3-iodo-2-propynyl butylcarbamate

Repeated dose toxicity: dermal

Administrative data

Endpoint:

sub-chronic toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1990-12-13 to 1991-12-06

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1991

Report date:

1991

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

EPA OPP 82-3 (Subchronic Dermal Toxicity 90 Days)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 411 (Subchronic Dermal Toxicity: 90-Day Study)

Deviations:

yes

Remarks:

please refer to "principles of method if other than guideline"

Principles of method if other than guideline:

Deviations: Salivary glands were not preserved as required by OECD 411 Guideline.

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

3-iodo-2-propynyl butylcarbamate

EC Number:

259-627-5

EC Name:

3-iodo-2-propynyl butylcarbamate

Cas Number:

55406-53-6

Molecular formula:

C8H12INO2

IUPAC Name:

3-iodoprop-2-yn-1-yl butylcarbamate

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 9011-6010

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 Laboratories, Inc., Portage, MI, USA
- Age at study initiation: approx. 54 d
- Weight at study initiation: 222 - 266 g (males); 156 - 192 g (females)
- Housing: individually
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 11

ENVIRONMENTAL CONDITIONS
- Temperature: 65 - 78° F (13.3 - 25.5 °C)
- Humidity: 40 - 70%
- Photoperiod: 12 /12 hrs dark / hrs light

Administration / exposure

Type of coverage:

semiocclusive

Vehicle:

polyethylene glycol

Details on exposure:

TEST SITE
- Area of exposure: dorsal trunk
- % coverage: approx. 10 % of body surface
- Type of wrap if used: Coban self adherent wrap
- Time intervals for shavings or clipplings: minimum once a week

REMOVAL OF TEST SUBSTANCE
- Washing: skin was wiped with clean gauze moistened with distilled water
- Time after start of exposure: 6 h

TEST MATERIAL
- Amount applied: 6 mL/kg, respectively
- Concentration: 8.33; 33.33; 83.33 mg/mL vehicle
- Constant volume used: 6 mL/kg bw
- For solids, paste formed: yes

VEHICLE
- Justification for use and choice of vehicle: PEG is an accepted vehicle by guidelines

USE OF RESTRAINERS FOR PREVENTING INGESTION: no. Harness and/or plastic collars were used to prevent excessive chewing on bindinw material

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Prior to initiation of the 91-day study, the analytical method was validated. Prestudy homogeneity and stability analyses were performed on concentrations of the test article which encompassed those used in this study. Each fresh dosing preparation was analyzed for test article concentration once per week during the first month and monthly thereafter.

Duration of treatment / exposure:

13 weeks (91 days)

Frequency of treatment:

6 h á 5 days per week

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

50 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

200 mg/kg bw/day (nominal)

Doses / concentrations 4

Dose / conc.:

500 mg/kg bw/day (nominal)

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: preliminary dose-range finder study
- Rationale for animal assignment: random

Positive control:

not applicable

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice daily

DERMAL IRRITATION: Yes
- Time schedule for examinations: daily prior to dosing

BODY WEIGHT: Yes
- Time schedule for examinations: weekly and at study termination

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes; weekly

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: prior to testing (day -4) and near conclusion of study (day 87)
- Dose groups that were examined: all

HAEMATOLOGY: Yes
- Time schedule for collection of blood: day 89 for hemolysate analysis and plasma cholinesterase and day 91 or 93 for haematology
- Anaesthetic used for blood collection: No
- Animals fasted: No
- How many animals: all
- Parameters examined: Erythrocyte count; Hematocrit (Hct); Hemoglobin concentration (Hgb); Mean corpuscular hemoglobin (MCH); Mean corpuscular hemoglobin concentration (MCHC); Mean corpuscular volume (MCV); Platelet count; Reticulocyte count; Total and differential leukocyte counts.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: day 91 or 93
- Animals fasted: No
- How many animals: all
- Parameters examined: Alanine aminotransferase (ALT) Albumin; Albumin/globulin (A/G) ratio; Alkaline phosphatase (ALP); Aspartate aminotransferase (AST); Calcium Chloride; Creatinine; Fasting glucose; Gamma glutamyl transpeptidase (GGT); Globulin (calculated); Phosphorus; Potassium; Sodium; Total bilirubin Total serum protein Urea nitrogen (BUN)

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes

HISTOPATHOLOGY: Yes

Statistics:

Statistical analyses were performed by a Digital VAX 11/730 computer. All analyses were two-tailed with a minimum significance level of 5%. Continuous data including body weight, weight gain, food consumption, organ weight and clinical pathology were analyzed by One Way Analysis of Variance (ANOVA). When significance was observed with ANOVA, control to treatment group comparisons were performed using Dunnett's Test.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Description (incidence and severity):

No treatment-related clinical signs were observed during the study. Incidental findings, which occurred sporadically throughout the groups, included scab formation at areas other than the exposure site, hairloss at various body regions, swelling of the pinnae, lacrimation, ocular discharge, dark material around the eyes, and nontreatment-related dermal irritation in the binder tape area.

