This is Steve Ember with the VOA Special English AgricultureReport.
Farmers have long put animal waste on their fields. They may alsouse human waste. Modern ways to process waste and make it safer touse have only been developed since the nineteen-seventies.
Treated waste products are called biosolids, or sludge. Theycontain nitrogen, phosphorus and potassium. Biosolids are removedfrom the wastewater systems of cities and other communities. Theyare treated in several ways to kill organisms that could spreaddisease.
In the United States, the government says sixty-percent of alltreated solid waste is used to fertilize land. This includes somefarmland. But the government says only one-tenth of one-percent ofAmerican farmland uses this kind of fertilizer from year to year.
There are two kinds of biosolids. Class A is considered free ofany organism that could be a danger to health. These organismsinclude viruses, bacteria and worms. Class B biosolids are notcompletely free of such organisms. So their use is restricted.
Another concern about biosolids is that they may contain chemicalpollution. Many kinds of chemicals can enter wastewater systems. Inthe United States, the Environmental Protection Agency has rulesabout the presence of nine chemicals in biosolids. The E-P-Arequires testing for levels of substances like arsenic, chromium,mercury and lead.
After five years of study, the E-P-A recently decided not torequire producers and users of biosolids to add dioxins to thislist. Dioxins are a group of organic chemicals that can stay for along time in the environment. There are concerns about greater riskof cancer and other disorders.
Dioxins are released by burning plastics and fuels like coal, oiland wood. They are also released by some kinds of chemicalmanufacturing. Paper production with the use of chlorine producesdioxins. So does cigarette smoke.
Environmental groups and others condemned the decision not to setrules for dioxins in biosolids. They point out that the use ofsludge products is a leading cause of dioxin in the environment inthe United States.
The E-P-A agrees that dioxins are highly poisonous. But theagency has also found that levels in the environment have beengreatly reduced in the last thirty years. It says there is notenough risk of new cancer cases in farmers and other people tosupport new rules.
This VOA Special English Agriculture Report was written by MarioRitter. This is Steve Ember.