“Killer” spices and toxic plastic
New research presented at the American Chemical Society meeting in Washington this week (and reported in National Geographic) suggests that herbs and spices may offer an alternative to chemical pesticides. Oils from thyme, rosemary, mint and other herbs should repel or kill insect pests when sprayed onto crops.
Research indicates that the oils interfere with insects’ nervous systems and can also disrupt insects’ cellular membranes. Scientists think that insects may be less likely to develop resistance to plant-based compounds because they tend to be complex chemical mixtures.
However there are drawbacks to the potential widespread application of herbs and spices as pesticides. The compounds tend to evaporate quickly and degrade in sunlight; they must therefore be applied every few days, rather than every few weeks for conventional pesticides.
Other research presented at the same meeting indicates that plastics degrade far faster in water than previously thought. Scientists thought that plastics broke down only at very high temperatures and over hundreds of years. Now, new research by a team in Japan shows that polystyrene can degrade at temperatures of only 36 degrees celcius in the sea. As it degrades, the plastic is leaching toxic chemicals such as bisphenol A into the water. Bisphenol A has been shown to disrupt the reproductive systems of animals. The researchers suggest that plastic should be considered a new source of chemical pollution in the ocean.
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