Methomyl

Phototransformation in soil

Link to relevant study record(s)

Reference

Endpoint:

phototransformation in soil

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

EPA Guideline Subdivision N 161-3 (Photodegradation Studies on Soil)

Deviations:

no

GLP compliance:

no

Specific details on test material used for the study:

- Substance name: [1-14C]Methomyl
- Lot #: 1800-056
- Purity: Not reported

Radiolabelling:

yes

Analytical monitoring:

yes

Analytical method:

high-performance liquid chromatography

other: LSC, TLC

Light source:

sunlight

Duration:

30 d

Temp.:

28 °C

Initial conc. measured:

1 other: lb/a.i. acre

Reference substance:

yes

Dark controls:

yes

Key result

DT50:

34 d

Test condition:

test substance in soil exposed to natural sunlight

Transformation products:

yes

Remarks:

Acetonitrile

Conclusions:

The test substance decomposed with a half-life of 34 days to form acetonitrile, the only detected radioactive decomposition product

Executive summary:

The study was conducted according to EPA Guideline 161-3. Radiolabeled [1-14C]test substance was applied evenly (at a rate equivalent to 1 lb/a.i. acre) to a thin layer of keyport silt loam and exposed to natural sunlight for 30 days at a temperature of 24-28°C. Under these conditions, the test substance decomposed with a half-life of 34 days to form acetonitrile, the only detected radioactive decomposition product. Controls kept in the dark did not decompose.

Description of key information

Study Type	Study Details	Value	Guideline	Reliability
Phototransformation in soil	Applied evenly to keyport silt loam and exposed to natural sunlight	DT50 = 34 days Decomposition product was acetonitrile	EPA 161-3	2

Key value for chemical safety assessment

Half-life in soil:

34 d