Pentadecan-15-olide

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

2.7 µg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.27 µg/L

Assessment factor:

100

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

10 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

21 mg/kg sediment dw

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

4.2 mg/kg sediment dw

Assessment factor:

50

Extrapolation method:

assessment factor

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

5.44 mg/kg soil dw

Assessment factor:

100

Extrapolation method:

assessment factor

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential to cause toxic effects if accumulated (in higher organisms) via the food chain

Additional information

Justification for Read-Across

Please refer to the justification document attached to section 13. 

Environmental fate and pathways

No information about the abiotic degradation of the substance is available. But as the substance is readily biodegradable (two reliable screening studies fulfilling the 10-day window), the substance is considered rapidly degradable in the environment. Therefore, no environmental persistence of the substance is anticipated and no further tests on degradation in the environment are necessary.

The adsorption potential of the substance was evaluated in a GLP OECD 121 study on a read-across substance (EC number: 422-320-3) in which a Koc of 44500 was determined. The substance can be considered as strongly binding to soil and sediment and therefore immobile in soil and sediments based on the system proposed by McCall et al. (1980).

Furthermore, it is assumed that the substance evaporates from water surfaces under environmental conditions due to its high Henry’s Law constant (68.1 Pa.m3/mol at 25°C).

The BCF of the substance was calculated using the BCF/BAF method of Arnot-Gobas including biotransformation rate, resulting in a BCF value between 500 and 1000 regardless of the trophic level. The B criterion is not fulfilled for the substance and thus, the substance is considered to be not bioaccumulative. It would be technically challenging to perform a BCF study on fish at concentrations below the NOEC (of 0.027 mg/L) as apart from the low water solubility, the substance also has a high adsorption coefficient and readily biodegrades. Furthermore the ready degradation implies rapid metabolism so significant bioaccumulation is not expected and an experimental BCF study would not be expected to add significantly to the knowledge already gained for bioaccumulation.

 

Aquatic Toxicity

To assess the aquatic toxicity of the substance, studies are available on the registered substance and on a read-across substance (EC Number: 422-320-3).

Three weight of evidence studies are available to assess the short-term toxicity of the substance to fish. The first weight of evidence study (Caspers, 1994) was performed according to EU Method C.1 with GLP statement on the registered substance but was not deemed as reliable as aeration was used and substance loss may have occurred due to this. The two other weight of evidence studies (Stäbler, 2005 and Sewell, 1995) were performed according to OECD Guideline 203 and EU Method C.1 with GLP statement on the read-across substance and were considered reliable with restrictions. No effects were observed on fish over a 96 hours study period at any concentration up to the solubility limit of the test substance. Therefore, no acute LC50 value can be calculated for fish.

Five studies are available to assess the acute aquatic toxicity to invertebrates, of which two were performed on the registered substance (Harris, 2013; Caspers, 1995) and three were performed on the read-across substance (Harris, 2013; Stäbler, 2005a; Stäbler, 2005b). In these 48 h daphnid acute studies, no effects were found up to and including the maximum solubility of the test substance in aqueous test medium, except the study from Stäbler (2005b) where effects were observed but well above maximum water solubility and quite obviously due to physical adhesion to an oily film at the test vessel surface. No EC50 can therefore be calculated for acute effects on invertebrates.

