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Ecotoxicological information

Endpoint summary

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Summaries of all Aquatic Toxicity Studies are summarized in table form in the individual endpoint summaries.

For all of the three species (fish, invertebrates and algae), valid acute toxicity tests with NaPT are available. Further to this, acute toxicity tests are given for the relevant major metabolites from the degradation process for pyrithione ; Pyrithione sulphonic acid, Pyridine sulphonic acid and Pyrithione disulphide.

 

In addition, long-term tests for fish, plants and invertebrates are provided. Most of these results are determined for the equivalent substances Zinc and copper pyrithiones.


Studies on fish

The acute studies on fish indicate that NaPT is toxic to fish. The LC50values range from 0.0066 to 1.3 mg NaPT/L with Onchorynchus mykiss (rainbow trout) being the most sensitive species. The NOEC for this study was 0.0026 mg NaPT/L.

Further, acute toxicity studies in fish for the major metabolites indicate that the most toxic substance is Pyrithione disulphide with a NOEC of 0.011 mg/L, to the freshwater species Pimephales promelas (Fathead Minnow), but that this is many times less toxic than the parent compound Sodium Pyrithione. However, Pyrithione disulphide is very short lived in the environment (photolytic half-life is 2.5 minutes) and the most relevant degradant of NaPT is Pyridine sulphonic acid (PSA). The NOEC for PSA is 46.9 mg/L for the rainbow trout.

Studies on invertebrates

Acutestudies on invertebrates indicate that NaPT is toxic. The LC50values range from 0.022 to 0.15 mg NaPT/L.The lowest NOEC for these studies was 0.011 mg NaPT/L.

 

Further, acute toxicity studies in fish for the major metabolites indicate that the most toxic substance is Pyrithione disulphide with a NOEC of 0.006 mg/L, to daphnia magna. Pyrithione disulphide is very short lived in the environment and the most relevant degradant of NaPT is Pyridine sulphonic acid (PSA). The NOEC for PSA is 51.1 for the eastern oyster.

 

Studies on Algae

 

Studies on algae showed NOEC values of 0.08 mg/L for Selenastrum capricornutum which indicates that NaPT is toxic. The LC50values range was 0.46 mg/L mg NaPT/L.

 

Again PSA gave much higher values of 5.46 mg/L for the NOEC with Selenastrum.

 

Effects on microbial activity.

 

Two activated sludge respiration inhibition studies were carried out on NaPT and and EC10 value of 1.0 mg/L was determined.

The information contained within this robust summary document comes from studies which are in the ownership of Arch Chemicals Inc. and which are protected in several regions globally. This information may not be used for any purpose other than in support of the Chemical safety Report submitted by Arch Chemicals Inc. under RegulationEC 1907/2006.