N-(hydroxymethyl)acrylamide

Neurotoxicity

Administrative data

Endpoint:

neurotoxicity: sub-chronic oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1983

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The incidence and severity of findings at other exposure levels was not reported and hence a NOAEL was not identifiable from this study.

Data source

Reference

Reference Type:

publication

Title:

Neurotoxicity Of Acrylamide And Related Compounds In Rats: Effects On Rotarod Performance, Morphology Of Nerves And Neurotubulin.

Author:

Tanii H. and Hashimoto K.

Year:

1983

Bibliographic source:

Arch. Toxicol. 54:203-213.

Materials and methods

Principles of method if other than guideline:

Neurotoxicity study in the rat.

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

N-(hydroxymethyl)acrylamide

EC Number:

213-103-2

EC Name:

N-(hydroxymethyl)acrylamide

Cas Number:

924-42-5

Molecular formula:

C4H7NO2

IUPAC Name:

N-(hydroxymethyl)acrylamide

Details on test material:

No data

Test animals

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: not specified
- Age at study initiation: not specified
- Weight at study initiation: not specified
- Fasting period before study: not specified
- Housing: not specified
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: not specified
ENVIRONMENTAL CONDITIONS
- Temperature (°C): not specified
- Humidity (%): not specified
- Air changes (per hr): not specified
- Photoperiod (hrs dark / hrs light): not specified
IN-LIFE DATES: not specified

Administration / exposure

Route of administration:

oral: drinking water

Vehicle:

water

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

90 days

Frequency of treatment:

Animals were dosed for 60-90 daysin drinking water in four different concentrations (four rats per dose level) chosen by preliminary experiments.

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 3.36, 5.41, 8.65, 13.8 mM
Basis:
nominal in water

No. of animals per sex per dose:

4 males

Control animals:

yes, concurrent vehicle

Details on study design:

0, 3.36, 5.41, 8.65, 13.8 mM in drinking water for 90 days is equivalent to approximately 0, 33.9, 54.6, 87.4, and 139.4 mg/ml, respectively

Examinations

Neurobehavioural examinations performed and frequency:

A modified apparatus of Dunham and Miya (1957), which consists of a 9-cm diameter, roughly surfaced PVC rod, rotated at 5 rpm, was used. Arithmetic means of the walking periods in five successive 60-s trials in each rat measured once a week for 90 days were calculated.

Sacrifice and (histo)pathology:

After treatment with the test compounds for 90 days, animals given the highest dose level were injected with heparin (sodium salt, 10,000 U/kg body weight). Thirty minutes later, they were anesthetized with pentobarbital sodium and perfused with 4% paraformaldehyde followed by 5% glutaraldehyde, each in 0.1 M phosphate buffer (pH 7.4), through the left ventricle using a pressure of about 110 mm of mercury. Tissue segments from tibial and sural nerves were immersed for 2 h in 2% Dalton's chrome osmium solution, dehydrated stepwise by ethanol, immersed in propylene oxide, and infiltrated with epoxy resin. The small segments of tissues were placed in molds containing epoxy resin and hardened by heat. Tissue blocks were cut in one micrometer sections and stained with 1% toluidine blue. All epon sections prepared were examined by light microscopy.
[3H]Cholchicine-binding to neurotubulin in nerve tissues: After 60-67 days treatment of animals with each test compound at the highest dose level shown in Table 1, sciatic nerves, brain (cortex and medulla), cerebellum and spinal cord (cervical and lumbar) from both treated and untreated were removed and chilled to 0~C. The binding assay was performed using the method principally the same as Borisy (1972). Tissues were washed with 67 mM phosphate buffer (0.1 M KCI, pH 6.8), homogenzied in the same buffer containing 0.1 mM GTP using a Polytron tissue homogenizer (Kinematica, Luzern, Switzerland) for 30s, and the homogenates were spun at 27,000g for 30 min at 4~C. A 0.1-ml portion of the supernatant (less than 0.3 mg protein) was incubated with 10 ~tlof 0.44 mM [3H]colchicine (specific activity, 0.21 Ci/mmol) at 37~C for 20 min. [3H]-colchicine-binding was linear up to 0.3 mg protein under these conditions. The reaction was stopped by adding 8 ml of ice cold 10 mM phosphate buffer (10 mM MgC12~pH 6.8). The protein was collected on four layers of DE81 Whatman filter discs under low vacuum and washed eight times with 10 ml of the same ice cold buffer. The filters were then placed overnight in a scintillation vial containing fluid (toluene; 2 parts, triton x-100; 1 part, PPO; 5g/l, POPOP; 0.25g/1), and radioactivities were measured in a scintillation counter (Mark III, Searle).

Statistics:

Body weight differences between the treatment and the control groups were tested for significance using analysis of variance. In other measurements, differences of values were examined using Student's t-test.

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

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 specified

Ophthalmological findings:

not examined

Clinical biochemistry findings:

not examined

Behaviour (functional findings):

effects observed, treatment-related

Gross pathological findings:

not specified

Neuropathological findings:

effects observed, treatment-related

Details on results:

CLINICAL SIGNS AND MORTALITY
Clinical signs of toxicity included weakness, tendency towards spreading and dragging of hind limbs and occasionally, amongst more severely affected animals, urinary incontinence; however it was not clear which groups these findings were seen in. BODY WEIGHT AND WEIGHT GAIN
Significant reductions in body weight gain was noted amongst all treated animals (6% reduction at the lowest exposure level, 43% at the highest).
WATER CONSUMPTION AND COMPOUND INTAKE (IF DRINKING WATER STUDY)
No data
NEUROBEHAVIOUR
Rotarod performance at day 90 showed impairment only at the two highest exposure levels (3/4 animals at 8.65 mM and 4/4 animals at 13.8 mM). No other rotarod results were available.
NEUROPATHOLOGY
Light microscopy examination showed moderate to severe changes: shrinkage and loss of myelinated fibers, myelin retraction, and corrugation of myelin sheaths. A significant reduction of the colchicine binding was also detected in the spinal cord of both cervical and lumbar regions. However, this reduction in colchicine binding was not seen in the brain or the cerebellum.
OTHER
Significant decreases were observed in the [3H]colchicine-binding in the sciatic nerve at 60 days of treatment.

Effect levels

1

Dose descriptor:

NOAEC

Effect level:

11 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male

Remarks on result:

other:

2

Dose descriptor:

LOAEL

Effect level:

17.5 mg/kg bw/day

Based on:

test mat.

Sex:

male

Remarks on result:

other:

Applicant's summary and conclusion

Conclusions:

N-methylolacrylamide induced neurotoxicity in the rat at 17.5 mg/kg bw/day. The NOAEL was approximately 11 mg/kg bw/day