Antifouling

Why the antifouling?

The fouling is the English term describing the spontaneous colonization of a support by the marine organizations. It is an absolutely normal phenomenon under water, in particular in the layers enlightened and rich in nutrient. It is at the origin of the structuring and the maintenance of many marine ecological niches. The fouling is the basic process which allows the permanent complexification of the écotone S and the creation of new ecological niches in water. On the natural substrates or the artificial reefs, it takes part besides in the purification of water.

The sea and moindrement the fresh water are naturally rich in Protéine S and Polysaccharide S mainly produced by the Plancton and the excreta of the watery million organizations which one can find in a few liters of sea water. Sea surface, or of fresh water, when it is not very agitated is covered with a permanent Biofilm. Under water, the hanging devices settle on any support immersed in the form of a film the thickness of to a few microns, after only a few seconds or a few minutes in a rich medium. This film provides to some Bactérie microscopic S, microalgues and watery mushrooms (known as organizations pioneers) a first source of food. The latter will enrich this film which will thicken in a thicker mucilagineux biofilm, becoming an increasingly complex substrate for colonies of protozoa then of fixed or mobile organizations (macroalgues, larvae of Invertébré S and Vertébré S, of which petrifying species which will become itself support for other species. Many larvae of marine organizations have astonishing capacity of fixing, even on alive, flexible supports and very mobiles (ex: Barnacle S on the skin of the whales).

Manufacturers

They meet every approximately four years since a first congress (" International Congress one Marine Corrosion and Fouling") held in France in 1964. They say to seek solutions posing less problems with the Environment. The last congress was held with San Diego in 2002, with the support of the Permanent International committee for Research on the Safeguarding of Materials in Seamen circle (COIPM) without a really satisfactory painting antifouling for the Environment not being still found, in spite of a very rich program and an constant improvement of knowledge corrosion degradation of immersed materials.

Active substances

The antifouling contains one or more molecules Toxique S for the organizations which fix themselves on the hulls of the ships or the objects immersed that one wants to protect. To be durably effective, these poisons must be released little by little by the medium (binder) which constitutes the base of this painting. A antifouling is thus always Polluant.

Prohibition of the tributylétain

The Tributylétain (TBT), very effective was the biocide more used in navy in the world, but this product, its molecules of degradation and its Métabolite S appeared seriously and durably pollutants. The TBT induces in particular at certain organizations a phenomenon of Imposexe (masculinisation of the female sexual organs in fact), with very weak dilutions, lower than the ng/L (out of fresh water or marine). Residues of the TBT, whose tin persist a long time in the sediments of the ports and on the sites of mud immersion of dredging and with their downstream following the handing-over in suspension if necessary. For these reasons, in November 1999, a resolution of the OMI (A.895) was proposed, adopt on October 5th, 2001, prohibiting paintings antifouling containing tin starting from January 1st, 2003. Their presence on the hull of a ship will be prohibited since 2008.

Alternatives to the tributylétain

The antifoulings without tin often have a medium vinyl or acrylic (famous less toxic) but the labels and the manufacturers omit to mention the nature and the proportioning of biocides (fungicidal insecticides and/or weedkillers) or additives which they contain. The antifoulings are conceived to be érodables in time on 1 or 2 years according to the number of layers. One also tested and developed materials high tech; polymers elastomers, new polymeric érodables, produced containing silicone, paintings with Teflon or autopolissantes containing water for better slipping on water, acoustic systems of waves generated by electric shocks, etc while hoping to reduce hangs it organizations on the hull but which still miss diffusion or experience feedback.

According to European Commission Project “ Assessment off Antifouling Agents in Coastal Environment ” (ACE), the analyzes of the residues released in water by these paintings give the following results:

it Cuivre is used the most for its toxicity on the phytoplankton and other organizations (It has been several centuries that one noticed that immersed copper and brass were not colonized by the watery organizations). Paintings contain it in the form of Cuprous oxide, Dioxyde of copper, Thiocyanate of copper, Acrylate of copper, copper powder in flake, copper hydroxide…

it Zinc is sometimes used in the form of Zinc pyrithione.

