Unconventional resources offer many substantial benefits, yet the rapid increase in production of these resources using hydraulic fracturing has generated scrutiny by some policymakers and advocates who cite health concerns. The Exploration and Production Health Issues Group was recently formed to provide research, scientific analysis, and guidance on health issues regarding unconventional-resource production (URP). The group is particularly focused on community health concerns, including those associated with the compositions of hydraulic-fracturing fluid and flowback, effects on aquifers, air emissions, and psychosocial stress related to operations.
Chemical Disclosure
Opinion polls have found that community residents are most concerned about the possibility of drinking-water contamination from hydraulic fracturing. The idea that fracturing fluids of unknown composition are pumped underground through groundwater is the cause of that concern. A key issue for the industry to address is communicating the full nature of this risk while maintaining the confidentiality of proprietary chemicals used. The composition of fracturing fluids is the intellectual property of companies that develop the wellsite. The skill required to identify the right fluid composition for particular fracturing operations is what keeps those companies in business. But the need to protect some portion of fluid compositions as confidential business information (CBI) has been exploited by some opposed to URP to spread fear about unknown toxic chemicals and the harm they may cause.
To address this challenge, the Groundwater Protection Council, an organization of state regulators, created FracFocus. FracFocus is a Web-based chemical disclosure registry where the nonconfidential chemicals used in fracturing for a particular wellsite are posted for public viewing. In many states, the use of FracFocus to disclose nonconfidential chemicals is mandatory. Some segments of the URP industry believe that additional steps must be taken to develop criteria to assess the suitability of a chemical for use in URP from the perspective of health, safety, and environmental effects, and they have been working to develop criteria and a user-friendly tool to implement those criteria in URP operations. While some chemicals will continue to be identified as CBI under existing regulations and policy, operators and service companies would apply the established criteria of suitability for hydraulic fracturing. The objective is to encourage continued development of new and improved fracturing fluids while maintaining the intellectual-property protections of the companies that develop them and enhancing public confidence that protection of health and the environment is integrated into the selection of chemicals.
The balance between the legitimate need to keep certain information confidential and the processes by which compositional information is provided to experts on a need-to-know basis should be communicated better to the public to help build and maintain trust.
Potential Health Effects
The Institute of Medicine Roundtable on Environmental Health Sciences, Research, and Medicine held a workshop on the Health Impact Assessment of Shale Gas Extraction in May 2012. The workshop brought together a range of experts from the natural-gas industry, regulatory agencies, and fields of environmental monitoring and occupational and community health. A key premise for the workshop was the recognition that shale-gas extraction is an emerging technology and that it will continue to be important in the years to come. Consequently, the environmental health community needs to begin to understand potential related health effects. Furthermore, the community should adopt an approach that recognizes that the role of the health community is not to decide whether or where the nation should use shale-gas extraction but rather to discuss potential health effects, to which individuals are more vulnerable, and how any proven effects can be mitigated.
The key health concerns identified at the workshop were the following:
- Respirable crystalline silica as an occupational health hazard
- Undefined exposures from hydraulic fracturing through contamination of drinking-water sources
- Community exposures to volatile organic compounds (e.g., benzene) emitted to ambient air
- Community effects from nonchemical stressors (e.g., psychosocial stress from noise, lights, or transient populations)
Workshop participants identified the following challenges that could impede the environmental health community in identifying and resolving potential health effects:
- Difficulty of engaging polarized stakeholders to share information—specifically, community groups; local, state, and federal governments; and industry.
- Data gaps (e.g., amount and type of emissions and discharges and baseline disease prevalence in local communities).
- Rapid advancement in gas-extraction technology and changing regulations mean that health-study findings may be questioned because the studies take a considerable amount of time and conditions will have changed during the course of the study.
Studies of the Potential for Adverse Health Effects
While there are allegations that URP is affecting health adversely, few credible peer-reviewed studies exist. Most of the allegations are based on anecdotal reports associating local URP with a wide range of effects, from mental stress and eye irritation to birth defects and cancer. But anecdotal reports do not address cause and effect and may be influenced by bias. What is lacking, but necessary to assess actual health risk from URP, are studies conducted according to standard scientific protocols, specifically studies that seek to identify a stressor or stressors originating from the operation, a plausible route or routes by which humans may be exposed, and clinically confirmed adverse health effects that can plausibly be caused by the stressors. In this context, stressors are often chemical contaminants but can be other factors, such as those that affect psychological health (e.g., constant noise and light, and fear because of perceived risks and loss of control).
The current body of literature on health effects from URP consists of two basic types of reports. The first are reports that do not include original data but rather summarize, interpret, or extrapolate from existing information. These reports may include speculation (e.g., about the nature and extent of human exposure) and, in those cases where the outcomes may be influenced by the bias of authors, therefore are unreliable for defining actual risk to health from URP.
