N-(carboxymethyl)-N-(phosphonomethyl)glycine

Repeated dose toxicity: dermal

Administrative data

Endpoint:

short-term repeated dose toxicity: dermal

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

From Aug. 28, 1985 to July 23, 1987

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted equivalent or similar to OECD Guideline 410.

Justification for data waiving:

other:

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1987

Report date:

1987

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 410 (Repeated Dose Dermal Toxicity: 21/28-Day Study)

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

no

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

N-(carboxymethyl)-N-(phosphonomethyl)glycine

EC Number:

227-824-5

EC Name:

N-(carboxymethyl)-N-(phosphonomethyl)glycine

Cas Number:

5994-61-6

Molecular formula:

C5H10NO7P

IUPAC Name:

2-[(carboxymethyl)(phosphonomethyl)amino]acetic acid

Details on test material:

- Name of test material (as cited in study report): glyphosate intermediate
- Physical state: Off-white solid
- Analytical purity: 97.97 %
- Lot/batch No.: Batch 900

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 Laboratory, Portage, MI
- Age at study initiation: Approximately 7 wk
- Weight at study initiation: Males- 208.0-230.8 g; Females- 149.4-177.1 g
- Fasting period before study:
- Housing: Individual suspended stainless steel cages, over paper bedding
- Diet: Basal Diet (Ralston Purina RODENT CHOW No. 5002), ad libitum
- Water: St. Louis public water supply, ad libitum


ENVIRONMENTAL CONDITIONS
- Temperature: 70-74 °F
- Humidity: 35-60 %
- Photoperiod: 12 h light/12 h dark cycle


IN-LIFE DATES: From: Aug. 28, 1985 To: Sept. 27, 1985

Administration / exposure

Type of coverage:

open

Vehicle:

other: Mineral oil

Details on exposure:

TEST SITE
- Area of exposure: 25 cm2

USE OF RESTRAINERS FOR PREVENTING INGESTION: Yes (plastic neck collar)

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Test material was stable over a 4 week test period as analysed by a flow injection mode, liquid chromatographic procedure. The homogeneity of the test material/ mineral oil slurry was determined to be adequate for study use. Data obtained from analyses of weekly mixture samples indicated 7 % or less difference from the target level

Duration of treatment / exposure:

28 d

Frequency of treatment:

6 h/d, 5d/wk

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 25, 150 and 500 mg/kg bw/d
Basis:
analytical per unit body weight

No. of animals per sex per dose:

Ten

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Dosage levels were based upon the results of a range-finding study.

Positive control:

Not reported

Examinations

Observations and examinations performed and frequency:

MORTALITY AND MORIBUNDITY: Yes
- Time schedule: Twice daily


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Once weekly


DERMAL IRRITATION (if dermal study): Yes
- Time schedule for examinations: Once per wk


BODY WEIGHT: Yes
- Time schedule for examinations: Once weekly


FOOD CONSUMPTION: Yes
- Time schedule for examinations: Once weekly



HAEMATOLOGY: Yes
- Time schedule for collection of blood: At termination of study
- Animals fasted: Yes (Food withheld overnight prior to blood collection)
- How many animals: All surviving animals
- Parameters checked: Total erythrocyte count (RBC), total leukocyte count (WOC), platelet count, hematocrit (Ret), level of hemoglobin (Hgb), and red blood cell indices (mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC)), Leukocyte differential, Reticulocyte count,


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: At termination of study
- Animals fasted: Yes (Food withheld overnight prior to blood collection)
- How many animals: All surviving animal
- Parameters checked: Albumin, total protein, blood urea nitrogen (BUN), total bilirubin, direct bilirubin, glucose, glutamic pyruvic transaminase (S-GPT/ALT), alkaline phosphatase, glutamic oxaloacetate transaminase (S-GOT/AST), globulin, gamma glutamyl transpeptidase (gamma-GT), creatinine, cholesterol (Chol), calcium, phosphorus, chloride, sodium, and potassium.

Sacrifice and pathology:

SACRIFICE: At termination of study
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes (High dose group was sacrificed on Day 16 due to severe dermal irritation; gross pathology and tissue analysis was done in mid dose group and control animals; histopathological analysis of only skin tissue was done in low dose group).

Other examinations:

None

Statistics:

- Dunnett's Multiple Comparison Test (two-tailed) (for body weights, food consumption, noncategorical clinical pathology data, absolute organ weights)
- Mann-Whitney Test with Bonferroni Inequality Procedure (for organ weight/body weight ratios)
- Fisher's Exact Test with Bonferroni Inequality Procedure (for incidence of microscopic lesions)
- Bartlett'sTest (to evaluate homogeneity of variances)
- Grubb's Test (to detect outliers)

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Dermal irritation:

effects observed, treatment-related

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

not examined

Details on results:

CLINICAL SIGNS AND MORTALITY: There were no mortalities during the study. However the highest exposure group was sacrificed prematurely (Day 16) due to severe dermal lesions.


