The first solid evidence that smoking causes cancer came in the 1950s, followed decades later by revelations that “second-hand” smoke also harms health. In mice, at least, exposure to these toxic leftovers causes lower infant weight and alters counts of blood cells associated with the body’s immune system, they reported in the Nature journal Scientific Reports. “Evidence is mounting that the residue lingering on indoor surfaces could be just as harmful — if not more — than second-hand smoke,” said the Lawrence Berkeley National Laboratory, which took part in the study.