Dichlobenil

Repeated dose toxicity: dermal

Administrative data

Endpoint:

short-term repeated dose toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 March 1995 to 13 December 1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1995

Report date:

1995

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPP 82-2 (Repeated Dose Dermal Toxicity -21/28 Days)

Deviations:

no

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Dichlobenil

EC Number:

214-787-5

EC Name:

Dichlobenil

Cas Number:

1194-65-6

Molecular formula:

C7H3Cl2N

IUPAC Name:

2,6-dichlorobenzonitrile

Test material form:

solid: particulate/powder

Details on test material:

- Physical state: solid
- Storage condition of test material: in the dark at ambient room temperature

Test animals

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Froxfield Farms (UK) Limited,
- Age at study initiation: 13 to 15 weeks
- Housing: individually in metal cages
- Diet: SDS Rabbit Diet SQC ad libitum
- Water: ad libitum
- Acclimation period: 21 days

ENVIRONMENTAL CONDITIONS
- Temperature: 16.5-22 °C
- Humidity: 40-68 %
- Air changes: approximately 19 per hours
- Photoperiod: 12 hours light/12 hours dark

IN-LIFE DATES: From: 15th March 1995 To: 20th June 1995

Administration / exposure

Type of coverage:

occlusive

Vehicle:

water

Details on exposure:

TEST SITE
- Area of exposure: 12 x 8 cm
- % coverage: approximately 10%
- Type of wrap if used: impervious bandage consisting of gauze covered with 'Elastoplast' elastic adhesive dressing backed with impervious 'Sleek' plaster.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): yes
- Time after start of exposure: 6 hours on each day

Duration of treatment / exposure:

6 hours per day

Frequency of treatment:

Daily for 21 consecutive days

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

100 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

300 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

1 000 mg/kg bw/day (nominal)

No. of animals per sex per dose:

Five

Control animals:

yes, concurrent vehicle

Examinations

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: three times daily

DERMAL IRRITATION (if dermal study): Yes
- Time schedule for examinations: daily

BODY WEIGHT: Yes
- Time schedule for examinations: prior to dosing on day 1 and then weekly intervals

FOOD CONSUMPTION:
- Food consumption for each animal determined: Yes

FOOD EFFICIENCY: No

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: prior to termination
- Anaesthetic used for blood collection: No data
- Animals fasted: Yes, overnight
- How many animals: all
- Parameters checked: packed cell volume, haemoglobin, red blood cell count, mean corpuscular haemoglobin concentration, mean corpuscular volume, platelet counts, total white blood cell count, thrombotest, differential white blood cell count

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: prior to termination
- Animals fasted: Yes, overnight
- How many animals: all
- Parameters checked: glucose, total protein, albumin, globulin, albumin/globulin ratio, urea nitrogen, creatinine, alkaline phosphatase, glutamic-pyruvic transaminase, gutamic-oxalaxetic transaminase, total bilirubin, sodium, potassium calcium, chloride, inorganic phosphorus, cholesterol

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
- The following organs were weighed: adrenals, brain, kidneys, liver, ovaries, spleen, testes.

HISTOPATHOLOGY: Yes
- The appearance of the following tissues was recorded: adrenals, aorta, brain, caecum, colon, duodenum, eyes, gall bladder, heart, ileum, jejunum, kidneys, larynx, liver, lungs, cervical and mesenteric lymph nodes, mammary glands, oesophagus, ovaries, pancreas, pharynx, pituitary, prostate, salivary gland, sciatic nerve, skeletal muscle, skin, spleen, sternum, stomach, testes and epididymides, thymus, thyroid/parathyroid, tongue, trachea, urinary bladder, uterus, vagina and any macroscopically abnormal tissue.

Statistics:

Where appropriate, the following sequence of statistical tests was used:
- if the data consisted predominantly of one particular value, the proportion of values different from the mode was analysed by Fisher's exact test followed by Mantel's test for a trend in proportions. Otherwise:
- Bartlett's test was applied to test for heterogeneity of variance between treatments.
- If no significant heterogeneity was detected, one way ANOVA was performed followed by Williams' test
- If significant heterogeneity was detected and could not be removed by log transformation, Kruskal-Wallis analysis of ranks was used followed by non-parametric equivalent of Williams' test (Shirley's test).

Covariate of analysis of organ weight data was performed using adjusted organ weights where a correlation between organ weight and body weight was established at the 10% level of significance.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Description (incidence and severity):

There were no treatment related clinical signs.

