Texas Commission On Environmental Quality Research Articles

Impacts of anthropogenic emissions and meteorology on spring ozone differences in San Antonio, Texas between 2017 and 2021

San Antonio has been designated as ozone nonattainment under the current National Ambient Air Quality Standards (NAAQS). Ozone events in the city typically occur in two peaks, characterized by a pronounced spring peak followed by a late summer peak. Despite higher ozone levels, the spring peak has received less attention than the summer peak. To address this research gap, we used the Weather Research and Forecasting (WRF)-driven GEOS-Chem (WRF-GC) model to simulate San Antonio's ozone changes in the spring month of May from 2017 to 2021 and quantified the respective contributions from changes in anthropogenic emissions and meteorology. In addition to modeling, observations from the San Antonio Field Studies (SAFS), the Texas Commission on Environmental Quality (TCEQ) Continuous Ambient Monitoring Stations (CAMS), and the spaceborne TROPOspheric Monitoring Instrument (TROPOMI) are used to examine and validate changes in ozone and precursors. Results show that the simulated daytime mean surface ozone in May 2021 is 3.8 ± 0.6 ppbv lower than in May 2017, which is slightly less than the observed average differences of −5.3 ppbv at CAMS sites. The model predicted that the anthropogenic emission-induced changes contribute to a 1.4 ± 0.5 ppbv reduction in daytime ozone levels, while the meteorology-induced changes account for a 2.4 ± 0.6 ppbv reduction over 2017–2021. This suggests that meteorology plays a relatively more important role than anthropogenic emissions in explaining the spring ozone differences between the two years. We additionally identified (1) reduced NO2 and HCHO concentrations as chemical reasons, and (2) lower temperature, higher humidity, increased wind speed, and a stronger Bermuda High as meteorological reasons for lower ozone levels in 2021 compared to 2017. The quantification of the different roles of meteorology and ozone precursor concentrations helps understand the cause and variation of ozone changes in San Antonio over recent years.

Industry sues EPA over ethylene oxide rule

A battle over the cancer risks of ethylene oxide air emissions from chemical plants has landed in court. The chemical maker Huntsman Petrochemical and two industry trade groups, the American Chemistry Council and the Louisiana Chemical Association, filed lawsuits Feb. 21 that challenge the US Environmental Protection Agency’s recent decision to maintain a 2020 regulation limiting ethylene oxide emissions from organic chemical manufacturing. That regulation relies on a controversial hazard assessment conducted by the EPA’s Integrated Risk Information System (IRIS) in 2016. The rule requires chemical manufacturers to reduce ethylene oxide emissions from equipment leaks, vents, and storage tanks to protect communities near industrial facilities. Industry wants the EPA to use a less protective risk assessment conducted by the Texas Commission on Environmental Quality (TCEQ). In December, the EPA rejected the TCEQ’s assessment . The EPA concluded that there is no scientific basis for changing its preference of using hazard

Understanding Regional Background Ozone by Multiple Methods: A Case Study in the Shandong Region, China, 2018–2020

AbstractUprising ground‐level ozone (O3) and its regional pollution in Northern China are attracting more attention. Besides local precursor emissions and photochemistry, background ozone and long‐range transport also contribute significantly to O3 concentrations. To quantify the regional background O3 concentrations and their temporal and spatial variations, multiple methods, including the principal component analysis (PCA) and the Texas Commission on Environmental Quality (TCEQ) method, were applied as a case study in Shandong province in Northern China, where serious O3 pollution occurred frequently yet the background contributions have not been well quantified. We used four methods to quantify the regional background O3: Method 1 is PCA analysis with only ambient O3 data as input; Method 2 is PCA analysis considering O3 and meteorological parameters; Method 3 combines multiple linear regression and the traditional PCA method; and Method 4 is based on TCEQ and consists of the lowest MAD8 O3 measured to represent regional background O3 concentrations. Results derived from multiple methods show an overall consistent trend with 2018–2020 averaged regional background O3 (MDA8) of 41.5 ppb, accounting for 79.4% of the total O3 in the region. From 2018 to 2020, the changes in regional MDA8 O3 estimated by Methods 1–4 are −1.8, 0.7, −2.4, and 0.4 ppb, respectively. Clear seasonal variations in the regional background O3 are observed, showing a pattern of summer > spring > autumn > winter. In addition, the regional ozone contribution at coastal cities was larger than that for inland cities with local O3 contribution gradually increasing from coastal areas to inland areas. The 3‐year average sea‐land breeze contribution to summertime O3 in the eastern coastal cities was estimated to be around 2.1%, while the local photochemistry to O3 in the inland cities was about 29.7% during ozone pollution episodes, with maximum contribution estimated up to 55.8%. Overall, our study provides insights into the regional background ozone and local photochemistry in Northern China.

