Sodium N-(hydroxymethyl)glycinate

Endpoint summary

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

November 17, 1983 - February 24, 1984

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP compliant study with detailed reporting of the results.

Qualifier:

according to guideline

Guideline:

EPA OPP 82-1 (90-Day Oral Toxicity)

Deviations:

no

GLP compliance:

yes

Limit test:

no

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, Inc., Wilmington, MA.- Age at study initiation: 5 weeks- Weight at study initiation: - Fasting period before study:- Housing: individually housed in stainless steel wire mesh bottom cages- Diet: certified feed, Ziegler Brothers, Gardners, PA, ad libitum- Water: ad libitum- Acclimation period: 14 daysENVIRONMENTAL CONDITIONS- A twelve hour light-dark cycle- Room temperature: between 68-74 ° F and - Humidity: between 40-60%.IN-LIFE DATES: From: October 6, 1983 (start test: November 17, 1983) To: February 24, 1984PREPARATION FOR THE STUDY:- Animals were assigned to groups by means of stratified randomization of body weights using a computer generated random number sequence. - Each animal assigned to a group was given a unique animal identification number.

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

The test ar­ticle was administered via gastric intubation {gavage) once daily for at least 90 consecutive days. The test article was administered as a 2% {w/v) aqueous solution. Individual dosages were calculated according to the following formula:Dosage level _____________ (ml/kg) x bodyweight (kg) = daily dose (ml)Concentration Individual animals in the control group {A) received vehicle { distilled water) only based on the following calculation: 8.0 ml/kg x body weight {kg)= daily dose {ml) Individual dosages were adjusted weekly based on the most recent weekly body weight. F·resh test solutions were pre-pared daily with the exception of weekend dosages which were prepared on Friday of each week.The test solution or vehicle (control group) was administered using a disposable # 10 French rubber Nelaton catheter (Rusch, Inc., New York, NY) attached to a disposable 1, 3 or 5 ml syringe.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

A 2% aqueous Suttocide A solution was allowed to stand at room temperature for 12 weeks. After weeks 1,2,3,4,8, and 12, the test solution and a freshly-prepared 2% aqueous Suttocide A solution were assayed using a colorimetric assay (at 580 nm) of methylol groups destructively removed from the hydroxymethyl glycinate by heating in strong sulfuric acid in the presence of l,8-dihydroxynaphthalene-3,6-disulfuric acid (chromotropic acid).

Duration of treatment / exposure:

90 days

Frequency of treatment:

once daily

Remarks:

Doses / Concentrations:10, 40, 160 mg/kg bwBasis:actual ingested

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

No further details

Positive control:

Not included

Observations and examinations performed and frequency:

CAGE SIDE/CLINICAL OBSERVATIONS: Yes - Time schedule: daily two mortality checks five hours apart, once daily for external signs of toxicity- Cage side observations checked in table were included (Appendix III of the study report).BODY WEIGHT and FOOD CONSUMPTION: Yes - Time schedule for examinations: measured prior to initiation of the study (day -1), weekly thereafter, and at the time of necropsy. - Food consumption: measured weekly. - Food efficiency: Yes OPHTHALMOSCOPIC EXAMINATION: Yes - Time schedule for examinations: on all rats prior to initiation of the study and on all rats after 13 weeks of dosing. - The eyes of all rats were examined by indirect ophthalmoscopy after pupil dilation with 1% Tropica-mide. CLINICAL LABORATORY STUDIES: Yes- Blood samples for hematology and clinical chemistry determinations and urine samples for urine analysis were collected after 6 and 13 weeks of dosing from all animals.- Blood was drawn from the periorbi tal plexus (orbital sinus puncture) under light ether anesthesia. - Animals were fasted overnight prior to blood collection.* HAEMATOLOGY: Yes- Parameters: hemoglobin; hematocrit; erythrocyte count; total and differential leucocyte counts platelet count. * CLINICAL CHEMISTRY: Yes- Parameters: urea nitrogen; glutamic pyruvic transaminase (GPT) glutamic oxaloacetic transaminase (GOT) calcium; phosphorus; chloride; sodium; potassium; glucose; total bilirubin; albumin; globulin; total protein ; creatinine * URINALYSIS: Yes - Parameters: appearance; specific gravity; occult blood; protein; pH; bilirubin; urobilinogen; ketones; glucose; microscopic examination of sediment NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes- gross necropsy included examination of the external sur-faces and orifices, the cranial cavity, carcass, the external and cut surfaces of the brain, the thoracic, abdominal and pelvic cavities and their viscera, and the cervical tissues and organs. Fresh organ weights were recorded and organ-to- body weight ratios calculated for the following tissues from all animals: brains, kidneys, liver, ovaries, testes.- Lungs were inflated under constant pressure with 4 % formaldehyde-1 % g lutaralde-hyde in a 176 mOsM phosphate buffer via the airways.- Urinary bladders were distended with formalin and left unopened for examination following fixation. HISTOPATHOLOGY: Yes - Microscopic examination of paraffin embedded hema-toxylin and eosin stained tissue sections (3-5 microns) was performed on the following organs and tissues from all rats in the high dosage and control groups which were sacrificed at termination and from one rat that died during the course of the study: adrenal glands liver spleen aorta stomach uterus brain-medulla/ponsovaries testes cerebellular cortexpancreas thymus esophagus pituitary gland thyroid (both lobes) and parathyroids heart rectum urinary bladder intestine, small (duodenum, jejunum, ileum) salivary gland (submaxillary) intestine, large (cecum, colon) sciatic nerve all gross lesionkidneys lung with mainstem bronchi lymph node (mesenteric)Microscopic examination of the following tissues and organs were conducted on all rats from the low and middle dosage: kidneys, lungs, liver and all gross lesions.