Four studies are available to assess the toxicity of the substance to aquatic algae. The first study (Caspers, 1996), assessed as the key study, was performed according to EU Method C.3 with GLP statement on the registered substance. Under the conditions of this test,no ErC50 value can be derived for algae either as insufficient toxicity was observed (72h-ErC50 > 0.47 mg/L, the highest tested concentration) but some effects were observed indicating a potential for mild toxicity close to the solubility limit in the early stages of the study, although the 72h-ErC10 value based on growth rate was greater than the solubiltiy limit at 0.42 mg/L. The other studies (Scheerbaum, 2005; Dengler, 2005; Sewell, 1995), assessed as supporting studies, were performed according to OECD Guideline 201 and EU Method C.3 with GLP statement on the read-across substance. No ErC50 value can be derived for algae because either insufficient toxicity was observed or effects were observed at concentrations greater than the solubility limit. However, some mild effects were observed, especially in the first day of the study although this diminished over the study period, indicating a mild potential for toxicity close to the solubility limit (worst case 72h-ErC10 value at 0.73 mg/L), but it is not clear if these effects are physical or due to actual toxicity of the substance. It is not possible to maintain this concentration under the conditions of an algae study due to degradation and adsorption of the substance during the test.In conclusion, according to the key study performed on the registered substance, no ErC50 can be derived for algae but the 72h-ErC10 at 0.42 mg/L is used as the key value, greater than the solubility limit of the registered substance.

One key study is available to assess the long-term toxicity to fish. This study (Sewell, 2003) was performed according to international guidelines with GLP statement on the read-across substance to assess the effects of the test material on freshly laid eggs of the fathead minnow (Pimephales promelas). Despite significant limitations concerning out of bounds and systematic differences between groups for temperature, unexplained mortality in a single replicate and statistical differnces between the control and solvent control, the study is nevertheless considered valid but an extreme worst caseendpointvalue. The NOEC value, based on the mean measured test concentrations of the centrifuged test media, was considered to be 0.027 mg/L, in terms of length and weight.

Two studies are available to assess the long-term toxicity of the substance to aquatic invertebrates.The first study (Caspers, 1996), assessed as the key study, was performed on the registered substance following a method similar to OECD Guideline 211 with GLP statement. The 21d-NOEC based on reproduction and the time-weighted mean of measured test concentrations of the test media was 0.068 mg/L.The second study (Sewell, 2002), assessed as the supporting study, was performed according to OECD Guideline 211 with GLP statement on the read-across substance. The 21d-NOEC based on the time-weighted mean of measured test concentrations of the test media was 0.039 mg/L. This result should be considered with care.Both effect patterns are similar between these two studies (100% mortality at the highest concentration in each test and no effects were observed at all other concentrations). This set of results is not ideal to derive a reliable NOEC as there is no dose response relationship, however, both the measured concentrations and effects observed of these studies seem very much consistent. The study from Caspers provides a better approximation of the NOEC value than the study from Sewell based on tested concentrations because the difference between the NOEC and the LOEC is significantly greater (a factor of 4.1) than for the study on the registered substance (a factor of 1.9). Therefore, the key value retained for the long-term toxicity to aquatic invertebrates is a NOEC value of 0.068 mg/L.

Two studies are available to assess the toxicity of the substance to microorganisms. The first activated sludge respiration inhibition test (Dengler, 2005), assessed as the key study, was performed according to OECD Guideline 209 and EU Method C.11 with GLP statement on the read-across substance. There was no inhibitory effect of the test item at any concentration. The EC50 and NOEC were above 100 mg/L. The second activated sludge respiration inhibition test (Caspers, 1996), assessed as the supporting study, was performed according to ISO Guideline 8192, similar to OECD Guideline 209 with GLP statement on the registered substance. No deviation from the negative control was observed, whatever the substance concentration, therefore the EC50 is considered to be greater than 10 000 mg/L. In conclusion, according to the key study, the key NOEC value used for chemical safety assessment is taken as 100 mg/L as a worst case value.

In conclusion, no effects were found in acute studies although they were observed in long term studies on daphnids and fish with fish being the most sensitive endpoint. The key NOEC value used for PNEC derivation is 0.027 mg/L, for fish.

Sediment Toxicity

Three key chronic studies according to the OECD Guideline 218, 225 and ISO 10872 (2010) with GLP standards are available conducted on a read-across substance (EC Number : 422-320-3).