- the Cupronickel is sometimes used

it Colophane (Rosine or Rosin) is often detected.

Among biocides salted out in water, one especially found the organochlorinated ones:

of dimethyl dichlorophenyl urea (Diuron) which one of the pesticides is often detected in water, but also in the rain (with in this case a supposed source of agricultural origin)
of 2-methylthio-4-tert-butylamino-6-cyclopropylamino-S-triazine (Irgarol 1051®)
of the 2,4,5,6-tetrachloroisophtalonitrile (Chlorothalonil)
of the 4,5 dichloro-2-n-octyl-4-isothiazolin-3-one (Seanine 211® - Kathon 5287), powerful phytotoxic
of the dichlorofluoro methylthiodimethyl phenyl sulphamide (Dichlofluanid)

In less quantity or less often, one also found

of the 2-thiocyanomethylthio benzothiazole (TCMTB), very powerful and toxic fungicide
of the 2,3,5,6-tetrachloro-4-sulfuronyl pyridine (TCMS Pyridine)
of the dithio carbamate of zinc (Zineb)
of arsenic trioxyde, powerful carcinogenic agent, very toxic and subjected to the Directive Sévéso;

These biocides are sometimes associated between them and/or with copper to obtain synergistic effects, to reinforce or widen their spectrum of action.

Toxicity

The tributylétain is toxic for the man. It is prohibited, but relatively remanent. The tin which composes it is not biodegradable. The solvents of the majority of the antifoulings are also toxic, and the active molecules of new the antifoulings are neither alleviating, nor sometimes less toxic than the tributylétain.

Their toxicity for the man is:

- direct following the inhalation of particles, for example during use of gun with painting without adequate mask, or during the sandpapering of the antifouling layer of a hull, or by passage through the skin following projections or contact with painting, or more rarely via an accidental ingestion, or for children who would carry to the mouth of the scales of painting (phenomenon known as of the “'' Pica ''”).

- indirect , by ingestion of shells filterers such as mould S, Oyster S, hull S, etc or other seafood (ex: sea urchins) or fish having grown downstream from sites of careenage (painting or scouring of ship hulls, large or small) or near immersed wrecks. The regular contaminated seafood consumption is suitable for induce acute diseases or chronicles related to heavy metals. It is current that waste of careenages is cleaned with the karcher and pushed towards water, or simply on the spot abandoned, although they answer the legal definition of the Toxic waste.

- allergic phenomena can also exist. The toxicity of metals vary according to the history and the genetics of the individuals.

Ecotoxicity

During several decades, paintings antifouling contained stannic derivatives (i.e containing tin, like TBT, tribultylétain), of which the toxic effects (and of disturbing hormonal) on the seamen circle were important, at the point to decimate natural populations of shells and to disturb the reproduction of many species. The use of these substances is from now on interdict within the framework of conventions of OMI. New the antifoulings is less toxic, but remain it nevertheless. They belong to the family of the Biocide S. This is why, their application to the gun with painting must be done with a mask. The brush application must be done with gloves and a suitable behavior and in broken down space.
Les holds and sites of maintenance of the ship hulls should be isolated from the aquatic environment, and the Déchet S treated like toxic waste and dangerous (they should not be hidden in the ground, nor incinerated).
Les carcasses of ships immersed to make artificial reefs of them should always be removed from their polluting elements (copper, brass, lead, machines, greases fuels, paintings…) and antifouling should be to them ideally pickled. Analyzes made on the moulds pushing around wrecks showed that they accumulated the heavy metals lost in water, in their flesh, but also in their shell. The metals contained by paintings and antifoulings have been neither biodegradable, nor dégradables.
Il appears plausible that the reduction of the populations of crabs and shellfish observed in all the ports for a few decades either partly due to the antifoulings. Locally, for example in the presence of earth electrode put at the sea on building sites of Soudage industrial to the arc, electric phenomena of field (anode/cathode) could perhaps reinforce the passage of metals in water, which would still reinforce the presence of poison in the sédimens near the building sites navals.
L' ecotoxicology of biocides in seamen circle is a science young and little equipped with means, but some indices let think that in the closed ports, by killing the organic matter, the antifouling could contribute to certain phenomena of Dystrophisation and of pullulation of undesirable species. The species of phyto- and zooplancton most sensitive to biocides disappear with the profit from undesirable or toxic algae (ex: Dinophysis), which could increase the risk of TIAC (toxinfection food), in particular diarrheas induced by consumption of bivalves polluted by this microalgue.

