Propyltriacetoxysilane

Short-term toxicity to aquatic invertebrates

Description of key information

Weight of evidence: Based on experimental results obtained in short-term toxicity to aquatic invertebrates studies with supporting substance acetic acid, read-across approach was applied and EC50 (48h) for propyltriacetoxysilane was calculated to be 89.59 mg/L (based on mobility and with no pH adjustment). 

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

89.59 mg/L

Additional information

Weight of evidence:

Read-across from experimental results with acetic acid:

In the first study, Janssen et. al., 1993 (reliability 2), an acute immobilisation test with acetic acid was performed according to an equivalent method to OECD Guideline 202. The EC50 in Daphnia magna for 48h exposure period was 65 mg/L (basis for effect: mobility). Based on this experimental result, read-across approach from the supporting substance acetic acid was applied and EC50 (48h) for propyltriacetoxysilane was calculated to be 89.59 mg/L (based on mobility and with no pH adjustment).

In the study by Bringmann et. al, 1982 (reliability 2), a largely standardized procedure of water toxicology for testing the potential toxic action of water pollutants measured by the immobilization of Daphnia magna according to DIN 38412, Part II guideline (Daphnia short-time test) was performed. The EC50 (48h, basis for effect: mobility) for acetic acid was 95 mg/L with no pH adjustment and 6000 mg/L with pH adjustment. Based on this result, read-across approach from supporting substance acetic acid was applied and EC50 (48h, basis for effect: mobility) for propyltriacetoxysilane was calculated to be 130.94 mg/L with no pH adjustment and 8270.11 with pH adjustment.

In the study by Dowden et. al., 1965 (reliability 4), the EC50 of 86 chemicals was determined using a standardised method. The 24h EC50 of acetic acid for Daphnia magna was determined to be 47 mg/L (basis for effect: mobility). Based on this result obtained with the supporting substance acetic acid, read-across approach was applied and the EC50 (48h, based on mobility) for propyltriacetoxysilane was calculated to be 64.78 mg/L.

In the published study by Saha et. al., 2006 (reliability 4), an acute toxicity test was performed with Moina micrura in a renewal system. Based on the experimental results obtained with the supporting substance acetic acid for Moina micrura (96h LC50 = 163.72 mg/L, basis for effect: mortality), the read-across approach was applied and the 96h LC50 for propyltriacetoxysilane was calculated to be 225.66 mg/L.

Supporting studies:

Read-across from experimental results with acetic acid and sodium acetate:

There are two supporting studies from Anderson, 1944 (reliability 4) and Bringmann et. al., 1977, (reliability 3) performed for the supporting substances acetic acid and sodium acetate respectively. In the first one and based on the experimental results with supporting substance acetic acid (16h NOAEC = 150 mg/L for Daphnia magna and basis for effect: mobility), read-across approach was applied and the 16h NOAEC for propyltriacetoxysilane was calculated to be 206.75 mg/L. In the second study and based on the experimental results with supporting substance sodium acetate (24h LC50 = 7170 mg/L for Daphnia magna and basis for effect: mobility), the read-across approach was applied and the 24h LC50 for propyltriacetoxysilane was calculated to be 7234.68 mg/L.

According to the available information on short-term toxicity to aquatic invertebrates, could be pointed out that the toxicity of propyltriacetoxysilane is caused by the pH effect of acetic acid since the read-across approach applied from experimental data with acetic acid (EC50 (48h): 89.59 mg/L, no pH adjustment; EC(24h): 130.94 mg/L) is much more restrictive than the results obtained with the read-across approach from experimental data with sodium acetate, the neutralised form of the acid (LC50 (24h): 7234.68 mg/L). In the same way, in the study performed by Bringmann et. al. 1982 with acetic acid and after applying the read-across approach, the LC50 (24h) calculated for propyltriacetoxysilane was 130.94 mg/L with no pH adjustment and 8270.11 mg/L with pH adjustment.

Key value for chemical safety assessment:

According to the read-across approaches from experimental results with supporting substance acetic acid, the propyltriacetoxysilane key value for chemical safety assessment is calculated to be EC (48h) = 89.59 mg/L (based on mobility, with no pH adjustment). This value is the most restrictive result and it was obtain in the reliable study by Janseen et.al., 1993 (Klimisch 2) during an observation period of 48 h. Although an EC (24h) = 64.78 mg/L was obtained by the read-across approach from the study by Dowden et. al., 1964, it was excluded for chemical safety assessment since the study was not assignable (Klimisch 4) with an observation period of 24 h.