Nowadays, research is showing that the "new car smell" we once treasured is dangerous to our health. Old and new cars are full of toxic chemicals, inside and out.

Asbestos, which is known to cause the deadly lung disease, mesothelioma, was still used by manufacturers as late as 1995. Many older cars still have asbestos in brake pads and clutch linings. If proper precautions such as respirators and disposal of used parts are not employed when repairing these parts, especially mechanics, sharp asbestos fibers may be inhaled where they cause scarring, and, over time, lung cancer.

In car interiors, studies have shown that without adequate ventilation, and when exposed to hot conditions such as open parking lots on sunny days, dangerous levels of benzene, phthalates and polybrominated biphenyl ethers (PDBEs) are released into the air inside the car, accumulating in the dust that collects on dashboards, window surfaces, seats and carpets.

Let's examine why these chemicals are used, their health effects, and whether there are less toxic alternatives to their use:

Benzene is a byproduct of petroleum, and accumulates in the liver and kidneys. Think of the many petroleum-based parts of your car interior: the plastics of the dashboard, vinyl seats, door panels, consoles and carpeting. On warm days, benzene is released from these parts and is inhaled. Avoid concentrated exposure by airing out your car before entering on hot days.

Phthalates keep the plastic parts of your car flexible. Modern cars are made with a great deal of plastic to reduce weight and increase fuel efficiency. Unfortunately, what works for the manufacturers is bad for your health. Phthalates are released by heat, and concentrate in dust and windshield film. Phthalates cause birth defects in rats, though research in humans is still widely debated.

PDBEs are used by car manufacturers as flame-retardants. Consider all the parts of your car's interior that catch fire, and that's where you'll find them. Carpets, the foam cushions of the seats, the fabric on the sun visor and seat covers, even your child's car seat is treated with PDBEs. Though human studies are ongoing, animal studies have shown that PDBE exposure causes neurological and reproductive problems.

What's being done about these dangerous chemicals? Car companies in Japan and Sweden are aware of these toxins and their health effects and are working to mitigate your exposure, using fewer chemicals and better-designed ventilation systems. Another company in Sweden has developed a citrus-based flame retardant that has no toxic side effects and may one day replace PDBEs. In the meantime, keep your car's interior ventilated in warm weather. Keep the dust down by wiping down surfaces and windows, and clean carpets and cloth seats frequently with a HEPA filter-equipped vacuum.