The risk of developing coronary heart disease is 25 percent higher for women smokers compared with men, according to a study published in the British medical journal \"The Lancet\". The authors say this could be due to the physiological differences between the sexes with cigarette smoke toxins having a more potent effect on women. The study by Dr Rachel R Huxley from the University of Minnesota and Dr Mark Woodward from Johns Hopkins University involved a meta-analysis of around four million individuals and 67,000 coronary heart disease events from 86 studies. The researchers found that the pooled adjusted female-to-male relative risk ratio (RRR) of smoking compared with not smoking for coronary heart disease (CHD) was 1.25 (25 percent) higher for women. This RRR increased by 2 percent for every additional year of follow-up, meaning that the longer a woman smokes, the higher her risk of developing CHD becomes compared with a man who has smoked the same length of time. The authors say, \"The finding lends support to the idea of a pathophysiological basis for the sex difference. For example, women might extract a greater quantity of carcinogens and other toxic agents from the same number of cigarettes than men. This occurrence could explain why women who smoke have double the risk of lung cancer compared with their male counterparts.\" Worldwide, there are 1.1 billion smokers, of whom a fifth are women. According to the Tobacco Atlas, India, with around a crore female smokers, ranks third in the top 20 female smoking populations across the globe, only the U.S. with 2.3 crore female smokers and China with 1.3 crore female smokers, are worse off.