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Toxicological information

Repeated dose toxicity: inhalation

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Administrative data

Endpoint:
sub-chronic toxicity: inhalation
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
1982-12-21 to 1983-04-22
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study is classified as reliable without restrictions because it was conducted according to OECD 413 guidelines and was GLP compliant.
Cross-reference
Reason / purpose:
reference to same study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1984
Report Date:
1984

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)
Deviations:
yes
Remarks:
Only a few major organs were examined histologically.
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
This substance is very similar with regard to health endpoints to the substance being registered.

- Name of test material (as cited in study report): Neodene 6 alpha olefin
- Substance type: C6 alpha olefin
- Physical state: Liquid
- Analytical purity: Not reported in study report, but published information states 97.2% 1-hexene
- Impurities (identity and concentrations): 1.1% trans-2-hexene, 0.6% cis-2-hexene, 0.5% cis and trans-3-hexene, and 0.6% 2-ethyl-1-butene
- Lot/batch No.: Stated as assigned WRC Tox sample No. 571D
- Stability under test conditions: Stable
- Storage condition of test material: Under nitrogen at room temperature
- Other: The characterization and stability were stated to be described in Analytical RIR 343, which was not provided in the study report.

Test animals

Species:
rat
Strain:
Fischer 344
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan Sprague-Dawley, Inc.
- Fasting period before study: No
- Housing: Individually
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: 19 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 24±2°C
- Humidity (%): 40 to 70%
- Photoperiod (hrs dark / hrs light): 12 hours dark/12 hours light

IN-LIFE DATES: From: 1983-01-07 To: 1983-04-22

Administration / exposure

Route of administration:
inhalation: vapour
Type of inhalation exposure:
whole body
Vehicle:
other: unchanged (no vehicle)
Remarks on MMAD:
MMAD / GSD: None
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus:7700 Litre King-Lar stainless steel/glass chambers housed in inhalation suites
- Method of holding animals in test chamber: None
- Source and rate of air: Main air supply line at an unspecified rate
- System of generating particulates/aerosols: A head space sweep technique using dry nitrogen through a mass flow controller into a stainless steel container supplied with a continuous feed of test material, then introduced into the main air supply line with a static mixing device, then fed into the exposure chamber
- Temperature, humidity, pressure in air chamber: 22 to 26 degrees Celsius and 30 to 63% humidity
- Air flow rate: 533 cubic meters to 578 cubic meters
- Air change rate: 1.3 to 1.6 cubic meters per minute

TEST ATMOSPHERE
- Brief description of analytical method used: The concentration of hex-1-ene was determined by gas chromatography using an 80/100 mesh Carbopak® column with 0.19% picric acid and flame ionization detection. Vapour concentration was determined about every ten minutes during exposure. Samples were taken near the centre of the chamber where the animals were positioned in the exposure chamber. Three Varian Vista Series 4600 Gas Chromatographs, calibrations performed daily, with one CDS 401 Chromatography Data System was used for the concentration analyses.
- Samples taken from breathing zone: Yes
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The analytical concentrations for the low, middle, and high exposures ranged from 297 to 300 parts per million, 990 to 1002 parts per million, and 2958 to 3000 parts per million, respectively. The analytical concentrations were slightly (<10%) lower than the calculated nominal concentrations.
Duration of treatment / exposure:
13 weeks
Frequency of treatment:
6 hours a day, 5 days a week
Doses / concentrations
Remarks:
Doses / Concentrations:
300, 1000, or 3000 parts per million
Basis:
analytical conc.
No. of animals per sex per dose:
Forty animals/sex/dose; ten animals/sex/dose for neuromuscular testing, ten animals/sex/dose for interim sacrifice at 7 weeks, and twenty animals/sex/dose for terminal sacrifice
Control animals:
yes, sham-exposed
Details on study design:
- Dose selection rationale: Based on an 11-day study (WRC-TIR-733)
Positive control:
none

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes, mortality and clinical signs
- Time schedule: Before and after exposure and once on days with no exposure

DETAILED CLINICAL OBSERVATIONS: No data reported.

BODY WEIGHT: Yes
- Time schedule for examinations: Pretreatment and weekly during exposure

FOOD CONSUMPTION: No

FOOD EFFICIENCY: No

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: Pretest, week 7 and week 13
- Anaesthetic used for blood collection: No data reported
- Animals fasted: Yes
- How many animals: Ten animals per sex and dose at study initiation, ten animals per sex and dose at 7 weeks, and twenty animals per sex and dose at week 13
- Parameters checked in table 1 were examined.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Pretest, week 7, and week 13
- Animals fasted: Yes
- How many animals: Ten animals per sex and dose at study initiation, ten animals per sex and dose at 7 weeks, and twenty animals per sex and dose at week 13
- Parameters checked in table 2 were examined.

URINALYSIS: Yes
- Time schedule for collection of urine: Weeks 7 and 13
- Metabolism cages used for collection of urine: No data reported.
- Animals fasted: Yes
- Parameters checked in table 3 were examined.

