t;')t/;J

ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF

PREVENTION,PESTICIDES A D 

TOXCI SUBSTANCES

August 31,2010

MEMORANDUM

SUBJECT: Environmental Fate Assessment of Terbutryn for Use in Indoor and

Outdoor Materials Preservatives

Cas No.: 886-50-0 DP Barcode(s): Q.371449

FROM:

PEER REVIEW: 

TO:

James Breithaupt, Agronomist

Risk Assessment and Science SuppBranch (RASSB) 

Antimicrobials Division (751OP)

Siroos Mostaghimi, Ph.D.- Af,_JJ/--'1L · 

Risk Assessment and Science Support Branch (RASSB) 

Antimicrobial Division (751OP)

Nader Elkassabany, Chief ¢

Risk Assessment and Science Support Branch (RASSB)

Antimicrobials Division (751OP)

Mark Hartman, Chief

Regulatory Management Branch II 

Antimicrobials Division (751OP)

Chemical Name

2-(tert-butylamino)-4-(ethylamino)

-6-(methylthio)-s-triazine

PC Code

080813

CAS#

886-50-0

Common Name

None

EXECUTIVE SUMMARY

This memorandum contains the environmental fate assessment for the proposed use of 

terbutryn (Troysan® Terbutec) in interior and exterior materials coatings at 0.02-0.5% by 

weight. These uses include joint cements, masonry coatings, paint, roof coatings, sealants, 

stuccos, plastics (vinyl, PJB), and wood protective stains. No studies were reviewed in this 

memorandum because all data were previously reviewed and accepted in various documents in 

the 1980's.
2

Test Guideline Result Degradates Comments/Reference

Hydrolysis (161 -1,

835.2120)

Essentially stable at pH

5, 7, and 9

Not applicable MRIDs 00147480,

00162356

Review dated 12/ I 0/86

Photodegradation in

water (161-2, 835.2240)

Half-life of 3 days

Half-lives of 7.5 hours

(non-sensitized) and 6.1-

7.8 hours (sensitized)

Major degradates: 

Deethylated terbutryn

Hydrated terbutryn 

(minus thiomethyl) 

Hydroxylated terbutryn 

(minus thiomethyl)

Major degrates: 

Hydrated terbutryn 

(minus thiomethyl) 

Deethylated terbutryn

MRIDs 00142912,

00162357

Review dated 12/10/86

Photodegradation on

soil (161-3, 835.2410)

96-128 hours Not available MRID 00062358

Review dated 12/I 0/86

Aerobic soil metabolism

(1 62-1 , 835.4100)

Half-life of 67days Major aerobic 

degradates: 

Deethylated terbutryn

Terbutryn minus tertiary 

butyl

MRIDs 00162359

40160301

Reviews dated 12/10/86 

and II /23/87

Anaerobic soil

metabol ism (162-2,

835.4200)

Half-l ives of 114-169 

days

No major degradates 

formed

MRIDs 00162359

40160301

Reviews dated 12/10/86 

and I I /23/87

Aerobic aquatic

metabolism (162-4, 835.

4300)

Half-Jives of62 and 35 

days for Rhine and Pond 

systems, respectively

No major degradates 

formed

Almost all residues in

water initially, but they 

partitioned to sediment.

MRID 00161360, 

Review dated 12/ I 0/86

Leaching-adsorptiondesorption (163-1,

835.1230)

Texture Kads Koc

Sand 42 2,380

Lm. Sd. 2.6 1,490

Not applicable MRIDs 00142913,

00147483,00147483,

0014785,00162361

ENVIRONMENTAL FATE

Terbutryn is a triazine compound that was previously used in row crops. It is essentially stable 

to hydrolysis (minimal degradation in 30 days), essentially stable to soil and aquatic metabolism 

(half-lives of 35-169 days), but can degrade rapidly in the presence of light without shading and 

suspended sediment (half-life of about three days). All reported metabolites and degradates 

contained an intact triazine ring without various constituents on the ring. Mobility of terbutryn in

soil was minimal with Kacts values of2.6-195 and Koc values of 1,490-12,442 ml/g. As expected,

sorption was related to clay and organic matter content because of the lack of positive or negative

electric charges. In the field, the half-lives were 17 days in Texas and 358 days in Nebraska. 

Some movement of parent compound and hydroxylated terbutryn occurred to the 12-

18 inch soil depth. In fish ponds, the half-lives for parent terbutryn were 7-14 days in water and

18-64 days for sediment. Table 1 below contains the tabulated study results. 

Table 1. Results of Environmental Fate Data for Terbutryn
3

Si.Lm. 13 1,513

Clay 195 12,442

Review dated 12/10/86

Terrestrial field 

dissipation (164-1,

835.6100)

Half-lives of 17 and 358 

days in TX and NE, 

respectively

Some movement of 

parent and hydroxylated 

terbutryn (minus 

thiomethyl group) into

6-18 inch depth in NE

MRID 00147486

Review dated 12/10/86

Aquatic field dissipation

(164-2, 835.6200)

Concentrations of parent

in water were l /251h of 

nominal by 14 days. 

Half-life of7-I4 days 

for water and 18-64 

days for sediment

Terbulethylazine

degradate was lll6

1 

hof

nominal in water by 14 

days.

Half-lives of7-14 days 

for water and 18-56 

days for 

terbulethylenazine

MRID 00038292

Review 8/10/89 Oneliner database

If there are any questions, please contact Jim Breithaupt at 703-305-5925 or at 

breithaupt. james@epa.gov.