The potential presence of drug residue contaminants in food products destined for human consumption is an increasingly popular topic of conversation in the industry but what are the main challenges facing the industry to tackle this potential issue?

Drug residue contaminants in food products is a discussion that involves the global community but each individual country or trade bloc has their own protocols and regulations relating to the control and monitoring of residues. The different legislations are designed to protect the general public as well as the food industry interests in their individual countries. Any business that wishes to sell their products within other countries or regions must meet their legislative requirements relating to drug residues. These differences in regulations have increased the need for increased dialogue on the issue as well as the implementation of effective monitoring systems.

The industry must deal with the potential of residues from antibiotics and growth promoting hormones entering the food chain. This will involve ensuring correct dosage per animal and also adhering to withdrawal periods set for their region. The second issue the industry faces is the stigma received from the misuse of these antibiotics and growth promoting hormones.

While there is a potential for misuse it should always be noted that a producer’s main concern should always be animal health, which leads to a quality end product. The use of antibiotics is to ensure the health of the animal and to reduce the potential knock on effect of untreated diseases which could create a downturn on yield. Growth promoting hormones are used to increase this yield also but should never be done so at the expense of a safe end product.

Residues from particular drugs in food produce can have serious implications for human health. As such many countries have set Maximum Residue Limits (MRLs) or tolerances for these residues in food.  The Maximum Residue Limit is the maximum concentration of a residue that can be present in a product from an animal or animal by product intended for the food supply. These MRLs mean that it is required by law in the enforcing countries that any product in the food chain cannot contain residue levels that are harmful to human health above these limits.

There has been controversy over measures to tackle drug residues in foods as there are no internationally accepted standards for many drugs. Ractopamine in particular has caused trade disputes as it is permitted in food production in some countries like the US & Canada, but the European Union, China, Taiwan and over 100 other countries have banned its use.

The real challenge the food industry faces is ensuring their testing methods are effective and reliable to ensure the safety of a variety of end products. To name a few of these diverse products we can look at the dairy, meat, seafood, feed and honey markets.

Dairy Market

The dairy industry is under constant scrutiny and pressure to constantly produce high volumes of milk whilst maintaining a superior standard of quality in their dairy products. As part of the production process various contaminants are administered to cattle in an effort to systematically treat various infectious diseases and maintain a healthy herd. A direct consequence of this is the requirement of routine monitoring and testing within farms and dairy processors to ensure that the levels of contaminants in milk are within legal regulations not exceeding Maximum Residue Limits and that unauthorised substances are not found at any level in milk.

Testing can be conducted at several points during the production process. Firstly, farm level testing can be carried out to screen milk from cows that have been separated from the herd and undergone antibiotic treatment. Secondly, the dairy processor is required to conduct testing both onsite taking samples from tankers and retrospective testing as a method of internal surveillance to ensure the milk supplied from several farms is within global regulatory limits. Thirdly, retailers can test the processed milk end product to guarantee the milk is antibiotic free before it’s added to supermarket shelves for consumers.

Meat Market

Global meat production and consumption have increased rapidly in recent decades. Worldwide meat production has tripled over the last four decades and increased 20 percent in just the last 10 years. Meanwhile, industrial countries are consuming growing amounts of meat, nearly double the quantity in developing countries. Mass quantities of antibiotics are used on livestock to reduce the impact of disease, contributing to antibiotic resistance in animals and humans alike. Worldwide, 80 percent of all antibiotics sold in 2009 were used on livestock and poultry, compared to only 20 percent used for human illnesses.

Growth promoters, which are tested for under the NRCP, are hormonal and antibiotic substances that may be used in food producing animals for growth promotion in livestock animals thus increasing the production of muscle meat and the reduction of fat. The type of growth promoter used is dependent on the animal species and mode of rearing with steroid growth promoters used for beef cattle and antibiotic growth promoters, which are usually added to feedstuffs, such as the coccidiostats used in the poultry industry and chlortetracycline used in the porcine industry. The rapid speed of meat production calls for the need to test for drug residues frequently to prevent them from ending up in the food chain.

