July 28, 2005

The hazards of flicking on a light switch

Candela Lighting Design and Consulting

There has been a big push in the design industry over the past 20 years to manufacture and use energy-efficient lighting products. Only recently has there been much discussion about the hazardous materials these products contain, yet manufacturers have been quietly reducing some of those materials to improve the environmental performance of their products.

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PVC and mercury information

Mercury is the material of greatest concern, but not far behind it is polyvinyl chloride, which is found in electrical equipment and many building materials.


Mercury is an element, therefore it does not break down into lesser substances. It travels through the atmosphere and eventually settles in lakes, streams and wetlands. Chemicals and bacteria alter mercury into a more dangerous form called methylmercury, which accumulates in the body over time and is very slow to dissipate.

Most Americans are exposed to mercury from eating fish. Fish that eat plankton and smaller fish have the highest concentration of mercury. The longer a fish lives, the more mercury it is likely to contain.

Fetuses and children under the age of 8 are four to five times more susceptible to mercury poisoning than adults. Exposure to mercury can permanently damage their developing brains and nervous systems.

According to a report from the White House Office of Science and Technology, one in 12 women carries enough mercury in her bloodstream to cause serious neurological damage and permanent reduction in IQ to their unborn children. A more recent EPA study estimates the number is closer to one in six women.

The reason this is so frightening is that it only takes a very small amount of mercury to cause serious damage. The equivalent of one fever thermometer can poison a 20-acre lake to the point where the fish would be considered unsafe to eat.

Mercury has many legitimate purposes, but even if alternates were found for all of its man-made uses, it is still a naturally occurring element and will always be present in the environment. What we can do is control its unnecessary penetration into the environment when it is disposed of.

Mercury is used in many medical measuring devices such as thermometers and blood pressure cuffs. Some health care providers are actively seeking and using alternatives to mercury-containing products where they can.

Mercury is also used in all fluorescent and most high-intensity-discharge lamps. The amount of mercury in lamps is related to the diameter and the length of the lamp. While the amount of mercury has decreased dramatically in the last 15 years, design professionals can minimize the amount of mercury that is used by carefully selecting the lamps they specify. Typically, a compact fluorescent lamp uses more mercury per lumen of light delivered than a 4-foot T8 lamp. A T5 lamp uses even less mercury than a T8 lamp.

Disposal of lamps is critical, as mercury is considered hazardous waste. While it's possible to simply throw lamps away if the quantities are small, it is best for everyone's health to recycle them so the mercury can be collected, purified and re-used.

It has been suggested that it would be better to use a non-mercury light source such as incandescent. But, if the power to provide the electricity for that incandescent lamp comes from a coal-fired power plant, the power plant puts more mercury into the atmosphere than the alternative fluorescent lamp would.

According to a 1997 EPA report, 33 percent of man-made mercury pollution is from coal-fired power plants. The list is rounded out with 19 percent from municipal waste combustion, 18 percent from industrial boilers and 10 percent from medical incinerators. All other sources amount to 20 percent.

This is a worldwide problem, for 85 percent of China's electricity is generated from coal-fired power plants. China's economy is growing faster than any other on earth, and electricity demand is growing with it.

Mercury travels in the atmosphere through rivers, lakes and streams, and does not recognize international borders.

Polyvinyl chloride

Also known as vinyl or PVC, polyvinyl chloride is ubiquitous in the building industry. In the electrical industry, PVC is typically found in plastic pipes and wire insulation. It's also a common material for windows and siding, window coverings, wall coverings and upholstery products.

PVC is a rigid, white material in its purest form. With the addition of plasticizers, it becomes softer and more pliable. PVC is dangerous when it's manufactured and when it burns, either accidentally or intentionally. Large amounts of chlorine — 66 percent of the world's chlorine supply — are required to manufacture PVC, with dioxin as a by-product.

Chlorine production uses 1 percent of the world's total electricity output — about 47 billion kilowatt hours a year. This amount is approximately equal to the output of eight medium-sized nuclear power plants. Mercury pollution is another by-product of chlorine production.

In the post-Sept. 11 world, large chlorine plants are now identified as potential terrorist targets. Reducing the need for chlorine would reduce this threat.

Dioxin is bio-accumulative — the more a person is exposed to it, the more it builds up in their system — and collects in fat deposits and breast milk. There is no known safe amount of dioxin. It is the most potent known synthetic carcinogen. Dioxin is found everywhere in the world, even in locations far from obvious sources.

There is no successful method of recycling PVC, a known carcinogen by some accounts since 1966. Evidence of its harmful qualities mounted in the 1970s and 1980s, but the product continues to be manufactured. In the United States, PVC is mainly produced in Louisiana and Texas.

Other additives used in PVC production are lead, which damages brain development and impairs cognitive ability; cadmium, which is a potent neurotoxin and carcinogen; and organatins, which suppress the immune system and disrupt the endocrine system.

The most common plasticizer for PVC is phthalate, which can be as much as 60 to 80 percent by weight of a product. Phthalate plasticizers aren't used in any other building material. They are a known carcinogen linked to increases in the rate of childhood asthma and reproductive problems including infertility, testicular damage, reduced sperm count, suppressed ovulation and abnormal development and function of testes. These plasticizers are released when PVCs are burned, and they leach out over time in landfills. They are also found in some cosmetic products.

Steps in the right direction

Fortunately, there are alternatives to many mercury and PVC products. The Healthy Building Network has a comprehensive list of alternatives to PVC for the construction industry.

Much of the man-made mercury pollution can be reduced by recycling mercury products at the end of their life. Reducing overall electrical use and finding alternative sources of renewable energy to reduce dependence on coal-fired power plants will also help, but it will take a great political will to accomplish this.

As individuals, what can we do? Look around your house. Change from incandescent to fluorescent lamps where you can. When remodeling, look at the content of the materials you are selecting and actively seek alternatives to products that contain PVC. These are small steps, but simply acknowledging our own impact on the earth is a step in a more sustainable direction.

Denise Fong is principal at Candela Lighting Design and Consulting. She presented on hazardous materials in lighting products at the Right Light 6 conference in Shanghai, China, this year.

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