A Brief Note on Antibiotic Residues in Milk

A Brief Note on Antibiotic Residues in Milk

Milk is an important and essential food for humans because of its richness in nutrients. It is highly valuable and consumed largely by people of all ages throughout the world. Milk is a perishable commodity susceptible for contamination with various chemical contaminants including Anthelmintic drugs, chlorinated pesticides, organophosphates, herbicides, fungicides, antibiotics, hormones and disinfectants. Antibiotic contamination of milk poses significant threat to safety of milk and is regarded as global public health hazard. Antibiotic residues are the parent drug compounds and their metabolites excreted through edible tissues of animals to which antibiotics in question are administered. Antibiotic residues in milk are of major public health significance since it causes carcinogenicity, teratogenicity, drug allergy, bone marrow toxicity, mutagenicity and gastrointestinal disorders. It is also responsible for emergence of drug resistant microorganisms and starter failure in dairy industry. Indiscriminate and extra label use of antibiotics, insufficient withdrawal period and lack of records are responsible for occurrence of antibiotic residues in milk. Milk and milk products contaminated with antibiotic residue above maximum residue limit (MRL) are considered unfit for human consumption. Hence, it is necessary to routinely screen milk samples for antibiotic residues.

Milk is defined as the physiological secretion of the mammary gland of mammals to provide nourishment to their young ones. Consumption of milk is necessary for new born of all mammalian species because it is primary source of nutrition for them before they are able to digest other types of food. More than 6 billion people worldwide consume milk and milk products; the majority of these people live in developing countries. India ranks first in milk production in the world (18.5%) with a total annual production of 165.4 million tones and per capita availability 355 g/day (DAHD&F). It is therefore important to provide due attention to the quality of milk produced and distributed to the consumers. Various harmful chemical substances contaminate the milk due to various reasons. Amongst, an array of such substances, veterinary drug residues in general, and antimicrobials in particular, pose major milk and milk products’ food safety issue. Milk is a staple food in Indian households. Dairy farmers are pressured to boost milk production to meet its rising demand, driven by high population growth, rising income, and urbanization . There exists a positive correlation between high milk yield and mastitis . Mastitis is predominantly a bacterial disease of the mammary gland of high-yielders . Antibiotics are often used or misused in the dairy sector for therapeutic and prophylactic purposes . Antibiotics are also eliminated in the milk till 7 days post-treatment . However, there is an absence of compliance to milk withdrawal periods following antibiotic administration, which leads to antibiotic residues in milk . Hence, improper use of antibiotic therapy in milch animals poses a threat to the public, especially if milk is consumed unpasteurized .

Consumers want to be confident that their food supply is free of contamination by herbicides, pesticides, drugs, or antibiotics. The presence of any drugs or antibiotic residues in any livestock product is illegal. Milk supplies containing detectable concentrations of any drugs are not acceptable. Unless drug residues are avoided to protect milk’s reputation as a healthy, safe food, the market becomes jeopardized. Approximately 5-10 percent of the consumer population is hypersensitive to penicillin or other antibiotics and suffers allergic reactions (skin rashes, hives, asthma, anaphylactic shock) at concentrations as low as 1 ppb penicillin. There is concern that small amounts of certain antimicrobial agents may significantly shift the resistance patterns in the microbial population in the human intestinal tract.

Most of the antibiotics are known to interfere with the manufacture of several dairy products. Antimicrobial concentrations of 1 ppb delay starter activity for cheese, butter, and yogurt and of other fermented dairy products. Antibiotics also decrease the acid and flavor production associated with butter manufacture, and they reduce the curdling of milk and cause improper ripening of cheeses. Antibiotic residues in milk and milk products may lead to:severe allergic reactions in sensitive consumers, culture failure and   subsequent loss of product, a change in consumer perception of milk being a pure, unadulterated, natural product. All of these concerns may result in major economic losses to the dairy industry.

Need of hour to overcome the effects of antibiotic residue in dairy products:

1. To protect consumers’ health

Antibiotics entering the food chain through dairy products may lead to allergic reactions in humans and antibiotic resistant strains of bacteria.

