Risk of Cancer in a Community Exposed to Per- and Poly-Fluoroalkyl Substances

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) emissions from a plastic coating industrial source in southern New Hampshire (NH) have contaminated at least 65 square miles of drinking water. Prior research indicates that high levels of PFAS are associated with a variety of adverse health outcomes, including an increased risk of cancer. Reports indicate that mean blood serum levels of perfluorooctanoic acid (PFOA), one type of PFAS, in residents of the exposed community are more than 2 times greater than the mean blood serum level in the US. Merrimack public water supply customers also have higher average blood levels of perfluorooctane sulfonic acid (PFOS) and perfluorohexane sulfonic acid (PFHxS) than the time-matched US average. A 2018 report concludes that the incidence rate of cancer in Merrimack does not exceed the incidence rate of cancer in NH in general. However, prior reporting on the risk of cancer in Merrimack is compared only to a state-wide metric influenced by the Merrimack cancer incidence.

METHODS

Our ecological study compared the risk in Merrimack, NH residents for 24 types of cancer between 2005 and 2014, targeted in a previous study, and all-cause cancers, to US national cancer rates and cancer rates in demographically similar towns in New England. Four New England "unexposed towns" were chosen based on demographic similarity to Merrimack, with no documented PFAS exposure in water supplies. We utilized unadjusted logistical regression to approximate risk ratios (RR) and 95% confidence intervals (CI) assessing the risk of cancer in Merrimack NH to each of the 4 comparator communities, the pooled comparator variable, and national average incidence.

RESULTS

Residents of Merrimack, NH experienced a significantly higher risk of thyroid cancer (RR = 1.47, 95% CI 1.12-1.93), bladder cancer (RR = 1.45, 95% CI 1.17-1.81), esophageal cancer (RR = 1.71, 95% CI 1.1-2.65), and mesothelioma (RR = 2.41, 95% CI 1.09-5.34), compared to national averages. Our work also suggests that Merrimack residents experienced a significantly higher risk of all-cause cancer (RR = 1.34, 95% CI 1.25-1.43), thyroid cancer (RR = 1.69, 95% CI 1.19-2.39), colon cancer (RR = 1.27, 95% CI 1.02-1.57), and prostate cancer (RR = 1.36, 95% CI 1.15, 1.6) compared with similarly exposed New England communities. Our results indicate that residents of Merrimack may also have a significantly lower risk of some site-specific cancers compared to national averages, including lower risk of prostate cancer (RR = 0.57, 95% CI 0.5-0.66), female breast cancer (RR = 0.60, 95% CI 0.52-0.68), ovarian cancer (RR = 0.52, 95% CI 0.33-0.84) and cervical cancer (RR = 0.29, 95% CI 0.12-0.69).

CONCLUSION

Merrimack residents experienced a significantly higher risk of at least 4 types of cancer over 10 years between 2005 and 2014. Merrimack is a community with documented PFAS contamination of drinking water in public and private water sources. Results indicate that further research is warranted to elucidate if southern NH residents experience increased risk for various types of cancer due to exposure to PFAS contamination.

Characterization and comparison of oxidative potential of real-world biodiesel and petroleum diesel particulate matter emitted from a nonroad heavy duty diesel engine

Little is known regarding the oxidative potential of biodiesel particulate matter (PM) relative to diesel PM emitted from heavy duty diesel (HDD) nonroad engines generated in real-world occupational settings. The composition of biodiesel and diesel PM can include transition metals, polar, and nonpolar organic species which can increase oxidative potential via production of reactive oxygen species (ROS). Elevated ROS can lead to oxidative stress and induce antioxidant defense, inflammation, and toxicity. This study characterized the chemical composition of PM (water soluble organic carbon and elemental metals) collected in a real-world occupational setting. ROS production in a human epithelial cell line (BEAS-2B) treated with biodiesel and diesel PM extracts was compared to oxidative potential measured by an acellular dithiothreitol (DTT) assay. The oxidative potential (DTT consumption rate) of diesel PM was 21% greater than biodiesel PM at the highest treatment concentration (60 μg/mL), yet the ROS generated in vitro were similar between fuel types. Average concentrations of Cu, Cr and Zn were higher in diesel PM compared to biodiesel PM. Additionally, there was a significant correlation between DTT consumption and Cu in diesel PM (r = 0.98), but not B20 PM. There was a strong correlation between WSOC content in diesel PM and ROS generated in vitro (r = 0.83), but no correlation between WSOC content in biodiesel PM and ROS. Taken together, the results indicate the influence of fuel type on the chemical composition and oxidative potential of PM generated by a nonroad HDD engine operated at a recycling center. While acknowledging the potential influence of other species of interest not measured (i.e., quinones), real-world petroleum diesel PM emissions had higher oxidative potential compared to biodiesel PM suggesting that biodiesel use may reduce risk to human health.

