1,4-diisopropylbenzene

Endpoint summary

Description of key information

Short term toxicity to fish

- MOE, 2000c: Orizias latipes, diisopropylbenzene (mixed isomers), 96 h, semi-static, no mortality at the limit of water solubility, LC50 = 0.707 mg/L, LC0 = 0.25 mg/L

- MOE, 2000b: Orizias latipes, diisopropylbenzene (mixed isomers), 96 h, semi-static, LC50 = 0.914 mg/L (95 % confidence interval: 0.718 - 1.19 mg/L). LC0 = 0.398 mg/L

- Ewell, 1986: Pimephales prolemas, m-diisopropylbenzene, 96 h, flow-through, no mortality at the limit of water solubility, LC50 > 0.91 mg/L, NOEC ≥ 0.91 mg/L

 

Short term toxicity to aquatic invertebrates

- MOE, 2000d: Short-term toxicity to D. magna, diisopropylbenzene (mixed isomers), semi closed system: EC50 (48h) = 0.392 mg/L (95 % confidence limit: 0.246 - 0.754 mg/L) and NOEC(48h) = 0.246 mg/L.

- Ewell, 1986: Short-term toxicity of m-diisopropylbenzene to Asellus intermedius (pillpug); Dugesia tigrina (flatworm), Gammarus fasciatus (sideswimmer); Helisoma trivolvis (snail), Lubriculus variegatus (segmented worm) and Pimephales promelas (fathead minnow); LC50 (96 h) > 0.90 and 0.92 mg/L, respectively (for pillbug, flatworm, sideswimmer, snail, segmented worm, and fathead minnow). EC50 > 0.92 and 0.94 mg/L, respectively (for water flea); NOEC = 0.90 and 0.92 mg/L (for flatworm, snail, segmented worm, and fathead minnow; The NOEC was not determined for the sideswimmers and pillbugs) and NOEC = 0.92 and 0.94 mg/L (for water fleas). 

 

Long term toxicity to aquatic invertebrates

- MOE, 2000e: according to OECD 211, Daphnia magna were exposed to diisopropylbenzene (mixed isomers) for 21 days.

Results:

LOEC: 0.168 mg/L
NOEC: 0.063 mg/L
EC50: 0.154 mg/L
LC50L: 0.220 mg/L

 

Toxicity to aquatic algae and cyanobacteria

- 2 OECD 201 studies are available using the mixed isomers (m- and p-) of diisopropylbenzene.

a) MOE, 2000g

EC50 (72h): 5.44 mg/L

NOEC (72h) value: 1.37 mg/L.

b) SIDS, 2002
EC 50: 2.7 mg/L
EC 10 or NOEC: 0.69 mg/L

 

Toxicity to microorganism

- Robilard, 1986:  non-guideline study with m-diisopropylbenzene, exposure to 0.22 mg/L of test item, the highest concentration tested, had no observed inhibitory effects on the microorganisms. Thus, the NOAEC is 0.22 mg/L.

Additional information

General considerations

The ecotoxicological potential of 1.3-diisopropylbenzene was investigated experimentally. In addition to data on the registered substance 1,3-diisopropylbenzene itself, data on Diisopropylbenzene (mixed isomers 1,3-diisopropylbenzene and 1.4-diisopropylbenzene) were considered to fulfill all relevant endpoints. The isomers indeed possess a great structural similarity and therefore it is obvious that the physico-chemical, toxicological and ecotoxicological properties are likely to be similar. For a detailed justification and further information about this procedure, please refer to the Justifications given in the respective target entries.

Taking all available data (incl. read-across) together, the aquatic toxicity was investigated experimentally towards all required trophic levels (fish, invertebrate and algae) and microorganisms. 

 

Short-term toxicity to fish

A 96 hour acute study (MOE, 2000c) with Oryzias latipes was conducted with the mixed isomers (meta and para) of test item under semi-static conditions. The test solutions were prepared using a solvent carrier with resulting test concentrations that exceeded the water solubility of the substance. The test resulted in a LC50 of 0.707 mg/L (95 % C.L.: 0.539 - 0.935 mg/L; measured concentrations) and a LC0 of 0.25 mg/L based upon mean measured concentrations.

A further short term toxicity to fish study (MOE, 2000b) was performed according to "Test Methods for New Chemical Substances: Algae Growth Inhibition Test, Daphnia Acute Swimming Inhibition Test, and Fish Acute Toxicity Test" Oryzias latipes was exposed to test item (mixed isomers: meta- and para- diisopropylbenzene) for 96 hours. It was determined that LC50 (96h) value is 0.914 mg/L (95 % confidence interval: 0.718 - 1.19 mg/L) and that LC0 (96h) value is 0.398 mg/L.

