Heavy metals are found naturally in elements with a high atomic weight and at least five times the density of water.
Their extensive dispersion in the environment has resulted from their numerous industrial, residential, agricultural, medicinal, and technical applications, raising worries about their possible consequences on human health and the environment.
Scientists have discovered that excessive amounts of heavy metals in rivers can contribute to increased antibiotic resistance.
Heavy metals increase antibiotic resistance
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The Newcastle University and the Indian Institute of Technology, Delhi conducted research on antibiotic and metal resistance in sediments from India's Ganges and Yamuna rivers, as well as streams in the River Tyne basin.
Heavy metals, which are abundant in the River Tyne watershed due to previous mining and industrial activities, are linked to antibiotic resistance levels in the river, according to the findings.
The same was observed in Indian rivers, particularly in industrialized regions.
The researchers explored the correlations between heavy metal concentrations, metal resistance gene (MRG) abundance, and antibiotic resistance gene (ARG) abundance and published their findings in the journal Environmental Pollution.
According to the study, MRG and ARG abundances rise when metal levels are greater, implying that areas with metal pollution have increased antibiotic resistance.
The findings indicated that metal pollution impacts resident bacteria, with Firmicutes and Bacteroidota being the most prevalent phyla in high metal pollution areas.
These bacteria are ubiquitous in metal-contaminated areas and have been found to contain MRGs and ARGs in groups called "gene cassettes," which explained why metal exposure can lead to antibiotic resistance.
According to the findings, the metal combinations that stimulate the highest bacterial responses are cobalt plus nickel and cobalt, zinc, and cadmium.
"The work does not necessarily suggest a health danger," said study co-author Professor David Graham of Newcastle University's School of Engineering, "but it illustrates that a river or stream without antibiotics pollution can nevertheless have heightened antibiotic resistance owing to other contaminants, such as metals," as per ScienceDaily.
Heavy metals can also affect organelles and other components
Heavy metals have been shown to influence cellular organelles and components such as the cell membrane, mitochondria, lysosomes, endoplasmic reticulum, nuclei, and several enzymes involved in metabolism, detoxification, and damage repair in biological systems.
Metal ions have been discovered to interact with cell components such as DNA and nuclear proteins, resulting in DNA damage and conformational changes that may lead to cell cycle regulation, cancer, or apoptosis, as per the journal Heavy Metals Toxicity and the Environment
Several research from researchers' lab has shown that reactive oxygen species (ROS) generation and oxidative stress play an important role in the toxicity and carcinogenicity of metals such as arsenic, cadmium, chromium, lead, and mercury.
These five elements are considered priority metals with significant public health implications due to their extreme toxicity.
They're all systemic toxins that have been shown to cause numerous organ harm even at low doses.
These metals are classified as "known" or "probable" human carcinogens by the United States Environmental Protection Agency (US EPA) and the International Agency for Research on Cancer (IARC) based on epidemiological and experimental studies showing a link between exposure and cancer incidence in humans and animals.