Effect of biodiesel fuel on "real-world", nonroad heavy duty diesel engine particulate matter emissions, composition and cytotoxicity

Biodiesel is regarded by many as a "greener" alternative fuel to petroleum diesel with potentially lower health risk. However, recent studies examining biodiesel particulate matter (PM) characteristics and health effects are contradictive, and typically utilize PM generated by passenger car engines in laboratory settings. There is a critical need to analyze diesel and biodiesel PM generated in a "real-world" setting where heavy duty-diesel (HDD) engines and commercially purchased fuel are utilized. This study compares the mass concentrations, chemical composition and cytotoxicity of real-world PM from combustion of both petroleum diesel and a waste grease 20% biodiesel blend (B20) at a community recycling center operating HDD nonroad equipment. PM was analyzed for metals, elemental/organic carbon (EC/OC), polycyclic aromatic hydrocarbons (PAHs), and nitro-polycyclic aromatic hydrocarbons (N-PAHs). Cytotoxicity in a human lung epithelial cell line (BEAS-2B) following 24h exposure to the real-world particles was also evaluated. On average, higher concentrations for both EC and OC were measured in diesel PM. B20 PM contained significantly higher levels of Cu and Mo whereas diesel PM contained significantly higher concentrations of Pb. Principal component analysis determined Mo, Cu, and Ni were the metals with the greatest loading factor, suggesting a unique pattern related to the B20 fuel source. Total PAH concentration during diesel fuel use was 1.9 times higher than during B20 operations; however, total N-PAH concentration was 3.3 times higher during B20 use. Diesel PM cytotoxicity was 8.5 times higher than B20 PM (p<0.05) in a BEAS-2B cell line. This study contributes novel data on real-world, nonroad engine sources of metals, PAH and N-PAH species, comparing tailpipe PM vs. PM collected inside the equipment cabin. Results suggest PM generated from burning petroleum diesel in nonroad engines may be more harmful to human health, but the links between exposure, composition and toxicity are not straightforward.

Petrodiesel and Waste Grease Biodiesel (B20) Emission Particles at a Rural Recycling Center: Characterization and Effects on Lung Epithelial Cells and Macrophages

Diesel engine emissions are an important source of ultrafine particulate matter (PM) in both ambient air and many occupational settings. Biodiesel is a popular, 'green' alternative to petroleum diesel fuel, but little is known about the impact of 'real world' biodiesel combustion on workplace PM concentrations and particle characteristics including size, morphology, and composition; or on biological responses. The objectives of the present work were to characterize PM workplace concentrations and tailpipe emissions produced by the combustion of commercially purchased low sulfur petrodiesel and a waste grease B20 blend (20% biodiesel/80% petrodiesel by volume) in heavy duty diesel (HDD) nonroad equipment operating in a 'real world' rural recycling center. Furthermore, we assessed the in vitro responses of cell lines representing human lung epithelial cells (BEAS-2B) and macrophages (THP-1) after 24 h of exposure to these real-world particles. Compared to petroleum diesel, use of B20 in HDD equipment resulted in lower mass concentrations of PM2.5, PM<0.25 (particle diameter less than 2.5 and 0.25 micrometer, respectively), and elemental carbon. Transmission electron analysis of PM showed that primary particle size and morphology were similar between fuel types. Metals composition analysis revealed differences between fuels, with higher Fe, Al, V, and Se measured during B20 use, and higher As, Cd, Cu, Mn, Ni and Pb concentrations measured during petrodiesel use. In vitro responses varied between fuels but data supported that waste grease B20 particles elicited inflammatory responses in human macrophages and lung epithelial cells comparable to petrodiesel particles. However, the effects were more pronounced with B20 than petrodiesel at the same mass concentration. Since the primary particle size and morphology were similar between fuels, it is likely that the differential results seen in the in vitro assays points to differences in the composition of the PM. Future research should focus on the organic carbon and metals speciation and potential impact of real world particles on reactive oxygen species generation and mechanisms for differences in the cellular inflammatory responses.

