Butyl isocyanate

Biodegradation in soil

Administrative data

Endpoint:

biodegradation in soil

Type of information:

experimental study

Adequacy of study:

other information

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study meets generally accepted scientific principles

Data source

Reference

Reference Type:

publication

Title:

Assessing N,N'-dibutylurea (DBU) formation in soils after application of n-butylisocyanate and benlate fungicides

Author:

Sassman SA, Lee LS, Bischoff M, and Turco RF

Year:

2004

Bibliographic source:

J. Agric. Food Chem. 52 (4), 747-754

Materials and methods

Principles of method if other than guideline:

The fate of [14C] n-butyl isocyanate in four different soils at two negative water potentials of 0.03 and 0.1 MPa was monitored. Standard soil microbial microcosms (see: Horwath WR and Paul EA (1994). Microbial Biomass. In: Methods of Soil Analysis. Part 2, Microbiological and Biochemical Properties; SSSA Book Series 5; Weaver RW, Angle JS & Bottomley PS (eds.), SSA, Madison WI, Vol. 36, 753-773) were used to assess transformation and degradation of n-butyl isocyanate in laboratory experiments

GLP compliance:

not specified

Test type:

laboratory

Test material

Reference

Name:

Unnamed

Type:

Constituent

Details on test material:

n-Butyl-1-[14C]butyl isocyanate; 23.5 mCi/mmol specific activity

Radiolabelling:

yes

Study design

Soil classification:

other: Soils were from agricultural fields in Costa Rica and Florida 

Initial test substance concentration

Initial conc.:

1.2 mg/kg soil d.w.

Experimental conditions

Temp.:

22.7 °C

Humidity:

0.03 other: MPa (negative water potential)

Results and discussion

Half-life / dissipation time of parent compound

DT50:

< 1 d

Type:

(pseudo-)first order (= half-life)

Remarks on result:

other: DT90: < 1 day(s)

Any other information on results incl. tables

RS-Freetext:
- In all cases n-butyl isocyanate rapidly declined after
application and was no longer detected by day 4. By day 2,
most of the n-butyl isocyanate was found as n-butylamine,
followed generally by a decline of concentration with time 
- Summary of n-butyl isocyanate mineralization rates (per
day): 
   soil     1       2        3        4 
0.03 MPa -0.101  -0.084   -0.109   -0.181 
0.1 MPa  -0.034  -0.032   -0.029   -0.081 
- Formation of dibutylurea from n-butyl isocyanate was not
detected in any of the soils incubated at the higher water
content (0.03 MPa). Under dryer conditions (0.1 MPa) small
amounts of dibutylurea at a maximum of 3.6 µg/kg (< 0.3 % of
applied n-butyl isocyanate) were detected in two soils 
- Volatilized n-butyl isocyanate was captured in the KOH
traps where it converted to dibutylurea 
- Mineralization rates were 2-5 times faster under the more
optimal conditions for microbial activity (0.03 MPa), and
mineralization was fastest for the soil with highest organic
carbon and total nitrogen contents