Livestock industry officials and the Bush administration say there's no conclusive proof, but doctors nonetheless are blaming hog farms for health problems suffered by some of their patients, according to The New York Times. The article claims a growing number of scientists and public health officials around the country say they have traced a variety of health problems faced by neighbors of large livestock farms to concentrated animal waste.

  Livestock trade officials and Bush administration regulators say more study is needed before any cause and effect can be proved. But Dr. Kaye H. Kilburn, a professor at the University of Southern California who studies the effects of toxic chemicals on the brain, said evidence strongly supported a link between the farms and the illnesses.

In Iowa, according to the article, state environment officials started conducting air quality tests for hydrogen sulfide and ammonia at six neighborhood locations around hog farms last month.

Brian Button, an air information specialist with the state, said preliminary data showed that 22 times in April, the gases exceeded the state's recommended air standards of 15 parts per billion of hydrogen sulfide and 150 parts per billion of ammonia, averaged over an hour. The highest level recorded for hydrogen sulfide was 70 parts per billion, a level that would have exceeded the air standards for at least six other states.

The New York Times