The Coating Conundrum
Incorporating Good Environmental Science in the Current Organotin Regulatory Debate. A draft Assembly Resolution (Annex 21/1 I) prepared by the Marine Environmental Protection Committee (MEPC) of International Maritime Organization (IMO) was recently approved by the 21st Meeting of the IMO General Assembly. In it, the General Assembly "agrees that the legally-binding instrument to be developed by the Marine Environment Protection Committee should ensure a global prohibition of the application of organotin compounds which act as biocides in antifouling systems on ships by 1 January 2003, and a complete prohibition of the presence of organotin compounds which act as biocides in antifouling systems on ships by 1 January 2008." Extensive discussions at the meeting took place in selecting the term should rather than shall which insinuates that the dates are impermanent, without specifically stating "tentative". Representatives from B1MCO, ICS, INTERCARGO, INTERTANKO. OCIMF and SIGTTO were concerned that the setting of firm dates could be interpreted as binding, and should be adhered to regardless of the outcome of the global legally-binding instrument under develop- ment (Annex 21/11/2). The Resolution requests a Conference in the 2000-2001 biennium to adopt a legal instrument (global convention) to implement a global ban on the use of organotin compounds. The present movement toward a global total ban suggests that the national approach has not been sufficient in some countries. Advocates of the global ban cite international findings of: (1) higher levels of TBT in surface waters of ports and open waters; (2) imposex still occurring and affecting larger number of snail species; (3) TBT bioaccumulation in selected fisheries; and (4) the availability of "comparable" alternatives (to TBT) with less environmental impact.
In the U.S. coastal zone, it is clear that federal and state regulations have had a significant impact on reducing TBT to well below the provisional water quality standards and in bivalve tissues. Current environmental and marine and estuarine water concentrations are well below predicted acute TBT toxicity levels. It should be noted that certain high use ports such as Galveston Texas, approximately 30 percent of the water measurements were above lOng/L. In the 1997 Navy Report to Congress, about 20 percent of all water samples (which sampled U.S. Navy Home Ports, even though the Navy does not use TBT) were at or above the provisional standard. However, less than five percent exceeded it in "ecologically significant" areas. Estimation of chronic toxicity effects using mean water TBT concentrations indicate that current levels would be protective of 95 percent of species. Analysis of allowable Daily Intake/Oral Reference Dose Values from market basket surveys and the NOAA National Status and Trends data suggest that there is no significant human health risk from consuming seafood contaminated with TBT. Most of the data that exceeded these values were from a few areas of high TBT input from ports, harbors and marinas (commercial shipping, shipyards and drydock facilities) and sites of previous contamination.
National regulations for TBT have proven to be the antithesis of the popular environmental cliche — "Think Globally and Act Locally." Legislative policies enacted by "regulated" countries to regulate the use of TBT to protect (their) local marine resources have subsequently had far reaching environmental and economic impacts which have in essence transferred TBT contamination to those countries least able to deal with it. Market forces are selective for cheap labor and cheap environments. "Unregulated" countries have unknowingly accepted the environmental and human health risks to gain the economic benefits from painting TBT on ships. Unfortunately, these countries may not have the funding or environmental expertise available for monitoring, research and technology development that is essential to use these modern high technology compounds. Therefore, they end up with more contamination because they do not have the neces- sary regulatory structure to prevent it. The regulatory discussion has lacked inclusive, comprehensive and public policy discussion of: (1) the economic benefits to shipowners from the use of TBT: (2) the "real" time period preferred for antifoulant protection on ships; (3) real drydock intervals (the three or five year debate); (4) the longlived, cost of environmental impacts in marinas, ports and harbors; (5) the harsh effects of market forces in nations without TBT regulations: (6) the lack of "acceptable and approved" alternatives in many nations; (7) the potential liability of shipowners and shipyards for TBT contamination in ports and waterways by the courts given the increased cost of dredging and disposal after the global ban; and (8) the recognition of the environmental benefits (reducing invasive species, fossil-fuel consumption and greenhouse gas generation) from using TBT. The regulatory debate is not attracting peer review by the scientific community. The environmental science in the documents submitted to MEPC and IMO need scientific peer review.
The organotin regulatory debate needs to balance environmental risk against benefits and effectiveness of available alternatives to TBT.
Today vessels can be painted with regulated or banned antifouling materials by boatyards in a country that does not have TBT regulations and subsequently travel in international and regulated national waters and bring the impact back to the country trying to prevent it. A severely biofouled ship can transport on its hull almost two million marine organisms, which is significant when compared to the numbers transported in ballast waters. This may become in the future a "show stopper" environmental problem as a major pathway of introducing marine exotic species (i.e., zebra mussel in the Great Lakes) because in today's better water quality in port and harbors, these species may survive and replace endemic ones. Warmer estuarine waters can induce spawning of the biofouling (or hitch hikers in the biofouling) from a vessel entering a port.
Alternatives to TBT are available, but not proven and accepted by regulatory bodies on a global basis. In the remaining 1,000 days before the proposed IMO ban, we need to implement an international independent process to expedite the IMO recommendation to evaluate and select alternatives to TBT. The added costs to shipowners if they to fail to find suitable alternatives to TBT and have to return to copper (which TBT replaced) have been estimated to range from $500 million to one billion dollars annually. These 1998 costs estimates are lower than the previous 1990 ones, because there are better Copper AF coatings, ablative systems and new selfpolishing co-polymers available today that have much improved performance.
However, many of the new coatings have cobiocide including organometals such as Zn- or Cu-Omadine (and others) which by company reports have extremely short half-lives, but have not been proven in the peer-review literature. Unfortunately, copper is becoming an environmental issue. It should be noted that effective September 1, 1999, Sweden and Holland have introduced bans on use of antifouling paints containing copper on pleasure boats.
Increasing the risk of shipowners to select alternatives that do not have longterm environmental or performance evaluations. The paint companies would like to reduce their risk by shifting the five-year antifouling warranty to three years. In a $500 million dollar annual antifouling marketplace, approximately 70 percent of the 27,000 vessels in global commerce today use TBT.
A third party, neutral, independent, international Marine Coatings Board has been proposed to complement national regulatory processes by providing international standardized scientific data and information to support the regulatory review and commercial selection processes. The cost of the Marine Coating Board to evaluate available alternatives has been estimated to be $10 million dollars per year or one to two percent of the estimated above annual direct costs to shipowners of not having comparable antifouling alternatives to TBT or only $1 dollar per day per vessel in global commerce.