Health Misinformation about Toxic-Site Harm: The Case for Independent-Party Testing to Confirm Safety

Does Hazardous-Waste Testing Follow Technical Guidance, Thus Help Protect Environmental Justice and Health?

Does representative hazardous-waste-site testing tend to follow or to violate government technical guidance? This is an important question, because following such guidance promotes reliable risk analysis, adequate remediation, and environmental-justice and -health protection. Yet only government documents typically address this question, usually only when it is too late, when citizens have already exhibited health harm, allegedly from living or working near current/former hazardous-waste sites. Because no systematic, representative, scientific analyses have answered the preceding question, this article begins to investigate it by posing a narrower part of the question: Does representative US testing of volatile-organic-compound (VOC) waste sites tend to follow or to violate government technical requirements? The article (i) outlines US/state-government technical guidance for VOC testing; (ii) develops criteria for discovering representative US cases of VOC testing; (iii) uses the dominant US Environmental Protection Agency method to assess whether these representative cases follow such guidance; (iv) employs the results of (iii) to begin to answer the preceding question; then (v) discusses the degree to which, if any, these results suggest threats to environmental health or justice. Our initial, but representative, results show that almost all US VOC-waste-site testing (that we investigated) violates government technical requirements and systematically underestimates risks, and this may help justify less expensive, potentially health-threatening cleanups, mostly in environmental justice communities. We outline needed future research and suggest two strategies to promote following government technical guidance for hazardous-waste testing.

Mechanistic insights into ball milling enhanced montmorillonite modification with tetramethylammonium for adsorption of gaseous toluene

Montmorillonite is widely used for pollutants adsorption due to its porous structure and low price. However, the low specific surface area and small porosity limit its application in gas adsorption field. In this study, montmorillonite was organically modified using a facile dry ball milling method by tetramethylammonium bromide. The adsorption behaviour of toluene as a model VOC compound on organic montmorillonite was systematically investigated through adsorption breakthrough curves, adsorption kinetics and isotherms. After modification by ball milling, the specific surface area of ball milling with tetramethylammonium bromide for montmorillonite modification (BMTMt) was increased from 20.6 m²/g to 186.4 m²/g, and the microporosity proportion was up to 47%. Dynamic adsorption experiments showed that the best performance of BMTMt for toluene (55.9 mg/g) was 6 times higher than that of original montmorillonite (8.8 mg/g). Compared with the water bath preparation method, ball milling method promoted the intercalation of tetramethylammonium bromide into the layers of montmorillonite, resulting in a higher proportion of micropores. Density functional theory calculations indicated that the interaction between tetramethylammonium bromide and montmorillonite was mainly electrostatic forces, and the enhanced adsorption performance for toluene was mainly through microporous filling. BMTMt was proved to be a promising adsorbent for VOCs removal.

Role of water in unexpectedly large changes in emission flux of volatile organic compounds in soils under dynamic temperature conditions

Understanding the diffusive transport behavior of volatile organic compounds (VOCs) in near-surface soils is important because soil VOC emissions affect atmospheric conditions and climate. Previous studies have suggested that temperature changes affect the transport behavior; however, the effect of these changes are poorly understood. Indeed, under dynamic temperature conditions, the change in VOC flux is much larger than that expected from the temperature dependency of the diffusion coefficient of VOCs in air. However, the mechanism is not well understood, although water in soil has been considered to play an important role. Here, we present the results of experiments for the upward vertical vapor-phase diffusive transport of two VOCs (benzene and tetrachloroethylene) in sandy soil under sinusoidal temperature variations of 20-30 °C, as well as its numerical representation. The results clarify that the unexpectedly large changes in emission flux can occur as a result of changes in the VOC concentration gradient due to VOC release (volatilization) from/trapping (dissolution) into water, and that such flux changes may occur in various environments. This study suggests the importance of a global evaluation of soil VOC emissions by continuous measurements in various soil environments and/or predictions through numerical simulations with thorough consideration of the role of water in dynamic soil environments.