The PVC debate continues

The PVC debate continues

Polyvinyl chloride (PVC) has been used for decades in the manufacturing of plastic products, including medical devices. Current evidence shows that the use of PVC has significant health implications at all stages in the lifecycle.

In 2020, the European Commission commissioned a study entitled The use of PVC in the context of a nontoxic environment. It aims to identify and describe uncertainties (particularly from chemicals perspective), about PVC production, recovery, and end of life treatment, and to help assess the role of PVC in the context of the European Green Deal and the Circular Economic Action Plan. The final report will be released next month.

Why is PVC a ‘problematic material’?

PVC is a soft, flexible plastic used to make clear plastic food wrapping, cooking oil bottles, teething rings, children’s and pets’ toys, and blister packaging for myriad consumer products. It is commonly used as the sheathing material for computer cables, to make plastic pipes and parts for plumbing, and in garden hoses.

See Figure 1 on page 46 for the use of PVC in a hospital setting.

Phthalates are used to increase the flexibility and durability of PVC products. Diethylhexyl phthalate (DEHP) is the most commonly used plasticiser for PVC. Soft PVC can consist of a high percentage of DEHP (up to 40%).

DEHP is not chemically bound to plastic materials and can therefore leach to into body fluids via ingestion, inhalation, dermal absorption, or intravenous route.

Medical procedures with potential for high exposure to EDCs include:

» Exchange transfusion of blood in neonates

» Extracorporeal membrane oxygenation treatment of neonates and of adults

» Total parenteral nutrition in neonates

» Haemodialysis in peripubertal males

» Haemodialysis in pregnant or lactating women

» Enteral nutrition in neonates and adults

» Heart transplantation or coronary artery bypass graft surgery

» Massive blood transfusion of red blood cells and plasma.

Impact of long-term exposure

Children – especially those treated in paediatric intensive care units – are at high risk of exposure due to their low body weights and their underdeveloped organs.

Research shows that such exposures may increase children’s susceptibility to several non-communicable diseases in adult life. EDCs are associated with diabetes, obesity, metabolic disorders, thyroid homeostasis, and an increases risk of hormone-sensitive cancers. They also have deleterious effects on male and female reproductive health.

In utero exposure to several EDCs was found to influence foetal growth and birth weight. Exposure to EDCs during the prenatal and perinatal period has been thought to influence the timing of puberty as well. Several studies evaluating the neurological development of children have shown associations of prenatal EDC exposure with adverse cognitive and behavioural outcomes. Furthermore, exposure has been associated with an increased risk of allergic diseases such as eczema and asthma.

Emerging evidence shows that EDC exposure also has epigenetic and transgenerational effects. EDCs have been shown to modify gene expression without mutating DNA, which is known as epigenetic change.

The known possible mechanisms of epigenetic changes include methylation of cytosine residues in DNA, post-translational modification of histones and altered microRNA expression.

These changes may lead to transgenerational effects on numerous organs and organ systems and are thought to be tissue-specific as well as dose-dependent.

Alternative plasticisers (PVC-free vs DEHP-free)

With growing concerns about DEHP toxicity, some product manufacturers are substituting alternative plasticisers for DEHP in various medical products rather than switching to alternative, non-PVC polymers that do not require plasticisers at all.

The toxicity of other plasticisers and their tendency to leach out of the PVC product can vary from DEHP. Some are less hazardous and have no-effect levels higher than DEHP.

However, many have not been as extensively studied as DEHP and related phthalates, particularly with regard to reproductive toxicity and endocrine disruption. Four of these alternative PVC plasticisers (1,2-cyclohexane dicarboxylic acid diisononyl ester, butyryl trihexyl citrate, tri-[2-ethylhexyl] trimellitate, dioctyl terephthalate) are included in the European Pharmacopoeia, in order to provide manufacturers with alternatives to DEHP in medical applications.

In 2007, Health Care Without Harm (HCWH) Europe documented hospitals across Europe that had begun phasing out PVC medical devices to protect patients from DEHP and other alternative plasticisers.

Among the alternative plastics that can be used for various medical products and devices are polyolefins, including polyethylene and polypropylene (polyethylene terephthalate) a polyester: multi-layer laminate plastics, polyurethane, silicone, ethylene-vinyl acetate; polycarbonate; and polystyrene.

Unfortunately, very few comparative lifecycle assessment studies exist for materials used in medical applications, and minimal environmental optimisation has taken place in medical products to date. In the Plastics Scorecard: Evaluating the Chemical Footprint of Plastics report, the chemical footprint of polyolefin and PVC in IV bags was compared.

The results of the comparison showed that the substitution of PVC bags by polyolefinbased polymers greatly reduced the chemical footprint of the products. Taking this into consideration, together with the large amount of waste produced by hospitals as a result of waste medical products, the potential of comparative lifecycle assessment studies identifying methods for environmental improvement is expected to be high.

Some of these alternative plastics are also used for food packaging and office supplies. For building products, there are a wide range of substitutes, including wood, linoleum, rubber, and a variety of other polymers suitable for various applications.

Each of these polymers also requires various additives depending on the intended application but at far lower levels than plasticisers used in flexible PVC. Life-cycle evaluations of the hazards of alternative plastics also vary, with some inherently safer than others. For example, polyurethane is one of the more problematic polymers, produced by combining an isocyanate with a polyol.

The global market for non-PVC IV bags is estimated at $1.1bn and is expected to rise steadily through 2025. North America dominated the non-PVC IV bags market and is expected to dominate throughout the forecast period. On the other hand, Asia Pacific is expected to experience the fastest growth, fuelled by factors such as the emergence of a large number of local players and increasing foreign direct investment.

Switching to safer alternatives

HCWH recommends healthcare facilities avoid PVC and DEHP and replace them with safer alternatives without compromising patient safety or care. Hospitals in the Practice Greenhealth network, a sister organisation of HCWH situated in the United States, have made eliminating PVC and DEHP a top priority. Practice Greenhealth offers step-by-step resources and product lists in the following product categories that will make it easier for any hospital to restrict the use of PVC and DEHP, and not only in medical devices:

» Medical products and devices

» Healthy interiors and furnishings

» Resilient flooring

» Carpets.

To access the list go to: https:// practicegreenhealth.org/sites/default/files/ upload-files/greenhealth_nov-dec12.pdf

Key messages and recommendations

1. PVC is the most environmentally damaging type of plastic and safer alternatives are already available for virtually all uses of PVC.

2. The available methods to manage PVC waste are not adequate to keep pace with current and unsustainable PVC production and disposal rates.

3. Eliminating PVC products is the best waste management option for both environment and human health.

4. Eliminating PVC to the highest extent possible is necessary to fulfil the ambitions of non-toxic environment initiatives.

References

Bosman R. Human and environmental health effects of plastic. Specialist Forum, 2021.

HCWH (2021). The polyvinyl chloride debate: Why PVC remains a problematic material. https://noharmuscanada.org/documents/polyvinyl-chloride-debatewhy-pvc-remains-problematic-material SF