USA Today’s Sloppy Sludge Statistics
The Sept. 30, 2002 edition of USA Today has a long article about the controversies surrounding treated human waste, which is often repackaged and used as fertilizer. Critics of recycling sewage in this way maintain that it is impossible to ensure that all human pathogens are removed, where the Environmental Protection Agency responds that if the sludge is used according to guidelines then it is safe.
One of the major problems seems to be that under EPA guidelines if a farmer uses treated waste on his field, the treated waste is supposed to be left alone for at least one month — plenty of time for the sun to wipe out human pathogens. Actually keeping humans out of contact with the sludge, however, appears to be difficult and the USA Today article includes several anecdotes of people who were sickened, and in some cases died, from diseases that they might have contracted after coming into contact with treated human waste.
But USA Today writer Kathleen Fackelmann also totally flubs statistics from a British Medical Journal study on just how big the risk of contracting staph infection from waste is. According to Fackelmann (emphasis added),
David Lewis, an EPA scientist who says he red flags he raised about sludge led to a job dispute with the EPA, which then assigned him to a post at the University of Georgia in Athens, says he has evidence that exposure to sludge might pose a health hazard. His study published in the July issue of British journal BMC Health suggests that people living near sludge sites run a 25% risk of getting infected with Staphylococcus aureus . . .
Lewis and his colleagues studied 48 people who lived near sludge sites and had symptoms of sludge exposure. The researchers found that one out of four people had developed an S. Auerus infection that required treatment.
But finding that 25 percent of the people near sludge sites who showed “symptoms of sludge exposure” had developed S. aureus is not the same thing as saying that “people living near sludge sites run a 25% risk of getting infected” with S. aureus.
This is a bit like saying that a study of 100 people with measles symptoms in the United States found that 90 percent actually had measles, so the general risk of getting measles in the United States is 90 percent.
Source:
Moving slowly on sludge. Kathleen Fackelmann, USA Today, September 30, 2002.
Tags: Uncategorized