Key Takeaways & Executive Findings
- •• • Global surveillance (2012–2024) identified Algeria and Iran as hotspots for tetracycline contamination in milk, with concentrations exceeding MRLs in some samples; Algeria, Bangladesh, and Kenya showed elevated β-lactam residues, necessitating targeted interventions. • • Health risk assessment revealed that while all individual HQ values were <1, the cumulative HI for multiple antibiotics in Algerian raw milk exceeded 1, indicating potential synergistic risks that single-compound assessments miss. • • The predominant tetracyclines (tetracycline, chlortetracycline, oxytetracycline) and β-lactams (penicillin, amoxicillin) align with global veterinary usage patterns, emphasizing the need for residue monitoring in dairy supply chains. • • Despite regulatory MRLs, a fraction of samples across countries exceeded these limits, underscoring gaps in enforcement and the necessity for robust analytical methods (LC-MS/HPLC) to ensure compliance and consumer safety.
Abstract
Antibiotics, widely used for disease prevention and growth promotion in livestock, are emerging contaminants with potential risks to human health via the food chain. This review systematically analyzed the sources and residual levels of tetracycline (TCs) and β-lactam antibiotics in raw, pasteurized, commercial, and ultra-high-temperature (UHT) sterilized milk from various countries between 2012 and 2024, based on quantitative detection methods such as LC-MS and HPLC. The highest concentrations of TCs were found in milk from Algeria and Iran, while β-lactam residues were most elevated in Algeria, Bangladesh, and Kenya. The predominant TCs were tetracycline, chlortetracycline, and oxytetracycline; β-lactams were mainly penicillin and amoxicillin. Health risk assessment using hazard quotient (HQ) and hazard index (HI) revealed that all individual HQ values were below 1, indicating no significant non-carcinogenic risk from single antibiotics. However, the HI for multiple antibiotics in raw milk from Algeria exceeded 1, suggesting potential cumulative health risks. Furthermore, some studies reported residue concentrations surpassing maximum residue limits (MRLs), underscoring the need for continuous monitoring and control. This review highlights the global variability in antibiotic contamination and the importance of comprehensive risk assessment to safeguard public health.
1. Introduction
The pervasive use of antibiotics in veterinary medicine and as growth promoters has led to their classification as emerging contaminants, with tetracyclines and β-lactams being the most extensively employed globally. In China, tetracyclines rank first and β-lactams third in veterinary antibiotic usage, reflecting a broader international trend. This widespread application inevitably results in residues in animal-derived foods, particularly milk, which is a staple in many diets. However, the contamination status and associated health risks of these antibiotics in milk remain inadequately characterized, especially given the variability in detection methods and regulatory oversight across countries.
Existing studies often rely on rapid screening kits that provide only detection rates without quantitative concentration data, limiting the ability to perform robust risk assessments. Moreover, the few quantitative studies that exist are geographically scattered and lack a comprehensive synthesis. This review addresses this gap by systematically analyzing peer-reviewed literature from 2012 to 2024 that employed LC-MS or HPLC for quantification, thereby providing a global perspective on tetracycline and β-lactam residues in milk. By evaluating both individual and cumulative health risks, this work aims to inform regulatory policies and highlight regions where intervention is most urgent, ultimately contributing to food safety and public health protection.
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ZHANG Xinyu, ZHANG Yi, YU Hui, LI Ke (2026). Contamination Status and Health Risk Assessment of Tetracycline and β-Lactam Antibiotics in Milk: A Global Review (2012–2024). Environmental Chemistry. https://doi.org/10.7524/j.issn.0254-6108.2025012404
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Frequently Asked Questions
What are the maximum residue limits (MRLs) for tetracyclines and β-lactams in milk, and how do the reported concentrations compare?
MRLs are set by Codex Alimentarius and national authorities; for tetracyclines, the MRL is typically 100 μg/kg, and for β-lactams like penicillin, it is 4 μg/kg. The review found that some samples from Algeria and Iran exceeded these limits for tetracyclines, while β-lactam residues in Algeria, Bangladesh, and Kenya also surpassed MRLs in certain cases, indicating regulatory non-compliance.
How does the health risk assessment (HQ and HI) account for cumulative exposure to multiple antibiotic residues?
HQ is calculated as the ratio of estimated daily intake to acceptable daily intake for each antibiotic. HI sums the HQs of all detected antibiotics in a sample. While individual HQs were below 1, the HI for Algerian raw milk exceeded 1, suggesting that the combined effect of multiple residues could pose a health risk, even if each individual antibiotic is within safe limits.
What analytical methods were used in the reviewed studies, and how do they affect the reliability of concentration data?
The review included studies using liquid chromatography-tandem mass spectrometry (LC-MS/MS) or high-performance liquid chromatography (HPLC), which offer high sensitivity and specificity. These methods are essential for accurate quantification at trace levels, enabling reliable risk assessments. Studies relying solely on rapid screening kits were excluded due to lack of quantitative data.
Which countries exhibited the highest contamination levels, and what factors contribute to these regional differences?
Algeria and Iran showed the highest tetracycline concentrations, while Algeria, Bangladesh, and Kenya had elevated β-lactam levels. These differences may be attributed to variations in veterinary antibiotic usage patterns, regulatory enforcement, agricultural practices, and the prevalence of substandard production conditions. The review underscores the need for region-specific monitoring and control strategies.
What are the implications of antibiotic residues in milk for public health, particularly regarding antimicrobial resistance?
Beyond direct toxic effects, sub-therapeutic concentrations of antibiotics in milk can contribute to the selection of antibiotic-resistant bacteria and resistance genes, which can be transferred to humans via the food chain. This poses a significant public health threat, as it may reduce the efficacy of clinically important antibiotics. The review emphasizes the importance of continuous surveillance to mitigate these risks.
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