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Environmental fate & pathways

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Biodegradation in water

The test substance (trade name: Clearlink 1000) was not found to be readily biodegradable.

Ready biodegradability of the test substance in water was measured by conducting a study in accordance with GLP and OECD Guideline 301 C (Modified MITI Test). This study was considered as reliable with no restrictions and hence used as a key value for hazard assessment and classification and labeling of the substance. Under the conditions of the key study, the test substance was not found to be readily biodegradable. The percentage of biodegradability on the basis of BOD, DOC and test material analysis was measured to be 2, 0 and 0 respectively.

 

Another supporting study was also performed to assess the ready biodegradability of the test substance by exposing it to municipal activated sludge microorganisms for 29 days under controlled environmental conditions. A method for quantitative analysis (LC-MS) was used to directly measure the substance in the test cultures over time, following a simple extraction procedure. Under the conditions of the supporting study, there was no observable loss of the test substance as measured by specific chemical analysis indicating a lack of ready biodegradability for the test substance. Based on the results of this study, the test substance was not observed to be toxic to the microorganisms as it did not inhibit removal of the reference substance (sodium dodecyl sulfate SDS) from the cultures. It was determined that the test substance is recalcitrant to biodegradation over 29 days of incubation, and would not be expected to appreciably biodegrade in an aerobic biological waste water treatment processes. In addition, based on the results of this study, it is unlikely that microbial adaptation toward Clearlink 1000 biodegradation would occur in those processes after prolonged exposures. Clearlink 1000 did not appear to be detrimental to the microbiological metabolic activity of the activated sludge based on the ability of the microbes to sufficiently biodegrade SDS in the presence of this substance.

Biodegradation in soil and sediments

The soil/sediment simulation testing is not mandatory information for this substance which is manufactured and used at tonnage band of 10-100 t/a. However, degradation rates in sediment and soil are assumed to be reduced by default if a substance is highly sorptive. As based on the measured adsorption coefficient of this substance (log Koc > 5.63), it has strong adsorption potential to solid particles. Therefore, the need of soil/sediment simulation testing was taken into account in the chemical safety assessment based on the exposure considerations (see ES&RC in CSR sections 9 and 10).

Part of a two part system, Clearlink 1000 is used as the activator for cross-linking in the production of polyurea coatings. In polymerized form, the polyurea coating is used for in-situ pipe rehabilitation coatings to repair/or extend the life of buried drinking water supply pipes which have corroded and diminished structural integrity. The formulation processes are closed where losses are reduced to the absolute minimum and there are no discharges to waste waters or to soil. In addition, during the coating application the releases of the substance to surface waters and soils are unlikely as processes are enclosed and controlled and the substance reacts on use to form a polyurea coating.

Part of a two part system, Clearlink 1000 is used as the activator for cross-linking in the production of polyurea coatings. In polymerized form, the polyurea coating is used for in-situ pipe rehabilitation coatings to repair/or extend the life of buried drinking water supply pipes which have corroded and diminished structural integrity.The formulation processes are closed where losses are reduced to the absolute minimum and there are no discharges to waste waters or to soil. In addition, during the coating application the releases of the substance to surface waters and soils are unlikely as processes are enclosed and controlled and the substance reacts on use to form a polyurea coating.

 

During the spray application, a small amount of material is oversprayed to the soil. This material represents the combination of the Part A and Part B sides, so the rapid polymerization to form the polyurea coating is underway.  This would result in ca. losses of 11 kg/a of polymerized waste, 0.01% of the total use of the substance (99 t/a).The coating is intentionally designed to have a ~30% overcharge of the reactive isocyanate component, so by design there is a minimal chance for any uncured amine to be present. This is validated by the migration reports from various drinking water approval agencies that show low levels of total organic content, and in cases where Clearlink 1000 itself was monitored, the migration concentrations were negligible from the cured coating. Products that are designed to be in contact with potable water must receive third party approval before the products can be applied in those applications. The requirements of these approvals vary by country, but typically there is a review of a product's formulation to perform some risk assessment on the raw materials.

 

There are several migration study results available for this polyurea coating product from different countries (see sections 9.2 and 10.2).Negligibleemissions of Clearlink 1000 are expected from the reacted material as has been concluded by the migration studies. As a conclusion on the exposure based considerations, the chemical safety assessment of this substance does not indicate the need for further testing of degradation in soils and sediments.