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Diss Factsheets

Toxicological information

Acute Toxicity: inhalation

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Administrative data

acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
22 march 2010 to 30 July 2010
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference Type:
study report

Materials and methods

Test guideline
according to guideline
OECD Guideline 436 (Acute Inhalation Toxicity: Acute Toxic Class Method)
GLP compliance:
yes (incl. QA statement)
Test type:
fixed concentration procedure
Limit test:

Test material

Constituent 1
Reference substance name:
Cas Number:
Constituent 2
Reference substance name:
Flue dust, portland cement
EC Number:
EC Name:
Flue dust, portland cement
Test material form:
solid: particulate/powder
Details on test material:
The test material was supplied by the sponsor in two containers, which were received in good condition. The first container labeled “Flue Dust T -fine (REACH); 03-2010; ECRA; Li, 10.3.10” with net weight 540 g and gross weight 607.19 g, was received on 11 March 2010 and was given the TNO dispense reference number 100070 (pertaining to batch number 03-2010-F1). The second container labeled “Flue Dust T (REACH); 03-2010; Li; ECRA european cement research academy” with net weight 1700 g and gross weight 2065.96 g, was received on 29 March 2010 and was given the TNO dispense reference number 100085 (pertaining to batch number 03-2010-F2). Animals were exposed to TNO dispense reference number 100085 only.

Flue Dust T –fine (REACH) is a beige/grey powder and has the following characteristics (as given by the sponsor):
Name : Flue Dust T –fine (REACH)
Chemical name : Flue dust, Portland cement (EC number 270-659-9)
Other name : Cement kiln dust
Batch numbers : 03-2010-F1 and 03-2010-F2
Purity : UVC substance
CAS registry number : 68475-76-3
Specific gravity : 2.9 kg/L (at 20 ºC)
pH : >11.5 in water, due to hydration reaction
Volatile : no
Hygroscopy : yes, but low
Particle size range : 0 – 6 µm
Stability : hydration reaction of clinker phases in contact with
water, other constituents are stable inorganic substances
Storage conditions : ambient temperature
Expiry date : 31 December 2010

Test animals

Details on test animals or test system and environmental conditions:
Adult, male and female Wistar outbred (Crl:WI[WU]) rats were obtained from a colony maintained under SPF-conditions by Charles River Laboratories. Three male and three female animals arrived on 7 April 2010 at an age of 7 weeks. They were taken in their unopened shipping containers to animal room 5.2.10, were checked for overt signs of ill health and anomalies, and were kept in quarantine. After approval of the lot (negative titers to micro-organisms tested in a few animals), quarantine was raised on 9 April 2010 and the animals were moved to 6.0.04, a similar animal room. The rats were separated by sex and uniquely identified by ear tattoo. Just before the start of the study on 21 April 2010, the animals were weighed. The average body weights of the rats on day 0 before exposure were 277.7 g and 190.3 g for the males and females, respectively. The duration of the acclimatization period was 12 days.

The animals were housed under conventional conditions in macrolon cages with bedding of wood shavings (Lignocel, type ¾, Rettenmaier, Rosenberg, Germany) and strips of paper (Enviro-dri, Lillico, Betchworth, England) as environmental enrichment. The number of air changes was about 10 per hour. The animals were housed three males or three females to a cage. During the exposure, the animals had no access to feed or water and were housed individually in the holders. After exposure, the animals returned to their living cages and were held for an observation period of 15 days before sacrifice and necropsy.

The temperature in the animal room was within the range of 20 – 24°C, except on 14 April 2010 when temperature was above 24°C (25.3°C at maximum) for a maximum period of 20 minutes, most probably due to cleaning activities with hot water. Relative humidity occasionally exceeded the range of 45 – 65% for short periods of time, probably due to cleaning activities or meteorological circumstances. On 24 April 2010, relative humidity in the animal room was below 45% (43.4% at minimum) for a maximum period of 20 minutes. A 12-hour light and 12-hour dark cycle was maintained.

Administration / exposure

Route of administration:
inhalation: dust
Type of inhalation exposure:
nose only
Details on inhalation exposure:
The animals were exposed to the test atmosphere in a nose-only inhalation chamber, a modification of the design of the chamber manufactured by ADG Developments Ltd., Codicote, Hitchin, Herts, SG4 8UB, United Kingdom (see Figure 1). The inhalation chamber consisted of a cylindrical stainless steel column, surrounded by a transparent cylinder. The column had a volume of ca. 50 liters and consisted of a top assembly with the entrance of the unit, a rodent tube section and at the bottom the base assembly with the exhaust port. The rodent tube section had 20 ports for animal exposure. Several empty ports were used for test atmosphere sampling, particle size analysis, measurement of oxygen concentration, temperature and relative humidity. The animals were secured in plastic animal holders (Battelle), positioned radially through the outer cylinder around the central column. Male and female rats were placed in alternating order. The remaining ports were closed. Only the nose of the rats protruded into the interior of the column.

The inhalation equipment was designed to expose rats to a continuous supply of fresh test atmosphere. To generate the test atmosphere, Flue Dust T –fine (REACH) was aerosolized using a dust feeder (Hethon Nederland BV, Hengelo, The Netherlands), a venturi and a jet mill (Institute’s design). The latter two were supplied with humidified compressed air. The resulting test atmosphere was led to the top inlet of the exposure chamber and from there to the noses of the animals. At the bottom of the unit, the test atmosphere was exhausted .

