Posted by : sanjay swain Wednesday, August 7, 2013

TRIBUTYLTIN (TBT) IS AN ACTIVE INGREDIENT IN CERTAIN ANTIFOULING PAINTS USED ON SHIPS AND IS ONE OF THE MOST DANGEROUS SUBSTANCES EVER DELIBERATELY INTRODUCED INTO THE MARINE ENVIRONMENT. AN EU BAN ON THE PRESENCE OF TBT-BASED ANTIFOULINGS ON SHIPS HULLS IN EU PORTS CAME INTO EFFECT ON 1ST JANUARY 2008.

THE SHIPPING INDUSTRY IS FACING A BAN BY 1 JANUARY 2008 ON ORGANOTIN-BASED ANTIFOULING COATINGS -- THE DOMINATE TYPE OF ANTIFOULING PAINTS USED WORLD-WIDE. TBT-BASED SELF-POLISHING COATINGS (SPCS) ARE EFFECTIVE UP TO 60 MONTHS. SPCS HAD A PREDICTABLE PERFORMANCE AND PROTECTED EFFECTIVELY THE HULL FROM FOULING. ENVIRONMENTAL CONCERN OF THE USE OF TBT ANTIFOULING PAINTS LED TO THE ADOPTION OF A LEGAL BINDING INSTRUMENT AT THE INTERNATIONAL MARITIME ORGANIZATION. EVEN THE BAN HAS NOT COME INTO FORCE, A GREAT NUMBER OF SHIP OWNERS HAVE ALREADY SHIFTED TO TBT-FREE ANTIFOULING COATINGS.

THE ALTERNATIVE TO TBT ANTIFOULINGS ARE ACTUALLY COPPER-BASED SELF-POLISHING COATINGS (SPCS) AND ABLATIVE AS WELL AS CONVENTIONAL FREE-ASSOCIATION PAINTS. TBT-FREE SPCS CAN ACHIEVE A 60 MONTH PERFORMANCE WHEREAS ABLATIVE AND CONVENTIONAL PAINTS REACH A MAXIMUM OF 36 MONTHS.

IN PARALLEL, THE EU-BIOCIDE PRODUCT DIRECTIVE IS STILL GOING TO BE IMPLEMENTED. ACTIVE SUBSTANCES USED IN BIOCIDES OR OF BIOCIDAL ANTIFOULING PAINTS HAVE ACTUALLY TO BE IDENTIFIED AND NOTIFIED. IT CAN BE ASSUMED THAT THE DIRECTIVE WILL LEAD TO AN ESSENTIAL REDUCTION IN THE NUMBER OF BIOCIDES AND THEIR PRODUCTS PLACED ON THE EU MARKET. ACTUALLY, APPROXIMATELY 30 ACTIVE SUBSTANCES ARE USED IN ANTIFOULING PRODUCTS. AS MOST OF THE GLOBAL ACTING PAINT MANUFACTURES ARE BASED IN EUROPE WITH JOINT-VENTURES IN ASIA, THE DIRECTIVE WILL HAVE WORLD-WIDE EFFECTS. OTHER COUNTRIES LIKE JAPAN, AUSTRALIA OR USA HAVE THEIR OWN APPROVAL REGULATIONS RESTRICTING THE NUMBER AND COMPOSITION OF PRODUCTS WITH REGARD TO EFFICACY AND ENVIRONMENTAL STANDARDS.

FURTHERMORE, NEW GENERATIONS OF BIOGENIC BIOCIDES OR ORGANIC BIOCIDES WHICH SHALL RAPIDLY DEGRADE IN SEAWATER OF ANTIFOULING PAINTS ARE GOING TO BE DEVELOPED AND A FEW ARE ALREADY AVAILABLE ON THE MARKET.

