Document ID: EPA-HQ-OPP-2007-0589-0014
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2007-07-25T04:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

OFFICE OF           

PREVENTION, PESTICIDES

  AND TOXIC SUBSTANCES

Date: July 11, 2007

MEMORANDUM

SUBJECT:	 ENVIRONMENTAL FATE SCIENCE CHAPTER ON:

COPPER NAPHTHENATE

 From:		A. Najm Shamim, PhD, Chemist

			Regulatory Management Branch II

			Antimicrobials Division (7510P)

To:		Tim McMahon, PhD, Risk Assessor and Senior Toxicologist

			Antimicrobials Division (7510P)

				And

			Kathryn Avivah, CRM for Copper -8-Quinolinoate RED

			Regulatory Management Branch II

			Antimicrobials Division (7510P)

Thru:		Diane Isbell, Team leader,

			Regulatory Management Branch II

			Antimicrobials Division (7510P)

				And

	

			Mark Hartman, Chief

			Regulatory Management Branch II

			Antimicrobials Division (7510P)

ENVIRONMENTAL FATE SCEINCE CHAPTER ON:

COPPER NAPHTHENATE

EXECUTIVE SUMMARY:

Copper Naphthenate is an antimicrobial pesticide registered for use as a
wood preservative and fungicide.  Copper naphthenate is a very stable
substance in water under aerobic and abiotic conditions, with an
estimated half life of more than three months1 and is highly to
moderately immobile in soils with an estimated Koc of over 30001.  It is
not highly water soluble and has a low vapor pressure (~ 10-4 mm Hg) and
air/water partition coefficient (estimated Henry Law Constant) for
copper naphthenate is ~ 9.804x 10-6  and therefore, copper naphthenate
is likely to evaporate from water surfaces  to a high degree as well as
it is likely to contaminate surface water by way of soil run-offs.
Copper naphthenate is likely to persist in water and soils.

Estimated log Kow for copper naphthenate is 4.1685 1 which indicates
that copper naphthenate can possibly be bioaccumulative in aquatic
organisms like fish.  Estimated half life in air is 8.858 hours
(measured against hydroxyl radical) and is not likely to be persistent
in air.

A laboratory study2 on southern yellow pine stakes has shown that copper
naphthenate does leach out from the surface and pressure treated wood. 
The rates of leaching from the surface and pressure treated wood follow
the order:  rate of leaching is highest in pH 5>> pH 7 > unbuffered
solution > pH 9.  The rate of leaching from surface treated wood at pH 5
is:  0.047 ppm/cm2 /day and for pH 9 it is 0.00048, ppm/cm2/day 100
fold-fold less. Similarly the rate of leaching from a pressure treated
wood at pH 5 is:  0.03 ppm/cm2/day and for pH 9 the value is 0.00029,
again the rate of leaching is 100-fold less.  Because of a high Koc,
copper naphthenate is likely to contaminate surface soils around the
treated wood.

			APPENDIX TO COPPER NAPHTHENATE SCIENCE CHAPTER

			

	SUMMARY OF THE STUDY:

The percent recoveries of the  copper spiked samples were as follows:

Spike level(ppb) 	pH 5		pH 7		pH 9		Unbuffered

100 			101		99		98		100

1000			96		94		96		101

Order of leaching: pH  5>> pH 7 > unbuffered > pH 9

At the end of 30 day period of the study  total copper leachate were
determined by using the following relationship: total copper leached
(ppm/in2 ) = total cooper leached (ppm) / exposed surface area (in2 )

Agency calculated the total copper leach in ppm/in2 and converted them
into ppm/cm2 and then calculated the rate (ppm/cm2/day) as shown in the
section D of this report below.

SUMMARY OF THE LEACHING DATA FOR SURFACE TREATED WOOD 

					Table 1

Matrix+	t 

0 hr	T

1 hr	t

1 d	t

7 d	t

14 d	t

21 d	T

28

d	Total

ppm	Ppm

/20.3in2	ppm/

cm2	Rate=

ppm/ cm2 /30d

pH 5	0.02*	2.1	11	32	42	48	52	187.12	9.2	1.4	0.047

pH 7	0.02*	0.6	2.3	3.12	3.0	2.7	2.4	11.02	0.54	0.083	0.0027

pH 9	0.02*	0.02	0.1	0.7	0.2	0.4	0.5	1.94	0.095	0.0145	0.00048

Unbuff.	0.02*	0.1	4.5	4.1	3.3	3.1	3.5	18.82	0.97	0.14	0.0046

Notes: 1) * means actual measured value is < 0.02; but for calculation
purposes, Agency has assumed the value = 0.02

2) + means samples in deionized water and buffered. Unbuffered means
deionized water which is not buffered.

SUMMARY OF THE LEACHING DATA FOR PRESSURE TREATED WOOD 

				Table 2

matrix + 	t=

0 hr	t=

1 hr	t =

1 d	t=

7d	t=

 

14 d	t=

21d	t=

30d 	total ppm	ppm /  20.3 in2	ppm/ cm2	Rate = ppm/

cm2/ 30d

pH5	0.02*	1.68	8.35	21.46	29.25	35.0	41.2	107.71	5.30	0.95	0.03

pH7

	0.02*	0.72	2.39	4.16	4.86	5.22	5.45	22.82	1.12	0.20	0.006

pH9

	0.0	0.08	0.37	0.77	1.08	1.35	1.66	5.31	0.26	0.047	0.0015

Un-buff	0.0	0.41	1.30	1.61	2.05	2.18	2.13	9.68	0.47	0.087	0.0029

Note: * and + have the same meanings as in Table 1

				BIBLIOGRAPHY

	1.	EPI Suite (version 3.12)

US EPA document MRID#: 438511-01:

Copper  Naphthenate Leachability From Treated Wood, A Non-Guideline
Study for the AD Fate  Data Requirements  1995, by A.C. Gallacher. Dept.
of Analytical Services, Ricerca, Inc. 7528 Auburn Rd.; PO Box 1000,
Painesville, Ohio, 44077-1000