NEWS OF THE W EEK
RAIL SAFETY PLAN PROPOSED TRANSPORTATION: Tougher, more resilient hazmat tank cars required
S
HIPPERS OF extremely hazardous chemicals, such as chlorine and anhydrous ammonia, will have to replace their existing fleet of rail tank cars with a new generation of more impact-resistant cars, according to a newly proposed federal plan to improve freight rail safety. The rule, proposed on April 1 by the Department of Transportation’s Federal Railroad Administration (FRA), will require tank cars that carry commodities posing poison inhalation hazards be constructed to resist puncture at speeds of 25 mph for side impacts and 30 mph for head-on collisions— more than double the puncture resistance speeds for existing tank cars. The performance-based standard will increase by 500% on average the amount of energy the tank cars are designed to absorb during an accident without penetration or rupture, according to FRA. UNION TANK CA R CO.
Federal government wants stronger tank cars for hazmat cargo.
SCIENCE © 2008
ANTIBIOTICS FOR A MEAL
This Achromobacter species can subsist on the blockbuster levofloxacin.
BIOCHEMISTRY: Hundreds of soil
bacteria thrive on antibiotics as their sole carbon source
F
LAME RETARDANTS, PCBs, and crude oil are all tasty snacks for certain bacteria, so why not antibiotics? New research shows that hundreds of bacteria found in a variety of U.S. soil samples can survive with only antibiotics as their carbon source. Eighteen synthetic and natural-product-based antibiotics, such as ciprofloxacin, penicillin, vancomycin, and levofloxacin, were tested as proxies for a square meal among soil bacteria (Science 2008, 320, 100). Some 600 types of bacteria have the metabolic machinery to subsist on a single type of antibiotic, says one of the researchers, Gautam Dantas, a postdoc in geneticist George Church’s laboratory at Harvard Medical School. Although the bacteria with a penchant for antibiotics are not necessarily human pathogens, many are closely related to bugs that do infect us. WWW.C E N- ONLI NE .ORG
12
“When the opportunity to make major advances in safety is within our reach, we should not settle for incremental measures,” FRA Administrator Joseph H. Boardman says. Under the proposed rule, half of each shipper’s fleet will have to meet the stricter standards within five years and all 15,300 tanks cars currently used to transport highly toxic chemicals will be replaced within eight years. The government estimates it will cost hazmat shippers a total of $350 million to make their tank cars more secure. The proposed rule also sets a speed limit of 50 mph for any train transporting poisonous materials. American Chemistry Council President Jack N. Gerard says his group’s 134-member companies are willing to invest in upgraded tank cars because “a commitment to safety is good business.” “We are pleased that DOT continues to take a holistic view of rail safety, focusing on both the design of tank cars and the operating conditions under which they travel,” Gerard says. The Association of American Railroads, which represents the freight rail industry, says it hopes the government’s action will be “a step forward in our quest to further improve the safety of cars carrying these extremely dangerous materials that railroads are forced to carry under federal law.” After a public comment period on the proposal ends on June 2, FRA will incorporate any revisions it believes are warranted and then issue a final rule later in the year. —GLENN HESS
“This is highly significant work,” comments Gerard D. Wright, a biochemist at McMaster University, in Hamilton, Ontario. “These organisms may not be pathogens themselves, but they could be sources of antibiotic resistance genes that could find their way into real pathogens through gene transfer.” The antibiotic-consuming bacteria were identified by placing soil samples in liquid media that contained only antibiotics as a carbon source and then isolating the surviving microbes. Bacteria are notably difficult to culture outside their niche; less than 1% of bacteria will grow in a lab. So the hundreds of types of antibiotic-munching bacteria cultured by the researchers are likely an underestimation of the total numbers of the kinds of bacteria that can subsist on antibiotics in the environment, Dantas notes. Stuart Levy, a medical microbiologist at Tufts University, finds the research “excellent” but interprets its results differently. “I think it’s great that bacteria can eat up antibiotics in the environment,” he says. By acting as bioremediators, these bacteria could mitigate the buildup of antibiotics in the environment, thereby reducing the overall selection pressure for the development of bacterial drug resistance, he says. “It would be great to harness their potential.” —SARAH EVERTS
AP RI L 7, 20 0 8
