CRITERIA FOR COMPOUND EVALUATION SYSTEM (CES)

A key aspect of food safety in the modern world is the control of residues in food that may result from the use of animal drugs and pesticides, or from incidents involving environmental contaminants. The United States has a complex residue control system with rigorous processes for approval, sampling and testing, and enforcement. Three agencies play major roles in protecting the public from residues left in food by drug, agricultural chemical, and environmental contaminants. The Environmental Protection Agency (EPA) regulates pesticides that can be used in food production and other industrial chemicals that have the potential for contaminating food. EPA sets the tolerances for pesticides and other chemicals. The Food and Drug Administration (FDA) regulates and inspects foods other than meat and poultry and regulates animal feeds. FDA determines if the drugs can be introduced into the market. This includes establishing tolerances for residues of animal drugs in edible tissues. The Food Safety Inspection Service (FSIS) of the U.S. Department of Agriculture is responsible for ensuring that meat and poultry sold in interstate commerce in the U.S. is safe, wholesome, and accurately labeled. As part of this responsibility, FSIS has since 1967 conducted the National Residue Program (NRP) to sample meat and poultry containing concentrations of residues that exceed the tolerances set by EPA and FDA. The specific objectives of the NRP are:

1. To assess and communicate the exposure potential from residues in the Nation's meat and poultry supply.
   
   
2. To prevent live animals with violative concentrations of residues in their tissues from being presented for slaughter.
   
   
3. To prevent edible tissues from slaughtered animals containing violative concentrations of residues from entering the food supply.

There are several hundred pesticides registered for use in the United States; pesticide residues may also occur in meat and poultry as the result of environmental contamination. The number of potential residues from animal drugs is equally impressive. It is not necessary, however, to monitor for residues of all chemicals, since they differ greatly in ability to produce a residue, degree of hazard to health, and potential for exposing the human population to their residues. In deciding where available resources and testing efforts should be assigned, FSIS must assess relative concerns for those residues most likely to have the greatest impact on public health. Similarly, the allocation of research and development resources must be based on the evaluation of the public health hazard.

For purposes of developing and managing the NRP, compounds are given precedence using a risk assessment procedure. The Compound Evaluation System (CES) was developed in 1985. Under the initial version of the CES, compounds that may leave residues were ranked both for toxicity and for probability of human exposure.

After several years experience with the CES, the Agency determined that additional criteria were needed in order to select chemicals for our testing program that are most likely to leave a residue. In the revised version, Second Edition, revised 1991, developed by the Residue Evaluation and Planning Division, USDA/FSIS/S&T, the CES has three potential factors, the first being whether the compound produces a residue. If so, the second CES factor is hazardous (adverse effects that may be produced by a given compound), which is ranked from A (high) to D (low) and Z (unknown). The third factor, exposure, involves such considerations as residue concentration and factors affecting concentration, such as use patterns, withdrawal times, and duration of consumption of product containing the residues of concern. Exposure is ranked from 1 (likely) to 4 (unlikely) to Z (unknown). The CES ranking, or risk characterization, is a product of both hazard and exposure. In summary, the basic approach to compound ranking consists of three elements:

1. Determining if a compound produces a residue; if so then,
   
   
2.  2. Assessing the toxicological hazardness of the compound
   
   
3.  3. Assessing the potential human exposure resulting from residues occurring in meat and poultry.

The Agency's ongoing evaluation of information for compound ranking is aided by an advisory board; the Surveillance Advisory Team which consists of scientists from EPA, FDA, and USDA. This advisory relationship is defined in a Memorandum of Understanding among the three agencies (FR, January 16, 1985).

Compounds may be rotated out of the NRP but can be added during the year if needed. Over the past ten years, virtually all drugs, pesticides and environmental contaminants for which suitable methods were available have been included in the NRP, except for compounds with especially low rankings; i.e., carboxin, tiamulin, etc.

