1-chloro-3-(4-chlorophenoxy) benzene

Endpoint summary

Description of key information

Concerning the acute oral toxicity of 3,4'-dichlorodiphenyl ether two in vivo studies were performed. Both can be assessed as reliable 
without restriction. However the results of the studies differ and lead to different  classification.
According to the precautionary principle 3,4'-dichlorodiphenyl ether should be classified and labelled. 

Additional information

Concerning the acute oral toxicity of 3,4'-dichlorodiphenyl ether two in vivo studies were performed.

Both studies comply with the OECD Principles of Good Laboratory Practice (GLP).

In the 1994 study 5 male and 5 female Wistar rats were dosed at a dose level of 2000 mg/kg bw. At this dose no animal died and no signs of toxicity or changes in body weight development were observed during the observation period of 14 days. Therefore the LD50 was regarded to be > 2000 mg/kg bw for both gender and not determined exactly (limit test according to OECD TG 401).

In the 2006 study 3 female Sprague Dawley rats were dosed at a level of 2000 mg/kg bw (step 1). Two animals died on Day 4 of the observation period. Then additional 3 females were dosed at 300 mg/kg bw (step 2) and observed for a period of 14 days. No mortality occurred and no clinical signs were observed. Finally 3 females were dosed at the same dose level, 300 mg/kg bw (step 3). Again no mortality and no clinical signs occurred. No remarkable changes in body weight were observed in the surviving animals. Thus the results of this study indicate that the test item, 3,4'-dichlorodiphenyl ether, has a toxic effect on the rat following oral administration of single dose of 2000 mg/kg bw. No mortality or other signs of toxicity were observed at 300 mg/kg. The mortality pattern demonstrates the acute oral LD50 to be less than 2000 mg/kg bw, but greater than 300 mg/kg bw. The LD50 cut-off amounts 1000 mg/kg bw.

Based on the data obtained under the conditions of the 1994 study the test substance 3,4'-dichlorodiphenyl ether should not be classified according to Directive 67/548/EEC (substances) and also not classified according toRegulation (EC) No 1272/2008 on classification, labelling and packaging of substances and mixtures(CLP).

 

Based on the data obtained under the conditions of the 2006 study, the test substance 3,4'-dichlorodiphenyl ether should be classified as Xn, R22 (harmful if swallowed) according toDirective 67/548/EEC (substances)and as Acute Tox. 4, H302 (Harmful if swallowed) according toRegulation (EC) No 1272/2008 on classification, labelling and packaging of substances and mixtures(CLP).

There is no obvious reason explaining the different test results in the two studies on Acute Oral Toxicity. Both studies are in accordance with OECD guidelines in force at time of study conduction (OECD TG 401 and OECD TG 423, respectively). Further on both studies are quality checked and in compliance with the Principles of Good Laboratory Practice. Therefore they should be assessed as reliable without restriction (Klimisch 1, GLP guideline study).There are also no known inter-strain differences between Wistar or Sprague Dawley rats with respect to the sensitivity on acute oral toxicity. The purity of both test items was high but nevertheless there may be different contaminants or side products in the test item which have not been reported. Therefore it may be possible that unknown components or influences had an impact on the study results. This can not finally be assessed.

Justification for classification or non-classification

According to the precautionary principle 3,4'-dichlorodiphenyl ether should be preliminary classified and labelled as “harmful if swallowed” Xn, R22, or Acute Tox. 4, H302, respectively.