Think smoking only a few cigarettes a day is not as dangerous as more frequent smoking? Think again. In a study published in Tobacco Control, researchers analyzed health data and smoking habits from 43,000 men and women in Norway over 30 years and found that light smoking (i.e., fewer than five cigarettes per day) significantly affects health in later life. Men who reported smoking one to four cigarettes daily tripled their risk of dying from lung cancer compared with nonsmokers. Women with the same habit had a risk of cancer five times greater than nonsmokers. Light smoking also tripled the risk of dying from heart disease in both groups. The authors point out that five cigarettes a day is not an appropriate threshold for safe use. (Tob Control, October 2005)

Do professional football players need to worry about their neurologic health after retirement? According to a study published in Neurosurgery, repeated concussions from blows to the head received during play increase the chance of developing certain dementias later in life. Retired players who reported having three or more concussions in their career (24 percent) had a fivefold greater chance of mild cognitive impairment and were three times more likely to report significant memory problems later in life than players without a history of concussion. Of the players who had at least one concussion, 17.6 percent noticed a permanent effect on their memory and thinking skills as they aged. The authors also found that professional football players had a 37 percent higher risk of Alzheimer’s disease than other men of the same age. (Neurosurgery, October 2005)

Having a twin may decrease your IQ, according to a study published in the British Medical Journal. Researchers studied data from more than 10,000 children born in Scotland between 1950 and 1956 and found that twins had lower IQ scores at seven and nine years of age than did their singleton relatives. At seven years of age, twins had a mean IQ that was 5.3 points lower than that of their singleton siblings; two years later the difference increased to 6.0 points. Twins are more likely to be born earlier in the gestational cycle and have lower birth weights than singleton babies, which contributes to the lower childhood IQ scores researchers say. (BMJ December 3, 2005)

Fruits and vegetables cause more food-related illnesses in the United States than meat or eggs. A report by the Center for Science in the Public Interest says that produce-related salmonella outbreaks sicken more people than outbreaks related to poultry. Bacteria such as salmonella and Escherichia coli infect animal and human manure, which in some countries is used as plant fertilizer. From 2002 to 2003, fruits and vegetables triggered 31 outbreaks of foodborne illness, whereas poultry caused 29 outbreaks. Produce, mostly tomatoes and sprouts, accounted for 20 percent of all outbreaks from 1990 to 2003. Because bacteria can adhere to the skin of produce, consumers should always rinse fruits and vegetables under running water. (CSPI, November 21, 2005)

Will toothbrushes soon be replaced by chewing gum? For soldiers in combat, they could be, according to a report by CNN. Soldiers in the field often lack the time and means to brush and floss on a daily basis, and the stress of combat can encourage bacteria to grow in the mouth. Researchers at the University of Kentucky are working on a prototype of a chewing gum that contains a special agent to fight bacteria and prevent plaque, cavities, and gum disease; soldiers can chew the gum instead of brushing their teeth. If the U.S. Army chooses to pursue the idea, the gum should be available within four years. (CNN. com, November 11, 2005)

According to a study published in the Journal of Urology, men with infertility are 20 times more likely to have testicular cancer compared with the general population. Researchers studied the charts of more than 3,800 men who presented with infertility and abnormal semen analysis during a 10-year period and found that 10 of the men had been diagnosed with testicular tumors. The control population, matched for age and race, had 10.6 cases of cancer per 100,000 men. When the groups were compared, the incidence ratio for the infertile group was 22.9. Researchers hope the study results could lead to earlier detection of testicular cancer. (J Urol, November 2005)