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Acute Toxicity: inhalation

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acute toxicity: inhalation
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Study period:
11th to 25th June 1985
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Comparable to guideline study with acceptable restrictions due to limited exposure concentration and duration. Exposure duration was not 4 hours. Can not be classified according to the EU as the animals were exposed for 1 hour and also the obtained results was a greater than value at a concentration of 1.67 mg/L (nominal) which would be in the range to be considered classifyable according to the DSD (67/548/EEC), however, since no mortality was observed it can not be classified either way.
Justification for type of information:
Category and read across justification attached in section 13 and in appendix of CSR

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
equivalent or similar to guideline
OECD Guideline 403 (Acute Inhalation Toxicity)
limited exposure concentration and duration
GLP compliance:
Test type:
standard acute method
Limit test:

Test material

Constituent 1
Chemical structure
Reference substance name:
Phenol, paraalkylation products with C10-15 branched olefins (C12 rich) derived from propene oligomerization, carbonates, calcium salts, overbased, sulfurized including distillates (petroleum), hydrotreated, solvent-refined, solvent-dewaxed, or catalytic dewaxed, light or heavy paraffinic C15-C50
EC Number:
Molecular formula:
Formula for a representative structure is C36H58Ca2O4Sx where x = 1,2. Actual molecular formula is not possible to generate. Substance is a UVCB.
Phenol, paraalkylation products with C10-15 branched olefins (C12 rich) derived from propene oligomerization, carbonates, calcium salts, overbased, sulfurized including distillates (petroleum), hydrotreated, solvent-refined, solvent-dewaxed, or catalytic dewaxed, light or heavy paraffinic C15-C50
Details on test material:
CAS 68784-26-9
EC 272-234-3

Test animals

Details on test animals or test system and environmental conditions:
- Source: Bantin and Kingman, Fremont, California
- Age at study initiation: The males were 118 days of age and the females were 118 days of age and at the time of exposure.
- Weight at study initiation: The males weighed 514-550 grams, and the females weighed 269-315 grams at the time of exposure.
- Fasting period before study: the animals had no access to food or water during exposure
- Housing: They were housed individually in wire-bottomed cages.
- Diet/water (e.g. ad libitum): They had free access to Purina Laboratory Rodent ChowR (#5001) and water except during exposure.
- Acclimation period: They were maintained for 77 days prior to exposure.

- Temperature (°C): 22.6-22.9°C
- Humidity (%): 59.0-66.5%
- Photoperiod (hrs dark / hrs light): The animals were on a 12-hour light/dark cycle: on at 0630 and off at 1830.

Administration / exposure

Route of administration:
other: Vapor and condensed aerosol inhalation
Type of inhalation exposure:
nose only
other: unchanged (no vehicle)
Details on inhalation exposure:
Five rats of each sex were exposed for 60 minutes to vapors and condensation aerosols from heated test material. The generation system consisted of a vertical three-inch steel pipe, approximately 24 inches long with threaded steel caps at each end. The bottom cap was drilled with two 1/8-inch pipe holes and fitted with 1/4-inch copper compression fittings.

The supply air was delivered via two 1/4-inch copper tubes to these two holes. The top cap was drilled and tapped to receive a 1/4-inch pipe fitting. Air and vapors of test material exited the steel pipe at this point. Another hole in the side of the pipe, approximately five inches from the bottom, contained a copper fitting which held a thermister probe from a Cole-Parmer Versa-Therm (Model 60648) proportional temperature controller. This probe monitored the temperature of the test material in the pipe. The pipe contained 1527 grams of the test material and 1638 grams of 5 millimeter diameter glass beads. The combined materials filled the generator to about half its capacity. The glass beads served to disperse the air flowing through the test material and increased the surface area of test material in contact with the air. A tight mesh stainless steel screen was fitted in the bottom pipe cap to prevent the glass beads from plugging the supply air inlets at the bottom of the pipe. The bottom third of the pipe was wrapped with an electric heating tape which was powered by the proportional temperature controller and maintained the test material at a temperature of 170°C. Vapors were generated by passing laboratory compressed air up through the hot test material. The vapors and the condensation aerosol, which formed as the vapors cooled, passed out the top of the generator via 3/8-inch Teflon tubing and into one side of a 500 ml three-neck flask. The vapors and aerosol passed out the other side of the flask, horizontally via glass tubing to a 1-1/8 inch copper tube, then vertically to the inlet of the chamber. No dilution air was added.

