In this video segment adapted from 'Need to Know,' learn about health concerns regarding exposure to chemicals used in natural gas drilling. An animation shows how the process of hydraulic fracturing-fracking-is used to extract natural gas. A reporter explains how the process may be polluting water resources with hazardous chemicals. Hear about health problems among people whose only common connection is proximity to gas drilling sites. In addition, learn about the challenges of investigating the possible link between the contaminants and illness because the gas industry is not required to disclose which chemicals they use in fracking fluids. [5:44]