<P> It is estimated that of the roughly 150,000 people who die each day across the globe, about two thirds--100,000 per day--die of age - related causes because they have aged . In industrialized nations the proportion is much higher, reaching 90 percent . Thus, albeit indirectly, biological aging (senescence) is by far the leading cause of death . Whether senescence as a biological process itself can be slowed down, halted, or even reversed is a subject of current scientific speculation and research . </P> <P> Leading causes of preventable death worldwide as of the year 2001, according to researchers working with the Disease Control Priorities Network (DCPN) and the World Health Organization (WHO). (The WHO's 2008 statistics show very similar trends .) </P> <Table> <Tr> <Th> Cause </Th> <Th> Number of deaths resulting (millions per year) </Th> </Tr> <Tr> <Td> Hypertension </Td> <Td> 7.8 </Td> </Tr> <Tr> <Td> Smoking tobacco </Td> <Td> 5.4 </Td> </Tr> <Tr> <Td> Malnutrition </Td> <Td> 3.8 </Td> </Tr> <Tr> <Td> Sexually transmitted diseases </Td> <Td> 3.0 </Td> </Tr> <Tr> <Td> Poor diet </Td> <Td> 2.8 </Td> </Tr> <Tr> <Td> Overweight and obesity </Td> <Td> 2.5 </Td> </Tr> <Tr> <Td> Physical inactivity </Td> <Td> 2.0 </Td> </Tr> <Tr> <Td> Alcohol </Td> <Td> 1.9 </Td> </Tr> <Tr> <Td> Indoor air pollution from solid fuels </Td> <Td> 1.8 </Td> </Tr> <Tr> <Td> Unsafe water and poor sanitation </Td> <Td> 1.6 </Td> </Tr> </Table> <Tr> <Th> Cause </Th> <Th> Number of deaths resulting (millions per year) </Th> </Tr>

What is the second leading cause of preventable deaths in the united states