SAN FRANCISCO (AP) — Some of the chemicals used in California’s fracking boom likely pose a risk to public health, and the state for years has failed to track and deal with those potential threats, a state-commissioned study concluded Thursday.The fracking study, required by state lawmakers and carried out by the California Council on Science and Technology and the Lawrence Berkeley National Laboratory, urged greater oversight of hydraulic fracturing and other intensive oil field production methods.“We found practices that we do not think are inherently safe that we think should be made safer,” Jane Long, an author of the study and researcher at Lawrence Livermore National Laboratory, told reporters.“Although air and water quality studies suggest public health hazards exist, many data gaps remain,” the report concluded.Public-health science nationwide and in California in particular is “playing catch up” with the surge in fracking and other intensive oil field production, the study added.Hydraulic fracturing injects chemicals and liquids at high pressure to force oil and gas out of underground formations. California is the country’s third-largest oil-and-gas-producing state. Fracking accounted for one-fifth of the state’s petroleum production in the last decade, and for roughly half of the 300 wells installed monthly in the same period.All but 5 percent of all fracking in the state occurs in central California’s San Joaquin Valley.