Archive: California copper legislation: From ban to reduced leaching rates
After several years, California legislation targeting copper-based antifouling coatings has been modified from banning copper to the determination of leaching rates.
"The people of the State of California do enact as follows:
SECTION 1. No later than February 1, 2014, the Department of Pesticide Regulation shall determine a leach rate for copper-based antifouling paint used on recreational vessels and make recommendations for appropriate mitigation measures that may be implemented to address the protection of aquatic environments from the effects of exposure to that paint if it is registered as a pesticide” (Assembly Bill No. 425). The Assembly approved the bill Sept. 6 on a unanimous 73-0 vote to concur with an amendment to add a co-author taken in the Senate. The bill passed the Senate Environmental Quality Committee by a unanimous vote on June 20. Gov. Jerry Brown has until Oct. 13 to sign or veto the bill.
Scientific studies had targeted the use of copper in antifouling paints as contributing to adverse water conditions in some California marinas irrespective of other relevant sources like commercial ships or the adjacent US-Navy base. Currently, California law requires every manufacturer, importer and dealer of any pesticide to obtain a certificate of registration from the Department of Pesticide Registration (DPR) before the pesticide is offered for sale. As previously reported, in the Port of San Diego, all eight marina basins have been found to have an overload of copper and the state has ordered at least one, Shelter Island Yacht Basin, to reduce its copper loading by 76 percent by the year 2028. The US-American Coating Association (ACA) and its Antifouling Workgroup (AFWG), strongly advocated against the bill banning copper for recreational boats. The proposed measure mandated the outright ban of these coatings for recreational vessels after 2019, if the low-leach-rate coatings did not appear to be reducing copper in marinas with Total Maximum Daily Loads (TMDL) for copper that must be met by 2022.
The legislation’s sponsor dropped the bill after ACA submitted a letter underscoring new evidence that could change how copper-impaired waters are defined. Specifically, the letter referenced EPA’s review of the Biotic Ligand Model (BLM) for marine waters and DPR’s reevaluation of copper as an approved biocide in antifouling paints. ACA believes that EPA’s BLM may well show that the copper threat to water bodies has been overstated. The BLM is a much more recent method of calculating metal toxicity, using 10 water chemistry parameters. As mentioned earlier, the BML discriminates between available copper cations and non-available chelated copper compounds. As in waters e.g. with high content of suspended matter available copper ions can rapidly be bound to organic particles and be inactivated. Thus, the total load of copper in a given water body applying the BML shall be regarded on this background.
Copper and cleaning
An interesting point in this debate is the aspect introduced by ACA and its AFWG that antifouling paints release copper at a controlled rate and that excessive underwater hull cleaning practices contribute a high percentage of the release of copper into marinas. Further, modern antifouling copper-based coatings are designed to be effective without frequent cleaning, and cleaning schedules should follow manufacturers’ recommendations.
In March 2011, members of the AFWG and other affected registrants received a data request from the California Department of Pesticides Regulation (DPR), “Clarification of Leach Rate Determination, Notice of Additional Data Requirements and Meeting Regarding the Reevaluation of Copper Based Anti-fouling Paint Pesticides.” The data requirement called for, among other things, a protocol to accurately determine the impact of underwater hull cleaning on overall copper release from antifouling paint.
In June 2012, ACA’s AFWG developed and submitted the “In Water Hull Cleaning and Passive Leaching Study Protocol” to DPR and coordinated the funding of the study among copper suppliers and copper-based antifouling registrants in California. The purpose of this study is to ascertain the effect of underwater hull cleaning methods on various types of antifouling paints and to quantify the amount of copper that enters the water column from passive leaching. The study will test the most contemporary antifouling paints used in Shelter Island yacht basin. This includes ablative coatings, which were not properly addressed in prior studies. ACA contracted with the Space and Naval Warfare Systems Command (SPAWAR), a subgroup of the U.S. Navy, and Scripps Institution of Oceanography and appointed a study overseer to visit the site and ensure adherence to the protocol. The study commenced on Aug. 13, 2012, and a draft report was issued to DPR on April 1, 2013. The final report will be published in the Journal of Biofouling and DPR will use the results of the study to inform the development of mitigation strategies."
As reported in previous news communications the cleaning of hulls on biocidal antifouling coating is getting common practice in recreational boats as well as commercial vessels. Paint manufacturers are not amused but tolerate this practice. It is assumed that depending on the cleaning technique applied at each cleaning activity 30 – 50 µm of the paint film will be removed. It is an easy calculation to predict the premature depletion of the coating. On the other hand as ACA states the cleaning activities may have contributed essentially to the increase of copper concentrations in the water and sediments. Whereas in commercial shipping cleaning activities are driven by high fuel prices and the weak efficacy of antifouling paints to prevent the formation of biofilms which contribute essentially to the increase in resistance and fuel consumption.