edge of rights-of-way. Public utility commissions typically do not comment on health impacts. Biological effects have been established for acute high level exposure to magnetic fields above 100 µT (1 G) (1,000 mG). In a residential setting, one study reported "limited evidence of carcinogenicity in humans and less than sufficient evidence for carcinogenicity in experimental animals", in particular, childhood leukemia, associated with average exposure to residential power-frequency magnetic field above 0.3 µT (3 mG) to 0.4 µT (4 mG). These levels exceed average residential power-frequency magnetic fields in homes, which are about 0.07 µT (0.7 mG) in Europe and 0.11 µT (1.1 mG) in North America. The Earth's natural geomagnetic field strength varies over the surface of the planet between 0.035 mT and 0.07 mT (35 µT – 70 µT or 350 mG – 700 mG) while the international standard for continuous exposure is set at 40 mT (400,000 mG or 400 G) for the general public. Tree growth regulators and herbicides may be used in transmission line right of ways, which may have health effects. Policy by country United States The Federal Energy Regulatory Commission (FERC) is the primary regulatory agency of electric power transmission and wholesale electricity sales within the United States. FERC was originally established by Congress in 1920 as the Federal Power Commission and has since undergone multiple name and responsibility modifications. Electric power distribution and the retail sale of power is under state jurisdiction. Order No. 888 Order No. 888 was adopted by FERC on April 24, 1996. It was "designed to remove impediments to competition in the wholesale bulk power marketplace and to bring more efficient, lower cost power to the Nation’s electricity consumers. The legal and policy cornerstone of these rules is to remedy undue discrimination in access to the monopoly owned transmission wires that control whether and to whom electricity can be transported in interstate commerce." The Order required all public utilities that own, control, or operate facilities used for transmitting electric energy in interstate commerce, to have open access, non-discriminatory transmission tariffs. These tariffs allow any electricity generator to utilize existing power lines to transmit the power that they generate. The Order also permits public utilities to recover the costs associated with providing their power lines as an open access service. Energy Policy Act of 2005 The Energy Policy Act of 2005 (EPAct) expanded federal authority to regulate power transmission. EPAct