Using Low-Cost Sensors to Assess PM2.5 Concentrations at Four South Texan Cities on the U.S.—Mexico Border

Low-cost sensors have been used considerably to characterize air pollution in the last few years. This study involves the usage of this technology for the first time to assess PM2.5 pollution at four cities on the U.S.–Mexico border. These cities in the Lower Rio Grande Valley Region of South Texas are Brownsville, Edinburg, Weslaco, and Port Isabel. A year-long sampling campaign was undertaken from 1 March 2021 to 31 March 2022. TSI BlueSky™ Air Quality Monitors were deployed concurrently at 11 different locations in these four cities. Twenty-four-hour PM2.5 concentrations from these sensors were then compared with ambient PM2.5 data available at the Texas Commission on Environmental Quality (TCEQ) Continuous Ambient Monitoring Station (CAMS) sites to elucidate spatial and temporal variability in the pollutant concentrations at the neighborhood level. The results indicate low to moderate spatial heterogeneity in the PM2.5 concentrations throughout the region. Our findings suggest that low-cost sensors in combination with CAMS sites have the potential to aid community monitoring for real-time spatiotemporal PM2.5 pollution patterns.

An Exploratory Investigation of Government Air Monitoring Data after Hurricane Harvey.

Southeast Texas is home to some of the largest refineries in the United States. During Hurricane Harvey, emergency shutdowns took place. In this exploratory investigation, we examine how government air monitors performed in measuring air quality in Beaumont, Texas during and in the months following Hurricane Harvey. Texas Commission on Environmental Quality (TCEQ) data from two active air monitors in Beaumont, Texas were analyzed during the year 2017–2018. Concentrations of sulfur dioxide (SO2), nitric oxide (NO), oxides of nitrogen (NOx), ozone, benzene, and hydrogen sulfide (H2S) were investigated. The number of hours and days no data were reported by air monitors were also investigated. Yearly maximum values (MAX, all in parts per billion (ppb)) in 2017 for SO2, NO, and NOx (53.7, 113.4, 134, respectively) and their respective standard deviations (SD: 1.3, 3.4, and 14) were higher as compared to 2018 (MAX, all in ppb and (SD) = 40.9, (1.4); 103.9, (3.3); 123.8, (14), respectively). The data capture rate for these chemicals were between 88 and 97% in both years. During the months following Hurricane Harvey (August–December 2017) there was an increase in most maximum values. The yearly averages for H2S were 0.68 ppb (SD 1.02) in 2017 and 0.53 ppb (SD 1.07) in 2018. Missing days were observed for both the H2S and NOx air monitors, with the highest number observed in 2017 (213 missing days) for the air monitor measuring H2S. We identified that residents of Beaumont, Texas are exposed daily to low-level concentrations of air pollutants. H2S is released each day at a level high enough to be smelled. Data capture rates for air monitors are not always above 90%. Improved air quality data and disaster preparations are needed in Beaumont, Texas.

