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Additional information

Ecotoxicity tests according to OECD Guidelines under GLP were available for the three trophic levels:

AQUATIC INVERTEBRATES:

Tin tetrachloride was investigated for acute toxicity to Daphnia magna in a static limit test according to OECD 202 under GLP. The 48-hour NOELR was determined to be >= 100 mg test item/L (nominal). The 48-hour EL50 value was determined to be > 100 mg test item/L (nominal). The validity criteria were fullfilled. It can be concluded that the EC50 is above the solubility limit of tin tetrachloride or its hydrolysis prproducts under the reported conditions. The concentration of free Tin(IV) was below the limit of detection.

ALGEA

Tin Tetrachloride was examined for toxicity on freshwater green algae Pseudokirchneriella subcapitata in a static dose-response test according to OECD Guideline 201 and ISO 14442 Water Quality - Guidelines for Algal Growth Inhibition Tests with Poorly Soluble Materials,Volatile Compounds, Metals and Waste Water. The medium was EDTA free to prevent from complexation of free tin(IV). The validity of the test desing was evaluated in a separate study with poatassium dicromate. All validity criteria were fullfilld. The 72-hour ErL50 value was observed to be >100 mg test item/L, the 72-hour EbL50 was determined to be between 1.0 and 3.2 mg test item/L and the 72-hour EyL50 was observed to be < 1.0 mg test item/L. The 72-hour NOELR were determined to be < 1.0 and the associated 72-hour LOELR are ≤ 1.0 mg/L for all endpoints. It can be concluded that the ICr50 is above the solubility limit of tin tetrachloride or its hydrolysis prproducts under the reported conditions. The concentration of free Tin(IV) was below the limit of detection.

FISH

The effects of Tin tetrachloride on Brachydanio rerio were investigated in an acute fish toxicity test with static desing at a limit dose of 1000 mg/L according to OECD 201 under GLP. The control was valid. Tin tetrachloride did not induce acute toxic effects in Brachydanio rerio at a nominal concentration of 1000 mg/L.

ADDITIONAL DATA

Further results were available in an OECD SIDS document (see table 1). Wong et al reported an IC50 of 12 mg/L for one of three examined algeal species, the other two were >5 and >50 mg/L. In summary these experiments support the thesis that toxicity from tin(IV) ions to aquatic organisms is restricted by the solubility limit of the hydrolysis products.

Table 1: Additional information from OECD SIDS

Species

Protocol/ Method

Duration

Test Substance Composition

Test System

Observations and Conditions

Result

Rating

Reference

Algae

Anabaena flos-aquae

(Blue-green algae)

Primary productivity

24 h

SnCl4

(purity unknown)

No Data, nominal

Test medium was buffered to pH 8.

IC50 >5 mg Sn/L

(>11 mg/L as SnCl4)

2

Wong et al. 1982

 

Scenedesmus quadricauda(Green algae)

Primary productivity

24 h

SnCl4

(purity unknown)

No Data, nominal

Test medium was buffered to pH 8.

IC50 >50 mg Sn/L

(>110 mg/L as SnCl4)

2

Wong et al. 1982

 

Ankistrodesmus falcatus(Green algae)

Primary productivity

24 h

SnCl4

(purity unknown)

No Data, nominal

Test medium was buffered to pH 8.

IC50 = 12 mg Sn/L

(26 mg/L as SnCl4)

2

Wong et al. 1982

 

Synechocystis aquatilis(Blue-green algae)

Growth and chlorophyll-a content

96 h

Stannic chloride pentahydrate

(purity unknown)

No Data, nominal

At pH 7, no inhibiting influence on the test species noted; growth comparable to controls. 

IC50 >10 mg Sn/L

(>23 mg/L as stannic chloride pentahydrate)

2

Pawlik-Skowronska et al. 1997

 

 Microorganisms                        

 OECD TG 209  Inhibition  30 min     

No Data, nominal

   EC0 = 5400 mg/L  2     Höchst AG 1994

CONCLUSION

The solubility of tin tetrachloride, respectively its hydrolysis products is limited. Based on the observed slight signs of toxicity in the algea test it can be assumed that the solubility limits the toxic effects. Nevertheless effects on aquatic organismns can be expected by pH-shifts, as 1 mol SnCl4 releases 4 mol of HCl. Based on current guidelines and practices labelling of tin tetrachloride as acute harmful to aquatic organisms is not indicated. This is contrary to the current EU legal classification, that classifies tin tetrachloride as acute auqutic 3 and chronic aquatic 3.

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