Heavy metals — they're not all rock and roll
Plenty of materials boast antimicrobial and antibacterial properties, characteristics which have been in particularly high demand of late as they can significantly reduce the spread of infection and disease. Michaël van der Jagt, CEO of Parx Materials argues that the behaviour of these materials could lead to catastrophic resistance problems and why, safe, holistic additives are essential for our future protection.
Antibiotic resistance represents a significant threat to global health. Less effective antibiotics are making a growing number of infections, including pneumonia and tuberculosis, more difficult to treat. The threat of antibiotic resistance is so prevalent that the World Health Organisation (WHO) states in its Antimicrobial Resistance Global Report on Surveillance that without urgent action, we are heading towards an era in which common infections and minor injuries can kill.1
The antibiotic resistance problem is largely attributed to the over-prescription and overuse of antibiotics, rather than the overuse of antimicrobial additives in materials. Resistance against material-based antimicrobials, however, also poses a real threat.
Materials matter
The term ‘antimicrobial’ describes anything that is used to prevent and treat infections in humans, animals and plants. This includes antibiotics and the additives used in materials for applications reliant on hygiene, including medical devices.
Similar to antibiotic resistance, antimicrobial resistance occurs when bacteria and fungi develop the ability to survive the biocides designed to kill them. As a result, the bacteria survive and grow, passing on the genetic changes that made them stronger, becoming potentially life threatening.
Most of today’s antimicrobial materials are made using silver ions — an additive that is incredibly effective at killing bacteria. Although heavy metals such as silver, mercury, arsenic and copper have been used as antimicrobial agents for thousands of years, this doesn’t mean they are safe or sustainable.
Toxicity risks
In the mid-20th century, organic antibiotics replaced most of these heavy metal-based additives. Yet, the past few decades have seen a resurgence of interest in using silver as a topical antimicrobial agent; for instance, silver sulfadiazine (SSD) is often used in wound healing bandages for burns. But just as mercury, arsenic and copper were replaced due to their toxic threat to the human body, silver poses a similar risk.
Silver’s sustainability problem
Despite the wealth of information published on metal toxicity, metal-containing additives are commonly used in consumer goods. In fact, the antibacterial properties of silver ions are often used as a marketing too. Similar to antibiotic resistance, could such common use of metal-containing antimicrobials lead to a loss in effectiveness? The answer is yes.
Unfortunately, this is already the case for silver- and copper-resistant bacteria, as demonstrated in research on “Efficacy of multiple metals against copper-resistant bacterial strains” by the University of Arizona.2 The 2012 study demonstrated that several copper-resistant bacterial strains were also resistant to silver and a combination of both metals, suggesting a shared resistance mechanism.
What is more concerning, perhaps, are the precise mechanisms by which silver ion-containing antimicrobials kill microbes, and their ultimate effect on the human body and the environment, which remains unclear. The only certainty is that, to kill the bacteria, these ions must migrate from the material in question, ultimately leaching into the environment and/or the human body.
The alternative
Using heavy metal ions for antimicrobial applications is unsustainable — for human health, the environment and for the efficacy of the materials themselves. A different, more holistic approach is therefore essential for our future protection.
The industry must depart from heavy metal additives and instead use materials with an intrinsic immune system; that is, materials that mimic the natural antimicrobial mechanisms of human skin. By mimicking the body’s own antimicrobial properties, the method can make plastics and polymers resistant to bacteria attachment and proliferation.
Parx Materials has developed a proven technique to achieve this biomimicry by incorporating a trace element that is found naturally in the human body. Saniconcentrate exhibits mechanical and physical properties that are bio-inspired, rather than reliant on toxic heavy metals. Using a trace element of zinc, the additive replicates the natural defence mechanism of the human skin. Bacteria are not attacked or killed; instead, they simply cannot attach and proliferate, allowing them to live out their natural lifecycle and die without spreading infection. This is a mechanism that the human immune system relies on. Crucially, it is also one to which bacteria do not build up a resistance.
Saniconcentrate does not contain biocides, silver, nano materials or toxic substances. Unlike many other additives, it does not migrate from the material.
The technology is already in use and has shown outstanding results in trials. A recent study evidenced that Saniconcentrate protects successfully against COVID-19, seeing a 99% reduction in the virus after 24 hours.3
No more migration
Another major concern about heavy metal additives is migration. Consider silver ions as an example. To be effective, ions are transported into bacteria cells to prevent cell division. This is achieved by binding to their DNA. The ions block the bacterial respiratory system, destroying energy production and essentially suffocating the bacteria until it is destroyed.
Although incredibly effective at killing bacteria, silver-based additives require ions to migrate from the material to work. This means the antimicrobial properties of the material will eventually wear off. It also means the silver ions are released into our environment, our oceans and in some cases, our bodies.
This is particularly concerning given that the most common applications of antimicrobial additives — food packaging, medical devices and personal protective equipment — are all examples of high-risk products. What’s more, with an increasing demand for antimicrobial materials amid the COVID-19 pandemic, the public will be exposed significantly more to materials containing migrating silver ions.
Taking a holistic approach
As we enter an era in which hygiene and cleanliness is crucial, we must consider the risks of mass deployment of heavy metal additives. They threaten our health, our environment and increase the risk of antimicrobial resistant bacteria. Despite their efficacy, using heavy metal additives is simply not sustainable.
To protect ourselves in the future, we must take a holistic approach to preventing the spread of bacteria. And what better method than replicating the immune response already found in the human body? Particularly for the medical plastics and medical devices realm, in which protecting against antimicrobial resistance is essential for long-term health.