Monitored Natural Recovery of Contaminated Sediment in Cottonwood Bay, Texas

ABSTRACT Monitored natural recovery (MNR) is a response action for contaminated sediment that relies on natural processes to reduce ecological and human health risks to acceptable levels over time. Multi-media long-term monitoring is necessary to verify remedy effectiveness and success. Whereas MNR has most often been employed together with other engineered remedies to address contaminated sediment, this case study describes an evaluation demonstrating the suitability of MNR with adaptive management as a stand-alone sediment remedial strategy for Cottonwood Bay, located in Dallas, Texas. Current risks at the Cottonwood Bay site are associated with human consumption of fish contaminated with polychlorinated biphenyls (PCBs). The lines of evidence used to evaluate MNR included documentation of source control; review of PCB burial/isolation and surface sediment recovery; evaluation of sediment deposition and sediment stability; and demonstration of decreasing temporal trends in fish tissue PCB concentrations. The multiple lines of evidence demonstrated that source control and natural recovery processes have contributed substantially to reduced concentrations of PCBs and metals in surface sediments and PCBs in fish. MNR has been approved by the Texas Commission on Environmental Quality (TCEQ) and is incorporated as a stand-alone remedy in the revised Remedial Action Plan (RAP) for Cottonwood Bay. A long-term monitoring plan is being implemented as part of an MNR response action to confirm decreasing trends in surface sediment and fish fillet PCB concentrations over time and to demonstrate the continued effectiveness of natural recovery processes.

Comparative Assessment of Pollutant Concentrations and Meteorological Parameters from TCEQ CAMS Sites at Houston and Rio Grande Valley Regions of Texas, USA in 2016

Spatial and temporal heterogeneity in pollutant concentrations exists at the intra-urban level. In this research work, the concentrations of various pollutants and meteorological parameters are characterized between various central ambient monitoring sites at Houston, TX, and the Rio Grande Valley Regions of South Texas. Meteorological (temperature, relative humidity, wind speed and direction) and pollutant (O3, SO2, CO, NO2, and various PM species) concentrations were downloaded from the appropriate Texas Commission on Environmental Quality (TCEQ) Central Ambient Monitoring Station (CAMS) sites for the year 2016. Correlation Analyses and Coefficient of Divergence (COD) analyses suggest that statistically significant differences occur between the various TCEQ CAMS sites in the Houston Region. Findings from this study will help the various stakeholders involved in assessing the overall air pollutants exposure burden for the local populations.

Assessment of traffic-related air pollution (TRAP) at two near-road schools and residence in El Paso, Texas, USA

Traffic-related air pollution (TRAP) and associated health risks at near-road communities have been studies extensively. As part of a larger air pollution health effects study in children with asthma, this research used on-site air quality monitors to characterize air pollutants at two near-road schools (CW and B) and a residential house (H) in El Paso, TX. The study sites were near a major inter-state roadway (US-54). Air quality data for PM2.5, PM10, NO2, and O3 was collected for ten weeks in Fall (2017). The spatial and temporal variability in the pollutant concentrations was compared with air quality data from Texas Commission on Environmental Quality (TCEQ) sites. Similar trends in measured pollutants were observed across all examined sites. Higher concentrations of PM10 were recorded at school B. Spearman correlations, coefficient of divergence, and diurnal graphs helped characterize the differences in the pollutant levels between these sites. The results suggest a spatial and temporal variability between the sites examined and available TCEQ sites. It is recommended that studies performed in this high-altitude arid region employ on-site measurements to avoid exposure misclassification and erroneous estimations from using urban central ambient monitoring sites (CAMS).

Groundwater Withdrawals Associated with Oil and Gas Production from Water Supply Aquifers in Texas: Implications for Water Management Practices