Another 96 hour acute study was performed similar to OECD guideline 203 (Ewell, 1986) and conducted with test item 1.3-diisopropylbenzene and fathead minnows (Pimephales promelas). The short-term toxicity study was conducted as part of a simultaneous toxicity study using seven species, one vertebrate and six invertebrates. The test was conducted as a limit test using a recirculating column elution apparatus providing a constant saturated solution. Analytical verification of the exposure concentrations was conducted at 0, 48, and 96 hours. The mean measured concentrations were 0.90 and 0.92 mg/L for replicates A and B respectively. No mortality was observed in this test at the mean measured concentration of 0.91 mg/L. The 96 hour LC50 was > 0.91 mg/L and the NOEC was ≥ 0.91 mg/L demonstrating no adverse effects at the limit of water solubility. The results of these studies suggest no acute effects to fish at the limit of water solubility.

 

Short-term toxicity to aquatic invertebrates

A 48 hour acute study with Daphnia magna (MOE,2000d) was conducted with the mixed isomers (meta- and para-diisopropylbenzene) under semi-static conditions. The test solutions were prepared using a solvent carrier with nominal concentrations ranging from 0.2 to 2.0 mg/L which all exceeded the water solubility of the substance. The test resulted in an EC50 of 0.392 mg/L and a LC0 of 0.246 mg/L based upon mean measured concentrations.

Another 48 hour Daphnia magna acute study was conducted with m-diisopropylbenzene as part of a 7 species study (Ewell, 1986). The study was conducted as a limit test using a recirculating column elution apparatus providing a constant saturated solution. No immobility to Daphnia magna (NOEC) was observed in this test at the mean measured concentration of 0.93 mg/L. Five other invertebrate species were also included in the 7 species studies and exposed for 96 hours. The LC50s for those 5 other invertebrate species were > 0.91 mg/L, the mean measured concentration of the saturated solution over 96 -hours. The results of these studies suggest no acute effects to invertebrate organisms at the limit of water solubility.

 

Long-term toxicity to aquatic invertebrates

A 21-day OECD 211 study (MOE, 2000e) was performed with the mixed isomers (m and p) of diisopropylbenzene using Daphnia magna performed under semi-static conditions. The test solutions were prepared using a solvent carrier at nominal concentrations between 0.012 and 0.600 mg/L. The study resulted in a NOEC of 0.063 mg/L and a LOEC of 0.168 mg/L based upon reproduction and the time weighted mean measurements of the test solutions. The 21-day LC50 for mortality of the parental organisms was 0.220 mg/L. These results suggest a lack of chronic or acute toxicity at the limit of water solubility.

 

Toxicity to aquatic algae and cyanobacteria

The toxicity to aquatic algae and cyanobacteria study (MOE, 2000g) was performed according to OECD guideline 201 under GLP compliance (reliability 1 - reliable without restriction). The purpose of the test: Growth inhibition test of the test substance (diisopropylbenzene - a mixture of the meta and para isomers) on algae (Selenastrum capricornutum) was conducted for 72 hours. The 50 % growth inhibition concentration (EC50) and the maximum No observed Effect concentration (NOEC) were determined. Green algae were exposed to test item for 72 hours. it was determined that EC50 (72h): 5.44 mg/L and NOEC (72h) value: 1.37 mg/L.

In a study conducted according to OECD Guideline 201 (Alga, Growth Inhibition Test; reliability 2, reliable with restrictions as original data not available, SIDS, 2002), Selenastrum capricornutum were exposed to diisopropylbenzene concentrations (a mixture of m-DIPB and p-DIPB, with o-DIPB as an impurity) for 72 h in closed system and EC50 and NOEC in respect to biomass and growth rate determined. The test was conducted using solvent (mixture of a dispersant of HCO40 and DMF) and the estimated values were higher than water solubility, however, analytical monitoring was done. In respect to biomass the 72 h EbC50 and NOEC were determined to be 1.6 mg/L and 0.31 mg/L (measured concentrations) and in respect to growth rate the 72 h ErC50 and NOEC were found to be 2.7 mg/L and 0.69 mg/L (measured concentrations), respectively. The EC50 and NOEC values are higher than the water solubility of DIPB thereby indicating that the substance is not toxic at the limit of water solubility.

As key values - despite the lower reliability score of the underlying study entry - the lowest available EC50 value of 0.69 mg/L and the lowest available NOEC value of 2.7 mg/L were included in a worst case approach. 

 

Toxicity to microorganisms

A radiorespirometric method was used to determine the compatibility of 1.3-diisopropylbenzene with secondary waste treatment microorganisms (Robilard, 1986). The procedure used microorganisms from a laboratory-maintained activated sludge unit. These microorganisms were exposed to (14C) glucose and 1.3-diisopropylbenzene. The extent of conversion of the (14C) glucose to (14C) carbon dioxide in the presence of the test article was compared to glucose conversion without test article. Exposure to 0.22 mg/L of 1.3-diisopropylbenzene, the highest concentration tested, had no observed inhibitory effects on the microorganisms.

 

Conclusion

In conclusion, based on the available studies, diisopropyblbenzene does not need to be classified for aquatic acute or chronic toxicity. 

Based on the arguments presented in the Read Across statement attached in IUCLID Section 13, it is clear that the source substance is a mixture of the target substance and its isomer and they show an identical toxicokinetic pattern and the data presented here can be used to fulfill the information requirements for the target substance 1.4-diisopropylbenzene.