Oh, the good old days of 1993. That was the year that our family got its first computer with a color screen and a CD-ROM. The internet was still years away for us. Imagine what other developments science and technology have given us since then. And yet, the US is still using rules developed in 1993 to govern sludge that is applied to farmland where food is grown. Small wonder that scientists found that those rules are outdated. In fact, they were outdated long before now. The National Research Council said they were already outdated by 2002. But what does industry say? Roughly: "Nothing to see here. Move along." No, these are definitely not the droids you're looking for.
But when their analyses included noroviruses, the yearly risk for infection via inhalation rose dramatically, to at least 1 in 1,000. Noroviruses cause more than half of all foodborne gastroenteritis outbreaks in the U.S., according to the Centers for Disease Control and Prevention.
This result, says Peccia, shows that the biosolids treatments that eliminate enteroviruses or Salmonella, or reduce them to levels the government deems acceptable, can leave behind potentially harmful levels of emerging pathogens. Unfortunately, very few epidemiological studies have looked at ties between infections and biosolids, Peccia says. As a result, he and his colleagues don't make firm recommendations on how to lower the risks. Still, Peccia says that a logical response from EPA would be to mandate that sewage sludge processors use the best available treatments, which heat sludge to effectively pasteurize it, and reduce the levels of pathogens like norovirus, he says.
This study demonstrates that testing for pathogens is "behind the times," says Michael Hansen, senior scientist with the nonprofit Consumers Union. EPA's ignoring emerging pathogens could result in underestimating risk by orders of magnitude, he says. However, Hansen worries even more about sewage sludge's potential for harboring toxic industrial chemicals like flame retardants, as well as pharmaceuticals excreted from the body, such as birth control drugs and antibiotics. These substances may cause illness if they are absorbed by crops and enter the food supply, he says, but none are being tested for or removed from sludge. [emphasis mine]
As for the lack of data on sludge and disease? The 2002 report from the National Research Council said the same thing. Let's hope the Obama EPA takes this more seriously than the Bush EPA did. |
