Volatile organic compounds (VOCs) in indoor air and tap water samples in residences of pregnant women living in an area of unconventional natural gas operations: Findings from the EXPERIVA study

Residential proximity to conventional and unconventional wells and exposure to indoor air volatile organic compounds in the Exposures in the Peace River Valley (EXPERIVA) study

BACKGROUND

In a previous study located in Northeastern British Columbia (Canada), we observed associations between density and proximity of oil and gas wells and indoor air concentrations of certain volatile organic compounds (VOCs). Whether conventional or unconventional well types and phases of unconventional development contribute to these associations remains unknown.

OBJECTIVE

To investigate the associations between proximity-based metrics for conventional and unconventional wells and measured indoor air VOC concentrations in the Exposures in the Peace River Valley (EXPERIVA) study samples.

METHODS

Eighty-four pregnant individuals participated in EXPERIVA. Passive indoor air samplers were analyzed for 47 VOCs. Oil and gas well legacy data were sourced from the British Columbia Energy Regulator. For each participant's home, 5 km, 10 km and no buffer distances were delineated, then density and Inverse Distance Square Weighted (ID2W) metrics were calculated to estimate exposure to conventional and unconventional wells during pregnancy and the VOC measurement period. Multiple linear regression models were used to test for associations between the well exposure metrics and indoor air VOCs. For exposure metrics with >30% participants having a value of 0, we dichotomized exposure (0 vs. >0) and performed ANOVAs to assess differences in mean VOCs concentrations.

RESULTS

Analyses indicated that: 1) conventional well density and ID2W metrics were positively associated with indoor air acetone and decanal; 2) unconventional well density and ID2W metrics were positively associated with indoor air chloroform and decamethylcyclopentasiloxane, and negatively associated with decanal; 3) drilling specific ID2W metrics for unconventional wells were positively associated with indoor air chloroform.

CONCLUSION

Our analysis revealed that the association between the exposure metrics and indoor air acetone could be attributed to conventional wells and the association between exposure metrics and indoor air chloroform and decamethylcyclopentasiloxane could be attributed to unconventional wells.

Altered oxidative stress and antioxidant biomarkers concentrations in pregnant individuals exposed to oil and gas sites in Northeastern British Columbia

Northeastern British Columbia is a region of prolific unconventional oil and gas (UOG) activity. UOG activity can release volatile organic compounds (VOCs) which can elevate oxidative stress and disrupt antioxidant activity in exposed pregnant individuals, potentially increasing the risk of adverse pregnancy outcomes. This study measured biomarkers of oxidative stress and antioxidant activity in pooled urine samples of 85 pregnant individuals living in Northeastern British Columbia, to analyze associations between indoor air VOCs, oil and gas well density and proximity metrics, and biomarker concentrations. Concentrations of catalase, superoxide dismutase (SOD), glutathione S-transferase, total antioxidant capacity, 6-hydroxymelatonin sulfate (aMT6s), malondialdehyde (MDA), 8-hydroxy-2'-deoxyguanosine (8-OHdG), and 8-isoprostane were measured using assay kits. Associations between exposure metrics and biomarker concentrations were determined using multiple linear regression models adjusted for biomarker-specific covariables. UOG proximity was associated with decreased SOD and 8-OHdG. Decreased 8-OHdG was associated with increased proximity to all wells. Decreased aMT6s were observed with increased indoor air hexanal concentrations. MDA was negatively associated with indoor air 1,4-dioxane concentrations. No statistically significant associations were found between other biomarkers and exposure metrics. Although some associations linked oil and gas activity to altered oxidative stress and antioxidant activity, the possibility of chance findings due to the large number of tests cannot be discounted. This study shows that living near UOG wells may alter oxidative stress and antioxidant activity in pregnant individuals. More research is needed to elucidate underlying mechanisms and to what degree UOG activity affects oxidative stress and antioxidant activity.

