Phenylhydrazine

Endpoint summary

Description of key information

Data on the acute toxicity of phenylhydrazine was available, including oral, dermal and inhalative acute toxicity data.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

80 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

LC50

Value:

2 093 mg/m³ air

Acute toxicity: via dermal route

Endpoint conclusion

Dose descriptor:

LD50

Value:

380 mg/kg bw

Additional information

Non-human data:

Acute toxicity data was available for different species. After oral administration oral LD50 values in the range 80–250 mg/kg bw were reported for the rat, mouse, guinea-pig, dog, and rabbit (Ekshtat, 1965; Pham, 1979). Clinical signs reported were motor excitation and tonic/clonic spasms.

Acute dermal toxicity studies in rabbits revealed 20–30 % mortality after exposure to 380 mg phenylhydrazine/kg body weight for 24 h, although no deaths occurred in rats at this dose, i.e. LD50 greater than 380 mg/kg bw (Derelanko et al., 1987). The toxic effects were characterized by destruction of red blood cells, causing a reduction in erythrocyte count, increased reticulocyte count, methaemoglobin formation, and the formation of Heinz bodies, and a cyanotic external appearance may develop. Enlargement and dark coloration of the spleen were also reported, effects considered to be secondary to the erythrocyte damage.

In an acute inhalation study LC50 values of 2745 mg/m3 (610 ppm) for rats and 2093 mg/m3 (465 ppm) for mice (Pham, 1979).

Phenylhydrazine is toxic by intraperitoneal administration, and LD50 values in the range 170-200 mg/kg body weight for i.p. administration in the mouse were reported (Parodi et al., 1981; Kostenko et al., 1985).

Human data: 

Occupational exposure data revealed some systematic toxicity effects following dermal contact to phenylhydrazine in liquid preparation. Systemic toxicity developed in humans after dermal exposure to liquid phenylhydrazine, despite immediate attempts to reduce exposure by removal of contaminated clothing and washing of skin (Schuckmann, 1969). Toxicity was manifest by damage to red blood cells, in one case resulting in haemolytic jaundice. No such systemic effects were reported in two cases of skin contamination with solid phenylhydrazine hydrochloride.

Justification for classification or non-classification

Oral:

Based on Directive 67/548/EEC (DSD) and Regulation 1272/2008/EC (CLP), phenylhydrazine was classified as toxic if swallowed (T, R25; cat 3, H301).

Inhalation:

Based on Directive 67/548/EC (DSD) and Regulation 1272/2008/EC (CLP), phenylhydrazine was classified as toxic if inhaled (T, R23; cat 3, H331).

Dermal:

Based on Directive 67/548/EC (DSD) and Regulation 1272/2008/EC (CLP), phenylhydrazine was classified as toxic in contact with skin (T, R24; cat 3, H311).