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Ecotoxicological information

Endpoint summary

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Description of key information

Additional information

A summary of the available aquatic toxicity studies for HHCB (GLP and completely documented) is provided in the below table (results expressed as mean measured concentrations)

Test species

Guideline

Results1(mg/l)

Remarks2

Pseudokirchneriella subcapitata3

OECD 201

72h-NOEC = 0.201

72h-LOEC5= 0.466

72h-ErC50> 0.854

72h-EbC50= 0.723 <0.678-0.778>

Key study, Rel. 1

Van Dijk 1997

72h static

Carrier: 0.005% DMF and 0.0­05% Tween 80

n=6

HPLC identification

Start conc. 71-102% of nominal

End conc. 54-85% of nomi­nal

Pseudokirchneriella subcapitata

OECD 201

72h-EC50 >0.7 mg/l

72h-NOEC = 0.23 mg/l

Supporting study, Rel. 2

Durjava et al. 2012

72h static

Daphnia magna

OECD 202

48h-NOEC = 0.3 mg/l <0.24-0.39>

Key study, Rel. 2

Durjava et al. 2012

48h static

Daphnia magna

OECD 211 (Cited as OECD Guideline 202, part 2)

21d-NOECrep = 0.111

21d-LOEC5= 0.205

21d-EC50rep = 0.282 <0.260-0.312>

21d-IC50= 0.293  <0.204-0.419>4

Supporting study, Rel. 1

Wüth­rich 1996a

21d semi-static

Carrier: 0.008% DMF and 0.002% Tween 80

n=5

HPLC identification

Conc.fresh 82-104% of nominal

Conc.used 63-91% of nominal

 

Acartia tonsa

OECD guideline for life cycle test with Acartia tonsa (draft document) based on OSPAR protocol /2/ and ISO 14669/3/

6d-NOECdevelop. = 0.038

6d-LOECdevelop5.= 0.075

6d-EC10develop.=0.044<0.030-0.055>

6d-EC50develop.= 0.131 <0.115-0.153>

Key study, Rel. 1

Bjørnstad 2007

6d static, daily feeding

Radiolabelled14C- HHCB solved in ethanol
(< 0.01%)

n=5

LSC identification

Conc. > 80% of nominal

Oryzias latipes

-

96h-LC50 = 0.95

Key study, Rel. 2

Pimephales promelas

OECD 210

36d-LOEChatch > 0.140

36d-NOECsurv. = 0.068,

36d-LOECsurv. = 0.140

36d-LC50 >0.140

36d-NOECgrowth = 0.068,

36d-LOECgrowth6= 0.140

36d-NOECdevelop.= 0.068,

36d-LOECdevelop.= 0.140

Key study, Rel. 1

Croudace 1997

32 days post hatch,

36 days overall

Solvent triethylene glycol

GC identification

Conc. 50-104% of nominal

Lepomis macrochirus

OECD 204

21d-NOECclinical signs = 0.093,

21d-LOEC5 = 0.182

21d-NOECgrowth = 0.182

21d-LC50 = 0.452 <0­.316-0­.911>

Supporting study, Rel. 1

Wüth­rich 1996b

Carrier: 0.005% DMF and 0.005% Tween 80

n=5

HPLC identification

Conc. 66-86% of nomi­nal

1    Measured concentrations, <95% confidence limits>

2    The number of concentrations tested (n) excludes control and solvent control

3    Former name Selenastrum capricornutum

4    Estimated 95% confidence limits after data reported by Wüthrich (1996c)

5    Dunnet’s test (p=0.05)

6    Wilcoxon rank sum test (p=0.05)

 

Test conditions related to the substance characteristics

HHCB is reported to be photodegradable (See IUCLID entry sections 5.1.1. and 5.1.3). The atmospheric half-life of HHCB was 4.9 hours (Syracuse estimation programme AOP) and in lakewater it was 109 (Buerge et al. 2003). Generally, the wave length of UV ranges from 180 to 400 nm. The wave length of visible light is > 400 nm. The UV/Vis spectrum of HHCB (IFF 2001), shows that there is absorption at wavelengths below 300 nm with peaks at 202-205, ca. 225, 271 and 280 nm. The molar absorptivity of HHCB was reported as 51,318 cm-1.M-1at 202 nm. HHCB does not absorb at wavelengths above ca. 325 nm.

In the laboratory test on photodegradation in water the light source was a mercury fluorescent lamp emitting UV-radiation between 300 and 460 nm, max 365 nm on the water surface or through a quartz test tube (Buerge et al. 2003). Hence, the photodegradation-induced half-life of 109 hours in the study by Buerge et al. is a consequence of absorption of UV light.

In growth inhibition tests with algae, generally fluorescent lighting tubes are used emitting wavelengths ranging between 400 and 700 nm at an intensity of approximately 8000 lux. Hence, the wave length of the illumination in the algae test is clearly above 325 nm, thus it will not cause photodegradation of the HHCB molecule. Moreover, there is a glass wall between the alga suspension and the light source, which would disrupt the penetration of UV radiation. The illumination in the other aquatic toxicity tests is at most daylight filtered by glass windows (aquaria) and glass vessel walls (so no UV light) or artificial light in the visible light spectrum. Hence, although photodegradation of HHCB may be considered a relevant degradation process in the atmosphere and in the upper layer of surfacewaters through penetration of UV light, it is concluded that photodegradation is of no significant influence on the outcome of the aquatic toxicity studies performed under normal laboratory conditions since the amount of UV light penetrating the test solutions will be negligible.

In view of the high logKow, the toxicity was not tested with short-term tests according to the base set, but in tests ensuring longer term exposure. Standard tests were carried out with algae, Daphnia and fish, and in addition a marine crustacean was tested. Because of the low water solubility of HHCB, it was necessary in the aquatic toxicity tests described below to prepare stock solutions using DMF as a solvent and Tween 80 as a dispersant or using triethylene glycol or ethanol as a solvent. These stock solutions were then diluted to reach the desired concentrations in the tests. The residual level of the solvent in the test vessel was always below the maximum level allowed by the test guidelines. Solvent controls containing equivalent levels of the solvents were used in all cases along with undosed water controls. HHCB has a strong tendency to sorb, thereby reducing the concentrations in solutions over time. Final concentrations in water were determined by HPLC or GC or, for radiolabelled HHCB, by LSC and the test concentrations are expressed as measured concentrations. Except for the highest concentration in the fish growth test, the tested concentrations did not exceed the water solubility limit.