The first key study (Sewell, 2003) evaluated the effect of the test substance on survival and reproduction to the sediment-dwelling oligochaete Lumbriculus variegatus. Following a range-finding study, 40 worms (4 replicates of 10 worms) were exposed to artificial sediment spiked with test material at nominal concentrations of 100, 180, 320, 560 and 1000 mg/Kg (dry weight of sediment) for a period of 28 days. The numbers of worms were recorded at the end of the test. Given the decline in measured test concentrations it was considered justifiable to calculate the results based on the mean measured test concentrations. The Day 28 EC50 (reproduction) based on mean measured test concentrations was 630 mg/Kg with 95% confidence limits of 470 - 1100 mg/Kg dw. The NOEC was 210 mg/Kg dw.

The second key study (Memmert, 2006) evaluated the toxic effects of the test substance on the development of sediment-dwelling larvae of the midge Chironomus riparius in water-sediment systems. Five concentrations of the test item (63, 125, 250, 500 and 1000 mg/Kg dry sediment) and 2 controls (a control and a solvent control group) were tested. The test item was spiked into the sediment and first instar larvae were subsequently introduced into the static sediment-water systems. First-instar larvae of Chironomus riparius were exposed for a period of 28 days to assess the impact on full maturation of the larvae to adult midges. Since the test substance showed the majority of degradation in the sediment between Day 0 and Day 7 of the test period, the results was based on the geometric mean value of the analytically measured concentrations in the sediment on Day 0 and 7 (192 mg/kg dw at nominal 1000 mg/kg dw). Thus, the 28-d NOEC was at least 192 mg/Kg dw and the 28-d LOEC was clearly higher than 192 mg/Kg dw as no effects were observed in this study.

The third key study (Winkelmann, 2013) evaluated the toxic effects of the test item on the development of sediment-dwelling Caernorhabditis elegans following the ISO 10872 (2010) with GLP statement. After a range finding study at 10, 100 and 1000 mg test substance/kg sediment dry weight, only the 1000 mg/kg dry sediment concentration was performed in the final study. 2 controls (a control and a solvent control group) were tested and a positive control with Benzyldimethylhexadecylammonium chloride (99.7 %) was also tested. The study was performed under a static system for 4 days. All results from the study lead to the conclusions that LOEC and NOEC (Mortality, Fertility, Reproduction, Growth) are above 1000 mg/kg sediment dry weight. No effects were observed in this study.

As the NOEC values of the second and the third key studies are not true NOEC values, the calculated NOEC of 210 mg/kg dw obtained in the first key study is used for the chemical safety assessment.

 

Terrestrial Toxicity

Three key studies are available to assess the terrestrial toxicity of the substance. These studies were performed on a read-across substance (EC Number: 422-320-3).

The first study (Shacklady, 2001) is an acute study, performed according to the OECD Guideline 207 with GLP statement, on the earthworm Eisenia foetida in an artificial soil. No acute effects were observed, therefore, the 14-d LC50 for the test substance to earthworms based on nominal test concentrations was greater than 1000 mg/kg dw, the maximum concentration tested.

The second study (Winkelmann, 2013) is a chronic study, performed according to the OECD Guideline 222 with GLP standards, on the earthworm Eisenia foetida, in an artificial soil. No chronic effect were observed, therefore, the 56d-NOEC based on mortality, growth and earthworm reproduction based on initial measured test concentrations was >= 544 mg/kg soil dry weight, the maximum concentration tested.

The third study (Teixeira, 2002) is an acute study, performed according to the OECD Guideline 208 with GLP standards, on seedling emergence and dry shoot weight of three plant species: oat (Avena sativa), soybean (Glycine max) and tomato (Lycopersicon esculentum). No toxicity was observed for all species during this period, therefore, the 26d- EC50 were greater than 1000 mg/Kg, the maximum concentration tested.

In conclusion, the acute EC50/LC50 values were greater than 1000 mg/Kg dw and the chronic NOEC value was >= 544 mg/Kg dw.

Conclusion on classification

As no acute toxicity was found in any case the substance should not be classified as acutely toxic.

As chronic aquatic toxicity was observed at 0.027 mg/L and the substance is readily biodegradable and the log Kow is >4, the substance is not classified under DSD but is classified as Chronic Category 2 under CLP.