Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. 
Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. What was studied?
This original research article investigated the complex interactions between heavy metals and antibiotic resistance genes (ARGs) in the soils of a dairy farm, with a specific focus on their co-selective pressures and impacts on bio-enzyme activity. Researchers aimed to elucidate how the distribution and abundance of eight heavy metals (As, Zn, Cu, Cr, Cd, Ni, Pb, Hg) relate to the presence and proliferation of 28 different ARGs within agricultural soils subjected to both antibiotic residues and heavy metal contamination. Utilizing advanced geographic information system (GIS) mapping, atomic fluorescence/absorption spectrometry, and quantitative PCR, the study visualized spatial patterns of pollutants, assessed pollution indices, and performed functional predictions based on 16S rDNA sequencing. A central emphasis was placed on understanding how these environmental factors jointly influence soil enzyme activities, which serve as indicators of soil health and bioremediation potential. The study also explored the co-occurrence and correlation of heavy metals and ARGs and discussed their implications for soil remediation and the design of enzyme-based smart materials relevant to heavy metal certification programs.
Who was studied?
The studied population comprised soils sampled from a dairy farm in Dulbert Mongolian Autonomous County, Heilongjiang Province, China. The farm, covering approximately 70,000 m² and housing around 200 dairy cows, provided a controlled agricultural environment with known animal husbandry practices, including the use of antibiotics and supplemental feed. Sixty-four soil samples were collected at depths of 10 cm (surface) and 50 cm (subsoil) across a systematically gridded area, ensuring spatial representation of both heavily trafficked and less-impacted zones. The samples were analyzed for heavy metals, ARGs, and bio-enzyme activity, reflecting the environmental impact of intensive dairy operations and their waste management practices. The microbial communities analyzed were those naturally present in the soil, influenced by both intrinsic (soil properties) and extrinsic (antibiotic and heavy metal inputs) factors.
Most important findings
| Critical Points | Details |
|---|---|
| Heavy metal pollution profile | Arsenic (As) was identified as the primary contaminant, with concentrations far exceeding regulatory standards and increasing with soil depth. Surface accumulations of Zn, Cu, and Cd were also notable. |
| ARG abundance and distribution | Tetracycline, sulfonamide (sul2), and β-lactam (blaTEM) resistance genes were most abundant, particularly in surface soils and in areas of higher cow activity. ARG abundance was generally higher in surface layers, with the exception of β-lactam genes, which increased with depth. |
| Correlation between heavy metals and ARGs | Statistically significant positive correlations (p<0.01) were observed between key heavy metals (As, Cu, Ni, Pb, Zn) and the abundance of specific ARGs, indicating that heavy metal contamination can co-select for antibiotic resistance in soil bacteria. |
| Impact on bio-enzyme activity | Functional analysis showed that antibiotics and heavy metals jointly suppressed bio-enzyme activities, especially those involved in core soil metabolic pathways, indicating compromised soil health. |
| Implications for remediation and certification | The study demonstrated that heavy metals and ARGs co-occur and interact in ways that can be visually tracked using GIS. The findings provide direct evidence for integrating heavy metal and ARG monitoring into certification and remediation protocols for agricultural soils, especially where animal farming is prevalent. |
Key implications
This research highlights the necessity for heavy metal certification programs to jointly monitor heavy metals and ARGs, as their co-occurrence can exacerbate environmental and public health risks. The significant correlations found suggest that regulatory standards should address both contaminants together. The suppression of soil bio-enzyme activity further emphasizes the need for integrated soil remediation strategies that consider both chemical and biological soil health indicators.
Citation
Qi Z, Qi Y, Le Z, Han F, Li F, Yang H, Zhang T, Feng Y, Liu R, Sun Y. The Interactions Between Antibiotic Resistance Genes and Heavy Metal Pollution Under Co-Selective Pressure Influenced the Bio-Enzyme Activity. Front Chem. 2021;9:691565. doi:10.3389/fchem.2021.691565
Heavy metals are high-density elements that accumulate in the body and environment, disrupting biological processes. Lead, cadmium, arsenic, mercury, nickel, tin, aluminum, and chromium are of greatest concern due to persistence, bioaccumulation, and health risks, making them central to the HMTC program’s safety standards.
Arsenic is a naturally occurring metalloid that ranks first on the ATSDR toxic substances list. Inorganic arsenic contaminates water, rice and consumer products, and exposure is linked to cardiovascular disease, cognitive deficits, low birth weight and cancer. HMTC’s stringent certification applies ALARA principles to protect vulnerable populations.
Cadmium is a persistent heavy metal that accumulates in kidneys and bones. Dietary sources include cereals, cocoa, shellfish and vegetables, while smokers and industrial workers receive higher exposures. Studies link cadmium to kidney dysfunction, bone fractures and cancer.
Nickel is a widely used transition metal found in alloys, batteries, and consumer products that also contaminates food and water. High exposure is linked to allergic contact dermatitis, organ toxicity, and developmental effects, with children often exceeding EFSA’s tolerable daily intake of 3 μg/kg bw. Emerging evidence shows nickel crosses the placenta, elevating risks of preterm birth and congenital heart defects, underscoring HMTC’s stricter limits to safeguard vulnerable populations.
Lead is a neurotoxic heavy metal with no safe exposure level. It contaminates food, consumer goods and drinking water, causing cognitive deficits, birth defects and cardiovascular disease. HMTC’s rigorous lead testing applies ALARA principles to protect infants and consumers and to prepare brands for tightening regulations.
Mercury (Hg) is a neurotoxic heavy metal found in various consumer products and environmental sources, making it a major public health concern. Its regulation is critical to protect vulnerable populations from long-term health effects, such as neurological impairment and cardiovascular disease. The HMTC program ensures that products meet the highest standards for mercury safety.
