Reaction mass of carbon tetrachloride and chloroform and 1,2-dichloroethane

Endpoint summary

Description of key information

No aquatic experimental studies were conducted on the multiconstituent substance (Flux1). To assess the aquatic toxicity of the registered substance, a constituent-based, Weight-of-Evidence approach, was performed.

The three major constituents were targeted, representing ca 95% of a typical composition (carbon tetrachloride (CAS n° 56-23-5),1,2-Dichloroethane (CAS n°107 -06 -2) and chloroform (CAS n° 67-66 -3)). Numerous published data were available, and a single consensus value was selected for each from a reliable source.

Short term toxicity studies were not used as long term toxicity studies were available for each constituent.

Three weight of evidence studies are available to assess the long-term toxicity of each constituent of Flux1 to algae:

Growth inhibition of freshwater algae Pseudokirchneriella subcapitata by carbon tetrachloride was measured according to OECD Guideline 201 (Gancet, 2011). The values obtained in this study can be retained as key information about algae toxicity of carbon tetrachloride: ErC50-72 = 20 mg/L and NOECr = 2.2 mg/L.

Growth inhibition of freshwater algae Selenastrum capricornutum by 1,2 -Dicloroethane was measured according to OECD Guideline 201 (Behechti, 1995). Based on nominal concentrations the 72-hour EC50 values for growth rate Selenastrum capricornutum was estimated to be 166 mg/L (closed system) and 213 mg/L (open system), based on measured values of 1,2 dichlorethane.

The toxicity of chloroform to the green algaeChlamydomonas reinhardtiiwas tested in a closed static test during a period of 72 hours at a temperature of 20 +/- 1 °C (Brack, 1994). The criterion for toxicity was the inhibition of the algal growth rate. The algal growth was inhibited by 10 % at a chloroform concentration of 3.61 (2.55 -4.72) mg/L and by 50 % at a chloroform concentration of 13.3 (11.0 -15.77) mg/L. In conclusion, the EC50 value for algal growth inhibition thus is 13.3 mg chloroform/L.

Three weight of evidence studies are available to assess the long-term toxicity of each constituent of Flux1 to fish:

The potential of carbon tetrachloride (CTC) to induce toxicity in Zebrafish (Brachydanio rerio, Hamilton-Buchanan, Teleostei, Cyprinidae) was evaluated in a survey study on different chlorinated organic solvents following OECD TG 204 (Röderer, 1990). Even though the OECD 204 is no longer generally considered acceptable by regulatory authorities as a chronic study, this is the only long term toxicity to fish study available on the main constituent of Flux1. This study is of good quality and presents a NOEC of 2.5 mg/L for CTC for prolonged toxicity (14-day) and it was thus considered acceptable based on the non-polar narcosis properties of the test substance and an acute/chronic toxicity comparison for each organisms supporting the conclusion that further studies on fish would not help us to refine the result.

The effects of 1,2 -dichloroethane on the early life stages of fathead minnow (Pimephales promelas) were determined under continuous-flow conditions for 32 days (Benoit, 1982). Based on a statistically significant reduction of fish weight the MATC (maximum acceptable toxicant concentration) of 1,2-dichloroethane in a fathead minnow early life stage test was 29 - 59 mg/L on measured concentrations.

The chronic toxicity study of Toussaint et al. (2001) used 14-day old fry Japanese Medaka fish (Oryzias latipes) that were continuously exposed to chloroform in a flow-through system for 6 and 9 months (similar to OECD 305). These authors demonstrated that a chronic exposure of Medaka fish to a chloroform concentration of 1.463 mg/L is causing significant effects on the histopathology of the gallbladder (lesions) and the bile ducts (abnormalities). Although these findings should be ecotoxicologically significant, this effect concentration will be considered as a NOEC because of the very specific effects that were observed at this concentration and the uncertainty about effects at the population level (it is not proven that there might be effects on population level with longer exposure periods).

