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Tributyltin, a pesticide part of a family of organotin compounds, is banned in many countries for its detrimental effects on aquatic ecosystems. It has been banned by the International Maritime Organization.

TBT chemical properties

TBT compounds are organic derivatives of tin (Sn4+), where 3 carbon atoms covalently bonds the tin. The general formula for these compounds is (n-C4H9)3Sn-X. The X could be either an anion or a group linked covalently through an atoms other than Carbon and Hydrogen. The physicochemical properties the X. When introduced into an aquatic environment, TBT adheres to bed sediments because of its high specific gravity and low solubility. However, the adsorption of TBT to sediments is reversible, and varies with the pH of the water. TBT can be released from the sediments, and back into the aquatic environment.

2) Uses of Tributyltin Tributyltin has successfully been used in a variety of ways, such as industrial cooling systems as a slimicide and as a molluscicide for schisto-somiasis control. Most importantly, TBT has been most utilized as a anti-fouling biocide and as a wood preservative. Tributyltin is used as a biocide against aquatic species to avoid contamination of equipment in aquatic environments. These TBT paints extended the life of antifouling coatings, and ships were able to continue operations for a longer time frame. The paints ensured fuel efficiency and delayed costly ship repairs. . However, the TBT used on the ship hulls was found to leach into, and severely damage, the marine,brackish and freshwater environment.

Tributyltin is released into the environment through various processes. It is discharged to surface water from the manufacture of tributyltin oxide (TBTO) and TBT self-polishing co-polymer paints.

3) Repercussions

One of the most problematic aspects of TBT is the accumulation in sediments and its long half life. TBT often bonds to suspended material and is carried down to the sediments, where it can remain from 7 to 30 years. The leeching of TBT into aquatic environements has been shown to cause many deleterious effects on the development and survival of the animals. TBT is biomagnified up the marine predators' food net and has a harmful effect on many layers of the ecosystem, effecting invertebrates and vertebrates, including humans. Additionally, TBT can be introduced into non-aquatic ecosystems because dissolved TBT can evaporate into the air and be dispersed by rain. .

Invertebrates Chironomus riparius has been used as a model invertebrate to test the effects of TBT on development and reproduction at sublethal concentrations found in marine environments. It was found that only 0.05 ng ml− 1 range is enough to have developmental effects on larvae. 10-100ng l-1 was enough to seriously offset the female to male ratio in the population. At 10ng l-1 females were at 55.6% of the population and 85.7% at 100 ng l− 1. These results contributed to data showing that male invertebrates are more sensitive to TBT, and that overall sensitivity may depend on gender. The results support claims that TBT has severley reduced populations of benthic invertebrates.

Toxicity test performed on freshwater gastropod Lymnaea stagnalis revealed that 10 μg l− 1 could entirely inhibit egg development. At 1000 ng l− 1 there was low survival, with abnormal embryonic development leading to inhibition of shell growth. Also observed effects of TBT, are the deformation of shells in oysters and the masculinization of female marine sails (imposex). 

Vertebrates Oryzias latipes, medaka, has been used as a model vertebrate organism to test for effects of TBT at developmental stages of the embryo. It was observed that developmental rate was slowed by TBT in a concentration-related manner and that tail abnormalities. While invertebrates and fish mainly uptake the organic contaminants from the surroundings, the main way that higher mammals like birds and mammals are exposed to TBT, is through the diet. Studies have shown that Tributyltin links to obesity, by activating retinoid X receptors (RXRS) which enter the nuclei of cells and switch on genes that cause the growth of fat storage cells. TBT compounds have been described to interfere with glucocorticoid metabolism, by inhibiting the activity of the enzyme 11beta-hydroxysteroiddehydrogenase type 2, which converts cortisol to cortisone.

TBT has been shown to lead to immunosuppression in mammals such as sea-otters and dolphins.

There has been evidence of resistant bacteria to tributyltin, which can pose harmful effects for the future of aquatic species.

4) Political Response

Tributyltin compounds have been included in the Rotterdam Convention and have been banned by the International Convention on the Control of Harmful Anti-fouling Systems on Ships of the International Maritime Organization. Both Canada and the European Community have issued a ban on the use of TBT anti-fouling paints. .

many countries have taken steps to regulate TBT

The use of anti-fouling paints containing TBT has been banned. registered as pesticide limiting content in paint limiting sale Because TBT is the most effective antifouling agent discovered, it is frequently used in antifouling paint throughout the globe. The Environmental Protection Agency (EPA) recognized that using TBT-based antifouling agents over the standard copper formula could save the United States Navy 130 million dollars a year. . EPA policies

5) Tin Poisoning

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1) Treatment

2) Related Diseases