Virtual water. Virtual water trade (also known as trade in embedded or embodied water) refers to the hidden flow of water if food or other commodities are traded from one place to another. For instance, it takes 1,340 cubic meters of water (based on the world average) to produce one metric tonne of wheat.
At the same time, researchers also say poor understanding of truly dangerous spider bites delays treatment when a person really has been bitten by a dangerous spider. For example, the bite of the brown recluse spider can cause death of a sizeable area of skin (skin necrosis) resulting in a deep, scarring ulcer. Yet even in areas infested with brown recluse spiders, true bites are uncommon. The analysis is published in the July 14 online issue of The Lancet.
However, some spiders produce toxic venoms that can cause skin lesions, systemic illnesses, and neurotoxicity. One of the more common bites is inflicted by the widow spiders (Latrodectus species). A bite from a widow spider results in muscle spasms and rigidity starting at the bite site within 30 minutes to two hours. Another common bite is inflicted by the recluse spider (Loxosceles species). Most bites from these spiders occur early in the morning and are initially painless. These bites usually progress to ulcerating dermonecrosis at the bite site. Spider bites can be prevented by simple measures.