According to Wikipedia, polyvinyl chloride - commonly abbreviated as PVC - is the third-most widely produced plastic in the world, after polyethylene and polypropylene. It is widely used in construction because it’s cheap, durable and easy to assemble. The annual global production of PVC is expected to exceed 40 million tonnes by 2016. In spite of its ubiquity, there is mounting pressure to ban it.

The use of PVC in electrical and data cabling installations is widespread in Australia, with most electrical and data cables being sheathed in the compound, and almost all conduits made from PVC as well. However, in recent years, there has been a move away from cabling and conduits that contain PVC insulation and/or sheathing and toward alternative compounds, driven largely by environmental issues and health and safety concerns.

It is a well-known fact that, in a fire, PVC-coated wires can form hydrogen chloride (HCl) fumes; the chlorine serving to scavenge free radicals that are present in the atmosphere and, thereby, providing the source of the material’s fire-retardant properties. However, HCl fumes can also pose a serious health hazard in their own right, because the fumes are toxic.

In electrical and data installations where smoke can be a major hazard (typically tunnels and large communal areas like airports and train stations) PVC-free materials are now being specified by many building owners and developers. Low smoke zero halogen (LSZH) cables and non-halogenated conduits are being used more frequently.

The drive to ban PVC

PVC is of particular concern to environmental groups because it contains high concentrations of chlorine (56%), along with various chemicals to make it suit specific applications. PVC cable insulation and sheathing, for example, contains ‘plasticisers’ that make it flexible. These chemicals, many of which are toxic, can leach out or be emitted into the atmosphere when burnt.

Greenpeace advocates the global phase-out of PVC because it claims dioxin, an environmental pollutant, is produced as a by-product of vinyl chloride manufacture and from the incineration of waste PVC.

A European Parliament report dated December 2009 proposed directives on the reduction of hazardous substances such as chlorine, mercury, PVC, cadmium and other heavy metals in waste from electrical and electronic equipment.

The report also commented that PVC is not a suitable material to even recycle, stating: “The recycling of WEEE [waste electrical and electronic equipment] containing brominated flame retardants, chlorinated flame retardants, PVC and its hazardous plasticisers provides no environmental benefit and is uneconomical. As a result, it is subjected to thermal treatment or disposal, which is likely to pose risks to human health or the environment, either directly through release of these substances to the environment, or indirectly through the formation of hazardous transformation products or secondary hazardous waste resulting from incineration.”

The report recommended: “The phase out of PVC should ... have priority over selective risk management measures, to guarantee a reduced release of PVC, of its additives and of hazardous combustion products.”

Environmentally friendly alternatives

LSZH-rated cables are commonly used in most parts of Europe and they are now becoming increasingly popular in Australia. LSZH is a material classification that typically denotes cable jacketing that is non-halogenated. It is composed of thermoplastic compounds that emit limited smoke and no halogen when LSZH-rated cables are exposed to flames or high-heat sources.

In the event of a fire, chlorinated materials release poisonous HCl that can form hydrochloric acid, whereas LSZH cables do not produce any dangerous gases, or gas/acid combination, or toxic smoke when it is exposed to flame.

Most major international cable manufacturers offer LSZH cables as part of their product range in Australia. And because many of them supply substantial volumes of LSZH cables into the European market, the manufacturing scale of economies mean that the price increment over PVC cable is generally quite negligible these days.

Environmentally friendly cabling is not limited to just cables. Conduits, which are commonly manufactured from PVC, are also available in non-halogenated compounds, although the range of companies offering them is not as wide as LSZH cables. You may recall that the 2000 Olympic Games in Sydney was billed as the ‘Green Olympics’. Part of the design brief was to ensure that no PVC was buried in the ground as part of the construction of the main stadium and the other facilities for the Games. So even back then, PVC was recognised as a serious environmental and health and safety concern. Unfortunately, we haven’t used the same diligence since then to ensure that new buildings and building refurbishments in Australia use more environmentally friendly materials. Interestingly, the Green Building Council of Australia awards Green Star credits to buildings that minimise the use of PVC in projects, so we are now seeing a stronger trend toward PVC alternatives that use non-halogenated compounds.

Local NSW conduit manufacturer Evcco has taken a strong stand on environmentally unfriendly materials. The company’s product portfolio is made up entirely of non-halogenated compounds. The product range is designated HFT (halogen free flame retardant) electrical conduit and fittings and provides significant environmental and safety benefits over PVC. These benefits include no aggressive fumes to endanger people’s lives, reduced smoke density for better visibility at fire exits and for rescue teams, and no corrosive and acidic gas formation that can damage electronic equipment, machines and buildings.

John McNab, Managing Director of Evcco, says that studies of construction fires point to PVC - the construction material of choice - as being highly dangerous to both personal health and the environment when burned: “PVC is one of the worst offenders when it comes to toxic substances. It can emit highly corrosive and toxic HCl when burned. It is also is a source of dioxin and phosgene gas when burned at temperatures below complete combustion. Coincidentally, phosgene, an odourless gas that can damage the lungs, is one of the substances used in chemical warfare. Samples of soot taken from fires in PVC-containing buildings that have burned have been found to contain dioxins in very high concentrations. The soot, however, represents only a small part of the problem: more than 90% of the dioxins produced in a structural fire are found in the gaseous phase and escape into the atmosphere.

Commenting on his company’s decision to use only non-halogenated compounds in their conduits, McNab says: “We are committed to minimising our environmental impact through an active and responsible approach, and implemented environmental and quality management systems that have given us both ISO 14001 and ISO 9001 certification.

“No chemicals are used in the manufacturing process and our products, which are easily recycled as they do not contain any organohalides or heavy metals.

“We have traditionally supplied a large percentage of our non-halogenated conduit range into major infrastructure projects like railways stations and tunnels, but we’re getting calls from a lot of smaller-scale commercial projects like offices and warehouses, where the owner, or developer is conscious of minimising the amount of hazardous substances that are being put into their project. Electrical contractors aren’t as proactive about it, but they’re gradually coming around as LSZH and non-halogenated products are being specified.”

Recycling

Halogenated organic compounds are typically classified as volatile organic compounds (VOCs), materials that are recognised as being environmentally unfriendly.

Generally speaking, halogenated compounds are less amenable to bioremediation (environmentally responsible recycling) than non-halogenated compounds. In fact, the more halogenated that a compound is, the more resistant it is to biodegradation. Incineration of halogenated compounds, for example, requires specific off-gas and scrubber water treatment for the halogen, in addition to the normal controls that are implemented for non-halogenated compounds.