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Administrative data

Description of key information

Acute toxicity: Oral: LD50 combined: 94 mg/kg bw (K, Reliability 1)

Acute toxicity: Dermal: not applicable as Chlorine dioxide is classified as corrosive

Acute toxicity: Inhalation: LC50 combined: 89,6 mg/m3=32ppm (K, Reliability 1)

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Dose descriptor:
LD50
Value:
94 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion
Dose descriptor:
LC50
Value:
89.6 mg/m³

Acute toxicity: via dermal route

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Acute toxicity: oral

A study was identified as the key study (Tos, 1996).The study was conducted according to the OECD guideline No. 401 and in compliance with GLP. Rats were administered Chlorine dioxide (as a 0.2 % solution in water) by gavage at doses of 20, 40 and 80 mg/kg bw.

Animals treated at the lowest dose showed hypoactivity, piloerection and hunched posture during the first three days of the study. Females treated at 40 mg/kg bw showed the same clinical signs up to day 5 of the study. Males treated at 40 mg/kg bw and all animals treated at the highest dose showed clinical signs involving the CNS, the respiratory tract, and also piloerectoin, hunched posture and salivation. All reviving animals recovered within days 4 -7 of the study. The autopsy of animals which died during the study showed test substance-related changes in the gastrointestinal tract: congestion and erosions with mucus or test substance presence in the stomach and thinning walls with catarrhal or catarrhal-hemorrhagic content in the intestine. Congestion of the lungs, of the kidneys and of the liver and decreased size of the spleen were also observed. Animals treated at 20 mg/kg bw not show any necroscopic changes at the autopsy performed at the end of the study. The surviving animals treated at the highest doses (40 and 80 mg/kg bw) showed changes in the stomach (thickening of the glandular mucosa) which were considered test substance related. Oral LD50Combined = 93.86 mg/kg bw (95% C.L. of 45.52 -193.53 mg/kg bw). Observed effects are related to the corrosive properties of ClO2.

Acute toxicity: dermal

In accordance with column 2 of REACH Annex VIII, the acute dermal toxicity study (required in section 8.5.3) does not need to be conducted as the substance is classified as corrosive to the skin based on the results of the acute oral toxicity study of Tos (1996).

Acute toxicity: inhalation

A study was identified as the key study (Schorsch et al., 1996). The study was conducted according to the EU Method B.2 and in compliance with GLP. Rats were exposed by oro-nasal inhalation to Chlorine Dioxide gas for 4 hours at analytical concentrations of 0, 46, 71, 107 and 128 mg/m3. Clinical signs observed in all dose groups included: respiratory distress (abdominal respiration, noisy respiration, labored respiration and nasal secretion) and general weakness (piloerection, hunched back, decrease of activity and weight loss / thin body condition). Lungs from treated animals showed frequent mottling, redness and depressed area. The main lesion induced by ClO2 is the destruction of alveolar walls, which created dose-related pulmonary emphysema lesions. Inhalation LC50combined = 89 mg/m3 air (95% CL 69 -119 mg/m3).

Justification for classification or non-classification

Harmonised classification:

Chlorine dioxide 0.2% is classified for acute oral toxicity as:

- Category 3 (H301 Toxic if swallowed) according to the CLP Regulation (1272/2008) as LD50was found to be between 50 and 300 mg/kg bw.

- Toxic if swallowed (T; R25) according to the Directive 67/548/EC as LD50was found to be between 25 and 200 mg/kg bw.

Chlorine dioxide is classified for acute inhalation toxicity as:

- Very toxic by inhalation (T+; R26) according to the Directive 67/548/EC as LD50was found to be < 0.5 mg/L/4h (gas).

Self classification:

Based on the results of the key study (Schorsch et al., 1996), Chlorine dioxide is classified for acute inhalation toxicity as:

- Category 1 (H330 Fatal if inhaled) according to the CLP Regulation (1272/2008) as LD50was found to be between 0 and 100 ppm (gas).