manure stinks for infant health. The manure generated by thousands of
cows or pigs doesn?t just stink ? it may seriously affect human health. Science
New research examining two decades? worth of livestock production data finds a positive relationship between increased production at industrial farms and infant death rates in the counties where the farms reside. The study reported in the February American Journal of Agricultural Economics implicates air pollution and suggests that Clean Air Act regulations need to be revamped to address livestock production of noxious gases.
The study, by economist Stacy Sneeringer of Wellesley College in Massachusetts, examined birth and death records from the National Center for Health Statistics and the increase in ?animal units? per county across the United States from 1982 to 1997. (Animal units are a normalizing unit used by the U.S. Department of Agriculture. One animal unit equals roughly 1,000 pounds of average live weight; or 250 layer chickens (for eggs); or 1.14 fattened cattle; or 2.67 breeding hogs.) An increase of 100,000 animal units in a county corresponded to 123 more infant deaths per year per 100,000 births. Doubling livestock numbers was linked to a 7.4 percent increase in infant mortality.
Ammonia, hydrogen sulfide and airborne particulate matter are all associated with livestock production, Sneeringer says. Exposure to the gases has been linked to respiratory distress in infants, while exposure in the womb has been linked to disorders that occur late in pregnancy or shortly after birth, and has also been linked to spontaneous abortions. Sneeringer found that about 80 percent of the infant deaths associated with increased livestock production occurred in the first 28 days of life.