Registration Dossier
Registration Dossier
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EC number: 214-946-9 | CAS number: 1222-05-5
Endpoint summary
Administrative data
Description of key information
Additional information
Abiotic degradation
Air: Phototransformation half-live in air was experimentally determined to be 3.7 hours.
Water: HHCB is considered hydrolytically stable under environmental conditions as HHCB does not contain any hydrolysable structures. However, phototransformation half-live in water ranged from 109 to 135 hours.
Biotic degradation
Ready biodegradability: In a study according to OECD TG 301B, HHCB did not mineralise, hence, HHCB is not readily biodegradable.
Degradation in aquatic compartment: The degradation in water is based on a WoE using 3 key studies, which together cover the OECD TG 309. The overall DT50 value for the aquatic compartment was determined to be 4.2 days at 20°C (7 days at 12°C). The key metabolite formed is HHCB-lactone for which a DT50 of 27 days at 12oC was found. This HHCB-lactone is further degraded to HHCB-hydroxylated- carboxylic acid and other hydroxylated HHCB products for which a DT50 was not derived and is further assessed in the bioaccumulation section.
Degradation in the sediment compartment: The degradation in sediment is based on a WoE, which does not completely cover the OECD TG 308, but the information is deemed sufficient also because of the available water and soil degradation information. The overall DT50 was determined to be 79 days at 12°C. The identity of the degradation products are anticipated to be similar to water.
Degradation in the soil compartment: The degradation in soil is based on a WoE using 3 key studies, which together cover sufficiently the OECD TG 307. The overall DT50 value was determined to be 35 days at 12°C. HHCB can be further degraded into HHCB-lactone and other more polar metabolites anticipated to be similar to metabolites in the water compartment.
Bioaccumulation
The aquatic BCF for HHCB 1584 l/kg is based on a WoE and the key value is derived from an aquatic OECD TG 305 test.
The aquatic BCF for HHCB-lactone is derived from the HHCB-dietary BMF, in which also the depuration of HHCB-lactone was measured, and this results in a BCF of 1293 l/kg
HHCB-hydroxylated-carboxylic acid has a negligible aquatic BCF based on the log Kow of 0.6 based on the dissociated acid at environmental pH as calculated with SPARC.
The terrestrial BCF for earthworms for HHCB is calculated with EUSES and results in a BCF of 2400 l/kg, which is considered conservative because it does not consider metabolisation of HHCB.
Air-breathing organisms accumulation: Though the bioaccumulation criteria in air breathing organisms are fulfilled for HHCB: Koa > 5 and Kow > 2, the criteria for absence of metabolisation and main excretion pathway via lungs are not fulfilled. Also the indicative final DT50 criteria are not fulfilled. After oral dosing of 2 and 20 mg/kg bw de half-lives in plasma and milk are < 24 hours In adipose tissue this DT50 is ca 50 hours. This latter DT50 can be compared to the indicative cut off mentioned in ECHA’s PBT guidance (R.11, page 84) of 2.5 days for shrews (a mouse species) and shows that there is no concern for air-breathing organisms (see also toxic-kinetic section).
Transport and distribution
Adsorption – Desorption (Koc): The Koc value was determined to be 14300 (log Koc 4.16) in an HPLC test (OECD TG 121) which indicates that the substance will have a high potential to adsorb to sediment/soil.
Henry's law constant: The Henry's law constant was calculated with EUSES using vapour pressure, water solubility and molecular weight and results in 11.4 Pa. m3/mol at 20°C (5.47 m3/mol at 12°C) indicating that volatilisation plays a minor role in the environmental behaviour of HHCB.
Biological monitoring: Several publications are available on HHCB found in aquatic compartment. A monitoring study was done in 2011 in Berlin sewage treatment plants which is used for assessment of wide dispersive use. The sludge concentration in the period 2000-2011 (actual measurements done in 2000, 2004 and 2011) showed little to no variation over time ranging from 7.8 to about 12 mg/kg dw. The higher value of 12 mg/kg dw was used to calculate the concentration HHCB in untreated wastewater. It has to be noted that this value should be considered as conversative as it takes into account the total volume of all HHCB instead of the actual IFF volume from its mass balance.
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