3.1 INTKCCUCITCN 



This Chapter summarizes information on registrations and use patterns of 

 organotin antifouling paints. Also included in this Chapter are sections 

 which review paint application and removal practices as they serve to 

 introduce organotin compounds into the marine environment. Antifouling 

 paint formulations vary in the percent by weight of organotin compounds 

 employed and in the manner or rate in which these compounds are made 

 available (or released) to the environment. The variation in release 

 rates of different paints is under extensive study by paint manufactures, 

 the U.S. Navy, and the Environmental Protection Agency. Since EPA's Data 

 Call-in Notice, nearly 80% of previous paint registrations have been 

 voluntarily cancelled. Most of these have been free association or high 

 release rate formulations. Therefore, past paint usage patterns may not 

 give an accurate picture of future organotin introductions to the 

 environment from paint formulations which remain registered. 



3.2 WORITWIDE PRODUCTION AND USE 



Zuckerman et al. (1978) estimated the annual world consumption of tin to 

 be 84 x 10 6 kg; of this, 4.5 x 10 6 kg was in the form of organotin 

 biocides (see Table 3.1) . Estimates by Davies and Smith (1982) , which are 

 some what higher than Zuckerman's suggest that the use of organotin 

 compounds in industry had risen to (30-35) x 10 6 kg by 1980. Of current 

 production, about two-thirds is used for stabilization of PVC plastics and 

 7.8% for biocides, see Figure 3.1. 



3.3 NATIONWIDE PRODUCTION AND USE 



Dibutyltin bisfisooctyl mercaptoacetate) dominates the market, constitu- 

 ting 33 x 10 6 of the 65 xlO 6 kg of alkyltin cxmpounds produced between 

 1965 and 1976. This is because the major area of utilization (70% of to- 

 tal annual production) is as a heat stabilizer for rigid and semi-rigid 

 PVC. Dioctyltin compounds are used only in PVC in contact with food; 

 dibutyltin dilaurate is used as a catalyst in foam and elastomer 

 production and as a poultry anthelmintic; and bis (tributyltin) oxide and 

 tributyltin fluoride are used as biocides. Table 3.2 summarizes the 

 number of organotin antifoulant paint registrants and the number of their 

 products on the market at the time of the EPA Data Call In Notice 

 (PD/1— July, 1987) . When EPA published its PD/1, it was estimated in the 

 document that in the U.S., that 250,000 pounds (113,600 kg) to 300,000 

 pounds (114,000 kg) of TOT compounds were used in antifouling paints 

 annually. However, information supplied by registrants in response to the 

 Dd revealed that the actual U.S. annual use of TOT in antifouling paints 

 was approximately 624,000 gallons of paint with over one million pounds 

 (450,000 kg) of TBI. Commercial vessels are the major users of TOT 

 antifouling paints although 33 % is applied to recreational vessels (EPA, 

 PD 2/3, 1987). Between 34,000 and 45,000 kilograms of the total is in the 

 form of tributyltin-bis-oxide. The U.S. Navy's proposed fleet-wide (600 

 ships) use of TOT paints would increase the U.S. annual usage an 

 additional 27,000 to 41,000 kilograms. 



III-l 



