Regulation of TBI release rates in organotin antifoulant paints are a step 

 in the right direction, however, we must not forget that the ambient 

 concentrations of TBT in harbors, estuaries and lakes are a product of at 

 least three key factors: (1) TBT paint release rates, (2) the total 

 wetted surface area of TBT painted boat bottoms in a water body, and (3) 

 flushing dynamics of a water body. The effectiveness of release rate 

 regulatory controls may be overridden by increases in boat density. 

 Control of only one of these factors may not prove to be sufficient. 



2.3.1.2 U.S. Environmental Protection Agency 



On January 8, 1986, the EPA announced the initiation of a Special Review 

 of all registered pesticide products containing TBT compounds used as 

 additives in antifouling paints applied to boat and ship hulls to inhibit 

 the growth of certain aquatic organisms. The decision to initiate the 

 Special Review was triggered when EPA determined that the pesticidal use 

 of these compounds resulted in TBT exposure to nontarget aquatic organisms 

 at concentrations resulting in acute and chronic toxicity, and when 

 applied as antifoulant paint, meet or exceed the risk criteria as 

 described in 40 CFR 162.11. A review of the information used to make 

 this decision was published in the "Tributyltin Support Document" (U.S. 

 EPA, 1985). 



In initiating the Special Review for TBT, the EPA identified significant 

 gaps in the technical information needed to support the registration of 

 TBT used in antifoulant paints. To obtain the information necessary to 

 assess the risks and benefits, EPA plans to issue a series of Data-Call-in 

 Notices (DCI's) to the registrants levying extensive data requirements to 

 continue their registration pursuant to EPA's authority under FIFRA. 

 Through the use of DCI's, EPA has requested data under several areas in- 

 cluding: (1) chemical release rate studies of TBT from antifoulant paints, 

 (2) product chemistry, (3) ecological effects, environmental fate, (4) 

 worker exposure, (5) quantitative usage, (6) efficacy of TBT products, (7) 

 specific toxicity tests with a wide range or organisms, and (8) specific 

 environmental monitoring data. For the release rate DCI, which was issued 

 July 1986, a protocol for testing and chemically measuring release rates 

 was developed in cooperation with the American Society for Testing and 

 Materials (ASTM) . The protocol provides information on daily release 

 rates and 6-^week cumulative release rates for different TBT paint pro- 

 ducts. Based on the rate of compliance with this DCI, about 300 of the 

 359 registrations for TBT were voluntarily cancelled within several 

 months. 



On October 1, 1987, EPA proposed certain restrictions on the sale and use 

 of TBT based antifouling paints. Specifically, the Agency proposed to: 



(1) Cancel all TBT antifouling paint registrations which either 

 exceed a short term cumulative release of 168 ug/cm 2 /first 

 14 days or exceed an average daily release rate of 

 4.0 ug/cm 2 /day. 



11-11 



