Sewage sludge is a great fertilizer for your garden. But does it also pollute your soil? A 25-member research team dug into the question -- especially the potential for sludges to introduce toxic metals into soil. Their finding: Some sludges can cause long-lasting soil contamination.
The key problem metal is cadmium.
The team, organized by the Council for Agricultural Science and Technology, reports: "Once applied to soil, the cadmium remains in place, doesn't leach downward appreciably, and may increase the cadmium content of crops for years."
Many sludges have little metal contamination and provide safe soil enrichment. But the study does show that care should be exercised both in selection of the sludge and in its use.m