Active ingredient: Synonym for active substance.

Active substance: Any substance or micro-organism, including a virus, that has a general or specific action: against harmful organisms; or on plants, parts of plants or plant products. Active substances are usually formulated with other materials in a pesticide product.

Acceptable Daily Intake (ADI): The acceptable daily intake is the amount of a substance which can be ingested every day of an individual's entire lifetime, in the practical certainty, on the basis of all known facts, that no harm will result. The ADI is expressed as milligrams (mg) of chemical per kg body weight of the consumer. The ADI is derived from the most appropriate NOAEL (qv) by applying an assessment factor normally 100.

Acute Reference Dose (ARfD): This is intended to define (on the basis of all known facts at the time of the evaluation) an estimate of a chemical substance in food (or drinking water), expressed on a bodyweight basis, that can be ingested over a short period of time, usually during one meal or one day, without appreciable health risk to the consumer.

Analyte: The name of the substance looked for and measured, if present. It might be a pesticide itself or a product from the pesticide as a result of degradation or metabolism.

Codex Alimentarius: Codex Alimentarius is a series of food standards and related texts that aim to provide a high level of consumer protection and fair practice in the trade of food and agricultural products.

Codex Alimentarius Commission (CAC): The organisation charged with the development of the Codex standards and texts. The Codex Alimentarius Commission is an intergovernmental body jointly sponsored by the Food and Agriculture Organisation (FAO) and the World Health Organisation (WHO). Membership is open to all Member Nations and Associate Members of the FAO and WHO and currently consists of over 160 countries.

Good agricultural practice in the use of pesticides (GAP): The nationally authorised safe uses of pesticides under conditions necessary for effective and reliable pest control i.e. the way products should be used according to the statutory conditions of approval which are stated on the label. GAP encompasses a range of pesticide applications up to the highest authorised rates of use, applied in a manner which leaves a residue which is the smallest practicable. Authorised safe uses are determined at national level and include nationally registered 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. 

Good Laboratory Practice (GLP): GLP is the organisational process and the conditions under which studies are planned, performed, monitored, recorded and reported. GLP ensures that the way the work is done is adequately standardised and of a sufficiently high quality to produce reliable results which can with confidence be compared with those of others carrying out the same work and applying the same general principles.

Limit of determination (LOD): The limit of determination is the lowest concentration of a pesticide or contaminant that can be routinely identified and quantitatively measured in a specified food, agricultural commodity or animal feed with an acceptable degree of certainty by the method of analysis. Also known as the Limit of Quantification (LOQ).

Maximum residue level (MRL): The maximum concentration of a pesticide residue (expressed as mg/kg) legally permitted in or on food commodities and animal feeds. MRLs are based on good agricultural practice data and residues in foods derived from commodities that comply with the respective MRLs are intended to be toxicologically acceptable. MRLs are not in themselves ‘safety limits’.

MRLs are intended primarily as a check that GAP is being followed and to assist international trade in produce treated with pesticides. MRLs are not safety limits, and exposure to residues in excess of an MRL does not automatically imply a hazard to health.

For some pesticides and commodities insufficient trials data are available on which to set an MRL. In these cases the MRL may be set at a default level i.e. the LOD. These MRLs are not based on GAP.

Codex or CAC MRLs: In cases where there is no UK or EC MRLs, the acceptability of residues may be judged against Codex Maximum Residue Limits. Although not embodied in UK statute, Codex limits are taken as presumptive standards. These limits give an indication of the likely highest residue that should occur in edible crops. These are based on worldwide uses, at the time of evaluation (date of setting the limits is specified and thus Maximum Residue Limit applicable up to that year, but will not take into account subsequent approved uses.)

It should be noted that there are occasions where the MRL that has been set may not reflect UK Good Agricultural Practice (e.g. the Codex MRLs for dithiocarbamates and propamocarb on lettuce). In such circumstances it is possible to exceed the Codex MRL through a UK approved use.

MRL exceedance: When a residue is found at a level higher than that set for the MRL.

Metabolite: A degradation or conversion product from a pesticide when it is metabolised.

No Observed Adverse Effect Level (NOAEL): The highest exposure level in a toxicity study at which there are no statistically significant and/or biologically significant increases in the frequency of adverse effects between the group of animals exposed to the test substance and its respective control group.

Pesticide: A pesticide is any substance, preparation or organism prepared or used for destroying any pest.

Pesticide Residues Committee (PRC): The Pesticide Residues Committee is an independent Non-Departmental Public Body. The Committee is made up of some members with a technical background (e.g. food safety/toxicological risk assessment), some with experience in the horticulture industry, and some with consumer/lay interests. The PRC is responsible for overseeing the Government's monitoring programme for pesticide residues. The PRC replaced The Working Party on Pesticides Residues (WPPR).

Risk Assessment: A risk assessment is carried out when residues are found in foods to determine whether, at the levels found, they present a concern for consumer health or not. Approval of a pesticide is only recommended when the consumer risk is acceptable.
Consumer risk assessments are carried out for both short term (peak) and long term intakes. These assessments use information on food consumption, collected in dietary surveys, in conjunction with the residue level found. Estimated intake for different consumer groups  is then compared to the Acute Reference Dose (ARfD) and to the Acceptable Daily Intake (ADI) set for the pesticide.
 
Reporting Limit: The lowest calibrated level employed during analysis to detect residues.

Residue: Residues may be present in vegetable and animal products following the application(s) of a pesticide(s). They may not only include the pesticide that was applied but other degradation or reaction products and metabolites that may be of toxicological significance. The levels or amounts of residues present are expressed in milligrams of the chemical in a kilogram of crop/food/commodity (mg/kg), or parts per million.