The other type of report is a study that examines data generated by credible protocols. Most of these are peer-reviewed publications.
Perhaps the most reliable type of study for assessing health risks from a common source is one following standard epidemiological methods. These studies are used to assess the incidence of disease or adverse health outcomes such as asthma, reproductive defects, and cancer. The basic characteristics of a robust epidemiology study are as follows:
- Accepted study design (e.g., cohort, case/control, cross-sectional, the latter with acknowledged limitations regarding temporality of cause and effect)
- Properly selected exposed and unexposed groups (or cases and controls) with matching or stratification of potential confounders (e.g., age, socioeconomic status, smoking/nonsmoking)
- Clinical documentation of health outcomes or another form of verification of health outcomes other than self-reporting
- Plausible exposure-pathway scenario from source to receptor, verification of the plausibility of the pathway, and proper exposure metrics to describe the pathway
- Adequate control of potential selection bias, not self-selection
- Adequate control of potentially confounding variables
- Adequate statistical analysis, incorporating effects of confounding, interaction, temporality, coexposures, possible bias, and model selection
- Adequate population sizes with proper documentation of precision (preferably confidence intervals)
- Adequate control of exposure classification bias, quantification of bias, or sensitivity analyses
- Proper interpretation of results, with strengths and weaknesses reflected properly; attention to internal consistency, coherence, multiple-hypotheses testing, and alternative explanation of effects (e.g., coexposures, socioeconomic changes)
- Peer review and publication in a reputable journal
Exploration and Production Health Issues Group
The increasing number of studies and reports alleging adverse health effects associated with proximity to URP activities suggests that a response from the URP community is needed. Reports of adverse health effects need to be examined for adherence to the epidemiological good practices. Investigation of baseline incidence of health effects in communities and of historical drinking-water quality before URP is needed to provide a benchmark against which to compare current values. Above all, accurate information about the incidence of health effects, about exposures to chemicals used in or resulting from URP activities, and about the risks of potential exposure to URP-related chemicals (rather than simply listing hazard characteristics of those chemicals) is needed in order to provide an accurate understanding of and communication about the possible health effects of URP activities.
In order to address these and other health-related issues, the petroleum industry has formed the Exploration and Production Health Issues Group. This multidisciplinary group is focused currently on community health issues related to URP with the objective of bringing accurate information to the discussion. Its approach includes
- Using evidence-based scientific principles to identify, analyze, and respond to health-related allegations associated with all facets of URP
- Using accepted principles to evaluate the risk posed by chemical components of fracturing fluids and flowback water while emphasizing the importance of exposure information in chemical risk assessment
- Developing and supporting research projects that provide sound data for industry and government risk-management decisions
- Communicating scientific findings by means of peer-reviewed publications
- Advancing public understanding of the benefits and risks from production of unconventional resources
Potential Areas of Study
Hydraulic fracturing uses large quantities of sand (silica) as a proppant, and the potential health effects of silica and associated exposure levels were determined to require further investigation. The Health Issues Group is currently collaborating with the National Industrial Sand Association on epidemiological studies of the health effects of silica to confirm safe exposure levels.
The Health Issues Group is investigating whether community studies can help determine if exposures are associated with defined adverse health outcomes. Several guidance documents for conducting community health studies are being considered.
Possible exposure to low levels of naturally occurring radioactive material (NORM) in flowback water has been raised as a potential health threat. The Health Issues Group is investigating the extent of possible exposures to NORM and the related risk. And the group continues work to enhance communication generally, regarding the health risk and benefits of URP.
Industry Activity To Minimize Risk
As with any industrial process, URP has associated risks, and industry has experience over several decades with effectively identifying and managing those risks. This is achieved through longstanding industry risk-management practices, by complying with existing regulations, and, in many cases, by going beyond regulatory requirements.
Through responsible operating practices, the industry has gone beyond meeting regulatory expectations in controlling the risks associated with URP and mitigating potential harms. Such standard operating practices appropriately control the pathways of exposure of hazardous chemicals to workers on the well pad as well as to surrounding communities. The industry is continuing efforts to identify community concerns and potential risks and increase its effectiveness in responding to them.
Community Outreach
Unconventional resources offer many substantial benefits, ranging from national to local interests. Yet it should be recognized that some who live in the vicinity of URP are genuinely confused and concerned about the potential effect of these operations on health. While this confusion may be the result of miscommunication, it is advisable that the industry increase its effort to communicate more effectively and be more transparent with all stakeholders.
This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 168518, “Collaborative Industry Initiative To Assess Potential Health Effects Related to the Production of Unconventional Resources,” by D.J. Devlin, ExxonMobil; P. Beatty and R.D. White, American Petroleum Institute; Z. Naufal, Chevron; and S.S. Sarang, Shell, prepared for the 2014 SPE International Conference on Health, Safety, and Environment, Long Beach, California, USA, 17–19 March. The paper has not been peer reviewed.