Couched in language peppered with mays, the article suggests that we are all being poisoned with PBDEs from sewage sludge applied to farmland. However, sludge with high concentrations of volatile organics isn’t qualified in most jurisdictions of which I am aware for land application. It’s usually sent to a landfill or incinerated. Couches and chair cushions don’t appear in sewage plants, and therefore PBDEs in those objects don’t appear in the plants’ sludge, at least not directly. Such objects go to landfills, and sludge from treatment of leachate from such landfills is never applied to land. Finally, in the United States, sludge is not supposed to be put on land growing crops for human consumption or for consumption by animals consumed by humans. I therefore suspect it to be highly improbable that there’s a direct connection between sludge and the dinner table in the United States.

McClellan G. Blair
Indiana, Pa.

The article appears to have a discrepancy. The text’s description of the structural similarities between the three types of molecules doesn’t agree with the figure of the structures of the molecules of PBDE-100, PCB-153, and thyroxine. The text states that the carbon rings of PBDE are joined by an oxygen atom, while those of PCB and thyroxine are joined by a carbon-carbon bond. In the figure, the rings in thyroxine appear to be joined by an oxygen atom in the same manner as the PBDE-100. Something seems awry.

Edward Brosius
Saline, Mich.

Correct. It’s incorrect. The text should have read: “In PBDEs and thyroid hormones, an atom of oxygen bridges the rings, whereas PCBs are linked by carbon-carbon bonds.” Therefore, says Thomas A. McDonald of California’s Office of Environmental Health Hazard Assessment, PBDEs structurally resemble thyroid hormones even more closely than they resemble PCBs. –The Editors This article presents incomplete information on polybrominated diphenyl ethers (PBDEs). The troubling aspect of this article is its call for reducing or banning the use of these life-saving products. The importance of brominated flame retardants should be pointed out in any article addressing their use because thousands of people are injured or die in fires around the globe each year. In the United States alone, fires kill about 4,000 people annually, with another 20,000 people suffering serious injury from burns and property losses totaling about $4.5 billion.

Courtney M. Price
American Chemistry Council
Arlington, Va.

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