While it's true that houseplants do help clean the air within a home, it is estimated that over 20 plants per room would be required to make an appreciable difference. That likely wouldn't be the case with a new genetically-modified ivy, however, which has proven to be highly effective at removing toxic chloroform and benzene from the air.

A team of scientists at the University of Washington started by creating a synthetic version of a gene, which provides the instructions for rabbits' bodies to produce a protein known as cytochrome P450 2E1. In all mammals including humans, 2E1 converts benzene into a chemical called phenol, and it converts chloroform into carbon dioxide and chloride ions. The protein is located in the liver, though, so it doesn't help neutralize airborne toxins.

The researchers proceeded to introduce the synthetic gene into regular pothos ivy plants, causing every cell in those plants to express 2E1. In lab tests, both the modified plants and regular ivy plants were placed in glass tubes, to which either benzene or chloroform gas was then added.

After an 11-day period, it was found that concentrations of the gases in the regular ivy tubes hadn't changed. In the modified ivy tubes, however, the chloroform concentration had dropped by 82 percent within just three days, and was almost undetectable after six. The benzene concentration, meanwhile, dropped by about 75 percent after eight days.

As an added bonus, the phenol, carbon dioxide and chloride ions produced by the 2E1 all help the plants to grow. Because pothos ivy doesn't flower in temperate climates, though, the plants' modified genes shouldn't spread into the environment – at least, not in cooler parts of the world.

It should be noted that the gas concentrations used in the experiments were much higher than those which would typically be found in a house, so it is thought that the modified ivy would be at least as effective in a home setting. That said, the plants would need to be kept in an enclosure, with a device such as a fan directing air from throughout the room across their leaves.

The scientists are now further modifying the plants to express another protein, which breaks down the formaldehyde which is emitted by certain wood products. Chloroform, incidentally, comes from chlorinated water, while benzene comes from the gasoline in cars or lawnmowers stored in attached garages. These chemicals' molecules are too small to be trapped by conventional air filtration systems.

"People haven't really been talking about these hazardous organic compounds in homes, and I think that's because we couldn't do anything about them," says Prof. Stuart Strand, senior author of a paper on the research. "Now we've engineered houseplants to remove these pollutants for us."

The paper was recently published in the journal Environmental Science and Technology.

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