BODY WEIGHT AND WEIGHT GAIN: Prior to their sacrifice on Day 16, males from the highest exposure level had slightly reduced body weights (14 % less than controls). Females at the same exposure level were not similarly affected. Both sexes at the low and mid exposure levels gained weight comparable to the control group.


FOOD CONSUMPTION: During the wk prior to their sacrifice, males from the highest exposure level ate significantly less diet (>25 % less than
controls). Food consumption in females at the same exposure level were not affected. Rats of both sexes at the low and mid exposure levels consumed similar amounts of diet as did the control level rats.


DERMAL IRRITATION: Dryness, redness, flaking/peeling, scabs, bleeding, necrosis and sloughing of skin observed at site of application. Males were more affected than females. The incidence and severity were dose related. However, low dose females were not affected and low dose males were only mildly affected. However, it is possible that the frequency and severity of lesion was enhanced by skin preparation (such as shaving nicks) and application of the vehicle.


HAEMATOLOGY: Both sexes at the mid dose group had increased WBC counts which appeared primarily due to lymphocytosis and may have been secondary to the skin lesions. Increased absolute neutrophils were noted for mid dose males, but with no statistical significance. Other statistically significant changes including mean corpuscular volume for low dose males, and absolute neutrophils for low dose females, were not dose related and were therefore not considered biologically significant. Furthermore, all of the hematologic parameters, including the increased WHC counts, were within the historical control range.


CLINICAL CHEMISTRY: Serum chemistry changes such as BUN, SGPT, calcium and sodium, although statistically significant, were within the normal historical range and were therefore not considered biologically significant or related to treatment.



GROSS PATHOLOGY: Sporadic differences in organ weight/body weight ratios (brain, heart, kidneys, liver) were not accompanied by other correlative findings. Hence, these changes were not considered biologically significant or treatment related. The incidence of exudate/scab formation and enlargement of elbow lymph node were increased in males at all dose levels and in females at the two highest doses. Enlarged elbow lymph nodes in all dose group males and in mid and high dose group females were probably secondary to the skin lesions. Histologically, the elbow lymph nodes from test and control animals were hyperplastic and did not appear microscopically different from each other.


HISTOPATHOLOGY: NON-NEOPLASTIC: The predominant finding in sections of treated skin from all mid dose males was significant ulceration with an overlying crust and underlying moderate, chronic active dermatitis, granulation tissue, loss of underlying hair follicles and adnexa, and with occasional follicular abscess. Moderate to marked acanthosis and hyperkeratosis were usually limited to the epithelium immediately adjacent to the ulcer. Histologically, treatment related severe ulcerative dermatitis occurred in mid dose animals but not in vehicle control animals. The intermittent distribution of moderately severe dermal lesions in low dose males and mid dose females suggests that some individuals may be more sensitive to the test material than others, or that the test material requires another factor (such as a prior break in the skin) to be irritating. Males were more severely affected than females, which may have reflected a sex related sensitivity to the test material or differences in behavioral response to dermal irritation.

Effect levels

Dose descriptor:

NOEL

Effect level:

150 mg/kg bw/day

Sex:

male/female

Basis for effect level:

other: Overall effects (Clinical signs; mortality; body weight; food consumption; haematology; clinical chemistry; gross pathology; histopathology)

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

None

Applicant's summary and conclusion

Conclusions:

Treatment-related skin lesions, often accompanied by secondary reactions, occurred at all exposure levels for males and at the two highest exposure levels for females. No evidence of systemic toxicity was observed at any of the tested dose levels. All of the abnormalities observed were probably attributable to localized irritation at the application site. Therefore, the mid dose level (150 mg/kg bw/d) was considered the no observed effect Ievel (NOEL) for systemic toxicity.

Executive summary:

A study was conducted to evaluate the repeated dermal toxicity of test material in Sprague Dawley rats.

 

10 animals/sex were exposed to test material (suspended in mineral oil) dermally at a concentration of 0, 25, 150, and 500 mg/kg/d for 4 wk (frequency: 6 h/d, 5 d/wk). Animals treated with mineral oil served as control.

 

Application of test material resulted in treatment-related dermal lesions at all exposure levels in males and at 150 and 500 mg/kg/d in females. The severity of the dermal lesions observed prompted the premature termination of the high dose group on Day 16 of the study. Additional effects observed at the low and mid dose evels, which were considered to be secondary responses to the dermal irritation, were decreased body weight and food consumption and elevated white blood cell and lymphocyte counts. No signs of systemic toxicity were observed at any exposure level.

 

In conclusion, treatment related skin lesions, often accompanied by secondary reactions occurred at all exposure levels for males and at the two highest exposure levels for females. All of the abnormalities observed were probably attributable to localized irritation at the application site. Therefore, the mid dose level (150 mg/kg bw/d) was considered the no observed effect Ievel (NOEL) for systemic toxicity.