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Short-term toxicity to fish

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Description of key information

The value of 149.5 mg (SO3)2-/L is put forward for the environmental classification of sulfite/disulfite compounds.	

Key value for chemical safety assessment

LC50 for freshwater fish:
149.5 mg/L

Additional information

Four reliable acute fish toxicity studies that could be used for the hazard and effects assessment of sulfites and disulfites were identified. Tested fish species were Brachydanio rerio (new name: Danio rerio), Salmo gairdneri (new name: Oncorhynchus mykiss) and Leuciscus idus. Tested compounds were potassium sulfite, potassium metabisulfite, sodium pyrosulfite and sodium sulfite.

 

Compound

MM

%S

LC50

(mg test item/L)

LC50

(mg S/L)

LC50

(mg SO32-/L)

K2SO3

158.26

20.3

316(1)

64.0

159.7

K2S2O5

222.32

28.8

681.2(2)

195.5

490.0

Na2SO3

126.4

25.4

316(1)

80.4

200.5

Na2S2O5

190.1

33.7

177.8 ((3)

60.0

149.6

(1): geometric mean of two concentration levels: 215 mg/L (0% mortality) and 464 mg/L (100% mortality)

(2): geometric mean of two concentration levels: 464 mg/L (10% mortality) and 1000 mg/L (100% mortality)

(3): geometric mean of two concentration levels: 147 mg/L (0% mortality) and 215 mg/L (90% mortality)

 

Expressed as sulfite (SO32-), the lowest 96h-LC50 was 149.6 mg sulfite/L, and this for the trout S. gairdneri (new name: O. mykiss) (test with sodium metabisulfite). This value is put forward for environmental classification purposes of sulfite/disulfite compounds.

It should be noted that in most tests the mortality was related to the sulfite-induced oxygen depletion of the test medium: concentration levels that previously resulted in 100% mortality showed no effect at all when the test media was aerated during the test period. For the test with the trout S. gairdneri,however, observed mortality was related to very low pH levels in the test medium upon addition of the test substance. At concentration level of 215 mg/L (90% mortality), pH levels were situated between 4.3 and 5.6.

 

The value of 149.5 mg SO32-/L is put forward for the environmental classification of sulfite/disulfite compounds.