The impact of antifoulings

Direct impact

Antifouling paints contain one or more molecules, called biocides, that are toxic for organisms as they may fix themselves onto the hull of boats. To have a long-lasting efficacy, these biocides have to be progressively diffused with a binding agent which is a base for antifouling paints. The diffusion of biocides is more or less controled in the time, depending on the paint matrix : erodable, semi-hard or hard. In all cases, paints systematically release toxic and polluting molecules.

It is important to know that products made of self-polishing matrixes such as silicone, or epoxy-based (Oceoprotec© Products) are not working with a release of active chemical molecules.

According to the European Commission Project , «Assessment of Antifouling Agents in Coastal Environment» (ACE), the analyses of residues discharged into the water by antifouling paints erodable, semi-hard or hard, attest of the presence of the following chemicals :

• Copper under the form of copper oxide, copper dioxide, copper thiocyanate, copper acrylate, copper flakes, copper hydroxide, etc (the multiplicity of the forms of copper identified is due to the fact that copper is an agricultural one, from wine regions).
• Zinc in the form of zinc pyrithione.
• Colophony (rosin).

We also find:

• Dichlorophenyl dimethyl urea (diuron), which is a pesticide frequently found in water but also in rain (then it is considered as from an agricultural origin).
• 2-methylthio-4-tert-butylamino-6-cyclopropylamino-s-triazine (Irgarol 1051®).
• 2,4,5,6-tetrachloroisophtalonitrile (chlorothalonil).
• 4,5 dichloro-2-n-octyl-4-isothiazolin-3-one (Seanine 211® - Kathon 5287), a powerful phytotoxic.
• Dichlorofluoro methylthiodimethyl phenyl sulfamide (dichlofluanide).

We also found, in a smaller quantity or less frequently :

• 2-thiocyanomethylthio benzothiazole (TCMTB), very powerful and toxic fungicide.
• 2,3,5,6-tetrachloro-4-sulfuronyl pyridine (TCMS pyridine).
• Dithio carbamate of zinc (zineb).
• Trioxyde of arsenic, powerful carcinogenic agent, very toxic and under the Seveso directive.

During their application, antifouling paints give off Organic Component Vapours (C.O.V). Some C.O.Vs present in certain antifouling paints have a direct effect on the human body, such as the tétrahydrofuran (attacking the liver and nerves), the trichloroethylene (harmful for the heart and carcinogenic), and glycol ethers with a short chain (specific toxicity for the bone marrow and the testicles).

Once active and during their whole life duration, antifouling paints are going to produce molecules classified depending on their toxicity as CMR (carcinogenic, mutagenic or toxic to reproduction), POP (Persistant Organic Pollutant), BPT ( persistent, bioaccumulative and toxic) and vPvB (very persistant and very bioaccumulative). Those substances are considered as endocrine disrupters. They stay in the environment for long periods of time before decomposing. They are toxic for humans as well as for the wild flora and fauna and their harmful effects are multiple. they can be found with concentrations at 70 000 times higher than those normally observed in the environment.

In the case of fauna, the effects of exposure to POPs have already been well-observed.
These substances have been established as causing congenital abnormalities, cancers and disfunctions  of the immune system and of the reproductive system. As an example, decline in population has been observed for certain species of marine mammals exposed to POPs (it is notably the case for the common seal, the harbour porpoise  the common dolphin and the beluga whale).

Copper does not enter the category of POPs, CMRs or BPTs.

Indirect impact

The maintenance and the repairing of boats often implies the use of polluting products. Two principle flows of pollution have to be taken into consideration : the hull-cleaning of boats and the falling of rainwater in the maintenance zones.

Indeed, hull-cleaning generates water dirty in metals and other biocides which pollute the water and the ground of the site if a treatment is not carried out. Furthermore rainwaters falling into these technical areas are charging themselves with diverse pollutants (paint fragments, fuel, oils, solvents, etc) and participate into creating pollution in the environment.

The micro waste coming from the work carried out on the hulls could contribute to a certain dystrophisation phenomenon and a growing population of uindesirable species in the areas with a lot sof boats. The most sensitive plankton species to biocides are disappearing and being replaced by undesirable or toxic algae that could increase the risk of TIAC (toxic infection of collective food sources), notably resulting in diarrhoea by consuming the seashells polluted by this micro-algae.

Certain biocides as well as other pollutants can accumulate in the biofilm appearing on the surface of calm waters and be « exported » with the wind towards the coasts and the land during storms, and could even kill the most sensitive plants on the coast.