The demand for water is continuing to increase as population and industry grow. The Natural Resources Defense Council indicated that Texas is at “extreme risk” for implementation of sustainable water management practices especially since groundwater is the supplier of much of the state’s freshwater. This study is designed to assess groundwater conservation practices in association with oil and gas production from the surrounding areas of the Carrizo-Wilcox formation in Texas. The results of this study reveal that the Railroad Commission of Texas (RRC), the governing agency for Texas oil and gas development, permits produced water to be discharged into surface waters if the discharged water quality meets Texas Surface Water Quality Standards (TSWQS) set by the Texas Commission on Environmental Quality (TCEQ) for the specific receiving water body. After careful evaluation of data provided by the Railroad Commission of Texas, it is believed that nearly 5,331,975 m3 (4,321 ac⋅ft) of produced water per year, with an average TDS of 960 mg L-1, is being removed from the Carrizo-Wilcox aquifer through discharge permits designated as “agricultural”. The RRC is not legally required to share the discharge information with local Groundwater Conservation Districts. Based on an evaluation of the reported Whole Effluent Toxicity (WET) test data, 69 discharges amount to total suspended solid (TDS) levels of less than 1,000 mg L-1, 35 are between 1,000-1,500 mg L-1, and 20 between 1,500 - 4,000 mg L-1. Although 69% of discharges exceed the secondary drinking water standard for TDS (500 mg L-1), the average of all discharges, 960 mg L-1, is in line with the arbitrary upper limit for freshwater based on the suitability for human consumption. In addition, the water quality of surface discharges complies with requirements for several water reuses associated with agricultural and industrial practices. The lack of communication between groundwater users leads to conflicting groundwater practices that have negative impacts such as contribution to aquifer over-exploitation and alteration of hydraulic gradients, in turn negatively impacting existing groundwater conservation efforts.

O3 Source Characteristics of an Industrial Area in the Yangtze River Delta Based on Boundary Observations

To study the characteristics of ozone sources in a petrochemical industrial park in Shanghai, O3 and its precursors were synchronously and continuously measured for 3 months(June-August 2020) alongside meteorological parameters using an online monitoring system. The Texas Commission on Environmental Quality(TCEQ) method and principal component analysis(PCA) were used to study the contribution of regional background and local O3 concentrations in the industrial zone, the results of which were compared. The results indicated that:① During the observation period, the dominant wind directions in the park were southeast and east, and the average temperature was 27.12℃. The daily average ρ(VOCs-36), ρ(NOx), and ρ(O3) was 32.05-240.51, 10.15-47.51, and 31.81-144.43μg·m-3, respectively. Alkanes are the most abundant of 36 VOCs; ② The regional background concentrations based on the TCEQ method ranged from 32.63 to 191.13μg·m-3, and the local concentrations ranged from 16.08 to 134.25 μg·m-3. The percentage contribution of the regional background ranged from 32.6% to 87.7%. The PCA analysis showed that the regional background concentrations ranged from 66.3 to 219.83μg·m-3; ③ The variations in local O3 concentrations based on the TCEQ analysis broadly correspond to the variations in ozone formation potential in the park. The two analysis methods were consistent, verifying that the results are reliable; and ④ After eliminating the calculation error caused by the abnormal concentrations recorded at some stations, the proportion of background O3 in the region was generally within the range 75%-95% during the observation period. Overall, regional transport was the main source of O3 in the industrial park, and O3 pollution in the surrounding cities should be the focus of pollution control alongside joint prevention and control measures in the Yangtze River Delta region.

Urban core-downwind differences and relationships related to ozone production in a major urban area in Texas

San Antonio, the second-most populous city in Texas and the seventh-most populous city in the United States (US), has been designated a marginal non-attainment area by the US Environmental Protection Agency with respect to the 2015 ozone (O3) National Ambient Air Quality Standard. While stationary air quality monitoring sites are operated in the region by the Texas Commission on Environmental Quality (TCEQ), there are limited in situ field measurements for O3 and its precursors in the urban core. To better understand O3 dynamics in San Antonio, a suite of meteorological and gas instruments was deployed during May 2017. We incorporate field measurements from two campaign sites and one TCEQ stationary monitoring site into a zero-dimensional O3 model to characterize the local formation and destruction rates of O3, hydroxyl radical (OH) reactivity of volatile organic compounds (VOCs), O3 production efficiency, and O3 formation regime in the urban core and directly downwind of San Antonio. Upwind/downwind differences indicate the importance of photochemical processing of VOCs with carbon-carbon double bonds. San Antonio was mostly in a nitrogen oxide (NOX)-sensitive regime throughout the daytime during the campaign period, with O3 formation peaking at noon in the city center and early afternoon at the downwind region. Formaldehyde (HCHO), isoprene, and alkenes dominated VOC reactivity, with alkenes and isoprene from San Antonio's core (upwind) likely contributing to the downwind formation of HCHO and enhancing its OH reactivity. However, their direct impact on downwind O3 production was not observed. Model results suggest further strengthening NOX emission controls to decrease O3 formation in San Antonio.

