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Human beings have been prettying up their homes for millennia. Australian aborigines have been getting busy with ochre on cave walls for at least 40,000 years and even the relatively recent Egyptians started decorating their pyramids around 2,500 BC.

Even early on, though, there was a price to pay for making our surroundings more appealing: chemicals in the paint contained substances toxic to both humans and the environment.

It's taken until now to develop paint that sticks to the walls in a pleasing fashion, without the potential to poison your home.

Shedding light on heavy effects

The ingredients used in ordinary paint are a well-kept trade secret. Most paint manufacturers will only divulge the four broad categories of ingredients that make up paint: pigments, solvents, binder and other additives.

Basically, colour comes from the pigment, while the solvent and binder provide the base for the pigment. In enamel or acrylic paints the solvent is a hydrocarbon - derived from fossil fuels - and in water-based paints it is mostly water.

The remaining additives, usually some kind of hydrocarbon, are used for purposes such as controlling drying times and preventing mildew formation.

The minerals and hydrocarbon solvents can be toxic for the environment, and in landfill can contaminate the surrounding earth for decades. One notable nasty is lead.

It's not news that lead is a health and environmental hazard - in fact, humans have known about lead's toxic effects for about 4,000 years.

Lead exposure can affect children's developing nervous systems, leading to speech, language and behavioural problems. In adults, lead exposure can cause high blood pressure, headaches, memory and concentration problems, kidney damage, mood changes, nerve disorders, sleep disturbances, and muscle or joint pain - just to name a few of the symptoms.

So if lead is so noxious, why was it added to paint in the first place? Naturally occurring lead oxide was being used in paints as a white pigment as early as the second century AD. Lead also has the added benefits of speeding up drying times, increasing durability, resisting moisture and freshening the appearance of paint.

For these reasons, Australian house paints still contained as much as 50 per cent lead until 1965. After that time, government regulation restricted lead content to one per cent, but it wasn't until 1997 that the limit for lead concentration was further reduced to 0.1 per cent.

While modern paint contains negligible levels of lead, if your house or apartment was built before 1965, then chances are it has lead paint on the walls.

Sanding and scraping is the usual method of removing paint, but this can become problematic if it's lead paint. Paint removal by blasting, burning, dry scraping, dry sanding, and using power tools creates the most serious dangers because the particles are small enough to be inhaled or deposited in furnishings or carpet, making complete removal extremely difficult.

"My advice is to get in contact with the local EPA, but if it's not flaky it may be safe to paint over and encapsulate it," says Steve Williams, of The Green Paint Shop in Brisbane. "[Paint company] Resene has a thick paint that bonds to the old paint."

He suggests using a licensed contractor to remove or paint over lead paint because they have the tools to deal safely with the hazard.

"They have professional vacuums with an industry filter…a HEPA [high-efficiency particulate air] filter," he says.

A volatile nature

With Australia's harsh climate and strong, bright sun, homeowners needed something to protect their weatherboard homes from the elements.

Petrochemicals derived from crude oil made great solvents for holding the pigment until it dried onto a surface, but in the process they gave paint another toxic element.

The solvents in paint evaporate easily because they are VOCs - a volatile organic compound. Some VOCs are carcinogens or nervous system toxins. They are also associated with other symptoms, such as headaches, fatigue, difficulty in breathing, and eye, skin and airway irritation.

Paints with high VOC content also present a serious environmental problem. If disposed of incorrectly, the effects range from contamination of groundwater or soil - which may result in the loss of plant and animal life - to fires or explosions.

Even today, many paints and wood finishes still contain VOCs, which are responsible for the heady fumes of a freshly painted room and can persist for years after application. Some paints can contain as much as 450 g/litre of VOCs.

Companies have since wised up and started producing low-VOC paints. Dulux has EnvirO2, an acrylic interior white base paint, and Wattyl has its i.d range. Both are low in VOCs (less than one gram per litre), which means low fumes and paint odours.

Painter Steve Williams says there are more low-VOC paints around these days. "But they are still a tiny proportion of the paint that is sold. It's still lagging behind Europe and the UK. Italy has been doing this for 20 years."

Natural aesthetics

A few keen independent distributors are supplying plant-based paints, which have zero or very low-VOC content. These natural paints are made from citrus, plant oils, waxes, plant-based solvents, earth and mineral pigments.

Natural milk paints are another style of natural paint. These are made from milk protein (casein) and earth pigments such as lime and clay. They come in powdered form, to be mixed with water. Milk paints contain no preservatives so should be applied quickly after mixing.

Many natural paints let surfaces breathe. This is very important in the long-term life of a building as it means that structures that have been painted can regulate moisture content.

Conventional petrochemical-based paints create a skin over the top of surfaces, in many cases preventing moisture from wicking away from the surface, which causes mould to build up and paint to peel.

Eco retail and service company Todae stocks BIO Paint, a biodegradable natural paint, "which means it's OK in the water system," says buyer Fiona Sessions. "BIO Paint has no smell and has less than one gram of VOC per litre. And that's just the lemon peel oil, rather than a petrochemical."

Williams also sells eco-friendly non-toxic paint at his Brisbane store. A former professional painter, he quit after developing dermatitis. He later formed Natural Painting People when he heard about environment-friendly paints.

"Eco-friendly paints have come a long way in ease of use, durability, colour and finish," says Williams. "But you'll never get a high gloss in a 'green' paint. There are a lot of chemicals associated with a mirror-like high-gloss finish."

Low-VOC paints are buyer-beware though - according to the Green Painters Association, low-VOC doesn't mean the paint is necessarily safe. While the base paint might contain less nasty chemicals, the tint in some eco-friendly brands might still have VOCs.

Also available is an energy-saving, non-toxic paint additive that prevents heat from the sun getting to the wall, and prevents heat escaping if applied to internal walls.

Thermilate, stocked by the Eco Living Centre in NSW, has a high fire rating and cuts energy use - and the need for air-conditioning or heating - by reducing heat loss or transfer through walls or ceilings.

The movement to phasing out environmentally harmful paints is slow, says Williams.

"Paint manufacturers are developing eco-friendly paints because they see a market for it, and so they can move quickly to respond to any future legislation in Australia. Consumers are driving the current small scale change, but only legislation will create the wholesale change within the industry."