Registration Dossier

Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
January - November 1977
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1977
Report Date:
1977

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
Deviations:
yes
Remarks:
no information on body weight changes, no raw data reported
GLP compliance:
no
Test type:
acute toxic class method
Limit test:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS

- Age at study initiation: 8 weeks
- Weight at study initiation: males ca. 195 g, females ca. 131 g
- Diet (e.g. ad libitum): stock diet
- Water (e.g. ad libitum): tap water
- Housing: wire screen cages
- observation period: 14 days

Administration / exposure

Route of administration:
inhalation: dust
Type of inhalation exposure:
whole body
Vehicle:
other: unchanged (no vehicle)
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure chamber volume: 1.5 m³
- Method of holding animals in test chamber: animals were housed in wire screen cages
- Source and rate of air: filtered air, flow rate: 1m³/h
- System of generating particulates/aerosols: the powder was continuously dispersed in air by means of a "Wright" Dust Feed Mechanism at a rate of 6g/m³


TEST ATMOSPHERE
- Brief description of analytical method used: particle size determinations and counts were carried out in samples taken from the atmosphere in the chamber with a cascade impactor
- Particle size distribution: 99 % particke size range of 0.6 - 2.4 µm
- Concentration in air: 259 mg/m³ (maximum attainable concentration)
- Determination of concentration: gravimetrically by passing measured amounts of chamber air through glass fibre filters

Analytical verification of test atmosphere concentrations:
yes
Remarks:
Determination of concentration: gravimetrically by passing measured amounts of chamber air through glass fibre filters
Duration of exposure:
4 h
Concentrations:
259 mg/m³ (maximum attainable concentration)
No. of animals per sex per dose:
Five
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: no data
- Necropsy of survivors performed: no data
- Other examinations performed: mortality, signs of intoxication
Statistics:
No data.

Results and discussion

Effect levels
Key result
Sex:
male/female
Dose descriptor:
LC0
Effect level:
> 259 mg/m³ air
Exp. duration:
4 h
Mortality:
Mortality did not ocur either during exposure or during the subsequent 14-day observation period.
Clinical signs:
other: Signs of intoxication did not ocur either during exposure or during the subsequent 14-day observation period.
Body weight:
No data.
Gross pathology:
No data.
Other findings:
Other observations:
During the first quarter of an hour of the exposure period the rats showed slight restlessness; during the remaining part of the exposure period they were asleep.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
As a four-hour exposure of rats to a dispersion of Dicyandiamid at a maximum attainable concentration of 259 mg/m³ of air did not cause mortality or any noticeable deleterious effects, it can be concluded that the powder has a very low acute inhalation toxicity. It is not likely, therefore, that the substance at concentrations up to 259 mg/m³ will present acute inhalation hazard to man.
Executive summary:

The aim of this study was to determine the 4 -hour LC50 value of Dicyandiamid. Each five male and female rats were exposed to the test atmosphere generated by dispersing the powder continuously in air by means of a "Wright" Dust Feed Mechanism at a rate of 6 g/m³ for four hours (whole-body exposure) at an actual concentration of 259 mg/m³ (maximum attainable concentration).

The animals were observed for mortality and signs of intixication during exposure and daily thereafter for 14 days. Particle determination and counts in air samples revealed a 99 % particle size range of 0.6 - 2.4 µm.

The four-hour exposure of the rats to a dispersion of Dicyandiamid at a maximum attainable concentration of 259 mg/m³ of air did not cause mortality or any noticeable deleterious effects, it can be concluded that the powder has a very low acute inhalation toxicity. It is not likely, therefore, that the substance at concentrations up to 259 mg/m³ will present acute inhalation hazard to man.

The acute inhalation (4 hour) LC50 for Dicyandiamid in the rat is higher than 259 mg/m³.