Air flow through the generator was maintained at an average of 18.6 l/min during the exposure. Air was drawn out of the chamber through the exhaust manifold at an average flow of 14.5 L/min. The total concentration of aerosol and vapor was estimated by drawing chamber air from the end of the chamber through a cold trap consisting of three glass U-tubes (20.7 cm high, 1.7 cm i.d.) connected in series with flexible tubing and rubber stoppers. The tubes were approximately two-thirds submerged in a dry ice-acetone bath. The cold trap sampling train was operated continuously throughout the exposure at a rate of 5 L/min. Therefore, the total exhaust flow was approximately 19.5 L/min creating a negative pressure of 0.1 to 0.2 inches of water in the chamber. The cold trap tubes were weighed before and after the exposure to determine the amount of material collected.

Concentration of the aerosol in the chamber was determined gravimetrically by drawing chamber atmosphere through 25 mm glass fiber filters in in-line filter holders. Samples were taken from an unoccupied exposure port at 2 L/min for five minutes. The samples were taken approximately every 10 minutes during the exposure. The main exhaust from the chamber was decreased during sampling in order to maintain the total exhaust flow constant.

Aerodynamic size of the aerosol was determined by taking a cascade impactor sample (Lovelace Multijet Cascade Impactor, In-Tox Products, Albuquerque, New Mexico) before and after the exposure period. The samples were taken at 20 LPM for three minutes from the exposure port used for concentration sampling. During particle size sampling, the main exhaust was turned off. The amount of material collected on each substrate was determined gravimetrically.

The Mass Median Aerodynamic Diameter (MMAD) and Geometric Standard Deviation (GSD) were calculated using the cutoff diameters for each stage supplied by the manufacturer and assuming a lognormal size distribution. The cumulative fraction on each stage was converted to the number of standard deviations from the median (Z-value). The natural logarithm of the effective cutoff diameter (ECD) of each stage was fitted to the equation in ECD = aZ + b using linear regression. The MMAD was calculated from this relationship where Z = 0 or the median of the distribution, MMAD = eb. The GSD was calculated from the slope of the equation, GSD = ea.

The exposure chamber was a nose-only device purchased from In-Tox Products, Albuquerque, New Mexico. It was constructed from aluminum and steel with 24 exposure ports on each side. The animals were restrained in tubes constructed of clear plastic and metal (25 cm long by E.5 cm inside diameter). The nose piece of each tube was inserted into an exposure port and two O-rings maintained a tight seal. The rats were secured in the tubes with a plastic plug. The test material was introduced into the top of the chamber where it was distributed to each exposure port via internal baffling. The exhaust was drawn out through an internal exhaust manifold via four ports at the end of the chamber. Although animals were exposed on only one side of the chamber, the entire exhaust manifold was operated to ensure even internal distribution. The chamber exhaust passed through the sampling trains or through two parallel in-line filters (Mine Safety Appliances, Pittsburgh, Pennsylvania) with particulate and organic vapor elements in each. The exhaust flowed through a flowmeter and then to house vacuum. Five rats of each sex restrained in the same manner but exposed only to room air served as controls.
Analytical verification of test atmosphere concentrations:
Total weight of material collected in this cold trap was divided by total volume of atmosphere sampled to estimate total exposure (combined aerosol and vapor) concentration.
Duration of exposure:
60 min
The average aerosol concentration was 0.87 mg/L. The concentration of vapors and aerosol combined (from the cold trap gravimetric analysis) was 1.67 mg/L.
No. of animals per sex per dose:
Five animals per sex per dose
Control animals:
Details on study design:
- Duration of observation period following administration: All animals were weighed before the exposure and 2, 7, and 14 days following exposure. Mean body weights for control and exposed animals were compared using a Student's t-test. The animals were observed for adverse effects during the exposure and then twice daily following exposure, except on weekends when they were observed only once.
- Necropsy of survivors performed: Yes, the animals were killed with an intraperitoneal injection of Sleep-Away following the 14-day observation period and were examined for gross pathological changes. The following organs and tissues were examined: skin, spleen, pancreas, stomach, small and large intestine, liver, adrenals, kidneys, reproductive organs, bladder, heart, thymus, salivary glands, lungs, trachea, thyroid, and fat. Skulls, kidneys, and a portion of the liver were preserved in 10% neutral buffered formal in (NFB) for possible future histological examination. The lungs were infused in situ via the trachea and preserved with NBF.
- Other examinations performed: The lungs were submitted for histopathological evaluation. The tissues were trimmed into consecutively numbered cassettes, one number per animal. Histology numbers, cross referenced to study, and animal numbers were recorded. After trimming, cassettes immersed in NBF were submitted to Histopathology Reference Laboratory, Oakland, California, for tissue processing and slide preparation. Tissues were subjected to standard paraffin embedding and routine five-micron H&E stained sections were obtained. Slides and blocks were returned to Chevron Environmental Health Center, Inc. and verified against one another, as well as the histology record on each animal. After verification of the animal-tissue-block count and the quality of each slide, the tissues were evaluated for microscopic abnormalities.
No data

