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EC number: 217-496-1
CAS number: 1873-88-7
No data are available for the registration substance.
A 28 day EC50 value of >6.5 mg/kg soil dw and an EC10
value of >6.5 mg/kg soil dw (highest nominal concentrations
tested) have been reported in an OECD TG 216 (Soil Microorganisms:
Nitrogen Transformation Test) for the effects of the structurally
related substance L3 on nitrate formation rate of soil microflora.
Additionally, a 28 day EC50 value of >8.5 mg/kg soil
dw and an EC10 value of >8.5 mg/kg soil dw (highest nominal
concentrations tested) have also been reported in an OECD TG 216 study
for the effects of the structurally related substance HMDS on nitrate
formation rate of soil microflora.
The data indicate that there were no inhibitory effects on the
soil micro-organisms. However, analysis of the test substance
concentrations in both studies show that test material was lost at the
very beginning of the test for HMDS and by day three of the test with
L3, with all concentrations below the limit of detection, therefore the
micro-organisms would have been exposed to unquantifiable, minimal
amounts of the test substance, if any at all. No dose-response
relationship was apparent for HMDS, and in view of the <LOQ recoveries
of test material, it is not appropriate to ascribe the absence of
effects to an absence of toxicity of HMDS.
Apparent significant effects (positive, non-inhibitory) on nitrate
concentration and nitrate transformation rate were observed in the study
with L3 in the 0.41, 0.81, 1.6, and 3.3 mg/kg treated soils at day 28;
replicates at equivalent test concentrations showed good repeatability.
No dose-response relationship was apparent, and in view of the <LOQ
recoveries of test material, it is not appropriate to ascribe the
observed effects to L3.
The results of these tests cannot be used for derivation of PNECs
and risk assessment.
L3 and HMDS have very high Henry's Law Constants and losses
through volatilisation during test media preparation and within the test
system were anticipated. Because of this, measures were taken during the
soil micro-organism test to minimise test substance losses.
An initial test was conducted with each substance using a closed
bottle system. During this test, nitrate levels decreased significantly
in all concentrations, including the control. The report authors
explained that this was most likely due to the test vessels being sealed
air tight, thus not supplying enough oxygen to allow the nitrifying
bacteria to convert the alfalfa nitrogen source to NO3. Thus
the study was repeated under a separate protocol, using a different test
During the definitive tests, the following measures were taken to
prevent loss of test item, while allowing for air exchange:
- The test vessels were sealed with perforated parafilm, which
allowed for air exchange and avoided loss in moisture.
- All test substance concentrations were dosed using gastight
Hamilton syringes in multiple spots underneath the soil.
- Soil was dosed at ~30% above the calculated maximum sorption
concentration to allow for some losses through volatility.
Despite these measures, significant loss of test material was
observed at a very early stage in both studies. It may therefore be
concluded that the soil micro-organisms were not exposed to adequate
concentrations of test substance, and the EC50 and EC10 values
determined are not representative of actual exposure of the test
organisms to the test substance.
H-L3 has similar physico-chemical and partitioning properties to L3 and
HMDS, meaning that similar losses from the test system would be expected
under equivalent test conditions. Based on these experimental findings,
the registrants consider it is not technically feasible to conduct an
OECD TG 216 test for the registration substance on the basis that the
test substance is too volatile to maintain adequate concentrations in
the test system.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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