Dermal irritation:

no effects observed

Description (incidence and severity):

There were no dermal reactions that were considered to be treatment related. In two animals from the control group, spots were observed during the last few days of the study.

Mortality:

no mortality observed

Description (incidence):

There were no treatment related mortalities.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

There were no statistically significant differences from the control group noted for body weight gains in any of the treatment groups.

Food consumption and compound intake (if feeding study):

effects observed, non-treatment-related

Description (incidence and severity):

The food consumption for low and high dose group females was slightly higher than control; these differences were however not considered to be 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

Description (incidence and severity):

There were no differences from the controls in the haematological parameters measured that were related to treatment.

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

Group mean values of significantly different biochemistry values were recorded. Cholesterol levels were higher than control for females of the high dose group. However, individual values were within the expected background range and in the absence of any related biochemical or pathological changes in the liver, this finding was not considered to be of toxicological importance.

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):

There were no differences from controls in organ weights that were considered to be related to treatment.

Gross pathological findings:

no effects observed

Description (incidence and severity):

The macroscopic examination performed at termination revealed no changes attributable to treatment.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

All of the lesions observed by microscopic pathology were minor in nature and not considered to be related to treatment.

Histopathological findings: neoplastic:

no effects observed

Other effects:

not examined

Effect levels

1

Key result

Dose descriptor:

NOEL

Effect level:

100 other: mg/kg/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Elevated cholesterol levels in high dose females (considered to be equivocal)

2

Key result

Dose descriptor:

NOAEL

Effect level:

300 other: mg/kg/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Elevated cholesterol levels in high dose females (considered to be equivocal)

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

Table 1: Group mean values body weights (g)

		Dose group (mg/kg/day)
Time (weeks)	Sex	Control	100	300	1000
0	M	2823	2929	2954	3029
	F	3144	3206	3083	3189
1	M	2911	3067	3102	3146
	F	3212	3319	3186	3370
2	M	3060	3230	3261	3326
	F	3363	3474	3352	3564
3	M	3200	3341	3337	3489
	F	3475	3631	3485	3631
Weight gain	M	377	412	383	460
	F	331	425	402	442

Table 2: Group mean values of food consumption (g/animal/week)

		Dose group (mg/kg/day)
Time (weeks)	Sex	Control	100	300	1000
1	M	1289	1339	1257	1237
	F	1240	1358	1208	1409
2	M	1277	1364	1357	1355
	F	1228	1416	1376	1397
3	M	1210	1289	1217	1262
	F	1258	1357	1321	1313
Cumulative value	M	3776	3992	3931	3855
	F	3725	4131	3905	4119

Table 3: Significantly different biochemistry values

		Dose group (mg/kg/day)
Parameter	Sex	Control	100	300	1000
Glucose (mg/dL)	M	128	139	140	147*
Protein (g/dL), total	F	5.7	5.9	5.8	6.2*
Glob	F	2.2	2.4	2.3	2.5*
Creatinine (mg/dL)	F	1.3	1.2	1.3	1.0*
GPT (mU/mL)	M	42	34	31*	31*
GOT (mU/mL)	F	10	16***	16***	9
Cholesterol (mg/dL)	F	43	50	47	64**

*significantly different from control (P<0.05), Williams' test

**significantly different from control (P<0.01), Williams' test

***significantly different from control (P<0.05), Student's t test

Table 4: Significantly different organ weights

		Dose group (mg/kg/day)
Organ	Sex	Control	100	300	1000
Adrenals	M	252	195***	237	232
Brain	F	9.42	8.85***	8.77***	9.18
Ovaries	F	0.223	0.350	0.267	0.365*

*significantly different from control (P<0.05), Williams' test

***significantly different from control (P<0.05), Student's t test

Applicant's summary and conclusion

Conclusions:

Under the conditions of the test, the test material had no toxic effect at any of the doses tested. The NOAEL was determined to be 1000 mg/kg/day and the NOEL was determined to be 300 mg/kg/day.

Executive summary:

In a GLP compliant repeat dose (dermal) study conducted in line with standardised guidelines OECD 401 and EPA OPP 82-2, the effects of the repeat dose of the test material in rats was determined.

Under the conditions of the test, no toxic effect was seen at any of the doses tested. The NOAEL was determined to be 1000 mg/kg/day and the NOEL was determined to be 300 mg/kg/day.