Environmental News Service
* * *Sewage Sludge Linked to Illnesses
ATHENS, Georgia, August 2, 2002 (ENS) - A study by researchers at the University of Georgia (UGA) links the use of sewage sludge as fertilizer with a host of health problems. Burning eyes, burning lungs, skin rashes and other symptoms of illness were found in the study of residents living near land fertilized with Class B biosolids, a byproduct of the human waste treatment process. Researchers found that affected residents lived within about one kilometer (0.6 miles) of land application sites and complained of irritation after exposure to winds blowing from treated fields.
Staphylococcus aureus infections, a condition causing symptoms like diaper rash, were found in the skin and respiratory tracts of some individuals. About 25 percent of the individuals surveyed were infected, and two died.
The 54 individuals surveyed lived near 10 land application sites in Alabama, California, Florida, New Hampshire, Ohio, Ontario, Pennsylvania and Texas. S. aureus is commonly found in the lower human colon and tends to invade irritated or inflamed tissue.
"The EPA did not consider S. aureus to be a significant public health risk even though it is a leading cause of hospital acquired infections and is commonly found in sewage," said David Lewis, a UGA research microbiologist also affiliated with the U.S. Environmental Protection Agency's (EPA) National Exposure Research Laboratory. "When approving sludge for use as a fertilizer, EPA looked at chemical and pathogen risks separately without considering that certain chemicals could increase the risk of infection."
Chemicals such as lime, which is added during sludge processing, can irritate the skin and respiratory tract and make people more susceptible to infection, Lewis explained.
Though modern treatment can eliminate more than 95 percent of the pathogens, enough remain in the concentrated Class B sludge leaving treatment plants to pose a health risk, Lewis said. In 1989, an EPA study found 25 groups of pathogens in sludge, including bacteria such as E. coli and salmonella, viruses, including hepatitis A, intestinal worms, harmful protozoa, and fungus.
Sludge also includes traces of household chemicals poured down drains, detergents from washing machines, heavy metals from industry, synthetic hormones from birth control pills, pesticides, and dioxins, a group of compounds that have been linked to cancer.
On July 2, the National Research Council of the National Academy of Sciences (NAS) concluded that there may be public health risks from using processed sewage sludge as a commercial fertilizer. About 60 percent of an estimated 5.6 million tons of dry sludge is used or disposed of each year in the United States.
"Most people are not aware this is going on in the U.S.," said Gattie. "Most people don't realize that a concentrated sludge of waste products is being processed into a cheap commercial fertilizer and applied to fields near our homes. 'Biosolids' does not connote 'sewage' to most people."
The study is the first linking adverse health effects in humans to the land application of Class B biosolids to be published in a medical journal. The article appeared in the July 2002 issue of a British medical journal, "BMC Public Health."
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