Certain biocides and other pollutants can accumulate in the Biofilm which is formed with the water surface calm and being “exported” with the spray towards the littoral and the interior grounds at the time of the storms, at the point to even affect to kill the most fragile plants of the coastal strip. It is plausible also that certain organizations can develop resistances to certain biocides.

Search for less toxic alternatives

One manufacturing markets an apparatus ( Shipsonic Ultra Sonic Algae Killer for ships ) adapted to the small boats, which one can use with the manner of a brush under the line of flotaison, on the boat with water. It is a transducer which emits Ultra-son S which prevent the fixing of marine organizations (petrifying shells, algae, organizations) by activating on microscopic scale a ultra-thin layer of water in contact with the hull (with phenomenon of bullage/cavitation), taking off the organizations which started to fix themselves at it. It must be frequently used, and it is not very practical for the parts far away from the water line (skittle.), but the advantage presents of not dispersing any toxic product in water. It would be advisable to check that he does not have indirect impacts on more distant organizations.

New materials have been being studied in laboratory for a few decades, of which some seek to imitate qualities of the Mucus marine organizations. Of a raised cost, if they prove rather resistant, they will be probably initially reserved for the ships of race or military uses or high added value.

Remarks

Many marine organizations have one or more fixed phases of life. Almost all the marine animals must deal with the colonization of their skin, cuticule or wraps external by other organizations (which are only seldom parasites, but which cling to the substrates that they find). Even animals like the whales, the cachalot, the orcs or the dolphins are confronted with these phenomena. Scientists study the properties of the skin of the dolphins, or the seals or otaries to try to develop new systems " antisalissures". The fish, as the algae are protected by their mucus, the Dauphin S and Orque S rub on the sandy bottom, but have a skin which limits the fixing of marine animals. As that of the Baleine S which must nevertheless support plates of several kilograms of organizations fixed on their skin. Under water, one observes that the shellfish of the type Crevette or Homard spend much time to smooth the antennas, the eyes and other bodies mobile and vital to take off about it the organizations which unceasingly start to fix themselves at it. for example http://www.ucs.louisiana.edu/~rtb6933/shrimp/clean.html. One is also interested in essential oils, of which menthol, without industrial application to date.

Prevention/Precautions

The antifoulings are by toxic nature. The immediate risks are irritating pulmonary, allergic and cutaneous. The long-term risks are badly known, but could include diseases degenerative, autoimmune, cancer, etc Their solvents are often xylenes and solvents naphtha containing of the benzene compounds (trimethylbenzene, ethylbenzene, metisylene, propylbenzene) which are also toxic.
L' application of antifouling should thus always be done with a protection of the skin and muqueues (clothing tight, glasses, gloves) and a respiratory protection (mask with cartridge) and nonsimple fiber mask.
Attention, decomposition of the majority of the antifoulings by the fire led to the gas emission, smoke and ashes highly toxic. The residues should not be thrown to water nor flarings or mixed with household waste.

external bonds

an alternative " verte" with the Chlorine and other pollutants usually used
Model of prediction of environmental contamination by the antifoulings
Search for alternative
European Program of research on the best strategies of use of antifoulings
European Program of research on hydrogels antifoulings

More/Sources;

11èmes days of the medicine of the Sailors, organized with the Ministry for Ecology and Sustainable development.
University of Western Brittany UBO (Brest-France)/Ifremer/SFMM
Médico de Sanidad Maritima ISM Tarragona (España)/SEMM/URV
Re-examined Medicina Maritima which produced several articles of which “toxicological Risks aboard ships” December 2004.

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