spectroscopy (HDAA Protocol) . In the report by Desmatics Corp. (1984) on 

 release rates of immersed panels coated with antifouling paint 

 formulations under (conditions of controlled temperature and pH in 

 laboratory circulation tanks) there is no mention of the time periods of 

 exposure, or area from which the release rates were estimated. 



In general, these release rate studies found relatively consistent values 

 once past the 30 day initial stabilizing period when the vessel is first 

 returned to the water after being freshly painted, except for one 

 product. A paint formulation for which a range of values was reported 

 rather than a measure of cent r al tendency. In these studies, leach rates 

 were measured periodically and were observed to decrease with increasing 

 time of submergence of the panels with the exception of one data set. All 

 tests found high variability between panels, indicating that further 

 development of application and measurement methodologies was required. 

 Consequently EPA and the D01.45 Subcommittee of the American Society of 

 Testing and Materials (ASTM, August 1, 1986) have developed a standardized 

 TBT release rate protocol to st a ndardize the test conditions and 

 procedures. The protocol was published as an attachment to EPAs Data Call 

 in Notice (EPA, July 29, 1986) . The standard unit that has evolved for 

 estimating TBT release rates from antifouling paints is the ug/cm 2 /d 

 [micro gram of TBT release per cm 2 of wetted vessel bottom per day] . 



Schatzberg (1986) has investigated the release rates of different TBT 

 paint formulations for up to 42 months (see Table 4.4) and determined TBT 

 release rates for three different regions of the U.S. (i.e. Miami, 

 Annapolis, and Hawaii) , and found some regional differences, but they were 

 not significant. However, Hall et al. (1986) studying the effect 

 temperature on TBT release rates have reported a reduction in release 

 rates by approximately one-fourth for a temperature change from 25°C to 

 10°C. (see Table 4.5). 



4.2.2 Estimates of TBT Release Rates from Removed Spent Film and Waste 

 Residues 



One of the areas of concern as a source of TBT into the environment is the 

 grit from sandpaper or sand blasting to remove a partially spent or fouled 

 paint film. The grit contains some of the spent paint film and is thus a 

 source of TBT if washed into the marine environment or if disposed in land 

 fills. Schatzberg (1986) devised a soil lysimeter to investigate the rate 

 of leaching of TBT from grit containing spent paint film. 



IV-5 