Seafood Market

The global aquaculture industry has grown steadily over the past five decades, increasing at an average rate of 3.2%. However, this growth has come at a cost, with the industry facing many new challenges. Farmed seafood is often treated with medicated feeds which contain antibiotics such as leucomalachite green and nitrofurans for example to prevent from disease spreading, they are also exposed to other harmful residues used to treat algae etc. within the ‘pens’ where they are kept.

The FAO (2012) reported that 38% of fish produced globally is exported, highlighting the imbalances in regional supply and the changing tastes of the global consumer. This increased level of exporting and importing shows the importance of drug residue screening within the global aquaculture industry. This increased level of exporting and importing shows the importance of drug residue screening within the global aquaculture industry.

Feed Market

The global animal feed processing market is estimated at US$21.61 billion in 2018 and is projected to reach US$ 26.62 Billion by 2023. The market is driven by factors such as the rising awareness of feed nutrition and health, technological advancements in the equipment industry and increase in the demand for feed around the world. Medicated feeds containing veterinary are often used to help prevent disease within livestock and there are MRLs for feed which has created the need for testing as high levels of residues can have an effect on livestock health and also transfer through to meat products for human consumption. With humidity levels rising in recent years there has been an influx in the level of mycotoxins found within feed and cereals. These toxins are fungal and can affect both livestock and human health for example mycotoxicoses which is a disease which can affect the respiratory system. The main cause of mycotoxins within stored grains are when the grain is damp or cracked and kept in insufficient storage conditions. These factors have made it necessary for feed and cereals to be tested for both drug residues and mycotoxins to ensure that they do not end up within the food chain.

Honey Market

The global honey market is growing at a rapid pace and the global consumption of honey is to reach 2.5 million tones by 2022. This growth is driven for consumers demand for natural and healthy alternatives to artificial sweeteners over cane sugar. There is also a growing awareness of the health and healing benefits of honey which is driving the demand for the use of honey for medicinal use, manuka honey sales continue to grow for its antibacterial and anti-inflammatory properties. The rapid rise in demand for honey outweighs the amount that can be produced in a natural form globally due to a decline in the number of bees. This has influenced the quality of honey being produced as some producers take to diluting natural honey with high-fructose corn syrups in order to supply the demand. There is a requirement for keepers to treat bee colonies with antibiotics to prevent CCD and other diseases such as varroa mites and there is a chance that these harmful drug residues can be transferred through to the end product ‘natural’ honey. The use of antibiotic drugs in apiculture is globally restricted and there are no MRLs set for antibiotics in honey as it a natural product and needs to be antibiotic free, this has cause the need for testing both for drug residues and the overall quality of the honey being produced.

Detection

Due to the requirement to use a variety of drug treatments in the food industry and also the potential economic benefits to be gained from the use of growth promoters, there will continue to be use in animal production. However, as analytical methods of detection become more sensitive, producers are given further options for testing.

The surveillance for the potential presence of these residues of veterinary substances is regulated by the EU Directive 86/469/EEC. This directive outlines the guidelines for sampling and testing within a residue monitoring programme.

The requirement to meet these standard and the MRLs and detection levels outlined in the legislation has created a need for analytical methods to become more sensitive to ensure correct analysis. On some occasions MRL’s have been lowered which require a technology sensitive enough to detect very low concentrations in a sample.

One such screening method that is commonly used is the Enzyme-linked immunosorbent assay (ELISA) methods, which work well for testing and providing accurate results.

Randox Food have developed another method of analysis using the Evidence Investigator which uses similar methodology to ELISA methods. The analyser uses biochip array technology (BAT) to perform simultaneous quantitative detection of multiple analytes from a single sample and can be used across multiple matrix types including the products produced by the industries mentioned.  The core technology is the Randox biochip, this contains an array of discrete test regions containing immobilized antibodies specific to the drug residues under test.

These methods are rapid, reliable, and sensitive so are able to detect residues in very small concentrations. The Randox methods are developed in line with EU Directive 86/469/EEC and as such are an effective testing method for multiple areas of the food industry.

For further information please contact the Randox Food Diagnostics team by emailing: info@randoxfood.com