The U.S. has about 15 million small recreational boats, 68,000 pleasure 

 yachts, and 87,000 commercial vessels. The total surface area needing 

 antifouling paint on the pleasure yachts and commercial vessels (excluding 

 small recreational boats) has been estimated to be approximately 440 

 million square feet. By comparison, the bottom hull area of the entire 

 U.S. Navy Fleet is approximately 11 million square feet, or 2.5 % of the 

 commercial vessels and private yachts. 



It should be noted that these estimates do not consider in the calculation 

 whether vessels are using low or high release rate paints, and that the 

 percentages are comparative percentage boat bottom for indicated vessel 

 types (which is the worst case example) . 



4.3 TOXICITY TO FRESHWATER AND MARINE ORGANISMS 



This Chapter has been prepared as an overview and summary of simple 

 bioassays and in-depth laboratory toxicity studies. In general, flow 

 through and static bioassay procedures generally follow a well documented 

 protocol, are laboratory oriented, and hence less expensive than field 

 studies. Consequently this is the area where the organotin toxicity 

 literature is richest, representing 38 percent of the toxicity papers 

 reviewed. However, much of this earlier bioassay data is suspect, many of 

 the studies were static (with one dosing) or static with daily renewal, or 

 nominal (without actual chemical testing of test container concentrations 

 - just calculated dosing) . The problems of concern here deal with 

 bioassays that were conducted at low ng/1 levels in which absorption to 

 test containers (walls, tubing, etc.) either greatly lowered actual 

 exposure concentrations or in some cases (daily repeated dosing) increased 

 exposure concentrations. The following sections present laboratory 

 determined toxicity data for a large group of organisms arranged in rough 

 phylogenetic order from bacteria to chordates. 



4.3.1 Fungi/Bacteria 



Tributyltin is used as a fungicide/bacteriacide to preserve wood exposed 

 to water. Tributyltin has also been used to inhibit the growth of odor 

 forming bacteria in clothing. Very little research has been done to 

 euclidate the bacteria species which are most susceptible to tributyltin. 

 Dooley and Kenis (1987) investigated Fhotobacterium phosphorem . a gram 

 negative marine bacteria and found that tributyltin had the highest 

 toxicity of all organotins. In general, they found that gram positive 

 bacteria were more sensitive to tributyltin than gram negative bacteria. 

 Pseudomonas aeruginosa , a gram positive bacteria, was found to debutylate 

 TBT at sublethal concentrations. In contrast marine strains of gram 

 negative bacteria have been shown to adsorb TBT to high concentrations on 

 their outer membranes without degradation of metabolic inhibitors 

 (G. Blair, personnel communication) . Another interesting observation 

 should be noted, researchers at NBS working with bacterial biofilms 

 acquired from immersed TBT painted panels in the marine environment found 

 that the bacteria in these biofilms were capable of uptaking TBT from 

 seawater to concentrations of greater than 350 ng/1 (Blair et al., 1987) . 



IV-11 



