The herb birthwort (Aristolochia), also called pipevines or Dutchman's pipes, contains a substance known as aristolochic acid which, the NIH's National Toxicology Program tells us, is a potent human carcinogen. It causes kidney disease, kidney failure, and urinary tract cancer.1
Aristolochia is now thought to be responsible for "Balkan endemic nephropathy" or BEN, and "Chinese herbs nephropathy" or CHN.2 (Nephropathy is kidney disease.)
In BEN, farmers along tributaries of the Danube were unknowingly grinding birthwort seeds along with wheat and making bread. Their exposure was low-dose but chronic. They were slowly poisoning themselves. In CHN, young women in Belgium who attended a "slimming" clinic received acute doses of Aristolochia in the Chinese herbs they took as therapy.
It looks like the epidemic of urinary tract cancer in Taiwan (the highest incidence of this cancer anywhere in the world) can also be blamed on aristolochic acid.3 (Nearly "1 in 3 patients are prescribed Aristolochia as part of traditional medical treatments delivered at doctor's offices.")
In 2001 the FDA issued an alert:
Aristolochic Acid: FDA Warns Consumers to Discontinue Use of Botanical Products that Contain Aristolochic Acid
In 2003, despite FDA warnings, aristolochic acid was found in 19 products and suspected to be present in an additional 95 products:
Aristolochic Acid, an Herbal Carcinogen, Sold on the Web after FDA Alert, New England Journal of Medicine, 2003
Arthur Grollman, one of the researchers in the PNAS study3, and lead author of a prior study that tied aristolochic acid to the Balkan tragedy said:
"An important message for Americans is that Congress is inviting similar problems in our country by not holding dietary supplements — which includes herbs — to reasonable standards of safety and efficacy. ... We simply don't know whether other herbal supplements like Aristolochia are being marketed right now."
Herbal 'Remedy' May Trigger Widespread Kidney Failure, USAToday, 8 April 2012
2Chinese Herbs Nephropathy And Balkan Endemic Nephropathy: Toward A Single Entity, Aristolochic Acid Nephropathy, Kidney International, April 2012
3Aristolochic Acid-Associated Urothelial Cancer In Taiwan, Proceedings of the National Academy of Sciences, April 2012
Photo of Aristolochia elegans/Dutchman's Pipevine from OnlinePlantGuide