An Examination of National Cancer Risk Based on Monitored Hazardous Air Pollutants

Abstract

Background: Hazardous air pollutants, or air toxics, are pollutants known to cause cancer or other serious health effects. Nationwide cancer risk from these pollutants is estimated by the U.S. EPA National Air Toxics Assessment. However, these model estimates are limited to the totality of the emissions inventory used as inputs, and further, they cannot be used to examine spatial and temporal trends in cancer risk from hazardous air pollutants. Objectives: To complement model estimates of nationwide cancer risk, we examined trends in cancer risk using monitoring data from 2013 to 2017 across the 27 U.S. National Air Toxics Trends Stations. Methods: For each monitoring site, we estimated cancer risk by multiplying the annual concentration for each monitored pollutant by its corresponding unit risk estimate. We examined the 5-y average (2013–2017) cancer risk across sites and the population levels and demographics within 1-mi of the monitors, as well as changes in estimated cancer risk over time. Finally, we examined changes in individual pollutant concentrations and their patterns of covariance. Results: We found that the total estimated cancer risk is higher for urban vs. rural sites, with the risk at seven urban sites (of 21) above 75 in 1 million. Furthermore, while most pollutant concentrations have not changed over the time period explored, we found 38 site-pollutant combinations that significantly declined and 12 that significantly increased between 2013 and 2017. We also identified a positive correlation between estimated cancer risk and percent of the population within 1-mi of a monitor that is low income. Discussion: Long-term trends show that annual mean concentrations of most measured air toxics have declined. Our evaluation of a more recent snapshot in time finds that most pollutant concentrations have not changed from 2013 to 2017. This analysis of cancer risk based on monitored values provides an important complement to modeled nationwide cancer risk estimates and can further inform future approaches to mitigate risk from exposure to hazardous air pollutants. https://doi.org/10.1289/EHP8044

Trends in air toxics cancer risk in Southern California, 1998-2018

“…This comparison found that the measured concentrations of formaldehyde were higher than the NATA estimates in most locations, and the average cancer risks estimated using monitoring-based data were 40% higher than modeled estimates based on the NATA study. For the two Southern California monitors in this study, the measurement-based cancer risks were 104% and 78% higher than the risks estimated based on NATA [7].…”

“…Two recent studies examined U.S. national trends using monitoring data [6,7] or modeling data [6]. Both of these studies focused on HAPs with unit risk estimates established by the U.S. EPA Office of Air Quality and Planning Standards, so the studies do not explicitly provide estimates of diesel PM-related risk, but do report trends and patterns for benzene, 1,3-butadiene, formaldehyde, and other toxics.…”

Tracking Source Variations of Inhalation Cancer Risks and Ozone Formation Potential in Hong Kong over Two Decades (2000–2020) Using Toxic Air Pollutant Monitoring Data

“…Exposure to these pollutants is linked to increased risk of developing cancer and various developmental, neurological, respiratory, reproductive, and other chronic health effects . Certain TAPs that have been extensively monitored worldwide include diesel particulate matter (DPM) and certain volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), and metal(loid)s. Quantification of inhalation cancer risks (ICRs) based on ambient TAP concentrations represents a viable approach for health risk assessment, providing guidance for risk management. − The United States Environmental Protection Agency (USEPA) is required to regulate 188 TAPs, of which 30 are further categorized as urban air toxics, requiring regulatory measures to address their sources . In 2019, the Ministry of Ecology and Environment of China issued the first list of toxic and hazardous air pollutants with six VOC species and five classes of metal(loid)s and their compounds, requiring enterprises and institutions that emit these air pollutants to both implement risk management at the source and put into practice an environmental management system for pollution sources…”

Environmental injustice in estimated cancer risk from airborne toxics exposure across United States communities

“…Using EPA regions, middle-class Black Americans are exposed to more air toxics than lower-class White Americans 7 . Urban areas have been shown to have twice the concentrations of polycyclic aromatic hydrocarbons, the majority of which come from diesel fuel 8,9 .…”