Poison We Are Eating-Neither Denied nor Accepted-A Story of MRL in Pakistan Vs International Scenario

Pesticides of all kinds especially of synthetic origins are being used as plant protectants though convincingly but aimlessly. An extreme desire is that without them no such profitable food can be there. But the use of pesticides keeping no hold or limit is, obviously threatening. Then we are in a position of neither denied nor accepted, i.e., we can not deny or reject the use of poisons to protect crop but simultaneously mentioned we cannot also in a position to accept these. Henceforth, as a conclusive evidence, what should be the final outcomes leading to a stalemate, it is ‘MRL or Maximum Residue Limit’ maintaining a permissible poison level protecting crops and human safety. Maximum Residue Limit can be defined as The MRL is the maximum concentration of a pesticide residue (expressed as mg/kg), recommended by the Codex Alimentarius Commission to be legally permitted in or on food commodities and animal feeds. MRLs are based on GAP data and foods derived from commodities that comply with the respective MRLs are intended to be toxicologically acceptable.

Maximum Residue Limit) The maximum concentration of residue resulting from the use of a veterinary drug (expressed in mg/kg or μg/kg on a fresh weight basis) that is recommended by the Codex Alimentarius Commission to be legally permitted or recognized as acceptable in or on a food. It is based on the type and amount of residue considered to be without toxicological hazard for human health as expressed by the Acceptable Daily Intake (ADI), or on the basis of a temporary ADI that utilizes an additional safety factor. It also takes into account other relevant public health risks as well as food technological aspects and estimated food intakes. The maximum residue level is estimated by the JMPR as the maximum concentration of residues (expressed as mg/kg) which may occur in a food or feed commodity following Good Agricultural Practices. The estimated maximum residue level is considered by the JMPR to be suitable for establishing Codex MRLs.

Followings are important ones:

1. JECFA Joint FAO/WHO Expert Committee on Food Additives
2. JMPR Joint FAO/WHO Meeting on Pesticide Residues

We are using a tremendous amount of pesticides in agriculture sector. They are toxic in nature. They can, and they do cause:

1. HUMAN HEALTH RISKS:(Occupational, Consumer, Intentional/Unintentional)
2. ENVIRONMENTAL CONSIDERATION (Pollution, Environ. degradation, Extinction of biodiversity)
3. TRADE CONCERNS (WTO, SPS & TBT measures)

Pakistan Perspective of MRLs and impacts: up to 2010.

JMPR assessment processes for pesticide residues

The “Joint Meeting on Pesticide Residues” (JMPR) is an international scientific expert body administered jointly by FAO and WHO. The JMPR WHO Core Assessment Group evaluates toxicology data for establishing acceptable daily intakes (ADIs) and acute reference doses (ARfDs) and the FAO Panel on Pesticide Residues in Food and the Environment evaluates pesticide residue data resulting from pesticide use according to good agricultural practice (GAP) to estimate maximum residue levels in food and feed commodities. Under GAP a pesticide is used for effective pest control, but leaving a residue that is the smallest amount practicable. The use must be safe for the user and the environment and residues in food must be safe for the consumer.

These are much important:

JECFA Joint FAO/WHO Expert Committee on Food Additives

JMPR Joint FAO/WHO Meeting on Pesticide Residues

Risk Assessment consists of four steps:

– Hazard identification

– Hazard characterization

– Exposure assessment

– Risk characterization

The factors considered for the establishment of MRLs include:

– residue definitions;

– species or crop;

– commodities (significance in trade and consumption);

– analytical methods suitable for enforcement purposes; and

– Good Agricultural Practice or Good Practice in the Use of Veterinary Drugs.

JMPR accepts national registered uses of pesticides as Good Agricultural Practice (GAP). The commended maximum residue levels depend mainly on the data from supervised residue trials

conducted in line with maximum registered uses (highest application rate, minimum pre-harvest interval, etc) within GAP. The trials should cover the range of conditions expected to occur in practice including application methods, seasons, cultural practices and crop varieties. When the number of trials is sufficient, JMPR estimates a maximum pesticide residue level for the commodity of trade and an STMR (median of the valid residue data, one point from each trial) and HR (highest of the valid residue data, one point from each trial) for the edible portion of the commodity.

The estimated maximum residue level is recommended to the Codex Committee on Pesticide

Residues (CCPR) for use as an MRL (maximum residue limit). The STMR and HR are used in longterm

and short-term dietary exposure estimates.