Results and discussion

Effect levels
Dose descriptor:
Effect level:
> 1.67 mg/L air
Based on:
test mat.
Exp. duration:
60 min
Remarks on result:
other: Actual test material concentration may have been underestimated.
No mortality after 1-hour exposure to combined aerosol and vapor concentration of 1.67 mg/L. All animals survived to termination of the
Clinical signs:
other: No clinical signs of toxicity were observed during the exposure or observation periods.
Body weight:
Treatment did not affect effect mean body weight or body weight gain in either sex.
Gross pathology:
Microscopic examination of lung tissue detected no abnormalities in treated or control groups.

Any other information on results incl. tables

The animals were exposed to the vapors and condensation aerosol from heated test material for 60 minutes. The average aerosol concentration was 0.87 mg/L. The concentration of vapors and aerosol combined (from the cold trap gravimetric analysis) was 1.67 mg/L. The average MMAD and GSD of the condensation aerosol based on gravimetric analysis were 3.70 pm and 1.59, respectively. Approximately 99% of the aerosol was smaller than 10 µm. The heated air stream from the generator caused the air in the chamber to rise three degrees above the room temperature during the exposure.

No signs of toxicity were observed during the exposure or 14-day observation period. A Student's t-test showed that body weights of exposed animals were not significantly different from the control animals. At necropsy, no gross pathological changes were observed that could be attributed to the exposure. No microscopic changes were observed in the lungs of the exposed animals that could be attributed to the exposure.

Applicant's summary and conclusion

Interpretation of results:
other: No data
Criteria used for interpretation of results: not specified
1-hour LC50 > 1.67 mg/L (males and females)
Executive summary:

In a study conducted broadly in line with OECD Guideline 403 and in compliance with GLP, five rats of each sex were given a nose-only exposure for 60 minutes to the vapors and condensation aerosol from heated test material. The average total aerosol concentration was 0.87 mg/L. The average concentration of vapors plus aerosol was 1.7 mg/L. The average Mass Median Aerodynamic Diameter (MMAD) of the aerosol, based on gravimetric analysis, was 2.70 µm. Five rats of each sex were exposed to room air only and served as controls.

No signs of toxicity were observed in any exposed or control animals during the exposure or the 14-day observation period following the exposure. There were no statistical differences in mean body weights between exposed and control animals of either sex.

No gross pathologic changes that could be attributed to the exposure were observed at necropsy following a 14-day observation period. No exposure-related histologic changes were observed in the lungs.

The study cannot be used to assign classifiation to the substance according to the current EU criteria as the animals were exposed for only 1 hour as opposed to the 4 hour described in Directive 67/548/EEC. There were no signs of mortality during the study and consequently the LC50 was determined to be > 1.67 mg/L (males and females).