1-nitropropane

Toxicity to aquatic algae and cyanobacteria

Description of key information

Two freshwater algal growth inhibition studies were conducted with 1-nitropropane according to the OECD 201 algal growth inhibition toxicity guideline.  The most recent test (2009) was conducted under GLP while the older test was a non-GLP study.  In addition, a QSAR value for freshwater green algae was generated using the USEPA ECOSAR v1.00 model as part of EPISuite v4. 
The key study for freshwater algal toxicity is the most recent Pseudokirchneriella subcapitata growth inhibition test.  This test was conducted under GLP, using sealed-vessel conditions to minimize loss of test chemical due to the volatile potential for the chemical.  Analytical verification of test solutions was conducted and demonstrated that test concentrations were on target.  The results are calculated based on geometric mean measured concentrations.  The 72-hour ErC50 (based on growth rate) was determined to be > 456 mg 1-nitropropane/L.
The supporting study determined a similar value with a 72-hour EC50 value of 98 mg 1-nitropropane/L.  The test organism was Desmodesmus subspicatus.  The report did not specify the endpoint so this could possibly be the cell density or area under the curve endpoints which would be expected to be lower than the growth rate endpoints.

Key value for chemical safety assessment

EC50 for freshwater algae:

456 mg/L

Additional information

Two freshwater algal growth inhibition toxicity tests were conducted with freshwater green algal species exposed to 1-nitropropane according to the OECD 201 algal growth inhibition test guideline. The most recent test (2009) was conducted under GLP while the older test was a non-GLP study.  In addition, a QSAR value for freshwater green algae was generated using the USEPA ECOSAR v1.00 model as part of EPISuite v4.

The key study for freshwater algal growth inhibition toxicity is the most recent test. This test was conducted under GLP, using sealed-vessels with zero-headspace to minimize loss of test material due to the volatile potential for the chemical. The test organism wasPseudokirchneriella subcapitata.  Analytical verification of test solutions was conducted and demonstrated that test concentrations were on target. The results are calculated based on geometric mean measured concentrations. The 72-hour ErC50 based on the specific growth rate endpoint was 456 mg 1-nitropropane/L.

 

The report for the earlier study did not provide adequate detail on test conditions or test methods to be considered a key study.  The test organism wasDesmodesmus subspicatus. The exposures were performed sealed test vessels with enriched CO2 atmospheres. Multiple exposures were conducted.  The mean 72-hour EC50 value was 1088 mg1-nitropropane/L. The report did not specify the endpoint so this could possibly be the cell density or area under the curve endpoints which would be expected to be lower than the growth rate endpoints.  

 

The ECOSAR LC50 value was 93.7 mg/L, which was considerably lower than the experimentally derived EC50 values.

                                                                                                              

These results indicate that 1-nitropropane is not dangerous to freshwater green algal species.