Identification and description of residues and methods

1. JECFA Joint FAO/WHO Expert Committee on Food Additives
2. JMPR Joint FAO/WHO Meeting on Pesticide Residues

Both involves the general process as:

1. Residue definition, chemical identity, and physicochemical properties (definitions, IUPAC names of compounds, their appearance, solubility in water etc).
2. Pharmacokinetic and metabolism data used for residue definition evaluation (The process by which a drug is absorbed, distributed, metabolized and eliminated by the body)
3. Analytical methods and residue stability in stored analytical samples
4. Fate of residues during commercial food processing
5. Field study data used to identify the MRL (Livestock feeding studies and animal treatments)

Acceptable daily intake (ADI). The ADI of a chemical is the estimate of the amount of a substance in food or drinking-water, expressed on a body-weight basis, that can be ingested daily over a lifetime without appreciable health risk to the consumer on the basis of all the known facts at the time of the evaluation. It is expressed in milligrams of the chemical per kilogram of body weight.

Supervised trials median residue (STMR). The STMR is the expected residue level (expressed as mg/kg) in the edible portion of a food commodity when a pesticide has been used according to maximum GAP conditions. The STMR is estimated as the median of the residue values (one from each trial) from supervised trials conducted according to maximum GAP conditions.

Acute Reference Dose (ARfD). The ARfD of a chemical is the estimate of the amount of a substance in  food or drinking water, expressed on a body weight basis, that can be ingested in a period of 24 h or less, without appreciable health risk to the consumer on the basis of all the known facts at the time of evaluation. It is expressed in milligrams of the chemical per kilogram of body weight.

Definition of residues. The definition of a residue for compliance with MRLs is that combination of

the pesticide and its metabolites, derivatives and related compounds to which the MRL applies.

Marker residue. The Codex defines a marker residue for veterinary drugs as a “residue whose concentration decreases in a known relationship to the level of total residues in tissues, eggs, milk or other animal tissues” based on a definition used by JECFA. The relationship between the concentrations of marker residue and total residues is usually established at representative time points during depletion in a study using radiolabelled drug.

Good Agricultural Practice (GAP) in the use of pesticides. GAP includes the nationally authorized safe uses of pesticides under actual conditions necessary for effective and reliable pest control. It encompasses a range of levels of pesticide applications up to the highest authorised use, applied in a manner which leaves a residue which is the smallest amount practicable. Authorized safe uses are determined at the national level and include nationally registered or recommended uses, which take into account public and occupational health and environmental safety considerations. Actual conditions include any stage in the production, storage, transport, distribution and processing of food commodities and animal feed.

Highest residue (HR). The HR is the highest residue level (expressed as mg/kg) in a composite sample of the edible portion of a food commodity when a pesticide has been used according to maximum GAP conditions. The HR is estimated as the highest of the residue values (one from each trial) from supervised trials conducted according to maximum GAP conditions, and includes residue components defined by the JMPR for estimation of dietary intake.

Maximum residue level The maximum residue level is estimated by the JMPR as the maximum concentration of residues (expressed as mg/kg) which may occur in a food or feed commodity following Good Agricultural Practices. The estimated maximum residue level is considered by the JMPR to be suitable for establishing Codex MRLs.

Maximum Residue Limit The MRL is the maximum concentration of a pesticide residue (expressed as mg/kg), recommended by the Codex Alimentarius Commission to be legally permitted in or on food commodities and animal feeds. MRLs are based on GAP data and foods derived from commodities that comply with the respective MRLs are intended to be toxicologically acceptable. The maximum concentration of residue resulting from the use of a veterinary drug (expressed in mg/kg or μg/kg on a fresh weight basis) that is recommended by the Codex Alimentarius Commission to be legally permitted or recognized as acceptable in or on a food. It is based on the type and amount of residue considered to be without toxicological hazard for human health as expressed by the Acceptable Daily Intake (ADI), or on the basis of a temporary ADI that utilizes an additional safety factor. It also takes into account other relevant public health risks as well as food technological aspects and estimated food intakes.

This article is collectively authored by Muhammad Wajid Javed¹, Dr. Dilbar Husain², Dr. Jam Nazeer Ahmad², Dr. Samina Jam Nazeer Ahmad¹, Dr. Ahmad Nawaz¹, Muhammad Saleem^1,2, Muhammad Ishfaq², Muhammad Jafir², Asad Aslam^1,2, Mir Nazeer Ahmed Maree^1. 1University of Agriculture Faisalabad. ²Entomological Research Institute, Ayub Agriculture Research Institute, Faisalabad