(S)-2-chloropropionic acid

Toxicity to reproduction: other studies

Administrative data

Endpoint:

toxicity to reproduction: other studies

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2 generation

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study with no deviations

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1997

Report date:

1997

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: OECD 416: Two Generation Reproduction

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

in vivo

Test material

Test material information

Constituent 1

Reference substance name:

2-chloropropionic acid

EC Number:

209-952-3

EC Name:

2-chloropropionic acid

Cas Number:

598-78-7

Molecular formula:

C3H5ClO2

IUPAC Name:

2-chloropropanoic acid

Details on test material:

Test materials: L-CPA

Description: Colourless Liquid
Lot/Batch: Bx 19 (Assigned CTL ref YO6206/004)
Purity: 96.6% w/w by calculation of which 92.7% L- and 4% D-

Stability: chemical stability of L-CPA in diet at concentrations 150 and 1500 ppm was considered satisfactory for 7 days at room temperature or 92 days in frozen storage.

Test animals

Species:

rat

Strain:

other: Alpk: APfSD (Wistar derived)

Sex:

male/female

Details on test animals or test system and environmental conditions:

Test animals
Species: Rat
Strain: Alpk:APfSD (Wistar-derived)
Age: 29 days old at dosing
Weight at dosing: 84.1 – 93.5g for F0 adults (includes males and females)
Source: Zeneca Pharmaceuticals, Alderley Park, Macclesfield, Cheshire. UK
Acclimatisation period:7 days prior to start of dosing
Diet: CT1, ad libitum
Water: Filtered mains water, ad libitum
Housing: Animals were housed, sexes separately, 2 aminals per wire cage. Females were housed individually during pregnancy and lactation.
Environmental conditions
Temperature: 21 +/- 2°C
Humidity: 55 +/- 15%
Air changes: At least 15 per hour
Photoperiod: 12 hours of light/12 hours of darkness

Administration / exposure

Route of administration:

oral: feed

No. of animals per sex per dose:

Groups of 26 male and 26 female rats (F0 adults) weaning Alpk:APfSD rats were fed diets containing 0 (control), 150, 500 or 1500ppm L-chloropropionic acid (L-CPA).

Details on study design:

Groups of 26 male and 26 female rats (F0 adults) weaning Alpk:APfSD rats were fed diets containing 0 (control), 150, 500 or 1500ppm L-chloropropionic acid (L-CPA) continuously until termination, with the exception of the 1500ppm females. The 1500ppm females were fed the test diet continuously up to the first generation lactation phase after which point the control diet was fed. At this stage the F1A litters in the 1500ppm group were between days 11 and 17 post partum.
The 1500ppm group was terminated at the end of the first generation period due to excessive maternal toxicity and high pup mortality.

The breeding programme was repeated in the controls, 150 and 500ppm groups with the F1 adults selected from the F1A offspring to produce the F2A litters after a 10 week pre-mating period.

Statistics:

Group mean values of the treated groups were compared with the appropriate control group using Student t-test (two sided) with the exception of pup organ weights.

Results and discussion

Effect levels

Dose descriptor:

NOEL

Effect level:

ca. 500 ppm

Based on:

test mat.

Sex:

female

Observed effects

Clinical findings which were attributed to treatment with L-CPA were confined to the 1500ppm group. During weeks 1-6 of the pre-mating period in the first generation signs of neurotoxicity were seen intermittently in several males and females and were characterised by prostration with gripping and biting the bars of the cage with some showing erection of the tail. These signs appeared to be triggered by external stimuli (cage opening), lasting for approximately 1-2 minutes and were followed by unsteady gait and muscle tremors. These signs were recorded as bizarre behaviour. Two males were killed as a result of these findings and loss of bodyweight, one in week 4 and one in week 6.

During lactation in the first generation bizarre behaviour or clonic convulsions were recorded for several females in the 1500ppm group on one or two days between days 5 and 15 post partum.

Offspring findings related to L-CPA were confined to the F1a litters of the 1500 ppm group. These findings were associated with the poor survival seen especially after day 15 in these litters. These were considered by the study director to reflect increased maternal toxicity rather than a direct response to the pups. This in turn almost certainly reflects the substantially increased feed intake during lactation, which at a constant dietary inclusion level gives a substantial increase of the received dose to the dams.

Applicant's summary and conclusion

Conclusions:

Based on this study there are no reproductive effects of L-CPA but the neurotoxic potential of the compound is confirmed in the parental animals.

Executive summary:

A two generation study was carried out in accordance with OECD 416, to assess the effect of L-2-Chloropropionic acid (L-CPA) on groups of 26 male and 26 female wistar derived rats.

The weanling rats were fed diet containing 0(control), 150, 500 or 1500ppm L-CPA ad libitum. The 1500ppm group was terminated after the first generation due to excessive maternal toxicity and high pup mortality.

The fertility and ability to reproduce of each generation of adult animals and the clinical condition, survival and subsequent growth of their off spring was observed and recorded.

Around day 29 post partum, ten male and ten female adults per generation were selected for a full examination post mortem in addition to any pups not selected to become F₁generation adults.

 

Clear signs of toxicity were seen in the F₀male and female rats dosed at 1500ppm L-CPA in the form of neurotoxicity with associated brain lesions and reductions in bodyweight gain and food consumption. The greatest reduction in bodyweight was around weeks 3 – 4 when the males were approximately 19% lower than the control and the females 9%.

No significant differences between the dosed animals and the control were observed in either the F₀or F₁adults at 150 or 500ppm dose levels.

With respect to the off spring, the only effect attributable to the L-CPA was the high incidence of F₁A pup mortality in the 1500 ppm group, however this was thought to be associated with increased maternal toxicity most probably as a result of increased food consumption, and therefore dose rate, during lactation.  There were no adverse effects on fertility or reproductive performance at dose rates of 150 or 500ppm.

Post mortem investigations showed a reduction in the brain weight of the F₀adults for both males and females in the high dose group. All F₀females in the 1500ppm group had necrosis of the granule cells in the cerebellium of the brain. This finding was not observed in the F₁females in the 500ppm group.

The no observed effect level was 500 ppm L-CPA in the diet.