CAMx simulations of the control of anthropogenic emissions on the reduction of ozone formation in Southeast Texas of USA

The elevated point and on-road emission sources have been identified to be the dominant anthropogenic categories contributing to ozone formation in Southeast Texas of USA. In this study, additional CAMx simulations were carried out to quantify the reductions of ozone concentration in response to the reductions of the two emission sources in the amount of 25, 50 and 75% from the Southeast region based on the summertime Ozone Episode provided by the Texas Commission on Environmental Quality (TCEQ). The simulation results were analyzed and reported in the form of Empirical Kinetics Modeling Approach (EKMA) diagrams and further confirmed through additional Ozone Source Apportionment Technology (OSAT) simulations available in CAMx. While the results are observed to be highly depending on the monitor station, they have indicated that the control of elevated point emissions is slightly more effective in ozone reduction than that of on-road emissions. Averagely, a sole reduction of 48.3% from the elevated point source, or a sole reduction of 61.0% from the on-road source, or a combined reduction of 30.0% each from the two sources are required to meet a potential future 8-h ozone NAAQS of 65 ppb. The current study has demonstrated that CAMx simulations are powerful for the practice and the developed methodology is beneficial to potential future practice when new ozone episodes become available.

Source apportionment simulations of ground-level ozone in Southeast Texas employing OSAT/APCA in CAMx

Ground-level ozone is a criteria air pollutant which can be transported into an area or produced locally through photochemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOCs) in the presence of sunlight. For an ozone nonattainment area, it is critically essential to know the sources of the observed ozone before a strategic implementation plan can be established for effective reduction of ozone pollution. In this study, source apportionment simulations of ground-level ozone were performed for the Beaumont-Port Arthur (BPA) Area in Southeast Texas employing CAMx (Comprehensive Air Quality Model with Extensions) through its two built-in tools, i.e., OSAT (Ozone Source Apportionment Technology) and APCA (Anthropogenic Precursor Culpability Assessment), involving the 2012 Ozone Episode developed by TCEQ (Texas Commission on Environmental Quality). The OSAT results have indicated that local emission sources play a major role (82%) in the observed local high ozone events in the BPA area; in the meantime, 14% and 4% of the observed ozone have been identified to have transported into the area from the Southwest Louisiana and Gulf of Mexico, respectively. The APCA results have indicated that the Elevated Point, On-road and Low Point emissions are three major anthropogenic sources contributed to the BPA ozone productions with 60%, 19.5% and 19.5%, respectively. The simulation results provide needed information for the development of an implementation plan for effective reduction of ozone pollution in an ozone nonattainment area.

