Irgarol

Three of the most commonly used antifouling booster biocides that are usually combined with copper or copper compounds are Irgarol 1051, Diuron, and Zn pyrithione. This study represents an assessment of the interactive effects of the antifouling biocides combined with each other, and with three heavy metals (Cu, Cd, and Zn) in binary mixtures, on the marine algae Chaetoceros gracilis. Seventy-two hour growth inhibition tests were carried out, and the IC50 values of the chemicals were determined along with growth inhibition (%) for several concentrations. The joint effect of the binary mixtures of all the chemicals was assessed by using two models, concentration addition model and the model of probabilities. The following increasing order of toxicity was obtained: Cd < Zn < Cu < Diuron < Zn pyrithione < Irgarol 1051. The interactive effects of the organic chemicals combined with each other on the growth of Ch. gracilis were firmly synergistic. Irgarol 1051 combined with Cd performed synergistic effects, and Zn pyrithione with copper and cadmium action was strictly antagonistic, and the results of the two models were in agreement in almost all mixtures.

Single and joint effects of two antifouling booster biocides, Irgarol 1051 (2-methylthio-4-tert-butylamino-6-cyclopropylamino-s-triazine) and diuron (1-(3,4 dichlorophenyl)-3,3 dimethyl urea), their metabolites, M1 (2-methylthio-4-tert-butylamino-s-triazine), DCPMU (1-(3,4-dichlorophenyl)-3 methyl urea), DCPU (1-(3,4 dichlorophenyl urea) and DCA (3,4-dichloroaniline), respectively, as well as copper were examined. Two phytoplanktonic microorganisms, the green alga Dunaliella tertiolecta and the diatom Navicula forcipata were exposed to various concentrations of the aforementioned compounds both alone and in binary mixtures during a period of 96 hr. Estimation of EC(50) values was performed by daily cell number counting of the tested microorganisms. The toxicity of the six compounds and the metal, applied singly, was found to be, in decreasing order, Irgarol 1051>diuron>M1>DCPMU>DCA>Cu>DCPU and Irgarol 1051>diuron>M1>DCA for the green alga and the diatom, respectively. Diatoms were found to be more sensitive in the presence of all the tested compounds, except diuron. Co-existence of irgarol 1051 and M1 revealed additive effects on both microorganisms. Same results were observed owing to the joint action of copper with either Irgarol 1051 or M1 for almost all the examined mixtures. Combined effects of diuron with its metabolites DCPMU and DCA resulted in synergism in almost all cases, for both species of phytoplankton. On the contrary, antagonistic effects were observed owing to the joint action of copper with either diuron or one of its metabolites.

Tides and freshwater inflow which influence water movement in estuarine areas govern the exposure-regime of pollutants. In this experiment, we examined the in situ impact of double pulses of copper and the herbicide Irgarol 1051 on the photosynthesis of the seagrass, Zostera capricorni. Despite a 4-day recovery period between the two 10 hr pulses of toxicant, the effective quantum yield of photosystem II (DeltaF/Fm') and total chlorophyll concentrations indicated that multiple-pulses had a greater impact than a single pulse. During the first exposure period, samples exposed to Irgarol 1051 had DeltaF/Fm' values as low as zero while controls remained around 0.6 relative units. After the second exposure period, treated samples recovered to only 0.4 relative units. Samples exposed to copper had DeltaF/Fm' values around 0.3 relative units during the first exposure period and while these samples recovered before the second dose, they remained below 0.2 relative units after the second exposure period. Alternate samples were also exposed to one toxicant, allowed to recover and then exposed to the other toxicant. DeltaF/Fm' values indicated that copper exposure followed by Irgarol 1051 exposure was more toxic than Irgarol 1051 exposure followed by copper exposure.

The herbicides Irgarol 1051 (2-(tert-butylamino)-4-cyclopropylamino)-6-(methylthio)-1,3,5-triazine) and Diuron (3-(3',4'-dichlorophenyl)-1,1-dimethylurea) are commonly incorporated into antifouling paints to boost the efficacy of the compound towards algae. Previous investigations have identified environmental concentrations of these herbicides as being a threat to non-target organisms, such as seagrasses. Their individual toxicity has been assessed, but they can co-occur and interact, potentially increasing their toxicity and the threat posed to seagrass meadows. Chlorophyll fluorescence (Fv:Fm) and leaf specific biomass ratio (representing plant growth) were examined in Zostera marina L. after a 10-day exposure to the individual herbicides. The EC20 for each herbicide was determined and these then used in herbicide mixtures to assess their interactive effects. Irgarol 1051 was found to be more toxic than Diuron with lowest observable effect concentrations for Fv:Fm reduction of 0.5 and 1.0 +/- ug/L and 10-day EC50 values of 1.1 and 3.2 ug/L, respectively. Plants exposed to Irgarol 1051 and Diuron showed a significant reduction in growth at concentrations of 1.0 and 5.0 ug/L, respectively. When Z. marina was exposed to mixtures, the herbicides commonly interacted additively or antagonistically, and no significant further reduction in photosynthetic efficiency was found at any concentration when compared to plants exposed to the individual herbicides. However, on addition of the Diuron EC20 to varying Irgarol 1051 concentrations and the Irgarol 1051 EC20 to varying Diuron concentrations, significant reductions in Fv:Fm were noted at an earlier stage. The growth of plants exposed to Diuron plus the Irgarol 1051 EC20 were significantly reduced when compared to plants exposed to Diuron alone, but only at the lower concentrations. Growth of plants exposed to Irgarol 1051 and the Diuron EC20 showed no significant reduction when compared to the growth of plants exposed to