Statistics:

Continuous data (body weight, food consumption, clinical parameters, absolute and relative organ weights) were analyzed using analysis of variance (Snedecor and Cochran, 1967). Differences between groups were identified using the Least Significant Difference test. Pathology inci- dence data were analyzed using Fisher's Exact test. For all statistical analyses, significance was juagea at the level of pi 0.05.

Clinical signs:

no effects observed

Description (incidence and severity):

One control male animal (7824004) died on day 49 of the study as a result of accidental overdose with the anes-thetic (ether) prior to blood collection. All other animals survived for the duration of the dosing period. None of the daily observations indicated any sign of toxicity or Suttocide A-treatment-related behavioral abnormality. Incidentally, swelling in the neck region occurred in all groups except the high dose females, primarily on days 13-21. This was most likely caused by an SDA virus, which is commonly found in young Sprague-Dawley rats. The episodes of swelling were transient and were no longer apparent after day 21. Incidentally, somw rats had sores caused by cage irritation, which did not interfere with the conduct of the study.

Mortality:

no mortality observed

Description (incidence):

One control male animal (7824004) died on day 49 of the study as a result of accidental overdose with the anes-thetic (ether) prior to blood collection. All other animals survived for the duration of the dosing period. None of the daily observations indicated any sign of toxicity or Suttocide A-treatment-related behavioral abnormality. Incidentally, swelling in the neck region occurred in all groups except the high dose females, primarily on days 13-21. This was most likely caused by an SDA virus, which is commonly found in young Sprague-Dawley rats. The episodes of swelling were transient and were no longer apparent after day 21. Incidentally, somw rats had sores caused by cage irritation, which did not interfere with the conduct of the study.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

No statistically significant differences between test and control group body weights occurred at any week for either sex. Treatment with Suttocide A for 90 consecutive days had no effect on body weight gain.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

No statistically significant differences in food consumption between animals treated with Suttocide A and the respective control animals were noted over the 90 day treatment period.

Food efficiency:

no effects observed

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Description (incidence and severity):

No statistically significant differences between Suttocide A-treated groups and the control for any parameter after six weeks. Slightly decreased eosinophil count in females at 10 mg/kg bw, and of hemoglobin and hematocrit in females at 10 mg/kg bw.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

The only statistically significant difference between groups treated with Suttocide A and the control group was a decrease in potassium levels in female rats at the 160 mg/kg level after 6 weeks of dosing, which was not considered treatment related.

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

No statistically significant (p<= 0.05) microscopic pathological effects related to Suttocide A doses were noted in either sex.

Histopathological findings: neoplastic:

no effects observed

Description (incidence and severity):

The only neoplastic lesion noted was a lipoma in the oviduct of one female animal at the 40 mg/kg level.

Details on results:

In summary, all non-neoplastic and neoplastic devi-ations from normal histologic morphology observed in this study were considered to be spontaneous in occurrence, fortuitous in distribution within test and control groups and unrelated to administration of Suttocide A.

Dose descriptor:

NOAEL

Effect level:

>= 160 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: overall effects: clinical signs; mortality; body weight; food consumption; food efficiency; ophthalmoscopic examination; haematology; clinical chemistry; urinalysis; gross pathology; organ weights; histopathology

Critical effects observed:

not specified

Conclusions:

Oral administration (via gavage) of Suttocide A for 90 consecutive days to Sprague-Dawley rats at levels of 10, 40 and 160 mg/kg body weight did not result in any significant toxicological or histopathological effects which were treatment related.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

160 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

GLP compliant study resulting in a NOAEL supported by a 28-day repeated dose test.

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Based upon the results of a 28 Day Oral Toxicity Study in Rats with Suttocide A, Lot #PL1-4D, no clinical signs indicative of systemic toxicity were observed during the test period. A statistically significant decrease in the male group mean body weights for the 640 mg/kg/day dose group was noted on Days 14 and 21 and pre- and post-dose salivation also occurred in this group. The majority of differences in endpoints between the control group and the test article dose groups were not dose dependent and within normal historical limits. Hence, these were considered as not toxicologically significant. Treatment-related focal subacute gastritis/ulceration of the glandular stomach was present in a few animals in the 640 mg/kg/day dose group. The changes in the stomach are believed related to the strong alkalinity of the test article. The decreased total serum protein and slight decreases in hemograms may reflect the possibility of malabsorption of nutrients and blood loss accompanying gastric mucosal damage at the highest dose. Based upon these findings, the target organ in this study was the stomach and, in the absence of histopathologic changes at lower Suttocide A doses, the no-observed effect level is considered to be 160 mg/kg/day.

Oral administration (via gavage) of Suttocide A for 90 consecutive days to Sprague-Dawley rats at levels of 10, 40 and 160 mg/kg body weight did not result in any significant toxicological or histopathological effects which were treatment related.

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
GLP compliant subchronis study.

Repeated dose toxicity: via oral route - systemic effects (target organ) digestive: stomach

Justification for classification or non-classification

Although the stomac was identified as a target organ in the 90-day oral toxicity study, the NOAEL of 160 mg/kg bw is well above the limit of 100 mg/kg bw set for classification as specific target organ toxicity – repeated exposure (STOT-RE). In addition, the effects seen at the LOAEL of 640 mg/kg bw were slight to moderate and only present in a part of the rats exposed.