The routine drops of gas spilled when people fill up at service stations can add up to environmental trouble, according to a new study published by researchers with the Johns Hopkins Bloomberg School of Public Health. The study developed a mathematical model and conducted experiments suggesting these small spills may cumulatively be a larger issue for soil and groundwater than previously thought. “Gas station owners have worked very hard to prevent gasoline from leaking out of underground storage tanks,” study leader Markus Hilpert, Ph.D., a senior scientist in the Department of Environmental Health Sciences, said in a news release. “But our research shows we should also be paying attention to the small spills that routinely occur.” Hilpert said pads underneath the pumps can accumulate significant amounts of gasoline, which can eventually penetrate the concrete — which is not impervious — and escape into underlying soil and groundwater, potentially impacting the health of those who use wells as a water source. Conservatively, the researchers estimate, roughly 1,500 liters of gasoline are spilled at a typical gas station each decade.