Thanks, just a note - the National Pollutant Inventory or NPI estimates DISCHARGE to air (and other media) but not the concentration that people are actually exposed to.  It is very difficult to estimate health impact from NPI data, but it is useful for helping to monitor sources and volume of pollution to continue to decrease emissions.  To monitor the risk of health impact the pollutant needs to be monitored in ambient air - if there is a plausible pathway and a risk assessment suggests it could achieve a concentration high enough to cause a health impact.