For more Interactions (Complete) data for 1,3,5-Triazine-2,4-diamine, N-cyclopropyl-N'-(1,1-dimethylethyl)-6-(methylthio)- (6 total), please visit the HSDB record page.

LC50; Species: Colinus virginianus (Northern Bobwhite Quail) age 12 days; diet >5620 ppm for 8 days /98% purity/

LC50; Species: Anas platyrhynchos (Mallard Duck) age 8 days; diet >5620 ppm for 8 days /98% purity/

LD50; Species: Colinus virginianus (Northern Bobwhite Quail) age 22 weeks; oral via capsule >2250 mg/kg /98% purity/

EC50; Species: Pseudokirchneriella subcapitata (Green Algae); Conditions: saltwater, static; Concentration: 10 ug/L for 72 hr; Effect: population, decreased abundance />98% purity/

For more Ecotoxicity Values (Complete) data for 1,3,5-Triazine-2,4-diamine, N-cyclopropyl-N'-(1,1-dimethylethyl)-6-(methylthio)- (23 total), please visit the HSDB record page.

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 250(SRC), determined from a structure estimation method(2), indicates that Irgarol 1051 is expected to have moderate mobility in soil(SRC). Volatilization of Irgarol 1051 from moist soil surfaces is not expected(SRC) given an estimated Henry's Law constant of 3.1X10-8 atm-cu m/mole(SRC) based upon its vapor pressure, 6.6X10-7 mm Hg(3), and water solubility, 7 mg/L(4). Irgarol 1051 is not expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(3). Using the modified Sturm test, Irgarol 1051 is not readily biodegradable(4), indicating that biodegradation is not an important environmental fate process in soil(SRC).

AQUATIC FATE: Based on a classification scheme(1), Koc values of 145-63,000 in sediment(2-3), indicate that Irgarol 1051 is expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is not expected(4) based upon an estimated Henry's Law constant of 3.1X10-8 atm-cu m/mole(SRC) derived from its vapor pressure, 6.6X10-7 mm Hg(5), and water solubility, 7 mg/L(6). Irgarol 1051 was reported to be stable to hydrolysis(7). According to a classification scheme(8), BCFs of 240 and 250 measured in fish(6), suggest bioconcentration in aquatic organisms is high. In marine microcosm studies, Irgarol 1051 had a half-life of 22.4-22.7 days, the major degradation product was 2-methylthio-4-tert-butylamino-6-amino-s-triazine which had a half-life of 21.8-23.6 days(9). The water residence time of Irgarol 1051 was reported as 10.2 years(10). Degradation rates in water and sediment were 0.0054/day and 0.086/year, respectively(10). Photo-degradation half-lives in various natural waters were reported as 1.38-60.72 hours(11-12).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), Irgarol 1051, which has a vapor pressure of 6.6X10-7 mm Hg at 25 °C(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase Irgarol 1051 is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 7 days(SRC), calculated from its rate constant of 2.4X10-12 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Particulate-phase Irgarol 1051 may be removed from the air by wet or dry deposition(SRC).

