Hydrocarbons, C10-C12, isoalkanes, <2% aromatics

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian germ cell study: cytogenicity / chromosome aberration

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Acceptable, well-documented study report equivalent or similar to OECD guideline 478.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1978

Report date:

1978

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 478 (Genetic Toxicology: Rodent Dominant Lethal Test)

GLP compliance:

no

Type of assay:

rodent dominant lethal assay

Test material

Test material information

Constituent 1

Reference substance name:

Hydrocarbons, C10-C12, isoalkanes, <2% aromatics

EC Number:

923-037-2

Cas Number:

0

Molecular formula:

None available - not a single isomer - see remarks

IUPAC Name:

Hydrocarbons, C10-C12, isoalkanes, <2% aromatics

Details on test material:

- Name of test material (as cited in study report): MRD-77-43
- Physical state: Clear, colorless liquid
- Storage condition of test material: sealed containers at room temperature
- Other:

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories
- Age at study initiation: Males (7-8 weeks); females pre-treatment mating period (8-9 weeks); females post treatment mating period (7-8 weeks)
- Weight at study initiation:
- Assigned to test groups randomly: [no/yes, under following basis: ]
- Fasting period before study:
- Housing: males were house individiually during the treatment period and hosed with two females per week during the 2 week pretreatment mating period and the 6 week post-treatment mating period. Females were housed individually during the pre-mating and post-mating periods and housed with males in a 2:1 ratio during mating.
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum):ad libitum

Administration / exposure

Route of administration:

inhalation: vapour

Details on exposure:

TYPE OF INHALATION EXPOSURE: whole body


GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
MRD-77-44 was transferred from a reservoir using a metering pump into a heated flask and flash evaporated. A stream of clean air was also passed through the flask and the vapor laden air transferred to a port in the chamber air inlet where it was diluted with normal chamber intake air to give the desired concentration.
- Exposure apparatus: inhalation chamber
- Rate of air: 125 liters/minute



- Air flow rate: 125 liters/minute
- Air change rate: 8 minutes
- Method of particle size determination:
- Treatment of exhaust air:


TEST ATMOSPHERE
- Brief description of analytical method used: Wilks Scientific Copr, Miran IA Ambient Air Analyzer (long path infrared)
- Samples taken from breathing zone: no

Duration of treatment / exposure:

Six hours /day

Frequency of treatment:

five days
Triethylenemelamine was administered by intraperitoneal injection (normal saline) as a single dose.

Post exposure period:

Following exposure, the males were mated with unexposed females (two female rats were mated with each male rat per week) for 6 consecutive weeks. The females were sacrificed 12 days after the last day of cohabitation

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
900 ppm
Basis:
nominal conc.

Doses / concentrations 2

Remarks:

Doses / Concentrations:
300 ppm
Basis:
nominal conc.

No. of animals per sex per dose:

Negative control: 10 males; 120 females during six week post-treatment mating period (two females/male/week)
Positive control: 10 males; 120 females during six week post-treatment mating period (two females/male/week)
300ppm MRD-77-43: 10 males; 120 females during six week post-treatment mating period (two females/male/week)
900ppm MRD-77-43: 10 males; 120 females during six week post-treatment mating period (two females/male/week)

Control animals:

yes

Positive control(s):

triethylenemelamine

- Route of administration: Intraperitoneal injection
- Doses / concentrations: 0.5mg/kg/bw

Examinations

Tissues and cell types examined:

Males: seminal vesicle, epididymides, prostate, and any abnormal lesion or tissue masses, testes.
Females: reproductive tissues examined (uterine horns preserved, implantation sites, resorption sites)

Statistics:

Comparisons were made during the treatment and post-treatment periods between negative control, positive control and test substance-treated groups by the chi-square method where applicable. Absolute data were compared using the F-test and Students t-test. When variances differed significantly, Students T-test was appropriately modified using Cochran’s approximation.

Results and discussion

Test results

Key result

Sex:

male

Genotoxicity:

negative

Toxicity:

no effects

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

valid

Applicant's summary and conclusion

Conclusions:

Interpretation of results: negative
When administered by vapor inhalation, MRD-77-43 is not mutagenic by the dominant lethal test. This finding does not warrant classification of (the test material as a genotoxin under the new Regulation (EC) 1272/2008 on classification, labeling, and packaging of substances and mixtures (CLP) or under the Directive 67/518/EEC for dangerous substances and Directive 1999/45/EC for preparations.

Executive summary:

In a dominant lethal assay,  MRD-77-43 was administered by vapor inhalation for six hours/day for five consecutive days to male rats at dose levels of 300 and 900 ppm to test for mutagenic potential.  Included in the study was a negative (chamber exposed) control group and a positive control group.  The latter received 0.5mg/kg of triethylenemelamine administered intraperitoneally on a single day, two hours prior to mating.  Each group contained 10 proven fertile rats.  Following exposure, the males were mated with unexposed females (two female rats were mated with each male rat per week) for 6 consecutive weeks.  The females were sacrificed 12 days after the last day of cohabitation.  Exposure of males to MRD-77-43 produced no adverse effects on mortality or body weight gain during the post-treatment mating period. Overall, no treatment related effects were observed on the number of pregnant females, number of implantations per litter, number of live fetuses, number of dead implantations, and the number of resoprtions.  Exposures to male rats had no effect on their ability to mate and impregnate females, and to produce live fetuses.  Based on these data, MRD-77-43 when administered by vapor inhalation to male rats is not considered mutagenic by the dominant lethal test.  This finding does not warrant the classification of MRD-77-43 as a genotoxin under the new Regulation (EC) 1272/2008 on classification, labeling, and packaging of substances and mixtures (CLP) or under the Directive 67/518/EEC for dangerous substances and Directive 1999/45/EC for preparations.