-made chemicals containing tin. They are used as pesticides (fungicides) and biocides in marine antifouling paints, wood preservatives and in some agricultural crop applications. These compounds can be toxic to wildlife, especially fish, molluscs and other water dwelling organisms and have been found to build up in the tissues of living organisms.

How is it released?

Release is primarily from their use as pesticides/antifouling agents and potentially in their manufacture, transport and storage. There are no natural sources.

Detailed information

Scientific name:

Triphenyltin hydride, C18H16Sn; triphenyltin fluoride, C18H15SnF; triphenyltin hydroxide, C18H16SnO

Other names:

TPT; Triphenylstannane; triphenylstannyl hydride; triphenyltin hydride; triphenyltin fluoride; triphenyltin hydroxide; triphenyltin acetate

CAS Number:

900-95-8 (acetate); 639-58-7 (chloride); 379-52-2 (fluoride); 76-87-9 (hydroxide)

The only known practical alternatives to triphenyltin and the similar tributyltin compounds known for their use in antifouling paints are cuprous oxide paints. These are less effective and cannot be used on vessels with aluminium hulls because the copper causes rapid pitting and perforation when used on an aluminium hull. Newer antifouling paints contain tributyltin bound in a resin that slowly degrades, releasing the tributyltin in a controlled, steady rate and can last for several years (depending on the thickness of the original application). Other advantages claimed for this 'self polishing' coating are constant reactivation of antifouling properties and even a reduction of fuel costs over and above the savings resulting from a clean hull by providing a surface that becomes smoother with time.

Major uses are as underwater antifouling agents (protect from algal and barnacle growths, etc.) in boat/ship paints, quays, buoys, crab pots and fish nets, and as fungicides in wood preservatives and on some agricultural crops. Triphenyltin hydroxide is also used as a stabiliser in plastics, such as PVC.

Triphenyltin compounds are generally colourless/white solids or liquids that are usually practically insoluble.

Where is it released?

Releases to the environment occur primarily by gradual release from their use in marine antifouling paints, as fungicides in wood preservatives, crop protection and potentially from their manufacture, transport and storage. High levels of TPT compounds have been found in water, sediment and biota near to pleasure boating activity, especially in or near marinas, boat yards and dry docks, where boat numbers are highest and paint is applied or removed. There are no natural sources of release to the environment.

Local environmental effects

Triphenyltin very toxic to fish and other marine life and contact with other wildlife should also be avoided. There is evidence for marine contamination and tributyltin compounds bioaccumulate in organisms. Triphenyltin compounds are not very soluble in water but tend to bind well to particles/sediment where they can persist for some time. High levels of triphenyltin and the similar tributyltin compounds have been found in water, sediment and biota near to pleasure boating activity, especially in or near marinas, boat yards and dry docks. Contact with land animals is likely to be largely limited to their use in wood preservatives.

Global environmental effects

No significant global impacts are considered likely.

Possible health concerns

Excessive exposure to some triphenyltin compounds may affect the eye, immune system, lung, reproductive system, skin, throat and the unborn child, and may cause cancer. The Environment Agency aims to ensure that environmental exposures are too low to harm human health.

Legislation

Why was this substance selected for the Pollution Inventory?

This substance is no longer reported to the Pollution Inventory. Over the period 1998-2001 reports were required but it was not reported in significant quantities.

Standard risk phrases for the pure substance

The standard risk phrases provided here are generally those used by suppliers of chemicals to describe substances - for example on packaging materials. The most important source of these phrases are the CHIP Regulations - Chemicals (Hazard Information and Packaging for Supply) - provided by the Health and Safety Executive. Some substances do not have CHIP risk phrases and in these circumstances we have used other risk phrases, the sources of which are indicated.

No risk phrases available for this substance

Controlling legislation and international agreements

Many countries have restricted the use of triphenyltin and tributyltin antifouling paints as a result of effects on shellfish. In the UK its use in antifouling paints is restricted to boats above 25m length. The UK legislation controlling its release are the Surface Waters (Dangerous Substances) (Classification) Regulations, 1997 (SI 1997/2560) and Pollution Prevention and Control Regulations. It is a UK 'Red list' pollutant, the presence of which in the environment is of particular concern. The sale and supply of antifouling paint products in the UK is also limited to those below certain concentrations under the 1986 Pesticides Regulations - The Control of Pesticides Regulations (as amended) (COPR), which was made under the primary UK legislation controlling pesticides - the Food and Environmental Protection Act (FEPA 1985 - as amended). The European legislation also relevant to its release is EC Directive 76/464: ?Pollution of the aquatic environment by dangerous substances? (plus daughter directives). TPT compounds are also listed as substances for priority action on their control under the OSPAR and Helsinki Conventions.

These factsheets have been compiled to provide users with information on the Pollution Inventory substances and represent our best efforts to summarise a large number of disparate and sometimes conflicting data sources. We emphasise that this information describes potential hazards rather than actual effects and that the Environment Agency seeks to regulate releases to minimise emissions and hence any risk of detrimental effects occurring.