In the United States, onshore oil and gas extraction operations generate an estimated 900 billion gallons of produced water annually, making it the largest waste stream associated with upstream development of petroleum hydrocarbons. Management and disposal practices of produced water vary from deep well injection to reuse of produced water in agricultural settings. However, there is relatively little information with regard to the chemical or toxicological characteristics of produced water. A comprehensive literature review was performed, screening nearly 16,000 published articles, and identifying 129 papers that included data on chemicals detected in produced water. Searches for information on the potential ecotoxicological or mammalian toxicity of these chemicals revealed that the majority (56%) of these compounds have not been a subject of safety evaluation or mechanistic toxicology studies and 86% lack data to be used to complete a risk assessment, which underscores the lack of toxicological information for the majority of chemical constituents in produced water. The objective of this study was to develop a framework to identify potential constituents of concern in produced water, based on available and predicted toxicological hazard data, to prioritize these chemicals for monitoring, treatment, and research. In order to integrate available evidence to address gaps in toxicological hazard on the chemicals in produced water, we have catalogued available information from ecological toxicity studies, toxicity screening databases, and predicted toxicity values. A Toxicological Priority Index (ToxPi) approach was applied to integrate these various data sources. This research will inform stakeholders and decision-makers on the potential hazards in produced water. In addition, this work presents a method to prioritize compounds that, based on hazard and potential exposure, may be considered during various produced water reuse strategies to reduce possible human health risks and environmental impacts.
Waters co-produced during petroleum extraction are the largest waste streams from oil and gas development. Reuse or disposal of these waters is difficult due to their high salinities and the sheer volumes generated. Produced waters (PWs) may also contain valuable mineral commodities. While an understanding of produced water trace element composition is required for evaluating the associated resource and waste potential of these materials, measuring trace elements in brines is challenging due to the dilution requirements of typical methods. Alternatively, inductively coupled plasma-optical emission spectrometry (ICP-OES) has shown promise as being capable of direct measurements of trace elements within PWs with minimal dilution. Here, we evaluate direct ICP-OES trace element quantification in PWs for seventeen trace elements (As,
Background
Industrial disasters have led to hazardous air pollution and public health impacts. Response officials have limited exposure guidelines to consult during the event; often, guidelines are outdated and may not represent relevant elevated-exposure periods. During the 2019 Intercontinental Terminals Company (ITC) fire in Houston, large-scale releases of benzene—a hazardous chemical and known carcinogen—presented a public health threat. This incident, among others, highlight the need for effective response and nimble, rapid public health communication.
Method
We developed a data-driven visualization tool to store, display, and interpret ambient benzene concentration information to assist health officials during environmental emergencies. Guidance values to interpret risk from acute exposure to benzene were updated using recent literature and regulatory guidance, which additionally consider exposure periodicity. The visualization platform can process data from several types of sampling instruments and air monitors automatically and publicly display information in real-time, along with the associated risk information, and action recommendations. The protocol was validated by retrospectively applying it to the ITC event.
Results
The new guidance values are 6- to 30-times lower than those derived by the Texas regulatory agency. Fixed-site monitoring data assessed using the protocol and revised thresholds, indicated an additional 8 shelter-in-place and 17 air quality alerts would have occurred. At least one of these shelter-in-place alerts corresponded to prolonged, elevated benzene concentrations (~ 1000 ppb).
Conclusion
This new tool addresses essential gaps in timely communication of air pollution measurements, provides context to understand potential health risks from exposure to benzene, and provides a clear protocol for local officials in responding to industrial air releases of benzene. This type of protocol has been identified as a critical need by several community groups in the Houston region who have expressed concerns about disparities in air quality attributable, in part, to industry air emission exceedances.
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