2. To safeguard

It is essential that the dairy industry as a whole produces high quality milk which is free from antibiotic residues.

3. To avoid heavy penalties for producers

In future, losses incurred by processors having to discard milk or may be passed back to the producer, while meeting the legal requirements of drug residue as prescribed by food standard authorities producer may penalizes.

4. To prevent losses to processors

Production of cultured dairy products can be adversely affected by traces of antibiotics, resulting in sub-standard product. Specifications for valuable home and export markets require dairy products to be free from antibiotics.

5. To comply with current legislation

Contamination of milk is an offence liable to prosecution,to ensure that food producers and handlers are not convicted of an offence which they took all reasonable care to avoid. It is therefore important that all milk producers are able to show that they have taken all reasonable precautions to ensure the safety of milk being sold by them.

Milk is a fundamental part of our diet, providing essential nutrients and contributing to our overall health. However, concerns have arisen regarding the presence of antibiotics in milk and their potential impact on human health. Antibiotics are commonly used in dairy farming to treat and prevent bacterial infections in cows, but their residues can find their way into the milk supply chain.

Types of antibiotics found in milk

There are several types of antibiotics that can be found in milk due to their use in dairy farming. These antibiotics are used to treat and prevent bacterial infections in cows. Here are some common types:

Beta-Lactams: This class of antibiotics includes penicillin and cephalosporins. They are frequently used in veterinary medicine for treating bacterial infections in cows.

Tetracyclines: Tetracycline and oxytetracycline are examples of antibiotics in this class. They are employed in dairy farming to combat various bacterial infections.

Macrolides: Erythromycin and tylosin fall under the category of macrolide antibiotics. They are utilized to treat specific ailments in cows, such as mastitis.

Sulfonamides: Sulfadimethoxine and sulfamethazine are commonly used antibiotics in dairy farming. They help control and treat bacterial infections in cows.

Cause of antibiotic residues

Increased demand of milk can only be met by implementing widespread animal husbandry practices. Use of veterinary drugs for curing of variety of ailments in farm animals is an integral component of such extensive animal husbandry practices. Antimicrobials are considered as the vital medicines to treat animal infections. They are also used at sub-therapeutic levels to increase feed efficiency, promote growth and prevent diseases (Ronquillo, 2016). The most possible cause of occurrence of drug residues in milk is the failure to observe prescribed withdrawal times (Van Dresser and Wilcke, 1989). But, In India, the extra label use of antibiotics, mainly dosages deviating from recommendations of the drug manufacturer fall under the main reason for occurrence of antibiotic residues in milk after the end of the withholding period in cows. The inappropriate and abusive use of veterinary drugs and negligence regarding withholding periods of milk can lead to the presence of residues of these compounds or their metabolites. Usage of antibiotics as feed additives is reported to be another mean of antibiotic residue prevalence in milk. It has been projected that usage of antibiotic as feed-additive has become an integral part of this intensive animal-production technology.

Source of drug residues in Dairy Products

To the dairy animalsfor disease therapy the drugs are administered via intramuscular or intravenous injections, oral administration, feed supplementation, or reproductive infusions. While the treating of mammary gland infections through intra-mammary or intravenous infusions. A FDA surveys indicate that improper use of drugs in the control of mastitis is the major source of residues found in the milk supply. Many drugs are retained in the animal body for longer times than indicated by label discard times. Consequently, milk samples remain positive for residues. A good example is penicillin with a recommended milk discard time of 72 hours. However, penicillin residue has persisted in milk for as long as 18 days. Some of the cephapirin treated cows were still positive at 48 hours after the recommended milk discard time.

Antimicrobial drugs administered for dry cow therapy do not appear to cause drug residues if milk is not shipped for the first four days after calving, if dry periods are recommendations are followed, dry cow therapy should not result in residues after calving. However, residues are possible and fresh cows should be tested, especially cows with short dry periods. Intrauterine infusions of drugs have caused detectable residues in milk. Few studies have reported residues caused by intrauterine treatment with tetracycline, dihydrostreptomycin, benzyl penicillin, oxytetracycline, sulfamethazine, penicillinand streptomycin. Even combiotic (procaine penicillin and dihydrostreptomycin) has been detected in milk for 24-48 hours after intrauterine infusion.

