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EC number: 247-148-4
CAS number: 25637-99-4
The selection of key information for this endpoint is complicated by the composition of the registered substance (reaction mass of three isomers), the insolubility of the registered substance and the variety of information available (both freshwater and marine algal studies).Selection of the key information would usually be made upon reliability and so all available studies have been scored according to the criteria of Klimisch et al, 1997, however due to the above differences in test method and principle additional factor concerning the selection of the key information must also be taken into account. These factors are detailed below:•The registered substance is a mixture of three isomers present at differing qualtities in the various grades of the substance however the γ-isomer is usually present at greater concentrations than the α- and β-isomers.•The registered substance is more soluble in marine water than freshwater (as shown in the water solubility studies), with each isomer having it's own limit of solubility.•The water accomodated fraction approach to test solution preparation has been shown to be unsuitable due to undissolved material present in the aqueous fraction even after settling (see water solubility studies).•The column elution method has been shown to produce test solutions which are disproportionately rich in the α- and β- isomers compared to the registered substance values.Due to the above concerns the following studies were selected as the key information for this endpoint.Desjardins et al (2004) - Toxicity study conducted on marine algaeRoberts & Swigert (1997) - Toxicity study conducted on freshwater algae
When added to freshwater, the
commercial HBCDD product was not acutely toxic to Selenastrum
capricornutum when tested at concentrations based on the water
solubility of the gamma diastereomer (Roberts and Swigert, 1997).
HBCDD's 96 hour EC10, EC50, EC90 and NOEC were all greater than water
solubility of the gamma isomer, on which the dose levels were based. The
highest nominal dose tested was twice gamma HBCDD’s water solubility. Dose
levels were 0, 1.5, 2.2, 3.12 4.6 and 6.8 µg/L (nominal). The
mean measured concentration (HPLC with UV/VIS detector) at the 6.8 µg/L
dose was 3.7 µg/L. The dose levels were based on the gamma isomer's
water solubility of 3.4 µg/L. At this level and the typical proportions
of the alpha and beta diastereomers in the commercial product, the alpha
and beta diasteromers were not quantifiable in water. Assuming the test
article was 80% gamma, approximately 4.6 µg/L of the commercial product
would be needed to generate the measured concentration of the gamma
diastereomer. Thus, the NOEC for the commercial HBCD product would at a
minimum be 4.6 µg/L measured or 8.1 µg/L nominal. Using the
WAF methodology, EPS and XPS boards flame retarded with HBCD were not
toxic to freshwater algae; the LL50 was > 100 mg board/L.
Walsh et al. (1987) reported
the combined effects of media and test chemicals in three species of
marine algae. A commercial HBCDD product was tested in three
species of marine algae using six different media. The EC50s were Chlorella
sp 96 hr EC50 > 1500 µg/L in all six media; S. costatum72
hr EC50 = 9.3-12 µg/L in the six media; T. pseudonana 72 hr
EC50 50-370 µg/L in the six media. In a guideline/GLP-compliant study
that used a generator column to generate test article-containing media
from a composite of the commercial HBCDD product, Desjardins et al.
(2004) reported the EC50 in S. costatum was greater than the sum
of the alpha (30.5 µg/L), beta (8.86 µg/L) and gamma (1.61 µg/L)
diasteromers measured in the media (EC50 > 41 µg/L) whereas the NOEC was
less than the sum of the three (NOEC <41 µg/L). In a second study
(Desjardin et al., 2005a) reported no effects in the marine algae Skeletonema
constatum in a 72 hour test,when the commercial HBCDD product
was added to test water with a co-solvent at concentrations equivalent
to the water solubility of the gamma diastereomer (EC50 > 10 µg/L). In a
third study using a generator column to produce test water from the
commercial HBCDD product, the EC50 (growth rate) was approximately equal
to the sum of the measured concentrations of the alpha (35.8 µg/L), beta
(15.2 µg/L) and gamma (3.5 µg/L) diasteromers in the media, which in
this case was 52 µg/L (Desjardins et al. 2005b). The generator column
produced a test media in which all three diasteromers were present at
approximately their individual water solubilities. Based on the
composition of the test article, approximately 620 µg of the commercial
HBCD product would need to be added to one litre
of marine water to achieve these concentrations. Thus, the commercial
HBCDD's EC50 would be >620 µg/L, while the NOEC would be <620 µg/L.
Using REACH Guidance R.10, Table R.10-1, an NOEC can be calculated as
follows: assume the LOEC = 620 µg/L given the effect of approximately
20%, then the NOEC=LOEC/2=320 µg/L.
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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