1,1,1-trichloroethane

Toxicity to aquatic algae and cyanobacteria

Description of key information

The existing data available had been reviewed by Euro Chlor (De Rooij et al. 2004). This review document evaluated algae studies on seven freshwater species and two marine species. A summary of the results of which are shown in the tables below. The only study rated by De Rooij et al 2004 as acceptable without restriction was the article published by Brack and Rottler (1994) on a series of chemicals. This work makes use of specific design in order to test volatile substance but it presents several drawbacks for hazard or risk assessment: apart from the fact that the species used is not among the standard ones referred to in the OECD Guideline 201, only biomass is provided. Recently, studies carried out on same substances as those tested by Brack and Rottler have delivered resullts significantly different, casting doubts on the validity of the latter.
A new study has been commissioned, under GLP conditions, according to OECD 201 and with specific technical provisions described in ISO 14442 standard dealing with algae testing of volatile substances. The results, retained as key study, gives an ErC50-72h = 41 mg/l and a NOECr = 7.8 mg/l.

Key value for chemical safety assessment

EC50 for freshwater algae:

41 mg/L

EC10 or NOEC for freshwater algae:

7.8 mg/L

Additional information

The study summaries evaluated by the reviewers in the Euro Chlor report are shown in table below.

Acute studies on freshwater algae.

Species	Duration	Study type	Endpoint	Conc. (mg/L)	SF 1000 (ug/L)	Validity	Comments	Reference
Chlamydomonas reinhardtii	72h	S,A,C	EC10 EC50	0.213 0.536	0.213 0.536	1	Biomass	Brack & Rottler 1994
Chlorella vulgaris	3h	S,C	EC50	153	153	2	^14CO2 uptake	Hutchinson et al 1980
Chlamydomonas angulosa	3h	S,C	EC50	280	280	2	^14CO2 uptake	Hutchinson et al 1980
Microcytis aeruginosa	8 days	S	LOEC	350	350	3	Growth, pH7.	Bringmann & Kuhn 1978
Scendesmus quadraticauda	8 days	S	LOEC	430	430	3	Growth	Bringmann & Kuhn 1978
Selenastrum capricornutum,	96h		EC50	>669	>669	3	Oxygen production	US EPA 1978
Chlooccales (mixed).	24h		EC10	100	100	4		Krebs 1985

Acute studies on marine algae

Species	Duration	Study type	Endpoint	Conc. (mg/L)	SF 1000 (ug/L)	Validity	Comments	Reference
Phaeodactylum tricornutum	?	?	EC50	5	5	2	^14CO2 uptake	Pearson & McConnell 1975
Skeletonema	?	?	EC50	>699	>699	3	Growth	US EPA 1978

No data is available to provide an EC10 value for marine algae is available in the literature. However as trichloroethane does not possess specific activity it is reasonable to suppose that the values would be similar to freshwater algae.

The new study commisioned in order to check validity of the results of the article published by Brack and Rottler confirms (as for other chemicals) that these results are to be considered as not valid, for some reason (experimental details lacking in the article). The new GLP compliant, carried out according to OECD 201 and specific conditions described in ISO 14442 for algae testing of volatile substances gives: ErC50-72h = 41 mg/l and a NOECr = 7.8 mg/l.