What San Francisco Found in Their Sludge

San Francisco has done tests of their own sewage sludge -- one ingredient in the compound that is given out to gardeners as "compost."

San Francisco's tests looked for heavy metals, PCBs, dioxins, volatile and semivolatile organic compounds, and pesticides. They didn't look for pharmaceuticals, steroids, hormones, or anything living, such as bacteria or parasites.
 
Some of the chemicals found include:

  • 1,2-Dibromo-3-Chloropropane, used as a soil fumigant until it was banned in 1979 for everything except Hawaiian pineapples. The maximum amount allowed in drinking water is 2 parts per billion. In 2009 tests, it was present in the sludge from San Francisco's Oceanside facility at 89 ppb.
  • Bis(2-ethylhexyl) phthalate is used as a plasticizer for PVC plastic. The safe amount set by the EPA is zero, and the maximum amount allowed in drinking water is 6 ppb. This was found in sludge from San Francisco's Southeast facility at 370 ppb.
  • 4-Isopropyltoluene is not regulated in California, but it is in Maine. The limit in Maine is 70 ppb. It  showed up in San Francisco's sludge at 540 ppb for the sample taken at the Southeast facility and at 420 ppb for the sample taken at the Oceanside facility.
  • Other hazardous chemicals, such as dioxins and furans, at dangerous levels.