Bis(4-methylbenzoyl)peroxide

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was performed under GLP according to protocol. It was reviewed in the HPV program and recorded in the OECD SIDS dossier as reliability 1.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

no

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Nominal and measured concentrations:

Nominal: 35, 46, 59, 77 and 98 mg/L

Reference substance (positive control):

not specified

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

46 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

74 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Conclusions:

This study is reliable. It is performed according to OECD guideline 201 under GLP and it was reviewed during the HPV process. The calculated endpoints are adequate for C&L and risk assessment purposes.

Executive summary:

For a freshwater algal species, Pseudokirchneriella subcapitata, the ecotoxicity of p-toluic acid was reported (MOE, 2003). The algal growth inhibition test (OECD TG 201) was carried out with nominal concentrations ranging from 35 to 100 mg/L in geometrical series (separating factor of 1.3) with a blank control. The concentration of test substance was monitored by analytical measurement using HPLC and showed that the mean measured concentration at each treatment group was 35, 46, 59, 77 and 98 mg/L, respectively. At the end of the test the test substance presented 99 - 101 % of nominal. At concentrations higher than 59 mg/L (mean measured concentration) significant inhibition of growth was observed. The Inhibition rate of growth rate at the concentration of 59, 77 and 98 mg/L were 6.5, 62 and 100 % (showed less cell count than initial), respectively, however pH at the start and the end in test water of corresponding concentrations were 6.9 - 7.8 (not harmful to algae), 6.6 - 6.8 (not harmful to algae) and 5.2 - 5.2 (slightly harmful to algae), respectively. The test is regarded as valid according to OECD TG 201 (updated version in 2006). From data on cell count the toxicity was calculated based on measured concentrations. The 72 h EC₅₀ values by rate method and area under growth curve method were 74 and 63 mg/L, respectively. Around these concentrations the low pH effect on algal growth should be negligible; therefore the reliability of toxicity presented here is regarded as high.

The 72 h NOECs by growth rate method and by area under growth curve method were estimated 46 and 46 mg/L, respectively.

Description of key information

For a freshwater algal species,Pseudokirchneriella subcapitata, the ecotoxicity ofp-toluic acid was reported (MOE, 2003). The algal growth inhibition test (OECD TG 201) was carried out with nominal concentrations ranging from 35 to 100 mg/L in geometrical series (separating factor of 1.3) with a blank control. The concentration of test substance was monitored by analytical measurement using HPLC and showed that the mean measured concentration at each treatment group was 35, 46, 59, 77 and 98 mg/L, respectively. At the end of the test the test substance presented 99 - 101 % of nominal.At concentrations higher than 59 mg/L (mean measured concentration) significant inhibition of growth was observed. The Inhibition rate of growth rate at the concentration of 59, 77 and 98 mg/L were 6.5, 62 and 100 % (showed less cell count than initial), respectively, however pH at the start and the end in test water of corresponding concentrations were 6.9 - 7.8 (not harmful to algae), 6.6 - 6.8 (not harmful to algae) and 5.2 - 5.2 (slightly harmful to algae), respectively. The test is regarded as valid according to OECD TG 201 (updated version in 2006). From data on cell count the toxicity was calculated based on measured concentrations. The 72 h EC₅₀values by rate method and area under growth curve method were 74 and 63 mg/L, respectively. Around these concentrations the low pH effect on algal growth should be negligible; therefore the reliability of toxicity presented here is regarded as high.

The 72 h NOECs by growth rate method and by area under growth curve method were estimated 46 and 46 mg/L, respectively.

Key value for chemical safety assessment

EC50 for freshwater algae:

74 mg/L

Additional information

Due to rapid hydrolysis of 895-85-2 (see van Dam, 2014), the aquatic results of p-toluic acid are considered most relevant.