Allergic to computing?

Over the years, many studies have linked skin rashes in some people to working long hours at personal computers. A Swedish study now finds a possible explanation: Certain computer monitors emit a chemical that can cause allergic reactions.

Three years ago, while analyzing pollution in samples of outdoor air, Conny Östman and his colleagues at Stockholm University realized that something in their lab was tainting the glassware they used. It was triphenyl phosphate, a flame retardant added to many plastics. The chemists eventually traced this contact allergen–which they later also found in the air of schools, daycare centers, and offices–to computers.

In the new study, the scientists tested 18 computers, each a different model. The plastic case on 10 of the monitors contained up to 10 percent triphenyl phosphate by weight. When turned on, the monitors heat caused the compound–which is not bound to the plastic–to start evaporating. Soon, a small but measurable amount of the pollutant tainted the air.

The emissions dropped quickly, however. After 10 days of operation, they had fallen to one-third the initial amount, the chemists report in the September, 2000 Environmental Science and Technology. After the equivalent of 2 years of office use, the monitors emitted the chemical at just 10 percent of their initial rate.

Theres no way for a consumer to identify which monitors harbor triphenyl phosphate, Östman observes. In fact, he obtained manufacturers documentation on all the polluting monitors stating that they didnt contain the flame retardant.

Östman says his team is expanding its search to other air pollutants emitted by computers and to other electronic products that might be polluting indoor air. He notes, for instance, that after one of his coworkers bought a new television, we analyzed the air in his living room and found nearly three times the triphenyl phosphate [concentrations] that we measured from new computers.

There are other flame retardants that chemically bond to plastic and so wont evaporate during a devices operation. Using them, Östman notes, would eliminate unnecessary chemical exposure [to a known allergen].

Toxic monitors

New computer models come out so frequently that the one you just bought seems obsolete the moment you get it home. This quick obsolescence encourages frequent purchases and creates a large, constant flow of computer systems into landfills. A new study demonstrates that this waste stream could be shedding lead into the environment.

The picture tubes in televisions and computer monitors employ lead-impregnated glass. This heavy metal shields viewers from most of the X rays generated when electrons collide with light-emitting phosphors to produce images. In color sets, the units face panel is fused to the funnel-shaped body in a process using extra lead. The fused glass is called frit.

Though anecdotal reports have hinted that picture tubes glass might leach the metal, no one knew how much, notes Timothy G. Townsend of the University of Florida in Gainesville. To fill that data gap, his team tested 36 picture tubes produced between 1984 and 1998. The units came from 15 manufacturers and had been marketed under 21 brand names.

The researchers disassembled the units and took samples from different portions of the tubes glass. Then, they crushed the glass into fine and coarse particles, shook 100 grams of each sample in a beaker of acidic water for several hours, and measured how much lead had leached into the water.

Federal law limits concentrations of lead in water to 5 milligrams per liter (mg/l). While lead leaching from crushed glass of black-and-white TV tubes and monitors never reached that limit, lead from all 30 color units exceeded that concentration, Townsend and his colleagues report in the Oct. 15, 2000, Environmental Science and Technology. Some glass tainted water with more than 200 mg/l of lead. When that glass was crushed to pieces less than 5 millimeters in diameter, it had the largest surface area and leached the most–often tainting water with 400 mg/l lead.

The researchers also discovered why color units leach so much lead: Its their frit, which is 70 percent lead by weight.

From now on, the researchers conclude, color picture tubes should be considered hazardous waste and kept out of landfills and municipal-waste incinerators.