Reaction mass of Phenol, dodecyl-, sulfurized, calcium salts and benzene and butene and calcium carbonate and calcium dihydroxide and sulphur trioxide

Toxicity to aquatic algae and cyanobacteria

Description of key information

A key study- The 72h EL50 of EC -903-161-3 on the growth of P. subcapitata was concluded to be > 100 mg EC-903-161-3/ L and the no-observed effect loading rate (NOELR) was concluded to be =100 mg/L. These values were adjusted to account for the base oil solvent content of the sample tested (40.2%) , therefore EL50 of > 59.8 mg/L & NOELR of =59.8 mg/L are derived.
A supporting study- The 72h EL50s of an appropriate analogue substance was concluded to be >1000 mg/L for growth & growth rate. The NOEL was concluded to be 1000 mg/L for growth rate and 125 mg/L for growth. 

Key value for chemical safety assessment

EC50 for freshwater algae:

59.8 mg/L

EC10 or NOEC for freshwater algae:

59.8 mg/L

Additional information

A key study was designed to determine the effects of EC-903-161-3 on the growth of Pseudokirchneriella subcapitata, a unicellular freshwater green alga, over a 72 h period. The study was performed as a limit test, using test solutions prepared at a loading rate of 100 mg EC-903-161-3/L. The test was conducted in accordance with procedures outlined in OECD Guideline 201 (2006), following procedures in OECD (2000) Guidance Document No. 23 on Testing Difficult Substances. Based on the results of a range finding test, the limit test was conducted with test solution prepared as Water Accommodated Fraction (WAF) at nominal loading rate of 100 mg EC-903-161-3/L. A control of untreated algal medium was also included. No inhibition of growth was observed during the course of the study. As there was no inhibition in average specific growth rate and yield, the 72 h EL50 of EC-903-161-3 on the growth of P. subcapitata is concluded to be >100 mg EC-903-161-3/L, under the conditions of the test. The 72 h no observed effect loading rate (NOELR) is concluded to be =100 mg/L.

A supporting study was performed to determine the acute toxicity of the water accommodated fractions (WAFs) of an appropriate analogue test substance to the alga Selenastrum capricomutum in a static system for a 72-hour period. Water Accommodated Fractions prepared at the following loading rates were tested; 1000mg/L, 500mg/L, 250mg/L, 125mg/L and 62.5mg/L. Algal nutrient media was used as a control. Three replicate chambers (and one fluorometer blank) of each WAF were tested. Samples were removed from each WAF and the control on Day 0 and from a composite of the replicates at termination. Samples were analyzed for Dissolved Organic Carbon (DOC). The results of the DOC analysis indicated that the concentration of dissolved organic carbon in the WAFs was below the minimum quantitation limit of 1 ppm. The calculated 72-hour NOELR (No Observed Effect Loading Rate) was 125mg/L based on growth (area under the growth curve), although the 500mg/L loading Rate was not statistically different from the control. The calculated 72-hour NOELR was l000 mg/L based on growth rate. The 50% Effect Loading Rate (EL50) is the calculated loading rate which results in a 50% reduction in growth (area under the growth curve) or growth rate relative to the control during a specified exposure period. The 72-hour EL50s were > l000 mg/L (the highest loading rate tested) for growth and growth rate based on exposure to the WAF of the test substance. The information in this study is considered to be useful in the support of the data for the Registration material.