Reaction mass of hexadecyl dihydrogen phosphate and cetyl alcohol (mono- C16 PSE and C16-OH)

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Reason / purpose for cross-reference:

data waiving: supporting information

Reference 2

Endpoint:

toxicity to microorganisms, other

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Study period:

1988

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

Refer to section 13 of IUCLID for details on the read-across justification. The study with the read across substance is considered sufficient to fulfil the information requirements as further explained in the provided endpoint summary.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

DIN 38412-27 (Pseudomonas putida Zellvermehrungshemmtest)

Deviations:

not specified

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

not specified

Test organisms (species):

Pseudomonas putida

Test type:

not specified

Water media type:

not specified

Limit test:

no

Total exposure duration:

30 min

Details on test conditions:

The oxygen consumption rate of a bacterial suspension fed with glucose as nutrient base was measured after a contact time of 30 minutes. The oxygen consumption rate of the same bacterial suspension in the presence of various concentrations of a test substance under otherwise identical conditions was also measured. The inhibitory effect of the test substance at a particular concentration was expressed as a percentage of the mean oxygen consumption rates of the controls. An EC0 value could be determined from these measurements.

Key result

Duration:

30 min

Dose descriptor:

EC0

Effect conc.:

ca. 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

inhibition of total respiration

Key result

Duration:

30 min

Dose descriptor:

EC10

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

inhibition of total respiration

Details on results:

The water solubility of the lowest carbon chain length of the compound was approximately 0.01 mg/L, therefore the EC50 was not achieved at the solubility limit.

Validity criteria fulfilled:

not specified

Conclusions:

Based on the results of the read across study, a similar absence of toxicity up to the solubility limit can be expected for the test substance.

Executive summary:

A study was conducted to determine the effect of the read across substance, 'alcohols, C16-18 and C18-unsatd.' (purity not specified), on oxygen consumption rate of Pseudomonas putida, according to the DIN 38412 part 27. The oxygen consumption rate of a bacterial suspension fed with glucose as nutrient base was measured after a contact time of 30 minutes. The oxygen consumption rate of the same bacterial suspension in the presence of various concentrations of a test substance under otherwise identical conditions was also measured. The inhibitory effect of the test substance at a particular concentration was expressed as a percentage of the mean oxygen consumption rates of the controls. The water solubility of the lowest carbon chain length of the compound was approximately 0.01 mg/L, therefore the EC50 was not achieved at the solubility limit. Under the study conditions, the read across substance EC0, EC10 and EC50 values were determined to be 10000, >10000 and >10000 mg/L (nominal), respectively (OECD SIDS, 2006). Based on the results of the read across study, a similar absence of toxicity up to the solubility limit can be expected for the test substance, 'mono- C16 PSE and C16-OH'.

Description of key information

Based on the available weight of evidence from studies on the main constituents, similar absence of toxicity up to highest soluble test concentrations can be expected for the test substance, ‘mono- C16 PSE and C16-OH’ in microorganisms. Further, as a conservative approach, the lowest NOEC value of 100 mg/L (nominal), has been considered further for hazard/risk assessment.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

100 mg/L

Additional information

In absence of specific study with the test substance, the toxicity to microorganisms endpoint has been assessed based on studies for substances representative of the two main constituents, which can be categorised as phosphate esters (PSE) and alcohol. The results are presented below.

Constituent 1: PSE - read across study:

A study representing the toxicity to microorganisms due to exposure to PSEs, is not required, because the endpoint can be assessed based on a OECD 301F study available with read across substance ‘mono- and di- C16 PSE, K+ and H3PO4’, whose applied test concentration are considered to in the range of concentrations that can be expected for the test substance in the influent of a sewage treatment plant. The mean toxicity control degradation achieved on Day 14 of the read across biodegradation study (OECD 301F), was determined to be 40% (based on combined ThOD/COD), which was >25%, indicating that the substance was not inhibitory at the test concentration of 100 mg/L (nominal). Therefore, based on the read across study, the NOEC for toxicity to microorganisms can be considered to be at 100 mg/L (nominal).

Constituent 2: Alcohol – read across study

A study was conducted to determine the toxicity of alcohols, C16-18 and C18-unsatd. (purity not specified)) inPseudomonas putida, according to the DIN 38412 part 27. In this study, the oxygen consumption rate of a bacterial suspension fed with glucose as nutrient base was measured after a contact time of 30 minutes. The oxygen consumption rate of the same bacterial suspension in the presence of various concentrations of a test substance under otherwise identical conditions was also measured. The inhibitory effect of the test substance at a particular concentration was expressed as a percentage of the mean oxygen consumption rates of the controls. The water solubility of the lowest carbon chain length of the compound was approximately 0.01 mg/L, therefore the EC50 was not achieved at the solubility limit. Under the study conditions, the read across substance EC0, EC10 and EC50 values were determined to be 10000, >10000 and >10000 mg/L (nominal), respectively (OECD SIDS, 2006). Based on the results of the read across study, a similar absence of toxicity up to the solubility limit can be expected for the test substance, ‘mono- C16 PSE and C16-OH’.

Overall, based on the available weight of evidence information from the read across studies of the main constituents, Similar absence of toxicity up to highest soluble test concentrations can be expected for the test substance, ‘mono- C16 PSE and C16-OH’ in microorganisms. Further, as a conservative approach, the lowest NOEC value of 100 mg/L (nominal), has been considered further for hazard/risk assessment.