Particle air pollution and gestational diabetes mellitus in Houston, Texas

BackgroundThere is mixed evidence implicating prenatal exposure to particulate matter <2.5 μm in aerodynamic diameter (PM2.5) in the risk of gestational diabetes mellitus (GDM) and only one study has examined exposure to PM2.5 constituents, which vary with location because of different emission sources. MethodsWe conducted a retrospective cohort study of singleton live births in Harris County, Texas from 2008 to 2013. With data from the Texas Commission on Environmental Quality (TCEQ), we spatially interpolated maternal exposures to total and speciated PM2.5, nitrogen dioxide (NO2) and ozone (O3) over the 12-week preconception period and trimesters 1 and 2. We estimated odds ratios (OR) and 95% confidence intervals (CI) for the association between pre-conception and pregnancy exposures to total and speciated PM2.5 and odds of GDM, adjusted for temperature and maternal covariates. We also evaluated confounding from NO2 and O3 exposures in multi-pollutant models. ResultsAn interquartile range (IQR) increase in total PM2.5 exposure was associated with elevated odds for developing GDM over the preconception (adjusted OR = 1.09, 95% CI: 1.06, 1.12), first trimester (OR = 1.13, 95% CI: 1.10, 1.17) and second trimester (OR = 1.13, 95% CI: 1.09, 1.17) periods. Effect estimates increased with adjustment for NO2 and O3. We observed modest increases in odds of GDM for IQR increases in first trimester ammonium ion PM2.5 (OR = 1.03, 95% CI: 1.00, 1.05) and sulfate PM2.5 (OR = 1.03, 95% CI: 1.00, 1.05) exposures, as well as preconception Cr PM2.5 exposures (OR = 1.05, 95% CI: 1.02, 1.07). ConclusionExposures to PM2.5, before and during pregnancy were associated with elevated odds of GDM. Mitigating air pollution exposures may reduce the risk of GDM and its long-term implications for maternal and child health.

Texas moves on ethylene oxide

Texas says ethylene oxide is far less hazardous than the US Environmental Protection Agency determined in 2016. The carcinogenic gas is a key building block for pharmaceuticals and plastics and is used to sterilize medical equipment. The chemical sector is a major emitter of this toxic pollutant. On May 15, the Texas Commission on Environmental Quality (TCEQ) set a risk-screening level of 2.4 ppb ethylene oxide inhaled cumulatively over a lifetime. The agency will use the number in decisions regarding air pollution permits. In contrast, the EPA’s 2016 assessment concluded that there is a one-in-a-million chance of developing cancer from inhaling 0.1 parts per trillion of ethylene oxide over a lifetime. The TCEQ’s action will make it easier for chemical companies to get air pollution permits from the commission for new facilities or plant expansions. It will also bolster the chemical industry’s fight against stricter EPA regulation. The Ethylene Oxide

Determination and Risk Assessment of Formaldehyde and Acetaldehyde in the Ambient Air of Gas Stations in Salvador, Bahia, Brazil

Formaldehyde (FA) and acetaldehyde (AA) were determined in the ambient air of five gas stations (GS) in the city of Salvador, Bahia State, Brazil, using three passive samplers exposed simultaneously for 8 h and analysis by high-performance liquid chromatography-ultraviolet detection (HPLC-UV). The concentration ranges found were 3.31-5.78 µg m−3 for FA and 10.5-28.2 µg m−3 for AA. These values were below the exposure limits recommended by national and international agencies for occupational environments, however, FA concentrations were above the more restrictive limit (3.30 µg m−3) stablished by Texas Commission on Environmental Quality (TCEQ) for long-term outdoor exposure. The lifetime cancer risks (LCR) found associated with the exposure of GS employees to these aldehydes over the 30-year period varied between 4.51 × 10−6-8.00 × 10−6 for FA and 2.46 × 10−6-6.60 × 10−6 for AA. These values are above the acceptable limit set by the USEPA (1.0 × 10−6), reinforcing the need for actions to minimize the occupational exposure, mainly to FA, which is associated with nasopharyngeal cancer.

Long-term Measurements of PM2.5 Concentrations in Lubbock, Texas

ABSTRACT Aerosol particles, such as PM2.5 (particulate matter with an aerodynamic diameter ≤ 2.5 µm), are an important yet variable component of our atmosphere; their presence defines the air quality and profoundly affects human health. In this project, we examine changes in the PM2.5 concentration, which is subject to temporal and spatial conditions and may vary by hour or day, in Lubbock, Texas, from 2001 to 2018. The hourly PM2.5 concentrations were measured at the local Texas Commission on Environmental Quality (TCEQ) station, analyzed for diurnal, weekly, monthly, seasonal, and yearly changes, and compared with meteorological parameters (such as the temperature, wind direction or speed, and visibility) recorded by the local National Weather Service station at Lubbock Preston Smith International Airport. In addition, we examined the effects of El Nino and La Nina on the PM2.5 concentration. The majority of the average daily PM2.5 values fell below the Environmental Protection Agency (EPA) daily threshold of 35 µg m–3, but many days exhibited high hourly concentrations, mainly due to dust storm events. No correlations were found between the concentrations and various meteorological parameters. Based on the hourly measurements, the diurnal distributions were bimodal, with morning and evening peaks, and the highest monthly averages were observed for April and June. A comparison of the PM2.5 concentrations during El Nino and La Nina revealed higher values during the latter, with the maximum concentrations occurring during weak La Ninas.