Breathing easier? The known impacts of biodiesel on air quality

Substantial scientific evidence exists on the negative health effects of exposure to petroleum diesel exhaust. Many view biodiesel as a 'green', more environmentally friendly alternative fuel, especially with respect to measured reductions of particulate matter in tailpipe emissions. Tailpipe emissions data sets from heavy-duty diesel engines comparing diesel and biodiesel fuels provide important information regarding the composition and potential aggregate contribution of particulate matter and other pollutants to regional airsheds. However, exposure - defined in this instance as human contact with tailpipe emissions - is another key link in the chain between emissions and human health effects. Although numerous biodiesel emissions studies exist, biodiesel exposure studies are nearly absent from the literature. This article summarizes the known impacts of biodiesel on air quality and health effects, comparing emissions and exposure research. In light of rapidly changing engine, fuel and exhaust technologies, both emissions and exposure studies are necessary for developing a fuller understanding of the impact of biodiesel on air quality and human health.

Evaluation of biodiesel's impact on real-world occupational and environmental particulate matter exposures at a municipal facility in Keene, NH

Many organizations are interested in biodiesel as a renewable, domestic energy source for use in transportation and heavy-duty equipment. Although numerous biodiesel emission studies exist, biodiesel exposure studies are nearly absent from the literature. This study compared the impact of petroleum diesel fuel and a B20 blend (20% soy-based biodiesel/80% petroleum diesel) on occupational and environmental exposures at a rural municipal facility in Keene, NH. For each fuel type, we measured concentrations of fine particulate matter (PM2.5), elemental carbon (EC), and organic carbon (OC) at multiple locations (in-cabin, work area, and near-field) at a materials recovery facility utilizing non-road equipment. B20 fuel use resulted in significant reductions in PM2.5 mass (56-76%), reductions in EC (5-29%), and increases in OC (294-467%). Concentrations of PM2.5 measured during petroleum diesel use were up to four times higher than PM2.5 concentrations during B20 use. Further analysis of the EC and OC fractions of total carbon also indicated substantial differences between fuels. Our results demonstrate that biodiesel blends significantly reduced PM2.5 exposure compared to petroleum diesel fuel in a workplace utilizing non-road construction-type equipment. While this suggests that biodiesel may reduce health risks associated with exposure to fine particulate matter mass, more exposure research is needed to better understand biodiesel-related changes in particulate matter composition and other exposure metrics.

Biodiesel versus diesel: a pilot study comparing exhaust exposures for employees at a rural municipal facility

Many organizations interested in renewable, domestic energy have switched from petroleum diesel to biodiesel blends for use in transportation and heavy-duty equipment. Although considerable evidence exists on the negative health effects of petroleum diesel exhaust exposures in occupational settings, there has been little research examining biodiesel exposures. Working collaboratively with a local municipality, concentrations of particulate matter (PM) and other air toxics were measured at a recycling facility in southwestern New Hampshire while heavy equipment operated first on petroleum diesel and then on a B20 blend (20% soy-based biodiesel/80% petroleum diesel). This pilot study used a combination of established industrial hygiene and environmental air monitoring methods to estimate occupational exposure profiles to PM and air toxics from combustion of petroleum diesel and biodiesel. Results indicate that B20 use dramatically reduces work area respirable particle, PM2.5 (PM < or = 2.5 microm in aerodynamic diameter), and formaldehyde levels compared with petroleum diesel. Some volatile organic compound concentrations were higher for petroleum diesel and others were higher for the B20 blend. Overall, this study suggests that biodiesel blends reduce worker exposure to and health risk from petroleum diesel exhaust, but additional exposure research is recommended.