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Animal Residue Data Sheet - MCPA

This Animal Residue Data Sheet sought to provide information on the potential residues of MCPA in animal commodities and animal feed commodities when MCPA products are used according to Australian good agricultural practice. However, inadequate data are available to allow the provision of full information. If further residues data become available, this Animal Residue Data Sheet will be revised.

MCPA is registered in Australia for use on wheat, barley, oats, triticale, sorghum, rice, linseed, peas, grass pastures, sub-clover, clover leys, corn/maize and oilseed poppies. MCPA can also be used for spot spraying and in non-crop areas, fallow land, industrial and commercial areas, rights of way. Details of the registered use patterns can be found on the approved labels of registered products containing MCPA as the active constituent.

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Current MRLs

The Australian MRLs for MCPA in food and animal feed commodities, as listed in Table 1 and Table 4 of the MRL Standard (as at 5 February 2003) are shown below. The residue definition for MCPA is MCPA per se.

Code Food MRL, mg/kg
Food Commodities
GC 0080 Cereal grains *0.02
Note: There are no MRLs established to cover approved uses in linseed, peas or oilseed poppies.
Animal Commodities
MO 0105 Edible offal (mammalian) *0.05
PE 0112 Eggs *0.05
MM 0095 Meat [mammalian] *0.05
ML 0106 Milks *0.05
PO 0111 Poultry, Edible offal of *0.05
PM 0110 Poultry meat *0.05
Animal feed Commodities
  No entries  
Note: There are no MRLs established to cover residues in grasses and clovers or forages and fodders of cereal grains and peas.

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Summary of Maximum Feeding Levels and Livestock Dietary Intakes

Limited data showing the magnitude of MCPA residues in crops and animals were located in the NRA archives and the open scientific literature.

The Extension Toxicology Network (EXTOXNET) Pesticide Information Profile for MCPA gave the following information: "Cattle and sheep fed MCPA in low to moderate doses in the diet for two weeks had no residues from levels less than about 18 mg/kg. At moderate continuous ingestion there was greater than 0.05 ppm in whole milk or cream. This level declined to non-detectable levels one or three days after the removal of MCPA from the diet." No reference to the source of this information was cited. [http://pmep.cce.cornell.edu/profiles/extoxnet/haloxyfop-methylparathion/mcpa-ext.html].

A brief abstract of a lactating goat metabolism study was located. 14C-MCPA was administered orally to lactating goats at a dose equivalent to 750 ppm in the feed for 3 days. Goats were sacrificed 22.5 hours after the last dose. Approximately 100% of the total administered dose was eliminated in the excreta. Milk and tissues accounted for <0.1% of the dose. MCPA was the major component of the residue in faeces and urine. The metabolite 4-chloro-2-methylanisole was the major residue in kidney, liver, muscle and fat with lower amounts of MCPA present in all tissues. MCPA accounted for a significant portion of the radioactivity in milk along with an unidentified component.

Three cows were fed MCPA in the feed at levels equivalent to 300 and 1000 ppm in the diet for 14 and 21 days respectively [J. Agr. Food Chem., 20, 5, 1972, p 963]

MCPA, ppm in the diet Days fed Residue in milk, mg/kg
MCPA 2-methyl-4-chlorophenol
300 3-13 <0.05 <0.05-0.08
1000 3-21 <0.05-0.07 <0.05-0.17

The available residue data for animal feed items have been summarised in Attachment 1. The overseas residue data for forages, fodders and pastures do not closely reflect approved Australian application rates and/or withholding period.

The following data are required to fully assess residues of MCPA in animals and animal feeds:

  • Full metabolism studies on target plants and farm animals
  • Animal transfer studies for farm animals
  • Residue studies for relevant animal feeds conducted according to Australian Good Agricultural Practice

MCPA is scheduled for re-registration by the US EPA in 2004/2005. Residue data developed for that review may be available at a later date.

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Attachment 1

Residues of MCPA in forage grasses in Canada. [Pesticide Science, 40, 2, 1994, p 127]. No indication of dry matter content was given

Location, grass variety Rate, kg ai/ha Days after treatment MCPA residue, mg/kg
var. Bromis inermis
Lethbridge, Canada 0.56 072856 38.10.08NDND
Edmonton, Canada 0.56 072856 24.90.39NDND
Beaverlodge, Canada 0.56 072856 56.40.330.01ND
var. Agropyron intermedium
Lethbridge, Canada 0.56 072856 32.30.160.02ND
Edmonton, Canada 0.56 072856 35.61.04NDND
Beaverlodge, Canada 0.56 072856 74.50.800.02ND
var. Elymus junceus
Edmonton, Canada 0.56 072856 48.32.690.07ND
Beaverlodge, Canada 0.56 072856 75.40.920.05ND

Residues of MCPA in triticale treated at the 4-6 leaf stage, Canada [Weed Technology, 1994, 38; 586-590]

Location, year Rate, kg ai/ha Plant part Pre-harvest, interval MCPA, mg/kg
Indian Head, Canada, 1979 0.28 Green plant 12142 13.80.008ND
Grain Maturity ND
Straw Maturity ND
Graysville, Canada, 1980 0.28 Green plant 12142 14.40.01ND
Grain Maturity ND
Straw Maturity ND

ND= not detected

Residues of MCPA in cereals, Germany, 1985 [Nachrichtenbl. Deut. Pflsnzenschutzd. (Braunschweig) 39, 1987]

Trial, crop Rate, kg ai/ha Pre-harvest interval MCPA, mg/kg
1, wheat 0.75 1249999 4.38 (foliage)
0.5 (foliage)
0.11 (straw)
<0.02 (grain)
2, oats 0.75 12487 0.34 (foliage)
0.05 (foliage)
<0.04 (straw)
3, wheat 0.75 1288585 9.65 (foliage)
1.05 (foliage)
0.80 (straw)
0.02 (grain)
4, wheat 0.75 1308787 2.03 (foliage)
0.53 (foliage)
<0.04 (straw)
<0.02 (grain)
5, wheat 0.75 1298484 7.35 (foliage)
<0.02 (foliage)
0.07 (straw)
<0.02 (grain)
6, wheat 0.75 1218080 0.40 (foliage)
0.13(foliage)
0.16 (straw)
<0.02 (grain)
7, wheat 0.75 7575 0.72 (straw)
<0.02 (grain)
8, barley 0.75 0185656 19.2 (foliage)
0.64 (foliage)
0.05 (straw)
<0.02 (grain)