ANTIFOULING PAINTS ARE USED TO COAT THE BOTTOMS OF SHIPS TO PREVENT SEALIFE SUCH AS ALGAE AND MOLLUSCS ATTACHING THEMSELVES TO THE HULL - THEREBY SLOWING DOWN THE SHIP AND INCREASING FUEL CONSUMPTION. IN THE EARLY DAYS OF SAILING SHIPS, LIME AND LATER ARSENIC WAS USED TO COAT SHIPS' HULLS, UNTIL THE MODERN CHEMICALS INDUSTRY DEVELOPED EFFECTIVE ANTIFOULING PAINTS BASED ON DIFFERENT PRINCIPLES.

THE COMPOUNDS KILL BARNACLES AND OTHER MARINE LIFE THAT HAVE ATTACHED TO THE SHIP - BUT IT AS WELL SLOWLY "LEACHES" INTO THE SEA WATER, PERSISTS IN SEDIMENTS, IS ADSORBED BY MARINE ORGANISMS AND BIOACCUMULATES ALONG THE FOOD CHAIN. ONE OF THE MOST EFFECTIVE ANTIFOULING PAINTS, DEVELOPED IN 1960'S, CONTAINS THE ORGANOTIN TRIBUTYLTIN (TBT), WHICH HAS BEEN PROVEN TO CAUSE DEFORMATIONS IN OYSTERS AND SEX CHANGES IN SNAILS. TBT CAN ACCUMULATE IN FISH, SEA BIRDS AND MARINE MAMMALS, WHERE IT CAN CAUSE SEVERE DAMAGE TO REPRODUCTION OR IMMUNE SYSTEMS. AS TBT COULD BE FOUND TO HAVE PROVEN ENDOCRINE PROPERTIES IN MARINE INVERTEBRATES - THIS COULD BE REPEATED EVEN FOR HUMAN CELL LINES - IS SHOULD BE SEEN AS ONE OF THE MOST HAZARDOUS SUBSTANCES EVER RELEASED TO THE MARINE ENVIRONMENT BY HUMAN ACTIVITIES.

IN 2000 THE "SENATOR FÜR UMWELTSCHUTZ BREMEN" INITIATED AN INQUIRY ON GERMAN SHIPYARDS, SHIPPING COMPANIES, STAKEHOLDERS AND PAINT MANUFACTURES CONCERNING THE SHIFT FROM TBT- TO TBT-FREE COATINGS. THE RESULT IS THAT AN APPRECIABLE CHANGE IS GOING ON IN GERMANY WITH UP 10% OF SHIPPING COMPANIES HAVING ALREADY CHANGED TO TBT-FREE COATINGS. BUT IT IS STILL STATED THAT NO EFFECTIVE AND ECONOMIC ALTERNATIVES ARE AVAILABLE.

FOR THAT REASON THE AVAILABILITY OF TBT-FREE ALTERNATIVES HAS TO BE BROUGHT TO THE ATTENTION TO THE MARITIME PUBLIC, LOCAL AUTHORITIES AND SHIPPING COMPANIES. E.G. THE PUBLICATION OF REFERENCE LISTS (TRACK RECORDS) OF SHIPS PAINTED WITH TBT-FREE COATINGS MAY BE VERY USEFUL TO CONVINCE SHIPPING COMPANIES THAT THE ALTERNATIVES HAVE PROVEN TO PERFORM WELL ON AN ESSENTIAL NUMBER OF SHIPS. THIS AND ADDITIONAL INFORMATION YOU'LL FIND ON THE FOLLOWING PAGES.


AN APPRECIABLE CHANGE TO TBT-FREE COATINGS IS ACTUALLY GOING ON. BUT IT IS STATED THAT NO EFFECTIVE AND ECONOMIC ALTERNATIVES ARE AVAILABLE. THE VAILABILITY OF TBT-FREE ALTERNATIVES HAS TO BE BROUGHT TO THE ATTENTION TO THE MARITIME PUBLIC, LOCAL AUTHORITIES AND SHIPPING COMPANIES. THE PUBLICATION OF REFERENCE LISTS OF SHIPS PAINTED WITH TBT-FREE COATINGS MAY BE VERY USEFUL TO CONVINCE SHIPPING COMPANIES THAT THE ALTERNATIVES HAVE BEEN PROVEN TO PERFORM WELL ON AN ESSENTIAL NUMBER OF SHIPS.

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