o-TOLUIDINE CAS N°: 95-53-4 - UNEP Chemicals

OECD SIDS o-TOLUIDINE
4.2 Terrestrial Effects
No data available.
4.3 Other Environmental Effects
No data available.
4.4 Initial Assessment for the Environment
o-Toluidine is a light yellow liquid becoming reddish brown on exposure to air and light with a
melting point of -24.4 for the α-form and -16.3 °C for the β-form, and a boiling point of 200.2 °C.
The density of the liquid is 0.9984 g/cm 3 at 20 °C. The vapour pressure is 34.5 Pa at 25 °C. The
measured log Kow is 1.40. The solubility in water is 15.0 g/l at 25 °C. The dissociation constant is
4.44 - 4.45. The flash point is 85 °C, the auto-ignition temperature 482 °C.
In the atmosphere o-toluidine is degraded by photochemically produced OH radicals. The half-life
is calculated to be ca. 2.9 hours.
With regard to its chemical structure o-toluidine is not expected to hydrolyse under environmental
conditions. o-Toluidine is readily biodegradable (MITI, comparable to OECD TG 301 C: biodegradation
65 % after 28 days, OECD TG 301 A: 88 - 90 % after 28 days, OECD TG 301 E: ca.
90 % after 28 days).
According to the Mackay fugacity model level I, the favourite target compartment of o-toluidine is
water with 91.8 %, followed by air with 7.8 %. The measured and calculated Henry’s law constants
(0.20 - 0.25 Pa m 3 /mol at 25 °C) prove a low to moderate potential for volatilisation from surface
waters.
The available experimental bioconcentration factors (BCF) for o-toluidine indicate no significant
potential for bioaccumulation in Pacific oysters (Crassostrea gigas) (BCF = 4.6 ± 0.8) or Common
bay mussels (Mytilus edulis) (BCF = 4.2 ± 0.7). The bioconcentration factor BCF = 2.4 for o-toluidine,
calculated from the octanol-water partition coefficient, confirms the low bioaccumulation
potential also for fish.
Koc values were calculated with PCKOCWIN v. 1.66 (Koc = 74) and with the TGD equation for the
anilines (Koc = 52). From the measured coefficient of distribution between the sediment and water
(Kd = 0.013) the Koc was calculated to 0.87. These results indicate a low sorption potential of
o-toluidine onto the organic phase of soil or sediments. However, adsorption of o-toluidine in soil
can be enhanced by ion-ion interactions as the results with clay minerals show.
Concerning the toxicity of o-toluidine to aquatic species reliable experimental results from tests
with fish, Daphnia, and algae are available. The tests were performed according to standard
procedures or similar methods. The lowest effect values (nominal concentration) from short-term
tests and from a prolonged fish toxicity test are:
Leuciscus idus: 96 h-LC50 = 82.5 mg/l
Poecilia reticulata: 14 d-LC50 = 81.3 mg/l
Daphnia magna: 48 h-EC50 = 0.52 mg/l
Daphnia magna: 96 h-EC50 = 0.249 mg/l
Chlorella pyrenoidosa: 96 h-EbC50 = 55 mg/l
Selenastrum capricornutum 72 h-ErC50 = 110.9 mg/l (72 h-EbC50 = 30.9 mg/l)
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