A Lawrence Berkeley National Laboratory researcher falsified data that had been considered crucial evidence of a link between electromagnetic fields from power lines and cancer in humans, according to a federal investigation. Robert P. Liburdy agreed to have scientific journals that published his studies in 1992 retract some of his data, but he denies any wrongdoing and claims that the overall conclusions of the articles he wrote remain valid. Debate has raged for some 20 years over whether electric power lines cause cancer, particularly childhood leukemia; this incident seems to strengthen the case that the lines are safe.