Leaching is the removal of sap after harvest. In many areas of the world, the sap levels in harvested bamboo are reduced either through leaching or postharvest photosynthesis. For example: Cut bamboo is raised clear of the ground and leaned against the rest of the clump for one to two weeks until leaves turn yellow to allow full consumption of sugars by the plant. A similar method is undertaken, but with the base of the culm standing in fresh water, either in a large drum or stream to leach out sap. Cut culms are immersed in a running stream and weighted down for three to four weeks. Water is pumped through the freshly cut culms, forcing out the sap (this method is often used in conjunction with the injection of some form of treatment). In the process of water leaching, the bamboo is dried slowly and evenly in the shade to avoid cracking in the outer skin of the bamboo, thereby reducing opportunities for pest infestation. Durability of bamboo in construction is directly related to how well it is handled from the moment of planting through harvesting, transportation, storage, design, construction, and maintenance. Bamboo harvested at the correct time of year and then exposed to ground contact or rain will break down just as quickly as incorrectly harvested material. Toxicity Gardeners working with bamboo plants have occasionally reported allergic reactions varying from no effects during previous exposures, to immediate itchiness and rash developing into red welts after several hours where the skin had been in contact with the plant (contact allergy), and in some cases into swollen eyelids and breathing difficulties (dyspnoea). A skin prick test using bamboo extract was positive for the immunoglobulin E (IgE) in an available case study. The shoots (newly emerged culms) of bamboo contain the toxin taxiphyllin (a cyanogenic glycoside), which produces cyanide in the gut. Uses Culinary The shoots of most species are edible either raw or cooked, with the tough sheath removed. Cooking removes the slight bitterness. The shoots are used in numerous Asian dishes and broths, and are available in supermarkets in various sliced forms, in both fresh and canned versions. The bamboo shoot in its fermented state forms an important ingredient in cuisines across the Himalayas. In Assam, India, for example, it is called khorisa. In Nepal, a delicacy popular across ethnic boundaries consists of bamboo shoots fermented with turmeric and