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Read across to CAS 36878 -20 -3. Study conducted to OECD test guidelines in compliance with GLP. LC50 > 10,000 mg/l. This is significantly higher than the water solubility for the substance, but is considered to be an accurate reflection of toxicity to the substance in the event of release.


To address the acute toxicity to aquatic invertebrates, two saltwater toxicity tests, using mysid shrimp are available; one on the substance itself, and one on a close structural analogue. The results of these are as follows:

CAS 68921-45-9: 96-h LC50 : 2.3 mg/l (1.3-10 mg/l; 95% confidence limits). 96-h NOEC < 1.3 mg/l.  

CAS No. 36878-20-3: 96 h EC50: c = 733 mg/l ; 96-h NOEC: c = 250 mg/l (WAF).

A study was conducted in accordance with OECD Guideline 211 to determine the effects of read-across substance, 4-(1-methyl-1-phenylethyl)-N-[4-(1-methyl-1-phenylethyl)phenyl]aniline, on the survival, growth and reproduction of the cladoceran, Daphnia magna, during a 21-day exposure period under flow-through test conditions. Daphnids were exposed to a geometric series of five test concentrations, a negative control (dilution water) and a solvent control (0.1 mL/L HPLC-grade dimethylformamide). The nominal test concentrations were 3.2, 6.3, 12.5, 25 and 50 μg active ingredient (a.i.)/L. Mean measured test concentrations were determined from samples of test water collected from each treatment and control group at test initiation, at approximately weekly intervals during the test and at test termination. The cladoceran, Daphnia magna, was exposed to Naugard 445 at mean measured concentrations of 1.9, 4.5, 11.4, 21 and 38 μg a.i/L under flow-through conditions for 21 days. There were no significant treatment-related effects on survival, reproduction or growth at concentrations ≤38 μg a.i./L. Consequently, the NOEC for reproduction was 38 μg a.i./L and the LOEC was >38 μg a.i./L. Based on the mean number of live neonates produced per reproductive day observed in the treatment groups, the 21-day EC10 and EC50 values were both >38 μg a.i./L, the highest concentration tested. The 21-day EC10 value based on the mean number of live neonates produced per adult at the beginning of the test was 16 μg a.i./L. Since the 95% confidence interval was outside of the data range used for the calculation, it was not reported. However, the EC10 value was not meaningful because the mean number of live neonates produced per adult at the beginning of the test in the 21 μg a.i./L did not follow a dose-response pattern. The EC50 value based on the mean number of live neonates produced per adult at the beginning of the test was >38 μg a.i./L, the highest concentration tested.


Read across to supporting substance CAS 36878 -20 -3. EC50 = 650 mg/l; NOEC 33 mg/l. Effects were determined to be algistatic based on the rapid re-growth of an aliquot of cells taken from 500 mg/L cultured in fresh control media. However the results do not trigger classification and labelling under Directive (EC) No 1272/2008 - the CLP directive.

Additional information

The substance has been supported under Environmental Protection Agency’s (EPA’s) High Production Volume (HPV) Challenge Program. The American Chemical Councils RAPA Panel, has derived a “Substituted Diphenylamines” category of chemicals for this substance, please refer to EPA reference 201-14700A located at

Relying on several factors specified in EPA’s guidance document on “Development of Chemical Categories in the HPV Challenge Program,” in which use of chemical categories is encouraged, the chemicals constitute a chemical category on the following basis:


Structural Similarity. A key factor supporting the classification of these chemicals as a category is their structural similarity (see Figure 1). All share a common starting material; Diphenylamine (Benzenamine, N-phenyl-, CAS# 122-39-4), a common synthetic pathway, and all compounds in this category are diamines with various substitutions.


Similarity of Physicochemical Properties. The similarity of the physicochemical properties of these materials parallels their structural similarity. All are off-white to light brown solids or viscous liquids intended for use as antioxidants in finished rubber articles or as antidegradant additives that extend the useful life of heavy-duty industrial functional fluids used in high-speed, high-temperature and/or high-load applications. As a class, these amine-based antidegradant compounds are less migratory (more polymer-bound) and less staining than the Substituted p-Phenylenediamine antidegradants. The use of these materials requires that they be stable under high temperatures. Their low volatility is due to their low vapor pressure, highly viscous or solid form. The existing information for these materials indicates that they have low water solubility and high flash points.


Fate and Transport Characteristics. Members of this category have been shown to be not readily biodegradable, so additional testing is not needed. The lack of water solubility of the members of this category makes hydrolysis testing unnecessary. These materials have been shown not to partition to water or air if released into the environment due to their low water solubility and low vapor pressure.


Toxicological Similarity. Review of existing published and unpublished test data for Substituted Diphenylamines shows the aquatic and mammalian toxicity among the materials within this category are similar.


Aquatic Toxicology. Data on acute fish toxicity, acute invertebrate toxicity, and alga toxicity were reviewed. With increasing molecular weight, the toxicity to aquatic organisms decreases. These materials have high estimated log Kowvalues, such that acute toxicity is not expected at or below their low levels of water solubility. For the purposes of the HPV Program, additional testing was not proposed for the members of this category.


Conclusion. Based upon the data reviewed in “Substituted Diphenylamines” category of chemicals, the physicochemical and toxicological properties of the Substituted Diphenylamine category members are similar and follow a regular pattern as a result of that structural similarity. Therefore, the definition of a chemical category has been met, and read across is considered appropriate for the category of chemical.