however, ranked last with a 3% increase in birth rates for teenagers. A study by West Virginia's Marshall University showed that 19% of babies born in the state have evidence of drug or alcohol exposure. This is several times the national rate, where studies show that about 5.9% of pregnant women in the U.S. use illicit drugs, and about 8.5% consume any alcohol. An Institute for Health Policy Research study determined that mortality rates in Appalachia are correlated with coal production. In twenty West Virginia coal counties mining more than a million tons of coal per year and having a total population of 850,000, there are about 10,100 deaths per year, with 1,400 of those statistically attributed to deaths from heart, respiratory and kidney disease from living in an Appalachian coal county. In 2015, McDowell County had the highest rate of drug-induced deaths of any county in the United States, with a rate of 141 deaths per 100,000 people. Four of the five counties with the highest rates of drug-induced deaths are in West Virginia (McDowell, Wyoming, Cabell and Raleigh Counties). American environmental attorney Robert Bilott exposed how DuPont had been knowingly polluting water with perfluorooctanoic acid (PFOA) in Parkersburg, West Virginia, since the 1980s. This battle with DuPont is depicted in the film Dark Waters. Life expectancy The residents of West Virginia have a lower life expectancy than the national average. In 2014 life expectancy for both sexes in the state was 76.0 years compared to 79.1 years for the United States as a whole. In 2014, males in West Virginia lived an average of 73.6 years compared to a national average of 76.7 years and females lived an average of 77.5 years compared to a national average of 81.5 years. Male life expectancy in West Virginia between 1980 and 2014 increased by 4.7 years, compared to a national average of a 6.7-year increase. Life expectancy for females in West Virginia between 1980 and 2014 increased by 1.7 years, compared to a national average of a 4.0-year increase. Life expectancy for both sexes is among the lowest of all states. Life expectancies in 2014 for both sexes in West Virginia counties ranged from a low of 70.3 years in McDowell County to a high of 79.3 years in Pendleton County. McDowell and several other West Virginia counties are among the counties in the U.S. with the lowest life expectancies.