The human health effects of unconventional oil and gas (UOG) chemical exposures: a scoping review of the toxicological literature

Many chemicals associated with unconventional oil and natural gas (UOG) are known toxicants, leading to health concerns about the effects of UOG. Our objective was to conduct a scoping review of the toxicological literature to assess the effects of UOG chemical exposures in models relevant to human health. We searched databases for primary research studies published in English or French between January 2000 and June 2023 on UOG-related toxicology studies. Two reviewers independently screened abstracts and full texts to determine inclusion. Seventeen studies met our study inclusion criteria. Nine studies used solely in vitro models, while six conducted their investigation solely in animal models. Two studies incorporated both types of models. Most studies used real water samples impacted by UOG or lab-made mixtures of UOG chemicals to expose their models. Most in vitro models used human cells in monocultures, while all animal studies were conducted in rodents. All studies detected significant deleterious effects associated with exposure to UOG chemicals or samples, including endocrine disruption, carcinogenicity, behavioral changes and metabolic alterations. Given the plausibility of causal relationships between UOG chemicals and adverse health outcomes highlighted in this review, future risk assessment studies should focus on measuring exposure to UOG chemicals in human populations.

Ambient Environment and the Epidemiology of Preterm Birth

Preterm birth (PTB) is associated with substantial mortality and morbidity. We describe environmental factors that may influence PTB risks. We focus on exposures associated with an individual's ambient environment, such as air pollutants, water contaminants, extreme heat, and proximities to point sources (oil/gas development or waste sites) and greenspace. These exposures may further vary by other PTB risk factors such as social constructs and stress. Future examinations of risks associated with ambient environment exposures would benefit from consideration toward multiple exposures - the exposome - and factors that modify risk including variations associated with the structural genome, epigenome, social stressors, and diet.

The human health effects of unconventional oil and gas development (UOGD): A scoping review of epidemiologic studies

OBJECTIVE

Unconventional oil and gas development (UOGD, sometimes termed "fracking" or "hydraulic fracturing") is an industrial process to extract methane gas and/or oil deposits. Many chemicals used in UOGD have known adverse human health effects. Canada is a major producer of UOGD-derived gas with wells frequently located in and around rural and Indigenous communities. Our objective was to conduct a scoping review to identify the extent of research evidence assessing UOGD exposure-related health impacts, with an additional focus on Canadian studies.

METHODS

We included English- or French-language peer-reviewed epidemiologic studies (January 2000-December 2022) which measured exposure to UOGD chemicals directly or by proxy, and where health outcomes were plausibly caused by UOGD-related chemical exposure. Results synthesis was descriptive with results ordered by outcome and hierarchy of methodological approach.

SYNTHESIS

We identified 52 studies from nine jurisdictions. Only two were set in Canada. A majority (n = 27) used retrospective cohort and case-control designs. Almost half (n = 24) focused on birth outcomes, with a majority (n = 22) reporting one or more significant adverse associations of UOGD exposure with: low birthweight; small for gestational age; preterm birth; and one or more birth defects. Other studies identified adverse impacts including asthma (n = 7), respiratory (n = 13), cardiovascular (n = 6), childhood acute lymphocytic leukemia (n = 2), and all-cause mortality (n = 4).

CONCLUSION

There is a growing body of research, across different jurisdictions, reporting associations of UOGD with adverse health outcomes. Despite the rapid growth of UOGD, which is often located in remote, rural, and Indigenous communities, Canadian research on its effects on human health is remarkably sparse. There is a pressing need for additional evidence.

Modelling spatial & temporal variability of air pollution in an area of unconventional natural gas operations

Despite the growing unconventional natural gas production industry in northeastern British Columbia, Canada, few studies have explored the air quality implications on human health in nearby communities. Researchers who have worked with pregnant women in this area have found higher levels of volatile organic compounds (VOCs) in the indoor air of their homes associated with higher density and closer proximity to gas wells. To inform ongoing exposure assessments, this study develops land use regression (LUR) models to predict ambient air pollution at the homes of pregnant women by using natural gas production activities as predictor variables. Using the existing monitoring network, the models were developed for three temporal scales for 12 air pollutants. The models predicting monthly, bi-annual, and annual mean concentrations explained 23%-94%, 54%-94%, and 73%-91% of the variability in air pollutant concentrations, respectively. These models can be used to investigate associations between prenatal exposure to air pollutants associated with natural gas production and adverse health outcomes in northeastern British Columbia.