Possible reasons for drug residues:

• Extended usage or excessive dosage of approved drugs.
• Poor records of treatment.
• Milker or producer mistakes accidental transfer into bulk tank.
• Failure to observe recommended label withdrawal time.
• Lack of advice on withdrawal period.
• Prolonged drug clearance.
• Treated-animal identification problems.
• Multiple dosing.
• Products not used according to label directions.
• Withholding milk from treated quarters only.
• Contaminated milking equipment.
• Early calving or short dry periods.
• Purchase of treated cows.
• Use of dry cow therapy to lactating cows.

Recommended use of on-farm drug residue testing

Certain situations have greater risks for residues. Withholding times on the label may have been established with healthy or high producing cows where the drug retention is less than occurs in sick or diseased cows. Consider using a drug residue screening test as follows:

1. Fresh cows, especially those dry treated and with dry periods of six weeks or less, cows that freshen early, cows which had been treated shortly before calving, or cows whose treatment status was unknown. Discard milk for the first three days after calving. This includes first lactation cows who had been treated with either a lactating or dry cow mastitis treatment prior to calving. Also, test cows that received intrauterine drug infusions.
2. At the end of the recommended milk discard time and after the milk becomes visually normal, test milk from any lactating cow treated for mastitis.
3. At the end of the veterinarian’s recommended withholding time, which should be stated on the drug label, test any cows treated “extra-label.” Also, test problem cows that have been treated longer than recommended, or with higher doses, or with combinations of drugs or special mixes.
4. All new additions to the herd including purchased cows or first lactation animals should be tested before their milk is added to the bulk tank.
5. Any cull cows that have been treated or baby calves that have been fed milk from treated cows should not be sold until the end of the withdrawal time for meat animals. Calves born to cows treated during the dry period may acquire tissue drug residues prior to birth or from drinking colostrums.

Effects of residues on health

Indians are developing resistance to antibiotics and, hence, falling prey to a host of otherwise curable ailments.Antibiotic residues in milk are of great public health concern since milk is being widely consumed by infants, youngster and adults throughout the globe. The residues of antibacterial drugs may present pharmacological, toxicological, and microbiological and immunopathological health risks for humans. Possible acute and chronic adverse effects of antibiotics residues have been suggested like transfer of antibiotic resistant bacteria to the human and some other possible effects include autoimmunity, carcinogenicity (sulphamethazine, oxytetracycline), mutagenicity, nephropathy (gentamicin), hepatotoxicity, reproductive disorders, bone marrow toxicity (chloramphenicol), allergy (penicillin). These hazards can be categorized in to two types as direct-short term hazards and indirect-long term hazards, according to duration of exposure to residues and the time onset of health effects. Antibiotics like beta-lactam group of antibiotics in spite of being in low concentration in milk causes allergic hypersensitive reaction in sensitized individual immediately after consumption which may be leads to direct health hazard while prolonged exposure to low levels of antibiotics leads to chronic toxic effects including carcinogenicity, teratogenicity, reproductive effects, development of antibiotic resistance bacteria in treated animals and disruption of normal healthy flora in the intestine. Chronic exposures to oxytetercycline include blood changes such as leucocytosis, atypical lymphocytes, and lung congestion, toxic granulation of granulocytes and thrombocytopenia purpura and brown discolouration of the teeth. Some antibacterial agents are used as feed additives in cattle feed like tetracycline, nitro furans and sulphonamides which may excrete in milk and may cause toxicological effects in human.

Implications of Antibiotics in Milk:

Development of Antibiotic Resistance: Regular exposure to antibiotics through milk consumption can contribute to the development of antibiotic-resistant bacteria in humans. This poses a significant public health concern as it diminishes the effectiveness of antibiotics in treating infections

Control of antibiotic residues in milk

In order to tackle the menace of antimicrobial residues in foods of animal origin such as milk, meat and their products, a number of international organizations such as the Codex Alimenterius Commission (CAC), European Economic Community (EEC), World Health Organization (WHO) and the Food and Agricultural Organization (FAO) are involved in regulating the use of drugs in animal production activities. For this purpose, these organizations have proposed maximum residue levels (MRLs) for livestock products based on regular monitoring, controlling and surveillance programmes with the aim of minimizing the risk to human health.

