Nitrogen monoxide

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: reliable conclusion that the study is impossible to perform

Data source

Reference

Reference Type:

other: Expert statement

Title:

Unnamed

Year:

2017

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

GLP compliance:

no

Remarks:

not applicable: study could not be carried out

Test material

Test material information

Constituent 1

Reference substance name:

Nitrogen monoxide

EC Number:

233-271-0

EC Name:

Nitrogen monoxide

Cas Number:

10102-43-9

Molecular formula:

NO

IUPAC Name:

oxidoamine

Results and discussion

Effect concentrations

Duration:

72 h

Remarks on result:

other: see results

Details on results:

Various contract laboratories were contacted to carry out an aquatic toxiicty study on algae on NO. None of them was able to carry out the requested study:

ENVIGO:
"The difficulties envisaged in preparing aqueous solutions of this gaseous test item coupled with the requirement to closely regulate pH levels to distinguish between pH induced toxicity and inherent toxicity mean that we are at the present time unable to commit sufficient resources to this project to be able to bring this to what we would consider a satisfactory conclusion. We are also unable to distinguish between the required analyte HNO3 and NO using currently available instrumentation at our site."

EUROFINS:
"Unfortunately, my research has not been conclusive and we are not able to do these test for two main reasons:
- The security: doing this test on gas demands high security conditions,
- Technical reasons. We do not have the experience to perform this kind of test on a gas and we don’t have the material to do this test on gas."

AGROCHEMEX:
"This is a study type we can offer and would be able to adapt the design to work with a gas, but unfortunately I do not think we could meet this timeline. We would however be happy to provide a report to state why the test would not be relevant in this situation. It is our opinion that your interpretation of the requirement is correct and that the pH adjustment seen from the nitric acid production would be the driving factor in terms of toxicity and that by pH correcting this you would not see the true toxicity."

TRISKELION:
"Triskelion is not having these studies in its portfolio."

CITOXLAB:
"Unfortunately we are not able to work with an insoluble gas in aquatic toxicology studies, as we have no experience in using this type of material in this type of study. We are sorry that we cannot assist you in the request."

LAUS:
"the test is not feasible in our lab for several reasons:
- the timeline is too short;
- the determination of N in the test solutions is difficult or not possible, due to a presence of N in the blank matrix
- the handling of gas is very difficult and need a lot of time for validation of method (if at all possible)"

Laboratoires des Pyrénées et des Landes:
"After discussion with my colleagues, I am very sorry but we cannot respond to your request. The fact that the test item is an oxidizing and compressed gas do not allow us to work on it, according to our internal safety procedures."

Applicant's summary and conclusion

Conclusions:

A total of 7 contract laboratories answered that they were unable to conduct the requested aquatic toxicity study on algae on NO.
This does not lead to a data-gap since the substance is a moderately soluble gas so it would not partition to water compartment: no Exposure. A detailed calculation of air-water partitioning coefficient can be found in the study waiver for Algae acute toxicity: Kair-water at 20°C = 21.4.