Unlocking the secrets: Volatile Organic Compounds (VOCs) and their devastating effects on lung cancer

Lung cancer (LCs) is still a serious health problem globally, with many incidences attributed to environmental triggers such as Volatile Organic Compounds (VOCs). VOCs are a broad class of compounds that can be released via various sources, including industrial operations, automobile emissions, and indoor air pollution. VOC exposure has been linked to an elevated risk of lung cancer via multiple routes. These chemicals can be chemically converted into hazardous intermediate molecules, resulting in DNA damage and genetic alterations. VOCs can also cause oxidative stress, inflammation, and a breakdown in the cellular protective antioxidant framework, all of which contribute to the growth of lung cancer. Moreover, VOCs have been reported to alter critical biological reactions such as cell growth, apoptosis, and angiogenesis, leading to tumor development and metastasis. Epidemiological investigations have found a link between certain VOCs and a higher probability of LCs. Benzene, formaldehyde, and polycyclic aromatic hydrocarbons (PAHs) are some of the most well-researched VOCs, with comprehensive data confirming their cancer-causing potential. Nevertheless, the possible health concerns linked with many more VOCs and their combined use remain unknown, necessitating further research. Identifying the toxicological consequences of VOCs in LCs is critical for establishing focused preventative tactics and therapeutic strategies. Better legislation and monitoring mechanisms can limit VOC contamination in occupational and environmental contexts, possibly reducing the prevalence of LCs. Developing VOC exposure indicators and analyzing their associations with genetic susceptibility characteristics may also aid in early identification and targeted therapies.

Density and proximity of oil and gas wells and concentrations of trace elements in urine, hair, nails and tap water samples from pregnant individuals living in Northeastern British Columbia

BACKGROUND

Oil and gas exploitation can release several contaminants in the environment, including trace elements, with potentially deleterious effects on exposed pregnant individuals and their developing fetus. Currently, there is limited data on pregnant individuals' exposure to contaminants associated with oil and gas activity.

OBJECTIVES

We aimed to 1)measure concentrations of trace elements in biological and tap water samples collected from pregnant individuals participating in the EXPERIVA study; 2)compare with reference populations and health-based guidance values; 3)assess correlations across matrices; and 4)evaluate associations with the density/proximity of oil and gas wells.

METHODS

We collected tap water, hair, nails, and repeated urine samples from 85pregnant individuals, and measured concentrations of 21trace elements. We calculated oil and gas well density/proximity (Inverse Distance Weighting [IDW]) for 4buffer sizes (2.5 km, 5 km, 10 km, no buffer). We performed Spearman's rank correlation analyses to assess the correlations across elements and matrices. We used multiple linear regression models to evaluate the associations between IDWs and concentrations.

RESULTS

Some study participants had urinary trace element concentrations exceeding the 95th percentile of reference values; 75% of participants for V, 29% for Co, 22% for Ba, and 20% for Mn. For a given trace element, correlation coefficients ranged from -0.23 to 0.65 across matrices; correlations with tap water concentrations were strongest for hair, followed by nails, and urine. Positive (e.g., Cu, Cr, Sr, U, Ga, Ba, Al, Cd) and negative (e.g., Fe) associations were observed between IDW metrics and the concentrations of certain trace elements in water, hair, and nails.

SIGNIFICANCE

Our results suggest that pregnant individuals living in an area of oil and gas activity may be more exposed to certain trace elements (e.g., Mn, Sr, Co, Ba) than the general population. Association with density/proximity of wells remains unclear.

Community Health Impacts From Natural Gas Pipeline Compressor Stations

Compressor stations maintain pressure along natural gas pipelines to sustain gas flow. Unfortunately, they present human health concerns as they release chemical pollutants into the air, sometimes at levels higher than national air quality standards. Further, compressor stations are often placed in rural areas with higher levels of poverty and/or minority populations, contributing to environmental justice concerns. In this paper we investigate what chemical pollutants are emitted by compressor stations, the impacts of emitted pollutants on human health, and local community impacts. Based on the information gained from these examinations, we provide the following policy recommendations with the goal of minimizing harm to those affected by natural gas compressor stations: the Environmental Protection Agency (EPA) and relevant state agencies must increase air quality monitoring and data transparency; the EPA should direct more resources to monitoring programs specifically at compressor stations; the EPA should provide free indoor air quality monitoring to homes near compressor stations; the EPA needs to adjust its National Ambient Air Quality Standards to better protect communities and assess cumulative impacts; and decision-makers at all levels must pursue meaningful involvement from potentially affected communities. We find there is substantial evidence of negative impacts to strongly support these recommendations.

