Pesticide, antibiotic and hormone residues in food are harmful

pesticides | antibiotics | hormones

Under some circumstances this may be true. It is not possible to give an unequivocal assurance that the use pesticides, antibiotics and hormones in food production will not result in residues that may be hazardous for some individuals. If the directions for the 'safe' use these substances are not followed (for example, if too much is used or it is applied at the wrong time) then there is the potential for hazardous residues to enter the food chain. The potential effects of these substances on health are one of the greatest concerns consumers.

Before looking at these substances individually, let us look at some of the factors that determine whether a particular food component - natural, deliberately added or contaminant - is likely to be harmful. The most important factor is the amount of the component that we consume. This is determined by both the amount of a particular food we eat and the level in the food. Even if the level of a particular contaminant is low, it could still be hazardous if we eat a lot of the food or foods in which it is present. Just as some people may be sensitive to particular foods, food ingredients or food additives, some may be sensitive to residues of pesticides, antibiotics and hormones in food. There is no evidence to suggest that this is a common phenomenon and it is certainly far less common than reactions to foods such as milk, eggs, fish, and shellfish and nuts.


Pesticide is a term encompassing a wide variety of substances used in food production to control undesirable plant, insect, and other animal populations. Many factors influence the persistence of pesticide residues in or on food. Residues may vary depending on the time between application and harvest, exposure to wind, rain, or sunlight, and the amount removed during processing (washing, peeling or cooking). Residues of pesticides can be found in many foods including breast-milk. Sometimes the amounts found are so low that it is not known if there is any biological significance. Particular care in assessing the safety of exposure to pesticide residues needs to be exercised for pesticides which could be transferred from food into breast milk and result in a relatively high exposure level to babies, and also to those which leave residues in foods which may be consumed in relatively higher amounts by children.

Only pesticides approved by the National Health and Medical Research Council are permitted to be used in Australia. The evaluative procedures and their limitations are similar to those outlined for the safety valuation of food additives (see What we Know About Food Additives). When used as recommended, the resulting residue in food, if any, should not constitute a hazard to health. The maximum residue levels of pesticides permitted in food are estimated on the basis that they do not constitute a health hazard for most consumers. However, because of the possibility of misuse and the uncertainty associated with estimating safe levels of pesticides, constant monitoring of foods for residues and safety is undertaken.

Decisions can only be made on the information available at the time. Clearly, if this is inadequate, approval should not be granted. However, from time to time additional scientific information becomes available and the 'safe' residue limit needs to be revised. This may result in a change of practice or a total banning of the pesticide. Surveys in Australia of selected pesticides show that exposure levels generally do not exceed those permitted by health authorities.


This is a group of drugs approved for use in animal led to stimulate growth and improve feed efficiency (so that less feed is required for growth) and also to reduce infection and stock loss. Higher levels are sometimes used (on prescription) for the prevention or treatment of infection. Following their use, a suitable lag time is necessary to prevent food contamination. The use of antibiotics in food production poses certain public health risks, including the emergence of antibiotic-resistant microorganisms and possible sensitive reactions in certain people. Resistance to antibiotics is not harmful in itself, but it may create health hazard if humans become infected with a strain microorganism that cannot be controlled by available antibiotics. The majority of allergic reactions have occurred with penicillin. The treatment of bovine mastitis with large doses of penicillin requires a withholding period before the residues in milk are reduced to acceptable levels. If the treatment procedure is not followed the residues may cause allergic reactions in sensitive people. It is possible that oral exposure to penicillin in milk may also cause some individuals to become sensitised.


Hormones can be used to accelerate the growth rate of animals so that they can reach market earlier. The most effective growth promoters are natural sex hormones or substances which imitate the action of the natural hormones. If hormones are used appropriately, the residues in food should be very low or undetectable and not result in a significant hormonal effect. In some countries, abuses in the use of these substances have occurred and hormonal treatment has left high residues in poultry, veal and eggs which have resulted in breast enlargement, premature cessation of pubertal development and ovarian cysts in children. In view of these potential health hazards it is important that foods are monitored for hormone use and residue levels. This does not appear to be done on a suitable scale in Australia.