IDENTIFICATION AND USE: Cybutryne is used as a booster algicide in antifouling paint. HUMAN STUDIES: Cybutryne induces HepG2 cell apoptosis through mitochondrial dysfunction and oxidative stress. ANIMAL STUDIES: Cybutryne inhibits the ATP synthesis. The analysis of the various steps involved in the ATP synthesis suggests that the inhibition is due to the opening of small-size pores. ECOTOXICITY STUDIES: When tested on early developmental stages of marine invertebrates cybutryne was found to be the least toxic among other commonly used 'booster'' biocides. However, it was more toxic when tested on the growth of autotrophic species. The toxicity of cybutryne towards periphyton and phytoplankton was shown to be higher than that of atrazine. It induced spermiotoxicity and embryotoxicity at environmentally relevant concentrations in Pacific oyster (Crassostrea gigas) gametes or embryos. It had a significant impact on meiofauna abundance, even at the lowest concentrations, causing a drastic decline in the abundance of nematodes (the dominant meiofaunal taxon) and an increase of the relative importance of oligochaetes. Other study evaluated the effects of cybutryne toxicity on the exoskeleton of Metanephrops japonicus, which is the outer layer facing the environment. Ecdysteroid receptor (Mj-EcR), trypsin (Mj-Tryp), and serine proteinase (Mj-SP) in the hepatopancreas were upregulated in response to different exposure levels of the biocide at day 1, 4, or 7. In contrast, gill Mj-chi5, Mj-Tryp, and Mj-SP exhibited late upregulated responses to 10 ug/L compared to the control at day 7. Mj-chi1 showed early upregulation upon exposure to 10 ug/L and Mj-chi4 showed no changes in transcription in the gill. Gill Mj-EcR presented generally downregulated expression patterns. In addition, decreased survival and change of exoskeleton surface roughness were observed in M. japonicus exposed to the three concentrations of the biocide. Separate studies have shown that cybutryne inhibits c

/AQUATIC SPECIES/ After the widespread ban of TBT /tributyltin/, due to its severe impact on coastal biocoenoses, mainly related to its immunosuppressive effects on both invertebrates and vertebrates, alternative biocides such as Cu(I) salts and the triazine Irgarol 1051, the latter previously used in agriculture as a herbicide, have been massively introduced in combined formulations for antifouling paints against a wide spectrum of fouling organisms. Using short-term (60 min) hemocyte cultures of the colonial ascidian Botryllus schlosseri exposed to various sublethal concentrations of copper(I) chloride (LC(50)=281 uM, i.e., 17.8 mg Cu/L) and Irgarol 1051 (LC(50)>500 uM, i.e., >127 mg/L), their immunotoxic effects /were evaluated/ through a series of cytochemical assays previously used for organotin compounds. Both compounds can induce dose-dependent immunosuppression, acting on different cellular targets and altering many activities of immunocytes but, unlike TBT, did not have significant effects on cell morphology. Generally, Cu(I) appeared to be more toxic than Irgarol 1051: it significantly (p<0.05) inhibited yeast phagocytosis at 0.1 uM (approximately 10 ug/L), and affected calcium homeostasis and mitochondrial cytochrome-c oxidase activity at 0.01 uM (approximately 1 ug/L). Both substances were able to change membrane permeability, induce apoptosis from concentrations of 0.1 uM (approximately 10 ug/L) and 200 uM (approximately 50 mg/L) for Cu(I) and Irgarol 1051, respectively, and alter the activity of hydrolases. Both Cu(I) and Irgarol 1051 inhibited the activity of phenoloxidase, but did not show any interactive effect when co-present in the exposure medium, suggesting different mechanisms of action.

/AQUATIC SPECIES/ The toxicity of the antifouling biocides Irgarol 1051, Diuron, Chlorothalonil, Dichlofluanid, Sea-nine 211, Copper pyrithione, Zinc pyrithione, Ziram and Zineb were evaluated on Nitzschia pungens and Artemia larvae. Results showed that EC50 for Irgarol 1051 was 0.586 ug/L was the strongest effect on N. pungens following by Copper pyrithione (4.908 ug/L), Ziram (5.421 ug/L), Zinc pyrithione (5.513 ug/L), Diuron (6.640 ug/L), Zineb (232.249 ug/L), Sea-nine 211(267.368 ug/L), Chlorothalonil (360.963 ug/L) and Dichlofluanid (377.010 ug/L) in 96 hr. In Artemia larvae, the biocides were evaluated the LC50 for larval survivals at 48 hr. Sea-nine 211 and Copper pyrithione were 0.318 and 0.319 mg/L. Chlorothalonil, Zinc pyrithione and Ziram were 2.683, 3.147 and 4.778 mg/L. Irgarol 1051, Diuron, Zineb and Dichlofluanid were 9.734, 30.573, 41.170 and 154.944 mg/L. These results provide baseline data concerning the toxicity of antifouling biocides against marine environment.

