Methyl isothiocyanate

Biodegradation in soil

Administrative data

Endpoint:

biodegradation in soil

Type of information:

experimental study

Adequacy of study:

other information

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: 3 a, b, c: Documentation insufficient for assessment; Significant methodological deficiencies (in comparison with standard and guideline methods)

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 1

Reference Type:

publication

Title:

No information

Author:

Tomlinson TG et al

Year:

1966

Bibliographic source:

J Appl Bact 29: 266-91

Reference 2

Reference Type:

publication

Title:

Unnamed

Year:

1989

Reference 3

Reference Type:

publication

Title:

No information

Author:

Verhagen C et al

Year:

1996

Bibliographic source:

Soil Biol Biochem 12: 1753-56

Materials and methods

Test material

Test material information

Constituent 1

Reference substance name:

Methyl isothiocyanate

EC Number:

209-132-5

EC Name:

Methyl isothiocyanate

Cas Number:

556-61-6

Molecular formula:

C2H3NS

IUPAC Name:

isothiocyanatomethane

Applicant's summary and conclusion

Executive summary:

In a soil biodegradation study, the biodegradation ofmethyl isothiocyanategenerally followed first order kinetics in soils previously untreated with the compound(1). In soils previously exposed tomethyl isothiocyanate,the biodegradation was generally much faster and the biodegradation did not follow first order kinetics(1). Even in soils that were previously untreated withmethyl isothiocyanate,an accelerated transformation (which did follow first order kinetics) was observed after an initial period (8-15 days) of first order transformation(1). Using the first order kinetics, the biodegradation half-life was estimated to range from 0.5 to 50 days(2). Generally, the transformation was appreciably faster in soils that have been previously treated with the chemical frequently(2). At or above concns of 0.8 mg/l,methyl isothiocyanateinhibited nitrification in the activated sludge process of sewage disposal(2).Methyl isothiocyanatewas confirmed to be biodegradable according to a Netherlands study that employed 10 soils under field conditions(3). Soil core samples from Dutch agricultural fields with a 4 year history ofmethyl isothiocyanatetreatment were incubated with the test compound for 1 to 14 days at 20 deg C; 50% degradation times ranged from 0.5 to 9 days(3).
[(1) Tomlinson TG et al; J Appl Bact 29: 266-91 (1966) (2) Smelt JH et al; J Environ Sci Health B24: 437-55 (1989) (3) Verhagen C et al; Soil Biol Biochem 12: 1753-56 (1996)]