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: Pretest and weekly during exposure
- Dose groups that were examined: All groups
- Battery of functions tested: Balance and neuromuscular coordination

OTHER: Sperm counts
Sacrifice and pathology:
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes (see table 4)
Other examinations:
The lungs, liver, kidney, brain, heart, spleen, and right testicle or uterus were weighed. Sperm counts, measured with a hemocytometer and phase-contrast microscope, were performed using the left testicle of each male rat after detunication, weighing, and homogenization.
Statistics:
Body weight differences were analyzed by analysis of covariance using initial weights of individual rats on day -2 as a covariate with the least squares difference test. Organ weight, clinical chemistry, haematology, urinalysis, and organ to body weight ratio data were analyzed by Dunnett’s t-test on the ranked data. Neuromuscular coordination data were adjusted by summing the time for the best 3 of 4 trials for each rat and analyzed by analysis of variance or analysis of covariance. All statistics were measured with p<0.05.

Results and discussion

Results of examinations

Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
effects observed, treatment-related
Clinical biochemistry findings:
effects observed, treatment-related
Urinalysis findings:
no effects observed
Behaviour (functional findings):
no effects observed
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
no effects observed
Details on results:
CLINICAL SIGNS AND MORTALITY: No deaths occurred. There were no clinical signs related to treatment.

BODY WEIGHT AND WEIGHT GAIN: Decreased body weight was observed in 3000-ppm females (statistically significant) and males (statistically significant only sporadically). The reported 4% reduction in body weight, while statistically significant, is of limited toxicological significance. (Table 5)

HAEMATOLOGY: There were no treatment-related findings at interim sacrifice. At terminal sacrifice, 1000-ppm females and 3000-ppm males and females had higher haematocrit and red blood cells, and in 1000-ppm and 3000-ppm females mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) were lower. Although these findings appear treatment-related, they were not associated with any histopathology findings, results are not dose related, and changes were within 5% of the control. (Table 6)

CLINICAL CHEMISTRY: There was an increase in phosphorus in males at all treatment concentrations, which may be due to a low level in the control. There was a consistent increase in phosphorus in 1000-ppm and 3000-ppm females at interim and terminal sacrifice (Table 7). The toxicological significance of this finding is doubtful.

URINALYSIS: There were no treatment-related changes.

NEUROBEHAVIOUR: There were no treatment-related effects.

ORGAN WEIGHTS: There was a slight (5% or less) but significant decrease in absolute and relative testes weight in 3000-ppm males that was not associated with any change in sperm parameters or histopathology. This decrease, while statistically significant, is of limited toxicological relevance. Other changes in organ weights were related to the reduced body weight.

GROSS PATHOLOGY: There were no treatment-related findings.

HISTOPATHOLOGY: NON-NEOPLASTIC: There were no treatment-related findings.

HISTOPATHOLOGY: NEOPLASTIC (if applicable): There were no treatment-related findings.

OTHER FINDINGS: There were no treatment-related changes in sperm counts.

Effect levels

Dose descriptor:
NOAEC
Effect level:
3 000 ppm
Sex:
male/female
Basis for effect level:
other: Equivalent to 10,326 mg/m3; no toxicologically relevant findings at the highest concentration tested.

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

Table 5. Body weight data

 

Body weight data expressed in grams (mean ± s.d.)

 

Males - ppm

0

300

1000

3000

Day 0

161.28 ± 2.61 n=40

159.84 ± 2.58 n=40

159.72 ± 2.93 n=40

161.58 ± 2.37

n=40

Day 33

250.1 ± 3.9

n=40

252.3 ± 3.1

n=40

246.2 ± 4.4

n=40

245.0 ± 3.2

n=40

Day 61

305.2 ± 4.3

n=30

305.2 ± 3.8

n=30

302.3 ± 5.3

n=30

295.1 ± 3.7

n=30

Day 89

338.9 ± 4.2

n=30

340.8 ± 4.0

n=30

339.7 ± 5.2

n=30

329.0 ± 3.6

n=30

 

Females – ppm

0

300

1000

3000

Day 0

126.04 ± 1.29 n=40

125.30 ± 1.28 n=40

125.69 ± 1.28 n=40

125.94 ± 1.31

n=40

Day 33

164.44 ± 1.90 n=40

162.93 ± 1.36 n=40

163.82 ± 1.47 n=40

160.18 ± 1.48

n=40

Day 61

183.80 ± 2.47 n=30

181.83 ± 1.61 n=30

181.23 ± 1.73 n=30

175.41 ± 1.75 *

n=30

Day 89

194.87 ± 2.62 n=30

194.62 ± 1.68 n=30

192.93 ± 2.02 n=30

187.08 ± 1.85 *

n=30

*Statistically significant at p<0.05.

Table 6. Selected Hematological Data

Hematological Data (mean ± s.d.)

