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Toxicity to microorganisms

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Endpoint:
toxicity to microorganisms, other
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
The study was well documented and meets generally accepted scientific principles, but was not conducted in compliance with GLP.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Non-quantitative study of effect of increasing concentration of test substance on the sewage treatment process
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Test organisms (species):
activated sludge
Test type:
flow-through
Water media type:
freshwater
Limit test:
no
Total exposure duration:
70 d
Remarks on exposure duration:
With stepwise increase of test substance concentration
Reference substance (positive control):
no
Duration:
53 d
Dose descriptor:
NOEC
Effect conc.:
300 mg/L
Nominal / measured:
nominal
Conc. based on:
not specified
Basis for effect:
other: MBAS reduction
Duration:
54 d
Dose descriptor:
LOEC
Effect conc.:
400 mg/L
Nominal / measured:
nominal
Conc. based on:
not specified
Basis for effect:
other: MBAS reduction
Details on results:
A artifical sewage treatment plant was continuously fed with nutrient and anionic surfactant plus increasing concentrations of HEDP. Up to a concentration of 300 mg/l the MBAS reduction (methylene blue substance - analytical parameter for anionic surfactants) was not impaired. After increase of HEDP concentration to 400 mg/L the MBAS reduction was reduced but recovered within 5 days. The MBAS reduction was reduced again after an increase of the HEDP concentration in the inflow to 600 mg/l.
Conclusions:
A non-standard study of effects on aerobic sewage treatment process micro-organisms was conducted according to generally accepted scientific principles but lacks detail in the study report. The result of a lack of effects on respiration up to 300 mg/L provides reliable evidence.
Endpoint:
toxicity to microorganisms, other
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
The study was well documented and meets generally accepted scientific principles, but was not conducted in compliance with GLP.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Non-quantitative study of effect of increasing concentration of test substance on the anaerobic sewage sludge treatment process
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Test organisms (species):
anaerobic sludge
Test type:
not specified
Water media type:
not specified
Limit test:
no
Total exposure duration:
11 d
Reference substance (positive control):
no
Duration:
11 d
Dose descriptor:
NOEC
Effect conc.:
200 mg/L
Nominal / measured:
nominal
Conc. based on:
not specified
Basis for effect:
other: sewage gas production volume
Duration:
11 d
Dose descriptor:
LOEC
Effect conc.:
500 mg/L
Nominal / measured:
nominal
Conc. based on:
not specified
Basis for effect:
other: sewage gas volume reduced and fermentation delayed
Details on results:
At 50 mg/L HEDP showed no effects.
At 200 mg/L the start of fermentation was delayed, but constant gas volume was achieved in the same period as in the control.
At 500 mg/L HEDP, the system was strongly disturbed, as indicated by a late beginning of fermentation, and greatly reduced sewage gas production volume.
Conclusions:
A non-standard study of effects on anaerobic sewage sludge treatment process micro-organisms was conducted according to generally accepted scientific principles but lacks detail in the study report. The result of a lack of effects on fermentation up to 200 mg/L provides reliable evidence.
Endpoint:
toxicity to microorganisms, other
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions
Remarks:
The study was conducted according to an appropriate national standard method. It was not compliant with GLP.
Qualifier:
equivalent or similar to
Guideline:
DIN 38412-8 (Pseudomonas Zellvermehrungshemmtest)
Version / remarks:
Test uses P phosphoreum. Also cites draft DIN Leuchtbakterientest.
Principles of method if other than guideline:
Short term test using luminosity of P. phosphoreum as an indicator of inhibition. Test using microtox reactor
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Test organisms (species):
Photobacterium phosphoreum
Test type:
not specified
Water media type:
freshwater
Limit test:
no
Total exposure duration:
30 min
Reference substance (positive control):
no
Duration:
30 min
Dose descriptor:
IC0
Effect conc.:
> 250 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: luminescence
Remarks on result:
other: IC0 estimates derived from tests conducted at 3 concentrations
Conclusions:
A reliable IC0 value of >250 mg/l has been determined for the effects of HEDP-xNa on the bioluminescence of the bacterium Photobacterium phosphoreum.

Description of key information

The available data provide a general weight of evidence of a lack of inhibition of aerobic and anaerobic WWTP micro-organisms at concentrations up to ca. 200 mg active acid/L, equivalent to 286 mg HEDP-4Na/L.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
286 mg/L

Additional information

A respiration inhibition test with aerobic bacteria P. putida following the test guideline DIN 38412 part 27 showed the result EC0 = 580 mg/L within a contact time of 30 minutes. However full details are not available. The general test principle was comparable to the OECD 209 method.

A non-standard reliable study of effects on anaerobic sewage treatment plant micro-organisms was conducted according to generally accepted scientific principles but lacks detail in the study report. The result of a lack of effects on bio-gas production up to at least 200 mg active acid/L provides reliable evidence.

A non-standard reliable study of effects on aerobic sewage treatment plant micro-organisms was conducted according to generally accepted scientific principles but lacks detail in the study report. The result of a lack of effects on MBAS reduction up to 300 mg active acid/l provides reliable evidence.

A reliable IC0 value of >250 mg/l has been determined for the effects of HEDP-zNa on the bioluminescence of the bacterium Photobacterium phosphoreum (Grohmann and Horstmann 1989).

These studies have been used as weight of evidence to demonstrate the low toxicity of HEDP-4Na to micro-organism toxicity.

Other data of rel. 4 have determined the low toxicity of HEDP-4Na towards micro-organisms.

HEDP acid (2809-21-4) can be read across to HEDP salts. The main assumption is that sodium is not significant in respect of all the properties under consideration (and would not influence effects on micro-organisms). In dilute aqueous conditions of defined pH a salt will behave no differently to the parent acid, at identical concentration of the particular speciated form present and will be fully dissociated. Hence some properties (measured or expressed in aqueous media, e.g. ecotoxicity) for a salt can be directly read across (with suitable mass correction) to the parent acid and vice versa.

Here, the value of 200 mg active acid/L may be directly read-across. It is convenient to convert the result into units of mg HEDP-4Na salt/L.

 

The NOEC for HEDP 2809-21-4 is 200 mg/L, which is equivalent to a NOEC value of 200 * 1.43 = 286 mg/L HEDP-4Na (CAS 3794-83-0)

 

Using: MW(HEDP-4Na)/MW(HEDP) = 293.96 / 206.03 = 1.43