Dermal irritation:

effects observed, treatment-related

Description (incidence and severity):

No signs of dermal irritation were observed in males or females of the 50 mg/kg/day group.
At the 200 mg/kg/day level, occasional slight erythema was observed in 4 males and 6 females, while slight desquamation was observed occasionally for 8 males and 7 females. For one 200 mg/kg/day female, moderate erythema was observed on one occasion and moderate desquamation was observed on two occasions. Eschar areas covered less than 10% of the exposure site for one 200 mg/kg/day male on three consecutive days which improved to focal and/or pinpoint areas of eschar on the following day. Focal and/or pinpoint areas of eschar were observed for three 200 mg/kg/day females, and on two occasions eschar areas covered less than 10% of the exposure site of one other 200 mg/kg/day female. The dermal irritation at the 200 mg/kg/day level was generally observed within the first few days of treatment and persisted less than two weeks.
Dermal Irritation was more severe at the 500 mg/kg/day level and was observed in all males and females at this level. The most common findings consisted of slight erythema and slight desquamation. Low incidences of slight edema, moderate erythema and moderate desquamation were also observed in both males and females at the 500 mg/kg/day level. Occasional focal and/or pinpoint areas of eschar were observed for 3 males and 6 females at the 500 mg/kg/day level. For one 500 mg/kg/day female, eschar covered less than 25% of the exposure site and showed signs of exfoliation. The dermal irritation for males and females at the 500 mg/kg/day level was generally observed within the first few days of treatment and persisted throughout the study.

Mortality:

no mortality observed

Description (incidence):

All animals survived to scheduled sacrifice on day 92 or 93, with the exception of one 50 mg/kg/day female that died during blood collection on day 89.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Mean male body weight and body weight gain were similar between the control and 50 mg/kg/day groups throughout the study.
At the 200 mg/kg/day level, male body weight gain was statistically reduced during study days 8-15 when compared to the control group. The reduction in weight gain for males at the 200 mg/kg/day level resulted in cumulative weight gains that were slightly lower than the control group beginning on days 1-15 and continuing throughout the study. Body weight gain for males at the 500 mg/kg/day level was statistically reduced during study days 1-8, while cumulative weight gain for males at this level was statistically reduced during days 1-8, 1-15, 1-22 and 1-29. Cumulative weight gain for males at the 500 mg/kg/day level remained slightly lower than the control group throughout the remainder of the study. In addition, the reductions in male weight gain at the 200 and 500 mg/kg/day levels resulted in group mean body weights that were slightly lower than the control group beginning on day 15 and continuing through the remainder of the study.

Mean body weight and weight gain for females were similar among the groups throughout the study.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

Male food consumption calculated as grams/animal/day was similar between the control and 50 mg/kg bw/d groups throughout the study. At the 200 mg/kg bw/d level, food consumption was statistically reduced during study days 8-15, 15-22, 22-29 and 57-64, when compared to the control group. Food consumption for males at the 500 mg/kg bw/d level was statistically lower than the control group during days 15-22 only.
Food consumption for females was similar among the groups throughout the study.

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

no effects observed

Description (incidence and severity):

No treatment-related ocular toxicity was noted in the treated rats.

Haematological findings:

no effects observed

Description (incidence and severity):

Statistically significant differences in terminal hematology data consisted of increased hemoglobin, hematocrit and eosinophils in the 500 mg/kg/ day females. These differences were not considered to be biologically meaningful since the changes were relatively minor and remained within expected ranges for rats of this age and strain.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

Statistically significant differences in terminal clinical chemistry data consisted of increased total protein in 200 mg/kg bw/d males; decreased glucose in 200 and 500 mg/kg bw/d males; decreased creatinine in 500 mg/kg bw/d males; increased calcium and phosphorus in 500 mg/kg bw/d males; and increased calcium and phosphorus in 500 mg/kg bw/d females. These differences were not considered to be biologically meaningful since the changes were relatively minor, remained within expected ranges for rats of this strain and age, and did not correlate with any abnormal histopathology. It should be noted that concentrations of the test article used in this study showed no evidence of inhibition of either RBC hemolysate or plasma cholinesterase. An incidental statistical increase in RBC hemolysate cholinesterase was observed in the 500 mg/kg bw/d males.

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

Absolute, but not relative heart weights of males in the 200 and 500 mg/kg bw/d groups were statistically decreased when compared to the control group. These differences were not considered biologically meaningful since they occurred in the absence of any clear dose response and did not correlate with any abnormal histopathology. No other statistically significant or biologically meaningful differences were noted in the absolute or relative organ weights of the treated rats.

