UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, DC 20460

			OFFICE OF  PREVENTION, PESTICIDES,  AND TOXIC SUBSTANCES

 								

	Memorandum								Feb.14, 2008

		

Subject:	Residue Chemistry/ Dietary Risk Assessment  Science Chapter for
Creosote (P1/P13 and P2 Fractions) Reregistration Eligibility Decision
(RED) Process

From:		A. Najm Shamim, PhD, Chemist

		Regulatory Management Branch II

		Antimicrobials Division (7510P)

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

		For Creosote RED

		Antimicrobials Division (7510P)

			And

		Jackie McFarlane, CRM for Creosote RED

		Regulatory Management Branch I

		Antimicrobials Division (7510P)

Thru:		Mark Hartman, Chief

		Regulatory Management Branch II

		Antimicrobials Division (7510P)

		

CREOSOTE - RESIDUE CHEMISTRY

Background

Creosote, an oil-based wood preservative, unlike pentachlorophenol,
historically has not had agriculture base uses, or any indirect food
contact uses, and hence was never a subject of FDA’s food basket
survey.  Creosote is a complex mixture of aromatic/ phenolic compounds
and from simple two ring cyclic organic hydrocarbons to five / six
membered fused cyclic substances. These polycyclic aromatic hydrocarbons
(PAHs) constitute about 85% of the total mixture of creosote.  These
PAHs range from being moderately water soluble ( see product chemistry
science chapter) to being practically insoluble ( chrysene, pyrene
etc.).  In a 1979 Document of the Environmental Protection Agency on the
Water-Related Environmental Fate of 129 Priority Pollutants
(EPA-440/4-79-029b, 1979, Volume II), the Agency observed: “ --under
most environmental conditions, the dominant aquatic transport process
for the polycyclic aromatic hydrocarbons will be adsorption onto the
suspended particulates.  The role of volatilization is unknown but under
certain conditions ( e.g., water agitation) it could be competitive with
adsorption.  The ultimate fate of naphthalene and possibly other
polycyclic aromatic appear to be biodegradable by microganisms and
metabolism ( biotransformation) by multi-cellular organisms.”  No
food-related exposure from the creosote mixture was indicated at that
time. 

The Agency issued a Position Document 4 ( PD 4) in 1984 on Wood
Preservative Pesticides specifically about Creosote, Pentachlorophenol
and Inorganic Arsenicals.  The Document stated that:   “The Agency was
concerned that food, feed and water may become contaminated from home
and farm use of pentachlorophenol or creosote products and that there
could be direct contact with domestic animals or livestock.”  Having
the same concern in mind the Agency earlier had proposed ( PD 2/3) to
include the label amendment: “Do not use creosote or pentachlorophenol
in a manner which may result in direct exposure of domestic animals or
livestock or in the contamination of food, feed, or drinking or
irrigation water (e.g., food crates, irrigation flumes, vegetable
stakes, feed lot bins and watering troughs.”  Therefore, in the PD 4,
the Agency established the Final Regulatory Position that all wood
preservatives such as oil-based creosote must include the following
information on their product use labels:  

“Do not apply where there may be direct contact with domestic animals
or livestock and where there may be contact with food, feed or drinking
and irrigation water.”  The Agency concluded that this statement on
the use labels for creosote application would eliminate the possibility
of liquid formulation contact with food, feed or water during the
pesticide application. (Wood preservative Pesticide: Creosote,
Pentachlorophenol and Inorganic Arsenicals, PD 4, Office of Pesticides
and Toxic Substances, Washington, DC 20460, July 1984).

RASSB is unaware of any reports which show migration of creosote or its
components into ground water.  Creosote is disposed off  in hazardous
waste landfills only after it has been treated to EPA-specified
standards (after the toxic phenolic components have been eliminated).

PAHs which constitute the largest percent of the creosote mixture have
been shown to partition between water, soil and animals.  The KOC of
some of the PAHs are high and have high binding constants with soil, and
bioaccumulation of some of these PAHs has been shown to take place with
benthic organisms.  A number of  bioaccumulation studies have appeared
in the recent literature and these indicate that the PAHs have a
tendency to bioaccumulate in a number  of aquatic organisms as well as
benthic ones.  (See science chapter on environmental fate of creosote). 
However, very few of these studies show that any significant
biomagnification in aquatic food chains take place.  In fact more
studies have shown that some of the PAHs are rapidly metabolized by
aquatic organisms and are thus eliminated from biological systems. 
Thus, though some of these PAH components may be present in human food
items, they should not occur at high levels; therefore, food chain
bioaccumulation does not appear to be of concern  in the dietary
exposure scenario.

Guideline Requirements

Table A lists the guidelines for residues on food or food contact
surfaces. The table also include if any of the guideline have been
submitted or were required by the Agency.

Series 860-Residue Chemistry Test Guidelines

Guideline No.	

Requirement	

Are the Requirements fulfilled?	

MRID/Reference



860.1000	

Background	

n/r1	

n/a2



860.1100	

Chemical Identity3	

n/r	

n/a



860.1200	

Directions for Use	

n/r	

n/a



860.1300	

Nature of the Residue-Plants, livestock	

n/r	

n/a



860.1340	

Residue Analytical Method	

n/r	

n/a



860.1360	

Multi Residue Method	

n/r	

n/a



860.1380	

Storage Stability Data	

n/r	

n/a



860.1400	

Water, Fish & Irrigated Crops	

n/r	

n/a



860.1460	

Food Handling	

n/r	

n/a



860.1480	

Meat/Milk/Poultry/Eggs	

n/r	

n/a



860.1500	

Crop Field Trials	

n/r	

n/a



860.1520	

Processed Feed/Food	

n/r	

n/a



860.1550	

Proposed Tolerances	

n/r	

n/a



860.1560	

Reasonable Grounds in Support of Petition	

n/r	

n/a



860.1650	

Submittal of Analytical Reference Standard	

n/r	

n/a



860.1850	

Confined Accumulation in Rotational Crops	

n/r	

n/a



860.1900	

Field Accumulation in Rotational Crops	

n/r	

n/a



Notes:

1.	n/r means not required

2.	n/a stands for not applicable

3.	It is a required study for product chemistry data requirements and
has been fulfilled ( see product chemistry science chapter).

 The Agency has minimal concerns about potential residues of creosote
for direct food contact, food contact surfaces, or biomagnification
through trophic transfer at this time.  However, if further scientific
research shows a high degree of bioaccumulation and biomagnification due
to exposure from creosote or some of its components, data may be
required in the future.

References /Bibliography

1.	OPPTS Test Guidelines; Series 860 ( Residue Chemistry).

2.	EPA’s Position Document 4 ( PD 4, July 1984, pp 174).

Water-Related Environmental Fate of 129 Priority Pollutants, Volume 2,
EPA 440/4-79-029b, December 1979.

Creosote, Toxicological Profile, US Department of health & Human
Services, PHS, Agency for Toxic substances & Disease Registry, Document
TP-90-09, December 1990.

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