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Developmental toxicity / teratogenicity

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developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
28th October to 26th November 1980
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Well conducted GLP study, similar to guideline

Data source

Referenceopen allclose all

Reference Type:
study report
Report date:
Reference Type:
Summaries of toxicological data. Toxicology of chlorinated paraffins
Serrone DM, Birtley RDN, Weigand W and Millischer R
Bibliographic source:
Fd Chem Toxicol. 25: 553-562
Reference Type:
secondary source

Materials and methods

Test guideline
equivalent or similar to guideline
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Does not include peroid from implantation to start of organogenesis (days 1-5)
GLP compliance:
Limit test:

Test material

Constituent 1
Reference substance name:
Alkanes, C10-13, chloro
EC Number:
EC Name:
Alkanes, C10-13, chloro
Cas Number:
Alkanes, C10-13, chloro
Details on test material:
- Name of test material (as cited in study report): short chain chlorinated paraffin (58% chlorination)
- Substance type: technical product
- Physical state: clear, slightly viscous liquid
- Analytical purity: "100%"
- Impurities (identity and concentrations): free hydrogen chloride (HCl) - 7ppm; no stabilisers
- Composition of test material, percentage of components: C10-13 chlorinated paraffin, 58% chlorination
- Purity test date: no data
- Lot/batch No.: R-201-198
- Expiration date of the lot/batch: "dependent on routine analysis"
- Stability under test conditions: "unstable"
- Storage condition of test material: -20oC

Test animals

other: COBS CD
Details on test animals or test system and environmental conditions:
- Source: Charles River breeding Labs, Portage, Michigan, USA
- Age at study initiation: approx. 12 weeks
- Weight at study initiation: 243 g on day 0 of gestation
- Fasting period before study: none
- Housing: singly in suspended wire-mesh cages
- Diet (e.g. ad libitum): Purina Certified Rodent Chow #5002, ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 14 days

- Temperature (°C): no data
- Humidity (%): no data
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 1980-10-28 To: 1980-11-26

Administration / exposure

Route of administration:
oral: gavage
corn oil
Details on exposure:
PREPARATION OF DOSING SOLUTIONS: Appropriate amount of chlorinated paraffin was weighed out, admixed with the vehicle and shaken by hand until homogeneous

- Justification for use and choice of vehicle (if other than water): corn oil - test material solubility
- Concentration in vehicle: at a concentration to permit administration at a constant volume of 0.5 ml/100 g bw
- Amount of vehicle (if gavage): 0.5 ml/100 g bw
- Purity: no data
Analytical verification of doses or concentrations:
Details on analytical verification of doses or concentrations:
Weekly samples of dosing solutions taken prior to dosing and the concentration of chlorinated paraffin measured viscometrically by comparison with known standards.
Details on mating procedure:
- Impregnation procedure: co-housed
- If co-housed:
- M/F ratio per cage: 1 to 1
- Length of cohabitation: no data
- Proof of pregnancy: vaginal plug/vaginal smear for sperm referred to as day 0 of pregnancy
- Any other deviations from standard protocol: none
Duration of treatment / exposure:
days 6 to 19 of gestation
Frequency of treatment:
Duration of test:
Animals sacrificed on day 20 of gestation
Doses / concentrations
Doses / Concentrations:
0, 100, 500 and 2000 mg/kg bw/day
nominal conc.
No. of animals per sex per dose:
25 pregnant dams/dose group
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: no data
- Rationale for animal assignment (if not random): sequential addition of mated females to the 4 dose groups


Maternal examinations:
- Time schedule: daily for mortality and overt changes in appearance/behaviour

- Time schedule: daily for clinical signs of toxicity

- Time schedule for examinations: on gestation days 0, 6, 9, 12, 16 and 20

- Sacrifice on gestation day 20 (and animals which died before day 20)
- Organs examined: uterus and organs of the abdominal and thoracic cavities

Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: location and numbers of viable and non-viable fetuses
Fetal examinations:
- External examinations: Yes; all per litter
- Soft tissue examinations: Yes; approx. half per litter
- Skeletal examinations: Yes; approx. half per litter
Male to female sex distribution and numbers of litters with malformations were compared using Chi square test with Yates' correction and/or Fisher's exact probability test.
The number of early and late resorptions and post-implantation losses were compared by the Mann-Whitney U-test
The mean number of viable foetuses, total implantations, corpera lutea and mean foetal body weights were compared by analysis of variance (one-way), Bartlett's test for homogeneity of variance and the appropriate t test
no data
Historical control data:
Yes - vitamin A

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:yes

Details on maternal toxic effects:
No biologically meaningful differences in the appearance or behaviour of rats were seen in the 100 mg/kg bw/day group when compared to the controls. Yellow/brown staining/matting of anogenital region, soft stools, red/brown staining in nasal region, lethargy, oily coat, emaciation and excessive salivation was seen in animals in the 500 and 2000 mg/kg bw/day treatment groups. Mean body weight gain of top dose animals was reduced between days 9 and 16 of gestation and 8 top dose animals died between days 15 and 20 of gestation of unknown, but probably treatment-related effects.

Effect levels (maternal animals)

open allclose all
Dose descriptor:
Effect level:
100 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: maternal toxicity
Dose descriptor:
Effect level:
500 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:yes

Details on embryotoxic / teratogenic effects:
No biologically meaningful or statistically significant differences were seen, compared to controls, in the mean numbers of viable foetuses, early or late resorptions, postimplantation loss, total implantations, corpora lutea, the foetal sex distribution or malformations in the 100 and 500 mg/kg bw/day groups, genetic and developmental variations in all groups, or the mean foetal body weights in the 100 mg/kg bw/day group. The statistically significant increase in mean foetal weight in the 500 mg/kg bw/day group was not considered to be treatment-related. Decreased foetal viability per dam and increased postimplantation losses were noted in top dose animals. Adactyly and/or shortened digits were seen in 19 foetuses from 3/15 litters examined from top dose animals.

Effect levels (fetuses)

Dose descriptor:
Effect level:
500 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: teratogenicity

Fetal abnormalities

not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Applicant's summary and conclusion

Treatment of pregnant rats with a C10-13 chlorinated paraffin (58% chlorination) by oral gavage from days 6 to 19 of gestation resulted in maternal toxicity at 500 and 2000 mg/kg bw/day (highest tested dose) and the appearance of foetal abnormalities at the top dose level only. No developmental effects were seen at 500 mg/kg bw/day and no adverse effects were seen in either dams or foetuses at 100 mg/kg bw/day.
Executive summary:

In a well conducted GLP study, similar to OECD Guideline 414, groups of 25 mated female COBS CD rats were given 0, 100, 500 or 2000 mg/kg bw/day of a C10 -12 chlorinated paraffin (58% chlorination) in corn oil by oral gavage on days 6 to 19 of gestation. Animal were killed on day 20 and the numbers and location of viable and non-viable foetuses, resorption sites and the total number of implantations and corpera lutea were determined. Appearance and body weight gain of dams was monitored and all foetuses were examined for external malformations. Approximately one half of the foetuses from each litter were examined for visceral malformations and the other half for skeletal abnormalities.

Clinical signs of maternal toxicity were seen in both 500 and 2000 mg/kg bw/day groups, comprising yellow or brown matting and staining of the coat in the anogenital region, red or brown staining in the nasal region, excessive salivation, lethary and emaciation. The effects were at an increased frequency in the top dose animals. A decrease in body weight gain from days 9 to 16 and 8/25 animals died between gestation days 16 and 20 in the top dose group. Significant increases in the numbers of post-implantation losses, due to both early and late resorptions, and a decrease in the numbers of viable foetuses was seen in the top dose group only. Foetal malformations (adactyly and/or shortened digits) were seen in 19 foetuses from 3/15 litters examined from the top dose animals.

Overall, no developmental toxicity was seen in animals in the 500 mg/kg bw/day group, and no adverse effects were seen in dams or foetuses in the control or 100 mg/kg bw/day groups. Therefore, the no-observed-adverse-effect level (NOAEL) for developmental toxicity in the rat in this study was 500 mg/kg bw/day.