 

Males - ppm

0

300

1000

3000

Haematocrit (%) (week 13)

44.4 ± 0.5

n=20

43.7 ± 0.7

n=20

45.0 ± 0.1

n=20

45.3 ± 0.3*

n=20

RBC (106/ mm3) (week 13)

6.58 ± 0.07

n=20

6.49 ± 0.12

n=20

6.65 ± 0.03

n=20

6.71 ± 0.05 *

n=20

 

Females – ppm

0

300

1000

3000

Haematocrit (%) (week 13)

40.9 ± 0.3

n=20

42.5 ± 0.7

n=20

43.1 ± 0.8 *

n=20

42.6 ± 0.05 *

n=20

RBC (106/ mm3) (week 13)

5.78 ± 0.05

n=20

6.01 ± 0.10

n=20

6.09 ± 0.11 *

n=20

6.04 ± 0.07 *

n=20

*Statistically significant at p<0.05

Table 7. Phosphorus levels in the blood

Clinical Chemistry Data (mean ± s.d.)

 

Males - ppm

0

300

1000

3000

Phosphorus mg/dL

(week 7)

6.98 ± 0.23

n=10

7.21 ± 0.26

n=10

8.18 ± 0.29 *

n=10

7.52 ± 0.23

n=10

Phosphorus mg/dL

(week 13)

6.42 ± 0.15

n=20

7.27 ± 0.20 *

n=20

7.22 ± 0.14 *

n=20

7.72 ± 0.34 *

n=20

 

Females – ppm

0

300

1000

3000

Phosphorus mg/dL

(week 7)

6.28 ± 0.57

n=10

6.39 ± 0.42

n=10

7.59 ± 0.37 *

n=10

7.78 ± 0.27 *

n=10

Phosphorus mg/dL

(week 13)

5.64 ± 0.19

n=20

6.07 ± 0.24

n=20

6.46 ± 0.24 *

n=20

6.85 ± 0.15 *

n=20

 *Statistically significant at p<0.05.

Applicant's summary and conclusion

Conclusions:
The NOAEC for this study was 3000 ppm (10,326 mg/m3) based on a lack of toxicologically relevant findings at the highest concentration tested.
Executive summary:

Justification for Read Across

Several criteria justify the use of the read across approach to fill data gaps fo risomerised olefins; alpha, internal, linear and branched – multiple carbon numbersubstances using linear alpha olefin substances. Studies indicate that changing the carbon number, the location of the double bond, or adding branching does not measurably alter effects on mammalian health endpoints. There is a consistent toxicity potency pattern for linear alpha olefins supported by a low toxicity concern for acute oral, dermal and inhalation exposure. These materials are slightly irritating to skin and slightly to non-irritating to eyes of rabbits. In repeat dose toxicity studies, hex-1-ene and tetradec-1-ene have shown comparable levels of low toxicity, with female rats exhibiting alterations in body and organ weights and changes in certain haematological values at the higher doses tested; male rats exhibiting nephropathy presumed to be associated with the alpha2u-globulin protein. Screening studies indicate that they are not neurotoxic (for hex-1-ene and tetradec-1-ene), do not produce adverse effects on reproduction or foetal development (hex-1-ene and tetradec-1-ene), and are not genotoxic (hex-1-ene, oct-1-ene, dec-1-ene, dodec-1-ene, and tetradec-1-ene). Study results for the aforementioned endpoints indicate a low hazard potential for human health. Since the addition of branching does not measurably alter the results of studies on mammalian health endpoints, there should not be any significant toxicological differences between substances in multiple carbon number isomerised olefins and linear alpha olefins.  Therefore, read across between these two categories can be justified.

In a 90-day inhalation toxicity study, Neodene 6 alpha olefin was administered to forty Fischer 344 rats/sex/concentration by dynamic whole body exposure at concentrations of 0, 300, 1000, or 3000 parts per million (corresponding to 0; 1033; 3442; or 10, 326 mg/m3) for 6 hours a day, 5 days a week, for 13 weeks. Ten of the animals/sex/concentration were used for neuromuscular testing, ten of the animals/sex/concentration were sacrificed after 7 weeks of exposure, and twenty animals/sex/concentration were sacrificed after 13 weeks of exposure.

Subchronic inhalation of Neodene 6 alpha olefin for 13 weeks did not produce any adverse respiratory, neuromuscular, or testicular effects in rats. Decreased body weight was observed in 3000 -ppm females (statistically significant) and males (statistically significant only sporadically). Decreased absolute liver and kidney weights were observed in 3000-ppm females; however, these findings were considered secondary to reduced body weight in the absence of histopathological findings in these organs. There were statistically significant differences in haematology and clinical chemistry values, but the changes were slight (generally within 5% of the control), were not dose related, and/or not associated with any histopathology findings.Increased phosphorus levels were reported in males at all treatment levels and females exposed to 1000 and 3000 ppm hex-1-ene. The toxicological significance of these findings is doubtful. The NOAEC is 3000 parts per million (10,326 mg/m3) based on a lack of toxicologically relevant findings at the highest concentration tested.

This study received a Klimisch score of 1 and is classified as reliable without restrictions because the study was conducted according to OECD 413 guidelines and was GLP compliant.