is harvested annually allowing for 100% harvest in a five-year period. In its natural environment it will need no irrigation, no pesticides, and no fertilizer. Bamboo has few pests so pesticides are not required. Bamboo certified to the standards of the Forest Stewardship Council (FSC) meets criteria for environmental sustainability and social responsibility, and several flooring products are available with this option. Bamboo can sequester up to 70% more carbon per year than a hardwood forest. All these factors keep the carbon footprint low. The United States Green Building Council's LEED program allows points for the use of bamboo floors by virtue of it being a rapidly renewable resource. Since the majority of bamboo timber comes from China, it has to be shipped to the international destinations by boat and then by truck to vendors. A study which compared the embodied energy (including transportation) of bamboo flooring from Hunan Province, China to Denver, Colorado favored locally sourced concrete above bamboo flooring due to the additional carbon costs associated with transport. Controversy exists over agricultural and manufacturing issues related to the production of bamboo floors, including the environmental effects of deforestation in order to plant bamboo and the use of carcinogenic chemicals such as urea-formaldehyde in the glues used for lamination in some products. Bamboo flooring has led to deforestation, as existing trees are cut down to be replaced with bamboo plantations; this results in soil erosion in the often hilly and mountainous areas occupied by forestland, along with a loss of biodiversity in the region as other flora and fauna are cleared for bamboo. Additionally, the use of pesticides, weed killers and fertilizers in bamboo production can have an effect on the environment. During the manufacturing of bamboo floors, some manufacturers use urea-formaldehyde as the adhesive for bonding the bamboo strips. According to the stringent California Air Resources Board (CARB) standards there can be no more than 0.05 ppm (parts per million) of outgassed formaldehyde. According to the USGBC's LEED standard products with Urea-formaldehyde do not qualify for the EQ 4.4 Low-Emitting Products category. Manufacturers are now offering formaldehyde-free bamboo flooring, but they can claim that they have "no added urea-formaldehyde" without providing substantial proof. Manufacturers may make use of equipment that may in itself be dangerous and polluting. Some manufacturers may require their products to be registered under International Organization for Standardization (ISO) standards 9001 for quality control and