Monuron

Acute Toxicity: dermal

Administrative data

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1986

Materials and methods

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

In general, the methods and procedures used were the same as those used in earlier work (Gaines (1960). The acute toxicity of pesticides to rats. Toxicol. Appl. Pharmacol. 2, 88-99 and
Gaines (1969). Acute toxicity of pesticides. Toxicol. Appl. Pharmacol. 14,515-534.)

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

1

Reference substance name:

Monuron

EC Number:

205-766-1

EC Name:

Monuron

Cas Number:

150-68-5

Molecular formula:

C9H11ClN2O

IUPAC Name:

1-(4-chlorophenyl)-3,3-dimethylurea

Test material form:

not specified

Specific details on test material used for the study:

technical grade

Test animals

Species:

rat

Strain:

Sherman

Remarks:

adult specific-pathogen-free (SPF)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: The rat colony was rederived via cesarean section and maintained under barrier conditions by the U.S. Centers for Disease Control, Atlanta, Georgia. Animals were transferred from the barrier facility at weaning and kept in conventional quarters until used
- Females (if applicable) nulliparous and non-pregnant: [yes/no]
- Age at study initiation: Adult animals were at least 90 days of age when tested.

Administration / exposure

Type of coverage:

not specified

Vehicle:

propylene glycol

Details on dermal exposure:

TEST SITE
- Area of exposure: the freshly shaved shoulder and back area

TEST MATERIAL
- Amount(s) applied (volume or weight with unit):Whenever possible the compounds were administered in volumes of 1.6 mL/kg body weight for dermal dosing. Dosage volumes were routinely 1.6-10 mL/kg for dermal dosing.
- Concentration (if solution): Whenever possible the compounds were formulated in varying concentrations.

No. of animals per sex per dose:

Minima of 10 animals per group and four dosage levels were used for each LD50 calculation.

Details on study design:

- Duration of observation period following administration: The animals were observed for at least 14 days after dosing or until recovered from signs of toxicity.

Statistics:

LD50 values and related parameters were calculated using a computer based implementation of Finney’s maximum likelihood probit technique (Lieberman, 1983).

Results and discussion

Effect levels

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 500 mg/kg bw

Any other information on results incl. tables

Table 1. Acute dermal toxicity of Monuron in rats^a

Common name	Age^b	Sex	Route	LD50 (mg/kg)
Monuron	A	M	Dermal	>2500^c
	A	F	Dermal	>2500^c

^a For dermal dosing, compounds were usually dissolved in xylene.

Dosage volumes were routinely 5-10 mL/kg for oral dosing and 1.6-10 mL/kg for dermal dosing. Exceptions to the above are noted.

^b A = Adult; W = Weanling.

^c In propyIene glycol suspension.

Applicant's summary and conclusion

Conclusions:

Dermal LD50 for monuron was > 2500 mg/kg.

Executive summary:

LD50 values were determined for 57 pesticides (among which Monuron) administered by the (oral or) dermal route to adult male and female Sherman rats. Many of these and earlier LD50 tests have been done in different years and in various months of the year. Since the LD50 value is influenced by variables such as species, strain, and test method, the best estimates of relative toxicity are derived from data collected in a single species and strain under identical conditions. The values for acute toxicity reported here represent the final compilation of data for the LD50 test program whose purpose was to establish a reliable data base on the relative toxicities of pesticidal chemicals in rats, and to obtain other pertinent information including the type, onset, and duration of toxic effects following a single dose.

Except as indicated the compounds were technical grade and were dissolved or suspended in xylene for dermal application to the freshly shaved shoulder and back area. Monuron was suspended in propylene glycol. Whenever possible the compounds were formulated in varying concentrations and administered in volumes of 1.6 mL/kg body weight for dermal dosing. Because of low toxicity or poor solubility of some of the compounds, it was sometimes necessary to adjust the dose volumes as indicated. Dosage volumes were routinely 1.6-10 mL/kg for dermal dosing.

Adult animals were at least 90 days of age and weanlings were 4-6 weeks of age when tested. Minima of 10 animals per group and four dosage levels were used for each LD50 calculation. The animals were observed for at least 14 days after dosing or until recovered from signs of toxicity. LD50 values and related parameters were calculated using a computer based implementation of Finney’s maximum likelihood probit technique (Lieberman, 1983).

As expected, nearly all of the compounds were substantially less toxic by the dermal route than by the oral route.

For Monuron dermal LD50 was > 2500 mg/kg bw in male and female adult rats.