Geochemical Characterization of Base Metals in Stream Water and Sediments in the Caddo Lake Watershed, Cass, Harrison and Marion Counties, Texas

The Caddo Lake watershed is located in northeastern Texas and encompasses much of Cass, Harrison, and Marion counties. The watershed is drained by major streams and tributaries flowing in an easterly direction over Eocene-aged rocks and sediments of the Wilcox and Claiborne groups, and empty into the western arm of Caddo Lake. Since 1995, Caddo Lake and some of its tributaries have been included on the State of Texas Clean Water Act 303(d) list by the Texas Commission on Environmental Quality (TCEQ) for impairment due to mercury content in edible tissue, depressed dissolved oxygen, base metal concentrations, and low pH values. The purpose of this multi-year study was to characterize base metal concentrations in stream water and sediments in the Caddo Lake watershed, and document the potential watershed transport and contribution to the impairment of Caddo Lake. Recent water (n = 58) and sediment (n = 116) sampling at 29 sites revealed copper, lead, and zinc concentrations within normal limits and below EPA actionable standards. Mercury concentrations were elevated at 21 of the 29 sampling sites, which could lead to methylation and bioavailability to organisms at all trophic level.

Risk of Cancer for Workers Exposed to Antimony Compounds: A Systematic Review.

Background: Antimony (Sb) trioxide and antimony trisulfide are “2B: Possibly carcinogenic to humans” and “3: Unclassifiable” according to the International Agency for Research on Cancer (IARC). The U.S. National Toxicology Program (NTP) concluded that antimony trioxide “is reasonably anticipated to be a human carcinogen based on studies in rats and mice”. We investigated the cancer hazard of antimony compounds for workers, a population with high exposure to antimony substances. Methods: Using the “Guidelines for performing systematic reviews in the development of toxicity factors” (Texas Commission on Environmental Quality (TCEQ) 2017) as a guidance, we established a human and an animal toxicology data stream in Medline and ToxLine. Data from this review were applied in a human health risk assessment. Results: A final pool of 10 occupational and 13 animal toxicology articles resulted after application of TCEQ guidelines. Conclusions: Antimony carcinogenicity evidence involving workers is inadequate, based on confounding, small sample sizes, incomparability across studies, and inadequate reference populations. An increased lung cancer risk cannot be excluded. Evidence for lung neoplasms caused by antimony trioxide inhalation in experimental animals is sufficient. Overall, carcinogenicity in workers is probable (International Agency for Research on Cancer (IARC) 2A). It remains unclear from what occupational exposure duration and dose this effect arises and whether exposure threshold values should be reconsidered.

Is it time to crack down on ethylene oxide?

Ethylene oxide is a basic chemical building block for a slew of modern products, including plastics and medicines. This seven-atom molecule is the simplest epoxide. But not much is simple in the debate over how much of this flammable gas—which is carcinogenic when inhaled—is safe for the public to breathe. The issue is coming to a head now because the US Environmental Protection Agency is under a court-imposed deadline to revise, by early next year, regulations on hazardous air pollution for plants that manufacture ethylene oxide. On one side of this controversy are makers of ethylene oxide. They have found a partner in the Texas Commission on Environmental Quality (TCEQ) to support their assertion that the gas is a far less potent carcinogen than the EPA concluded in 2016. Texas is home to 5 of the nation’s top 10 emitters of ethylene oxide, according to 2017 chemical release data, the