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EC number: 225-768-6 | CAS number: 5064-31-3
Toxicity to microorganisms
Administrative data
Link to relevant study record(s)
Description of key information
Swisher et al. (1967) provided results from a continuous biodegradation study with activated sludge. Results indicate a NOEC of > 270 mg/L Na3NTA (> 200 mg/L NTA). A read-across approach from H3NTA to Na3NTA is applied (for justification of read-across please refer to IUCLID section 13).
Key value for chemical safety assessment
- EC10 or NOEC for microorganisms:
- 270 mg/L
Additional information
Swisher et al. (1967) presented results from continuous and semicontinuous biodegradation study for NTA and is considered the Key Study. Results indicated a NOEC of > 270 mg/L Na3NTA (>200 mg/L NTA).
Bringmann et al. (1980) provided a toxicity threshold value of > 400 mg/L NTA (>540 mg/L Na3NTA) for Chilomonas paramaecium using an analogous method of the cell multiplication test. Bringmann & Kuhn (1977) determined the toxicity threshold (TT) value of (EC5) of >10,000 mg/L Nitrilotriacetic acid (NTA) for Pseudomonas putida using an analogous method of the cell multiplication test. Bringmann (1978) and Bringmann and Kuhn (1980) provided results for microorganisms using an analogous method of the cell multiplication test where the EC5 was >800 mg/L NTA (>1,100 mg/L Na3NTA) for both studies. While these studies provide support for the toxicity of NTA to protazoan species, the purpose of the protazoan tests were not for effects to STP. Therefore, they were determined to be not relevant for calculating the PNEC. Canton and Sloof (1982) provided an EC50 range of 3,200 -5,600 mg/L NTA for Pseudomonas fluorescens eight hour exposure. This study is not considered valid as glucose was used as the testing substrate. All of the studies (except for Swisher et al.) are considered unreliable but can be used as weight of evidence for the toxicity of NTA to microorganisms. Results from these studies are generally within the same toxicity range. As described in the EU Risk Assessment - Trisodium Nitrilotriacetate Report (2005), it can not be ruled out that toxic effects could be due to nutrient deficiency caused by the chelating effects of NTA and the resulting reduced concentrations of essential metals within the test solutions. However, these results can provide a conservative approach.
| Species | Test Duration | Effect Measured | Endpoint | Endpoint Value (mg/L) | Reference | Reliability |
| Pseudomonas fluorescens | 8 hr | cell inhibition / biomass | EC50 | 3,200 - 5,600 | Canton and Sloof 1982 | 3 -not reliable |
| Pseudomonas putida | 16 hr | cell inhibition / biomass | EC5 | > 10,000 | Bringmann and Kuhn 1977 | 3 -not reliable |
| Chilomonas paramaecium | 48 hr | cell inhibition / biomass | toxicity threshold | > 400H3NTA or > 540 Na3NTA | Bringmann et al. 1980 | 3 -not reliable |
| Entosiphon sulcatum | 72 hr | cell inhibition / biomass | toxicity threshold | > 800 H3NTA or > 1,100 Na3NTA | Bringmann 1978 | 3 -not reliable |
| Uronema parduzci | 72 hr | cell inhibition / biomass | EC5 | > 800 H3NTA or > 1,100 Na3NTA | Bringmann and Kuhn 1980 | 3 -not reliable |
| activated sludge | 90 days | biodegradation | NOEC | > 200 H3NTA or> 270 Na3NTA | Swisher et al. 1967 | 2 - reliable with restrictions |
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