/AQUATIC SPECIES/ Macroalgae depend on carbon-concentrating mechanisms (CCMs) to maintain a high photosynthetic activity under conditions of low carbon dioxide (CO(2)) availability. Because such conditions are prevalent in marine environments, CCMs are important for upholding the macroalgal primary productivity in coastal zones. This study evaluated the effects of seven antifouling compounds-chlorothalonil, DCOIT, dichlofluanid, diuron, irgarol, tolylfluanid, and zinc pyrithione (ZnTP)-on the photosynthesis and CCM of sugar kelp (Saccharina latissima (L.)). Concentration-response curves of these toxicants were established using inhibition of carbon incorporation, whereas their effects over time and their inhibition of the CCM were studied using inhibition of O(2) evolution. ...Exposure to all compounds except ZnTP (< 1000 nM) resulted in toxicity to photosynthesis of S. latissima. However, carbon incorporation and O(2) evolution differed in their ability to detect toxicity from some of the compounds. Diuron, irgarol, DCOIT, tolylfluanid, and, to some extent, dichlofluanid inhibited carbon incorporation. Chlorothalonil did not inhibit carbon incorporation but clearly inhibited oxygen (O(2)) evolution.

Irgarol 1051 was detected in macrophytes and algae (Potamogeton lucens, Potamogeton pectinatus, Vaucheria spp., Elodea nuttallii) at 53-103 ng/g dry weight in samples collected Sep 1994 to Apr 1995 from Port d'Ouchy, Switzerland(1). At Buchillon, an unpolluted reference site, Irgarol 1051 was detected in Zannichellia palustris at 4-5.2 ng/g(1).

EPA has released the Interactive Chemical Safety for Sustainability (iCSS) Dashboard. The iCSS Dashboard provides an interactive tool to explore rapid, automated (or in vitro high-throughput) chemical screening data generated by the Toxicity Forecaster (ToxCast) project and the federal Toxicity Testing in the 21st century (Tox21) collaboration. /The title compound was tested by ToxCast and/or Tox21 assays/[USEPA; ICSS Dashboard Application; Available from, as of August 9, 2018: http://actor.epa.gov/dashboard/]

Irgarol 1051 was detected in 7 of 24 sewage sludge samples collected Jan and May 2001 from 12 waste water treatment plants in Switzerland at 1.5-30.4 ug/kg dry weight(1). The concentration of Irgarol 1051 in leachates from short-term immersion, permanent immersion and irrigation test was 0.4-1.0, 1.2-3.4 and 0.5-1.7 mg/L, respectively(2). Influent and effluent concentrations of Irgarol 1051 from four German wastewater treatment plants collected Jun 2012 were 2.3-16 and 2.9-14 ng/L, respectively(3).

Using a structure estimation method based on molecular connectivity indices(1), the Koc of Irgarol 1051 can be estimated to be 250(SRC). According to a classification scheme(2), this estimated Koc value suggests that Irgarol 1051 is expected to have moderate mobility in soil. In sediment, log Koc values of 2.16(3) and 2.4-4.8(4) were reported. These correspond to Koc values of 145 and 250-63,000, respectively. A Koc of 3100 in sediment was also reported(5). A log Koc value of 2.7 (Koc 500) was reported in secondary sewage sludge(6).

/ALTERNATIVE and IN VITRO TESTS/ In this study, HepG2 cells were exposed to 0.04-40 mg/L Irgarol 1051. Results show that Irgarol 1051 can damage cell morphology and cause a significant decrease in cell viability. Positive staining by Annexin V, caspase-3 activity enhancement, and the damage in cell ultrastructure indicated an apoptotic mode of cell death for 4.0 mg/L Irgarol 1051 treatment. At the same time, caspase-9 was also significantly induced by 0.4 and 4.0 mg/L Irgarol 1051 at 72 hr, which suggests that the intrinsic mitochondria pathway was involved in the apoptosis. The mitochondrial membrane potential decreased significantly after the HepG2 cells were exposed to Irgarol 1051 for 6 and 72 hr. Especially, the translocation of cytochrome c from mitochondria to cytosol was recorded, supporting the idea that the mitochondrial pathway was involved in the apoptosis signal pathways induced by Irgarol 1051. The significantly increased levels of intracellular reactive oxygen species (ROS) and an immediate ROS burst were also recorded. The results here may imply that Irgarol 1051 induces HepG2 cell apoptosis through mitochondrial dysfunction and oxidative stresses. Although it is possible that this chemical has no detrimental effects on human health at the environmentally relevant concentration, it may cause problems to top coastal predators due to bio-accumulation through the food chain.

Irgarol 1051 was detected at approximately 0.2 ng/g in zebra mussel (Dreissena polymorpha) collected Aug 1994 to Apr 1995 from Port d'Ouchy and Buchillon, Lake Geneva, Switzerland(1). Irgarol 1051 was not detected (detection limit 0.76 ug/kg wet weight) in green mussel (Perna viridis) samples collected Apr 19-20, 2004 from six sites along the coast of Thailand(2).

Chemical: 1,3,5-Triazine-2,4-diamine, N-cyclopropyl-N'-(1,1-dimethylethyl)-6-(methylthio)-

Irgarol: HSNO Approval: HSR003184 Approved with controls