Update  on Antibiotic Residue In Milk in India

Food Safety and Standards Authority of India (FSSAI) has informed that it has specified the standards of milk under Food Safety and Standards (Food Products Standards and Food Additives) Regulations, 2011. Further, the tolerance limits for various antibiotics and veterinary drugs in milk and other food products is specified in sub-regulation 2.3.2 of Food Safety and Standards (Contaminants, Toxins and Residues) Regulations, 2011 and amendments thereof.

All Food Business Operators involved in processing and sale of milk are required to adhere to the specified Regulations. Implementation and enforcement of Food Safety and Standards Act, 2006 primarily lies with State/UT Governments. Commissioners of Food Safety of States/UTs conduct surveillance, sampling, inspection and enforcement drives through their food safety officials to ensure the quality and safety of milk and milk products conforms to specified standards.

FSSAI has recognized and notified 240 National Accreditation Board for Testing and Calibration Laboratories (NABL) accredited food testing laboratories across the country. Also, for on-the-spot testing of adulterants in milk and milk products, 173 mobile food testing laboratories equipped with rapid milk analyzer have been sanctioned/ provided to the States/UTs.

Department of Animal Husbandry and Dairying (DAHD), Government of India has informed that it had issued an advisory to all States and Union Territories regarding the judicious use of antibiotic for treatment of ailing food producing animals. Further, it was also advised that use of antibiotics should be discouraged, if not essential and development, production and use of alternative antibiotic free growth promoters should be encouraged.

The National Milk Safety and Quality Survey, 2018 was conducted by FSSAI. The details of the survey are available on the website of FSSAI i.e https://www.fssai.gov.in/upload/press_release/2019/10/5da973ffaefcfPress_Release_Milk_Survey_Report_18_10_2019.pdf

The Union Minister of State for Health and Family Welfare, Dr. Bharti Pravin Pawar stated this in a written reply in the Lok Sabha today, 01 APR 2022.

CONCLUSION

Noticeable concentrations of antibiotic residues in milk supplies higher than the MRLs are illegal which should be checked to avoid public health hazard. People should ensure strict adherence to the prescribed withdrawal time of the drugs. One practical approach to cut down the residues in milk would involve good hygiene and good management practices at farm and the milk processing units. For ensuring human food safety, establishment of regulatory standards and good management practices are essential components to reduce the risk of antibiotic residues in milk supply. Antibiotic residues can be avoided in milk by judicious and proper use of antibiotics, enforcing governmental regulations and following withdrawal period. Screening tests used for detection of antibiotic residues helps in assuring the safety and quality of milk that finally reaches consumers. The implementation of nationwide food safety program and performance of routine surveillance studies on dairy products helps in preventing the marketing of contaminated products. Dairy farmers and para veterinary staff must be made aware of consequences of unnecessary use of antibiotics in dairy animals. Therefore the utmost care should be taken during the milking routine to minimize the risk of antibiotics entering the food chain. Milk of the highest quality is necessary to meet present and future market requirements and consumers now demand milk products of the highest quality and safety. Where drugs are used on the dairy herd there is always a risk of antibiotic contamination of milk. Therefore the utmost care should be taken during the milking routine to minimize the risk of antibiotics entering the food chain. All these must be checked as it causes health concerns in humans.

Compiled  & Shared by- This paper is a compilation of groupwork provided by the Team, LITD (Livestock Institute of Training & Development)

 Image-Courtesy-Google

 Reference-On Request

MANUAL FOR ANALYSIS OF ANTIBIOTICS AND HORMONE RESIDUES

ANTIBIOTIC RESIDUES IN MILK -A PUBLIC HEALTH CONCERN

https://fssai.gov.in/upload/uploadfiles/files/Manual_Antibiotics_Hormones_Residues_09_01_2017(1).pdf

ANTIBIOTIC RESIDUES IN MILK -A PUBLIC HEALTH CONCERN

Please follow and like us: