No comprehensive study has been done of the health implications of fracking, the method used to extract pockets of natural gas deep within the earth. Fracking uses fresh water under pressure, which releases a toxic flowback to the surface. Michelle Bamberger, a veterinarian, and Robert Oswald, a Cornell biochemist, have done a study of livestock, wildlife and people in the gaslands of Pennsylvania. They found that cattle exposed to fracking fluid have a high rate of stillbirths, cleft palates, contaminated milk and death. Cats and dogs have seizures, stillbirths, fur loss and vomiting. Humans experience headaches, rashes, nosebleeds and vomiting. In separate research, high levels of benzene were found in western Colorado communities close to fracking operations. In humans, benzene causes leukemia, birth defects and breast cancer (Orion, September/October).