But, according to a series of studies published last week, regulations haven't kept up with the changes to this industry.

There are many problems associated with large concentrated feed lots, but the most serious is the volume of manure generated by all these animals.

Animals produce a lot of waste. Some of the bigger feedlots produce as much waste as a good-sized city.

But there are no sewage processing plants at these factory farms. Instead, waste is usually dumped into lagoons -- huge, stinking pits that do a poor job of containing the many contaminants found in manure.

According to a report published in Enivronmental Health Perspectives, an online scientific journal, "Generally accepted livestock waste management practices do not adequately or effectively protect water resources from contamination with excessive nutrients, microbial pathogens and pharmaceuticals present in the waste."

Source: Roanoke