Irgarol

Irgarol 1051® (n°CAS: 28159-98-0)) is a Biocide Pesticide powerful Algicide of the family of the Triazine S, used in the Antifouling S to replace the prohibited Tributylétain.

It acts by inhibiting the Photosynthèse, by blocking of the transport of the electrons in the photosynthetic process. Irgarol is released little by little from painting and kills (to very low dose are enough) the vegetable organizations which try to fix themselves on the hull, but also organizations belonging to the Phytoplancton, with the Périphyton, even the Macrophyte S (higher plants).

chemical Name: 2-méthylthio-4-tert-butylamino cyclopylamino-6- (1,3,5-triazine)
Molecular weight: 257,37
Formula: C11H19N2S
Solubility in water: weak
Steam pressure: 6,6 X 10-7 mmHg (=> Peu volatile)
Log P: 2,8 O (=> Modérément lipophilic)

Degradation (; in days)
Hydrolysis: > ½ 200 days life, stable out of sterile water, with the darkness
Photolysis out of fresh water: ½ life 36 days if there is photodegradation, i.e. in the presence of light, according to the latitude, of the season, the depth, of turbidity, the orientation, etc
Aerobic metabolism by the micro-organisms 96 days out of fresh water (starting from a certain depth the medium becomes anoxic. Eutrophication and the dystrophisation can decrease the oxygen rates, even to reduce them to zero)
the anaerobic metabolism seems without effect on the product (not of degradation)

Ecotoxicology

The algicide effect protects the hulls from the boats but in the mediums where water is renewed little, or in the closed lakes, it can have important direct impacts for the phytoplankton and the périphyton in the medium, even on the macrophytes (higher plants), and of the indirect impacts on oxygenation and pH of the medium as on the Food chain whose photosynthesis is the base. The famous watery plant most affected by this Polluant (Navicula pelliculosa) is sensitive torates of less 100ng/L where a Daphnie will be it to 1 mg/L.

Synergistic effects are possible with other components of antifoulings (copper in particular) or others polluants.
Its rate of diffusion starting from a painted hull or a painted immersed object is estimated has approximately 2.5 μg/cm ² /jour (or 9.131.250 μg per painted square meter and per annum). Irgarol - according to a simplified modeling (see bond at the foot of the page) - would concentrate in a lake rather on the surface (35 ng/L, is 35 μg/m ³) where it can be degraded by photolysis if water is transparent and by microbes (if water is oxygenated enough).

High rates, of 0,803 µg/L (either 803 µg/m ³) and of Diuron and 0,102 µg/L (or 102 µg/m ³) of Irgarol were measured in Rade of Brest in 2003-2004 (attention, part of Diruon could come from biocides used downtown or and washed upstream by the Pluie S) And one found according to IFREMER up to 6,7 µg/L (6700µg/m ³, either 6,7 mg/m ³) of Diuron and 1,7 µg/L (1700µg/m ³, or 1,7 mg/m ³) of Irgarol elsewhere in marina S or port areas. (These figures are not necessarily the maximum ones, because these measurements are rare. But these rates are already enough high to induce an effect on the phytoplankton, and perhaps in these zones on all the food chain. Let us note that these rates are well beyond the European standards of potability and that moulds and oysters or scallops can grow in the vicinity or downstream from these zones and be marketed.

While degrading itself on the surface under the action of the light (photolysis), or when it is biodégradé by microbes, the irgarol leaves several breakdown products or Métabolite S whose triazine says “GS 26575” écotoxique than its molecule mother (Irgarol) but more persistent than she in the Environment and preserving properties biocides.

Toxicology

One lacks toxicological data for the man.

Internal bonds

External bonds

Simulation of dispersion and time of degradation in the lake lake Pavin (Puy-de-Dôme, Auvergne, France)
Doc. of Ifremer on the toxicity of Diuron and Irgarol 1051 on '' Chaetoceros gracilis '' ([[diatom] marine)]

Category: ecotoxicology

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