Acephate

B-4

1989

Acepromazine

B- 4

1991

Aflatoxin

A-4

1985

Aklomide

Z-4

1991

Alachlor

A-2

1985

Albendazole

A-2

1987

Aldicarb

B-4

1994

Aldrin

B-4

1994

Ametryn

D-4

1990

Amitraz

B-3

1989

Ampicillin

B-2

1985

Ampicillin trihydrate

B-2

1985

Amprolium

A-4

1990

Arsanilic acid

C-1

1987

Atrazine

C-3

1985

Azaperone

B-4

1986

Benomyl

B-3

1986

BHC

B-2

1987

Cadmium

B-4

1985

Cambendazole

A-4

1993

Captan

B-3

1987

Carbadox

A-3

1987

Carbarsone

C-2

1987

Carbaryl

C-2

1988

Carbofuran

C-3

1986

Carbophenothion

B-4

1994

Carboxin

C-4

1987

Ceftiofur

B-4

1992

Chloramphenicol

A-2

1985

Chloramphenicol palmitate

A-2

1985

Chlordane (technical)

A-2

1987

Chlorpyrifos

B-4

1986

Chlortetracycline

B-2

1992

Clenbuterol

B-4

1991

Cloprostenol

B-4

1988

Clorsulon

D-4

1990

Coumaphos& oxygen analog

B-2

1988

Cyanos (3-phenoxyphenyl) methyl-4-chloro-alpha-(1-methylethyl) benzeneacetate [Fenvalerate]

D-3

1989

Cypermethrin

B-3

1989

Cyromzine

B-3

1989

2,4,D (technical)

B-2

1987

Dalapon

A-3

1985

Damiozide

B-3

1985

DDT

B-3

1989

Decoquinate

Z-4

1986

Deltamehrin

C-4

1989

Dibutyltin dilaurate

A-1

1988

Dichlorvos

B-4

1987

Dieldrin

B-3

1994

O,O-diethyl S-[2 -(ethylthio)ethyl] phosphorodithioae (Disulfoton)

A-2

1988

Dihydrostreptomycin

A-1

1989

Dimethoate

B-3

1986

Dimethylsulfoxide

A-4

1989

Dimetridazole

A-4

1993

Dinoprost tromethamine

B-4

1988

Diphenylamine

B-4

1985

Dodecachlorooctahydro-1,34-metheno-2H-cyclobuta [cd]pentalene[Mirex]

A-4

1992

Endrin

A-4

1994

Ethalfluralin

A-4

1993

Ethylene dibromide

A-4

1986

Febantel

A-4

1993

Fenbendazole

B-3

1987

Fenthion

C-3

1985

Fluycthrinate

B-4

1994

Furazolidone

A-1

1987

Gentamicin sulfate

B-2

1986

Gentian Violet

A-2

1991

Halofuginone

A-1

1989

Heptachlor and heptachlor expoide

A-1

1987

Hexachlorobenzene (HCB)

A-3

1989

Hexazinone

D-1

1985

Hygromycin B

A-3

1991

Ipronidazole

Z-4

1986

Ipronidazole hydrochloride

Z-4

1986

Ivermectin

B-1

1986

Lead

B-4

1985

Levamisole

C-2

1985

Levamisole hydrochloride

C-2

1985

Lincomycin

D-4

1992

Lindane

A-2

1986

Linuron

A-3

1989

Mebendazole

B-4

1986

Melengestrol acetate

B-4

1989

Methamidophos

A-4

1990

Methoxychlor

D-4

1987

Methyl bromide

B-4

1986

Methylene chloride

A-2

1986

Monensin

B-3

1985

Monuron

B-4

1990

Naled

B-4

1987

Neomycin sulfate

B-3

1986

Nicarbazin

B-3

1990

Oxfendazole

B-4

1993

Oxytetracycline hydrochloride

B-1

1992

Paraquat

A-4

1986

PCB's

A-4

1985

Penicillin

A-2

1992

Pentachlorophenol (PCP)

B-1

1985

Permethrin

B-2

1987

Picloram

C-4

1989

Prometryn

C-3

1987

Propanil

A-4

1991

Propazine

C-4

1988

Ronnel

C-4

1994

Roxarsone

C-3

1987

Silvex

A-3

1986

Simazine

C-3

1988

Spectinomycin

B-2

1991

Streptomycin

A-3

1986

Styrene

C-2

1989

Sulfadimethoxine

A-3

1992

Sulfamethazine

B-1

1985

Sulfaquinoxaline

B-1

1987

Sulfathiazole

B-1

1987

2,4,5-T

A-3

1985

Tetracycline hydrochloride

A-1

1992

Thiabendazole

B-2

1987

Thiram

A-2

1990

Tiamulin

D-3

1989

Toxaphene

A-2

1985

Trenbolone acetate

C-4

1990

Trichlorfon

B-3

1985

Trifluralin

C-4

1986

Triphenyltin hydroxide

B-4

1986

Tylosin

D-2

1989

Virginiamycin

D-4

1989

Xylazine

Z-4

1986

Zeranol

C-2

1986

Zinc

D-4

1985