Document 9JdZkYEvNR3zNVQMdmQ0gZXye

CREDIT: MICHAEL S. YAMASHITA/CORBIS Downloaded from www.sciencemag.org on November 3, 2008 TOXICOLOGY Factory Study Shows Low Levels of Benzene Reduce Blood Cell Counts There's no doubt that benzene, a widely used than did unexposed workers. But this also industrial chemical, can be harmful. Workers held true for the 109 workers exposed to less highly exposed to benzene fumes, for exam- than 1 ppm benzene, even after controlling ple, run an increased risk of leukemia and for smoking and other potential confounding bone-marrow toxicity. But the risk from factors. These workers had on average 15% to smaller exposures is unclear. Now a tightly 18% fewer granulocytes and B cells than did controlled study in Chinese factories, reported unexposed workers--raising concerns about on page 1774, provides reason for concern: bone-marrow health, says Qing Lan of NCI. Workers who inhaled less than 1 part per mil- Luoping Zhang of the University of Cali- lion (ppm) of benzene--an exposure consid- fornia, Berkeley, and others in the research ered safe under U.S. occupational guide- team also studied the effect of benzene on the lines--had fewer white blood cells than did unex- posed workers. Although the workers weren't sick, the results hint that low doses of benzene may alter the bone marrow and could lead to health problems, some experts say. The study also provides the first direct evidence in humans that benzene harms the progenitor cells that give rise to blood cells. "It really breaks new ground Hazard? A study of shoe workers in China suggests that even low on the potential effects of doses of benzene affect blood cells. low levels," says toxicolo- gist Bernard Goldstein of the University of progenitor cells that give rise to blood cells. Pittsburgh's School of Public Health. They found that the ability of progenitor cells Benzene is ubiquitous. People are com- to grow and multiply declined with higher ex- monly exposed to it from secondhand ciga- posures. "The key point is that high levels of rette smoke, gasoline vapors, and air pollu- benzene had a more toxic effect on the pro- tion, although typically only on the order of genitor cells than on mature cells," says study parts per billion. Studies of the chemical's co-author Nathaniel Rothman of NCI. "That health effects in industrial settings, where may suggest we're underestimating the effects benzene is used as a solvent and in chemical of benzene by just studying mature cells." manufacturing, led the United States in 1987 But Richard Irons of the University of to regulate the maximum allowable work- Colorado Health Sciences Center in Denver place exposure at 1 ppm of benzene aver- and Fudan University in Shanghai suggests aged over 8 hours. that counting progenitor cells from blood To determine whether blood cells are samples probably does not accurately reflect affected at even smaller exposures, a group of what's happening to such cells in bone mar- researchers from the U.S. National Cancer row. Irons, who leads a $20 million indus- Institute (NCI) in Bethesda, Maryland, the try-funded study of benzene effects in Chinese Center for Disease Control and Pre- Shanghai, also says it's possible that the low- vention in Beijing, the University of Califor- dose changes seen in the Science paper stem nia, Berkeley, and other institutions compared from exposure to other chemicals or factors 250 workers exposed to benzene-laden glues such as nutrition. "Because the magnitude of in two shoe factories in China to 140 unex- the changes are so small, it becomes diffi- posed workers who sew clothes in other Chi- cult to discriminate between transient effects nese factories. The researchers carefully and benzene toxicity," he says. gauged benzene exposure by taking urine Still, the findings may lead to demands samples and testing air in the factories, as well for lowering the benzene exposure stan- as at each worker's home. After 16 months, dard, says geneticist Gilbert Omenn of the they took blood samples from the workers. University of Michigan Medical School in As expected, workers exposed to benzene Ann Arbor: "This paper should cause a stir at levels of 1 ppm and higher had fewer white in occupational and environmental health blood cells, such as granulocytes and B cells, circles." ERIK STOKSTAD www.sciencemag.org SCIENCE VOL 306 3 DECEMBER 2004 Published by AAAS ScienceScope No Meeting of Minds on NIH Honoraria Ban Intramural scientists at the National Insti- tutes of Health (NIH) remain upset about a proposed ban on university honoraria after meeting this week with NIH Director Elias Zerhouni."This meeting did not really explain what the rules are," says Alexander Wlodawer, a cancer institute lab chief. Zerhouni and his deputy Raynard King- ton held a closed-door meeting with lab chiefs and many institute directors after more than 170 senior scientists endorsed a letter protesting a proposed ban on hono- raria from institutions receiving NIH grants (Science, 19 November, p. 1276). Participants said that NIH has yet to clarify its policies on matters such as teaching and whether speaking, even on official duty, could pose a conflict. But some were encouraged by Zer- houni's promise to carve out "exceptions" for some activities, such as bona fide awards, and to set up a "mechanism" for collecting staff input. JOCELYN KAISER Salmon Plan Raises Hackles PORTLAND, OREGON--The Bush Administra- tion's plan to protect salmon on the Colum- bia and Snake rivers is a "step backwards," according to 250 fisheries scientists who have signed a last-ditch petition seeking changes in the court-ordered plan.A draft of that docu- ment became final on 30 November. An earlier plan was dismissed by Federal District Judge James Redden, who will also review the new plan, for relying on ques- tionable recovery actions. Critics say the current version sidesteps the problem by reinterpreting provisions of the Endangered Species Act, arguing that fisheries managers need only ensure the survival of species rather than their recovery."The new analysis is an alarming sea change in approach with no supporting scientific justification," the petition concludes. ROBERT SERVICE Swiss Endorse Stem Cell Law BASEL--In the first-ever national referen- dum on the issue, Swiss voters have over- whelmingly approved the use of human stem cells for research. On 28 November, two out of three voters endorsed a law passed last December that allows scientists to use stem cells harvested from embryos no older than 7 days.The law bans thera- peutic cloning and research on the embryos themselves and requires several layers of approval, including the consent of the donors."This is incredibly encouraging for us," says Patrick Aebischer, president of the Swiss Federal Institute of Technology in Lausanne. GISELLE WEISS 1665