Three weight of evidence studies are available to assess the long-term toxicity of each constituent of Flux1 to invertebrates:

The long-term toxicity to aquatic invertebrates of CTC was investigated with Daphnia magna according to OECD 211 compliant to GLP standards to give a NOEC of 3.1 mg/L (based on growth as well as reproduction effects) (Thompson 1997). There was a significant effect on reproduction (number of offspring per parent) and final length of the parent Daphnia at a nominal concentration of 5.6 mg/L. There were no effects at or below a nominal concentration of 3.2 mg/L. The 21-days NOEC and LOEC were 3.1 and 5.7 mg/L, respectively.

The effects of 1,2 Dichloroethane on the growth and reproduction of Daphnia magna were assessed in an unaerated, static, 28 -day test (Call 1983). Based on the mean adult length and number of neonates per adult per reproduction day, the overall 28-day NOEC was determined to be 10.7 mg/L based on measured concentration.

The toxicity of chloroform to the reproduction of Daphnia magna was tested in a 21 day test in accordance to the recommendations of the German Federal Environmental Agency on the Performance of Testing (January 1984) (Khün, 1989). The 21-days NOEC value was 6.3 mg/L (minimal measured concentration) based on parental mortality, reproduction rate and appearance of first offspring.

Four weight of evidence studies are available to assess the toxicity of each constituent of Flux1 to microorganisms:

Results of growth inhibition toxicity tests on cultures of Pseudomonas putidaare described on 156 chemicals (Bringmann & Kuehn, 1980). Results on carbon tetrachloride are summarized here. It is reported that Toxicity Threshold (EC3 -16h) is 30 mg/L. Analogous experiment on protozoa Entosiphon sulcatum (also relevant for micororganisms toxicity assessment) shows a TT (EC5 -72h) of 770 mg/L. An experiment on algae (Scenedesmus quadricauda) is also reported with a TT (EC3 -7d) > 600 mg/L. In these two cases results will not be considered as reliable as reported concentrations are above water solubility limit and because signifcant loss of CTC may happen during long exposure periods. In conclusion, Toxicity Threshold (EC3 -16h) or NOEC value of carbon tetrachloride is 30 mg/L.

One study was designed to determine the effects of 1,2-dichloroethane on sewage sludge micro-organisms by measuring the respiration rate after exposure to the test substance after a 3 h contact time OECD 209. Based on the results of this study the IC50 -24h of 1,2-dichloroethane on activated sludge is 2780 mg/L, using a design that prevents losses by volatilisation.

A modified respiratory inhibition test on chloroform was carried out with activated sludge obtained from a wastewater treatment plant (Blum, 1991). Sealed 125-mL serum bottles supplied with 50 mL of additional pure oxygen were used in the test. The toxic effect on aerobic heterotrophs was determined by measuring the oxygen demand at approximately 0.5-days intervals. It was found that after 15 hours the respiration of aerobic bacteria was inhibited by 50 % at a concentration of 640 mg/L, which was taken as the EC50 value.

In conclusion, the table below summarized the results for each constituents:

CTC	Acute values L(E)C50, mg/L	Chronic values NOEC/EC10, mg/L
Fish	24.3 mg/L	2.5 mg/L
Aquatic Invertebrates	35 mg/L	3.1 mg/L
Aquatic algae	20 mg/L	2.2 mg/L
Microorganisms	/	30 mg/L

1,2-DCE	Acute values L(E)C50, mg/L	Chronic values NOEC/EC10, mg/L
Fish	136 mg/L	29 -59 mg/L
Aquatic Invertebrates	155 mg/L	10.7 mg/L
Aquatic algae	166 mg/L	/
Microorganisms	2 780 mg/L	/

Chloroform	Acute values L(E)C50, mg/L	Chronic values NOEC/EC10, mg/L
Fish	18.2 mg/L	1.463 mg/L
Aquatic Invertebrates	29 mg/L	6.3 mg/L
Aquatic algae	13.3 mg/L	3.61 mg/L
Microorganisms	640 mg/L	/