Gross pathological findings:

no effects observed

Description (incidence and severity):

Gross necropsy findings were generally unremarkable. Individual findings occurred with a similar frequency among the groups.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Test article-related changes in the skin at the application site were observed in most males and females from the 200 and 500 mg/kg bw/d groups. These changes consisted primarily of minimal to mild hyperkeratosis which occurred in 17/20 rats from the 200 mg/kg bw/d group and 16/20 rats from the 500 mg/kg bw/d group. Hyperkeratosis correlated with the slight desquamation of the application site observed in most rats of the 500 mg/kg bw/d group. In addition, minimal to mild acanthotic thickening of the epidermis was seen in 2/20 rats from the 200 mg/kg bw/d group and 11/20 rats from the 500 mg/kg bw/d group. Mild ulceration and accompanying exudate upon the epidermal surface occurred in a single 500 mg/kg bw/d female. Minimal hyperkeratosis at the application site was also observed microscopically in one male and one female from the 50 mg/kg bw/d group, while minimal acanthosis was observed in one control female. The changes in the control and 50 mg/kg bw/d groups were considered to be due to the experimental procedure rather than a specific effect of the test article. No other treatment-related microscopic changes were observed in rats from any of the study groups.
Overall, the test article effects at the 200 and 500 mg/kg bw/d levels, including the 500 mg/kg bw/d female with mild ulceration, were very mild and would be expected to be quickly reversed upon cessation of test article application.

Histopathological findings: neoplastic:

not examined

Effect levels

1

Key result

Dose descriptor:

NOEL

Effect level:

50 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

dermal irritation

2

Key result

Dose descriptor:

NOAEL

Effect level:

200 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

dermal irritation

3

Key result

Dose descriptor:

LOAEL

Effect level:

500 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

dermal irritation

Target system / organ toxicity

Key result

Critical effects observed:

no

Applicant's summary and conclusion

Conclusions:

The test item was applied to Sprague Dawley rats for 91 day in doses of 50, 200, and 500 mg/kg bw/d. Based on observations in this study, NOEL was determined to be 50 mg/kg bw/d, whereas NOAEL was considered to be 200 mg/kg bw/d.

Executive summary:

The potential toxic effects of the test item were evaluated in this 91 -day dermal toxicity study in Sprague-Dawley rats. The study consisted of a control group and three treatment groups with ten animals per sex per group. The test article was dissolved in PEG 400 and administered five days/week, under semi-occlusive conditions, at levels of 50, 200 and 500 mg/kg bw/d. All doses were given at a constant volume of 6.0 mL/kg. Control animals were administered PEG 400 under the same experimental conditions and at an equivalent dose volume.

The rats were observed daily for clinical signs of toxicity and application sites were examined prior to dosing for adverse skin reactions. Individual body weights and food consumption were measured weekly. Ophthalmological examinations were performed on all animals prior to the initiation and near the conclusion of the study. Blood samples were obtained from all animals on study day 89 for determination of cholinesterase activity. This clinical parameter, cholinesterase activity, was selected by the Sponsor since the test substance is a carbamate pesticide and this class of chemicals is known to inhibit cholinesterase activity. All surviving animals were bled at study termination (day 92 or 93) for evaluation of hematology and biochemistry parameters. A complete gross necropsy examination was performed on all animals. Fresh organ weights were obtained from surviving animals and selected tissues and organs were collected from each animal. All tissues from control and high-dose animals and the treated skin, untreated skin, lungs, liver, kidneys and gross lesions from all low and mid-dose animals were examined microscopically.

No treatment-related mortality or clinical signs of toxicity were observed during the study. Treatment-related decreases in body weight gain and/or food consumption were observed in the 200 and 500 mg/kg/day males during the first four weeks of treatment. The reduced mean body weights of these rats remained slightly lower than controls during the remainder of the study. No adverse body weight or food consumption effects were observed in the 50 mg/kg bw/d males or in females from any of the study groups. There were no apparent test article-related changes observed among the groups concerning ophthalmology, clinical pathology, gross necropsy, or organ weight data. Similarly, no treatment-related differences in RBC hemolysate or plasma cholinesterase levels were noted. Dose-dependent dermal irritation was observed in males and females at 200 and 500 mg/kg bw/d levels. The irritation was mild at the 200 mg/kg bw/d level and consisted primarily of slight erythema and slight desquamation. At the 500 mg/kg bw/d level, the irritation was more severe and consisted of slight erythema, slight desquamation, and low incidences of slight edema, moderate erythema and moderate desquamation. Dermal irritation at the 500 mg/kg bw/d level progressed to focal and/or pinpoint areas of eschar in a few animals. Microscopic evaluation of the treated skin revealed hyperkeratosis and acanthotic epidermal thickening in rats of the 200 and 500 mg/kg bw/d groups. The dermal changes were expected to be reversible upon cessation of treatment. No treatment-related signs of dermal irritation were observed in males or females of the 50 mg/kg bw/d group.

Based on these results, a dosage level of 50 mg/kg bw/d was determined to be a no-observed-effect level for 91-day dermal administration of test item in rats.