Estimation of exposure to particulate matter in pregnant individuals living in an area of unconventional oil and gas operations: Findings from the EXPERIVA study

Northeastern British Columbia (Canada) is an area of oil and gas exploitation, which may result in release of fine (PM_2.5) and inhalable (PM₁₀) particulate matter. The aims of this study were to: 1) apply extrapolation methods to estimate exposure to PM_2.5 and PM₁₀ concentrations among EXPERIVA (Exposures in the Peace River Valley study) participants using air quality data archives; and 2) conduct exploratory analyses to investigate correlation between PM exposure and metrics of oil and gas wells density, proximity, and activity. Gestational exposure to PM_2.5 and PM₁₀ of the EXPERIVA participants (n = 85) was estimated by averaging the concentrations measured at the closest or three closest air monitoring stations during the pregnancy period. Drilling metrics were calculated based upon the density and proximity of conventional and unconventional oil and gas wells to each participant's residence. Phase-specific metrics were determined for unconventional wells. The correlations (ρ) between exposure to PM_2.5 and PM₁₀ and metrics of well density/proximity were determined using Spearman's rank correlation test. Estimated PM ambient air concentrations ranged between 4.73 to 12.13 µg/m³ for PM_2.5 and 7.14 to 26.61 µg/m³ for PM₁₀. Conventional wells metrics were more strongly correlated with PM₁₀ estimations (ρ between 0.28 and 0.79). Unconventional wells metrics for all phases were positively correlated with PM_2.5 estimations (ρ between 0.23 and 0.55). These results provide evidence of a correlation between density and proximity of oil and gas wells and estimated PM exposure in the EXPERIVA participants.

Distribution characteristics, air-water exchange, ozone formation potential and health risk assessments of VOCs emitted from typical coking wastewater treatment process

Coking industry has been considered as important source of volatile organic compounds (VOCs) emissions. However, few studies have emphasized the occurrence and adverse effects of VOCs from coking wastewater treatment processes. In this research, pollution profiles of both air and water phase VOCs in a typical coking wastewater treatment plant were investigated in terms of distribution characteristics, air-water exchange, ozone formation potential (OFP) and associated human health risks. Thirty VOCs were detected in the air phase, in which benzene and naphthalene were found to be the major VOCs with total contribution of 87.81 %. Nineteen VOCs were detected in the water phase, in which benzene, naphthalene and toluene contribute most to total VOCs with total contribution of 75.1 %. The regulating tank (RT) was the major source of VOCs, and the emission rate of total VOCs from all unites was 2711.03 g/d with annual emission of 0.99 t. The emission factor was estimated to be 1.36 g VOCs/m³ wastewater. The air-water exchange was assessed using the Fugacity model, and water-to-air volatilization was predominant based on the net flux of air-water exchange. OFP evaluated by emission factor indicated that the total OFP in RT was the highest (1.52 g O₃/m³ wastewater), and toluene contributed 41.8 % of the total OFP, followed by naphthalene accounting for 38.7 % The total carcinogenic risks were in the range of 8.60 × 10^-6 to 2.18 × 10^-3, in which the RT exceeded the significant risk threshold (>1 × 10^-4). The non-carcinogenic risks of hazard quotient value in RT also exceeded the risk threshold (>1), and naphthalene was the major contributor accounting for 79.02 %. These results not only provided comprehensive knowledge on pollution profiles and environmental risks of VOCs during coking wastewater treatment processes, but also facilitated the implement of VOCs regulation and occupational health protection strategies in coking industries.

Temporal Trends of Racial and Socioeconomic Disparities in Population Exposures to Upstream Oil and Gas Development in California

