Pyridine-2-thiol 1-oxide, sodium salt

Toxicity to aquatic algae and cyanobacteria

Key value for chemical safety assessment

EC50 for freshwater algae:

0.46 mg/L

EC50 for marine water algae:

0.001 mg/L

EC10 or NOEC for freshwater algae:

0.08 mg/L

EC10 or NOEC for marine water algae:

0 mg/L

Additional information

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.

 

Further studies with the freshwater algae Anabaena flosaque using ZPT gave a value of 0.0038 mg/L.  

 

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

Table 6.1.5.1: Growth inhibition effects of NaPT on algae

Guideline / Test method	Species	Endpoint / Type of test	Exposure			Results (mg/L)		Remarks	Reference
			design	duration		NOEC	EC50
OECD 201	Fresh water algae Selenastrum capricornutum	Growth inhibition	Static	72 hours		0.08  (72 hr)	0.46 (72 hr)		6.1.5.001 ESPTF 7041-301 Smyth et al (1994)

Table 6.1.5.2: Growth inhibition effects of Pyridine-N-oxide-2-sulfonic acid on algae

Guideline / Test method	Species	Endpoint / Type of test	Exposure			Results (mg/L)		Remarks	Reference
			design	duration		NOEC	EC50
US EPA – 122-2	Fresh water algae Selenastrum capricornutum	Growth inhibition	Static	120 hours		11.8 (120 hr)	36.3 (120 hr)		6.1.5.006 EZPTF 7041-311 Boeri RL, Kowalski PL, Ward TJ (1994)

Table 6.1.5.3: Growth inhibition effects of Pyridine Sulphonic acid on algae

Guideline / Test method	Species	Endpoint / Type of test	Exposure			Results (mg/L)		Remarks	Reference
			design	duration		NOEC	EC50
US EPA – 122-2	Fresh water algae Selenastrum capricornutum	Growth inhibition	Static	120 hours		5.46  (120 hr)	28.9  (120 hr)		6.1.5.007 EZPTF 7041-312 Boeri RL, Kowalski PL, Ward TJ (1994)

Table 6.1.5.4: Growth inhibition effects of 2,2’-(pyridyl-N-oxide) disulphide on algae

Guideline / Test method	Species	Endpoint / Type of test	Exposure			Results (mg/L)		Remarks	Reference
			design	duration		NOEC	EC50
US EPA – 122-2	Fresh water algae Selenastrum capricornutum	Growth inhibition	Static	120 hours		0.080 (120 hr)	0.140 (120 hr)		6.1.5.004 EZPTF 7041-310 Ward TJ, Magazu JP, Boeri RL (1995)

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.