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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Administrative data

Description of key information

Acute toxicity data for styrene oxide are available for the oral, dermal and inhalation route.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Dose descriptor:
4 290 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion
Dose descriptor:
2 450 mg/m³ air

Acute toxicity: via dermal route

Endpoint conclusion
Dose descriptor:
1 060 mg/kg bw

Additional information

In an acute oral toxicity study, groups of 5 nonfasted, Carworth-Wistar rats weighing 90 to 120 g were given a single oral dose of styrene oxide at doses not reported in detail and observed for 14 days.Theoral LD50is 4290 mg/kg bw (95% C.I. 3070 - 5980).

In an acute dermal toxicity study, using the one-day cutt method of Draize, groups of four male New Zealand giant albino rabbits were exposed to the closely clipped fur to 1/10 of the body surface. The dose retained beneath an impervious plaster film for 24 hours. Mortality was considered complete after additional 14 days. The dermal LD50was determined to be 1060 mg/kg bw(95% C.I. 630 - 1790).

In an acute inhalation toxicity study, groups of 6 young adult male Carworth-Wistar rats were exposed by inhalation route to vapours of styrene oxide for 4 hours at concentrations of 500 ppm. Animals then were observed for 14 days. At a concentration of 500 ppm 2 of 6 animals died. The inhalatory LC50was determined to be 500 ppm, corresponding to 2.45 mg/L (2450 mg/m³) for 4 hours.


Findings with respect to specific target organ toxicity are not reported in neither of the publications.


Justification for classification or non-classification

Based on the results the following classification of styrene oxide according to Directive 67/548/EEC and GHS Regulation EC No 1272/2008 with respect to acute toxicity is required.


Acute toxicity route


Directive 67/548/EEC

GHS Regulation EC No 1272/2008


LD50 4290 mg/kg bw

no classification

no classification


LD50 1060 mg/kg bw

Xn; R 21

Cat. IV


LC50500 ppm vapour (2.45 mg/L)

Xn; R 20

Cat. III


* For the dermal route styrene oxide is subject to legal binding classification