People living near oil and gas development are exposed to multiple environmental stressors that pose health risks. Some studies suggest these risks are higher for racially and socioeconomically marginalized people, which may be partly attributable to disparities in exposures. We examined whether racially and socioeconomically marginalized people in California are disproportionately exposed to oil and gas wells and associated hazards. We longitudinally assessed exposure to wells during three time periods (2005-2009, 2010-2014, and 2015-2019) using sociodemographic data at the census block group-level. For each block group and time period, we assessed exposure to new, active, retired, and plugged wells, and cumulative production volume. We calculated risk ratios to determine whether marginalized people disproportionately resided near wells (within 1 km). Averaged across the three time periods, we estimated that 1.1 million Californians (3.0%) lived within 1 km of active wells. Nearly 9 million Californians (22.9%) lived within 1 km of plugged wells. The proportion of Black residents near active wells was 42%-49% higher than the proportion of Black residents across California, and the proportion of Hispanic residents near active wells was 4%-13% higher than their statewide proportion. Disparities were greatest in areas with the highest oil and gas production, where the proportion of Black residents was 105%-139% higher than statewide. Socioeconomically marginalized residents also had disproportionately high exposure to wells. Though oil and gas production has declined in California, marginalized communities persistently had disproportionately high exposure to wells, potentially contributing to health disparities.

Volatile organic compounds in water matrices: Recent progress, challenges, and perspective

Volatile organic compounds (VOCs) are a group of organic compounds that have a molecular structure containing carbon and their chemical properties allow them to be easily converted to steam and gas and remain for a long period of time and have diverse effects on the environment. The purpose of this study is determination of the concentration of VOCs such as alachlor, anthracene, benzene, bromoform, chloroform, heptachlor, isophorone, tetrachloroethylene, γ -chlordane, toluene, etc. in water matrices. The results showed that among studies conducted on VOCs, the concentration of tetrachloroethylene, m,p-xylene, and toluene were at the top in water matrices, and the lowest average concentrations were found in chloroform, anthracene, and butyl benzyl phthalate. In terms of VOC concentrations in water matrices, China was the most polluted country. Moreover, the data analysis indicated that China was the only country with carcinogenic risk. A Monte-Carlo simulation showed that although the averages obtained were comparable to the acceptable limits, for heptachlor, the maximum carcinogenic risk is achieved at a level that is slightly over the limit, only 25% from the population being exposed.

Spatiotemporal Correlation Analysis of Hydraulic Fracturing and Stroke in the United States

Hydraulic fracturing or fracking has led to a rapid growth of oil and gas production in the United States, but the impact of fracking on public health is an important but underresearched topic. We designed a methodology to study spatiotemporal correlations between the risk of fracking and stroke mortality. An annualized loss expectancy (ALE) model is applied to quantify the risk of fracking. The geographically and temporally weighted regression (GTWR) model is used to analyze spatiotemporal correlations of stroke mortality, fracking ALE, and nine other socioeconomic- and health-related factors. The analysis shows that fracking ALE is moderately correlated with stroke mortality at ages over 65 in most states of fracking, in addition to cardiovascular disease and drug overdose being positively correlated with stroke mortality. Furthermore, the correlations between fracking ALE and stroke mortality in men appear to be higher than in women near the Marcellus Shale, including Ohio, Pennsylvania, West Virginia, and Virginia, while stroke mortality among women is concentrated in the Great Plains, including Montana, Wyoming, New Mexico, and Oklahoma. Lastly, within two kilometers of the fracking mining activity, the level of benzene in the air was found to be significantly correlated with the fracking activity in Colorado.

Volatile organic compounds: A proinflammatory activator in autoimmune diseases

The etiopathogenesis of inflammatory and autoimmune diseases, including pulmonary disease, atherosclerosis, and rheumatoid arthritis, has been linked to human exposure to volatile organic compounds (VOC) present in the environment. Chronic inflammation due to immune breakdown and malfunctioning of the immune system has been projected to play a major role in the initiation and progression of autoimmune disorders. Macrophages, major phagocytes involved in the regulation of chronic inflammation, are a major target of VOC. Excessive and prolonged activation of immune cells (T and B lymphocytes) and overexpression of the master pro-inflammatory constituents [cytokine and tumor necrosis factor-alpha, together with other mediators (interleukin-6, interleukin-1, and interferon-gamma)] have been shown to play a central role in the pathogenesis of autoimmune inflammatory responses. The function and efficiency of the immune system resulting in immunostimulation and immunosuppression are a result of exogenous and endogenous factors. An autoimmune disorder is a by-product of the overproduction of these inflammatory mediators. Additionally, an excess of these toxicants helps in promoting autoimmunity through alterations in DNA methylation in CD4 T cells. The purpose of this review is to shed light on the possible role of VOC exposure in the onset and progression of autoimmune diseases.