During the generation of the test atmosphere, the settings of the dust feeder and the air pressure on the jet mill were recorded at regular intervals (approximately each half hour). The airflow through the exposure chamber at the pressure settings of the jet mill and the venturi was determined in a preliminary experiment and was established to be 89.25 L/min. The animals were placed in the exposure unit after stabilization of the test atmosphere. The period between the start of the generation of the test atmosphere and the start of exposure of the animals was 27 minutes. The concentration C in a perfectly stirred test atmosphere in a chamber with volume V (L) and flow F (L/min) increases according to C = C ∞* (1 – e -(F*T/V) ), in which T (min) is the time and C ∞is the steady state concentration. Hence T 95 , the time it takes to reach 95% of the steady state concentration is given by e -(F*T95/V) = 0.05, from which it follows that T 95 was approximately 1.7 minutes. In practice, after the start of the generation the aerosol will spread from the top to the bottom and T 95 will be shorter than in a perfectly stirred chamber.

Analytical verification of test atmosphere concentrations:
Duration of exposure:
ca. 4 h
Actual concentration
The actual concentration (± standard deviation, number of measurements) of Flue Dust T –fine (REACH) in the test atmosphere during exposure was 6.04 g/m
3 (± 0.54, n=14; indicating that the concentration in the test atmosphere was amply above the target limit concentration of 5 g/m3.

Nominal concentration
The nominal concentration, calculated from the total amount of test material used (by weighing) and the air flow was 14.51 g/m3. This indicates a generation efficiency of 42%, which is within the range expected for aerosol generation.

No. of animals per sex per dose:
Control animals:
Details on study design:
Behaviour, clinical signs, and mortality
The rats were visually inspected just before exposure, for reactions to treatment during the exposure, shortly after exposure, and at least once daily during the observation period.

Body weights
Body weights of the animals were recorded just before exposure (day 0), on days 1, 3 and 7, and on day 15 prior to necropsy. In addition, animals were weighed on day 2, because of their ill health.

At the end of the 15-day observation period, animals were killed by exsanguination from the abdominal aorta under pentobarbital anaesthesia (intraperitoneal injection of sodium pentobarbital) and examined for gross pathological changes.

Results and discussion

Effect levels
Key result
Dose descriptor:
Effect level:
> 6.04 mg/L air (nominal)
Based on:
test mat.
Exp. duration:
4 h
One female animal (No. 3) was found dead after approximately three hours of exposure.
Clinical signs:
other: All animals demonstrated a decreased breathing rate during exposure, which became more severe with time. Clinical signs observed shortly after exposure in surviving animals included slight to moderate laboured breathing, slight to moderate rales, slight
Body weight:
All animals showed substantial body weight loss during the first few days after exposure (Table 3). Although a small decrease in body weight gain is expected due to the constraint of the animals during exposure, effects of this magnitude are considered treatment-related. Body weights recovered during the second week of the 15-day observation period.
Gross pathology:
The nose of the female animal that died during exposure seemed blocked, with brown powder on the exterior of the nose. In addition, the animals’ lungs were red discoloured with several petechiae .
Necropsy of the surviving rats at the end of the observation period revealed petechiae in the medial lung lobe of one male animal, which was not considered to be related to the exposure. No other macroscopic abnormalities were observed at necropsy.

Applicant's summary and conclusion

Interpretation of results:
Category 5 based on GHS criteria
One female animal died during exposure. All other animals survived the 14-day observation period. It is therefore concluded that the 4-hour LC50 of Flue Dust T –fine (REACH) is above 6.04 g/m3 for male and female rats. According to the OECD Guideline for Testing of Chemicals 436, the test material should be classified as Category 5 of the Globally Harmonized Classification System (GHS); according to the EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) regulation (EC) No. 1272/2008, the test material does not need to be classified.
Executive summary:

The aim of the present study was to investigate the acute inhalation toxicity of Flue Dust T –fine (REACH) in rats for REACH registration and classification purposes. Therefore, three male and three female animals were exposed to a target limit concentration of 5 g/m 3 during a single period of four hours. Animals were kept for an observation period of 15 days before sacrifice. To characterize the toxicity, the animals were observed during exposure, shortly after exposure and daily thereafter, body weight was measured before exposure and 1, 2, 3, 7 and 15 days after exposure and the animals were examined for gross pathological changes at necropsy.

The actual concentration during exposure was 6.04 ± 0.54 g/m 3 . The mass median aerodynamic diameter was 3.5 and 3.8 µm (duplicate measurements) and the distribution of particle sizes had a geometric standard deviation (gsd) of 2.2 and 2.1, respectively.

Animals demonstrated a decreased breathing rate during exposure, which became more severe with time. One female was found dead after 3 hours of exposure. At necropsy, the nose of this animal seemed blocked and the animals’ lungs were red discoloured with several petechiae. Clinical signs observed after exposure in surviving animals included breathing abnormalities, soiled eyes, nose and fur, blepharospasm, encrustations around the eyes, nose and mouth, dark eyes, and sluggishness. Female animals were slightly more affected than males. Generally, abnormalities were no longer seen after 5 to 6 days. Substantial body weight loss was observed during the first few days after exposure, which recovered in the second week of the 15-day recovery period.

Macroscopic examination at necropsy revealed red discoloured lungs with several petechiae in the animal that died during exposure, and the animals’ nose seemed blocked. No treatment-related gross abnormalities were found in the surviving animals at the end of the recovery period.

Physical obstruction of the nose may well have played a role in the observed respiratory abnormalities and mortality. Since rats are obligatory nose breathers, the relevance of this model for human exposure may be questioned for these effects.