Virus combats deadliest cancers A common, otherwise harmless human virus not only kills virulent drug and radiation-resistant breast cancer cells but stimulates the body's anti-cancer immune system, say Canadian researchers who are now trying to devise 'a powerful virus-based anti-cancer therapy'. The reovirus is known to be effective against regular cancer cells, but the Dalhousie Medical School team has shown that it also kills the stem cells that continuously produce new cancer cells. The team tested the reovirus on fresh cancer tissue from a patient rather than cells developed for laboratory use, according to healthday.com. Pollution linked to low birth weight Regular exposure to air pollution, particularly traffic fumes, during pregnancy appears to be associated with lower birth weight, say US researchers, based on studies of almost 336,000 babies over four years matched with air-quality records. However, team leader David Rich, of the University of Medicine and Dentistry of New Jersey, says the results don't prove that pollution directly affects fetal growth. Further studies are planned, WebMD reports. Marijuana, cigarette combo risky Smokers who also use marijuana may be at high risk of a group of lung diseases, including emphysema and chronic bronchitis, say Canadian researchers, based on a study of more than 875 people aged 40 and over. However, there didn't appear to be any strong link between smoking only marijuana and higher risk of these diseases. Team leader Wan Tan, of the University of British Columbia, says the two may act 'synergistically' to heighten the risk, with marijuana smoke possibly sensitising the airways and making them more vulnerable to the ill effects of tobacco, Reuters reports. Multivitamins don't live up to claims Almost a third of the multivitamins tested by a US consumer group contained significantly more or less of what they claimed or were contaminated with lead. Several products, including three for children, exceeded the generally accepted upper limits for the likes of folic acid, niacin and zinc. Of five general multivitamins tested, two were short on ingredients: one had only half the folic acid claimed; the other had only 70 per cent of the calcium, Reuters reports. Full results are available at consumerlab.com Job promotion takes toll on health Getting a promotion at work can not only be bad for your health but leave you with less time to see a doctor, say British researchers, based on studies of about 1,000 people promoted between 1991 and 2005. The team wanted to test whether improved job status was associated with better health, AFP reports. Instead, they found 'the mental health of managers typically deteriorates after promotion - in a way that goes beyond short-term change', says researcher Chris Boyce, of the University of Warwick. The study concluded that promotion produces 10 per cent more mental strain, but leaves you with 20 per cent less time to visit the doctor. Negative workplace ups depression Even without being promoted, a bad work environment can significantly increase the risk of being depressed, say Finnish researchers, based on a three-year study of more than 3,300 workers. Those who felt team spirit was poor, for example, were 61 per cent more likely to have a depressive disorder than those who felt team spirit was good, and 53 per cent more likely to have used antidepressants. However, the team from the Finnish Institute of Occupational Health found no link between a bad workplace and alcohol abuse, WebMD reports.