The U.S hog production industry has been continually subjected to rapid structural changes since the early 1990s. The industry's move towards more concentrated large hog farms and geographical concentration of such farms, have triggered public concerns over the dangers such big animal feeding...

Many countries have achieved moderate to dramatic growth during the last few decades, and the world-widely continued economic growth results in increased wealth and deteriorated environment. The relationship between economic growth and environmental quality has received great attention in...