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The presence of microplastics (MPs) in marine environments has been extensively documented. However, studies of terrestrial species are scarce. Fecal samples (105) of lagomorphs were collected at sites with different levels of urbanization in the Baja California Chaparral and analyzed to quantify and characterize MPs found in the feces. The lagomorph species recorded in the study area are the desert cottontail rabbit (Sylvilagus audubonii), brush rabbit (Sylvilagus bachmani), and black-tailed jackrabbit (Lepus californicus), which play important roles in the food web of the chaparral ecosystem. Microplastics were identified using attenuated total reflectance Fourier transform infrared spectroscopy. Microplastics were detected in 49 % of the samples, with fibers being the dominant shape found (72 %). Most (75 %) of the MPs were1 mm in size, with a mean length of 0.93 ± 0.99 mm (median 0.60 mm, range 0.02 -5 mm). Polyamide was the dominant polymer (54 %), indicating that MPs are likely derived from textiles; polyethylene was also abundant (27 %). A difference was also observed in the abundance of MPs in feces from sites with different levels of urbanization, with the highest abundance in feces from the urban sites.

Nanomaterials (NMs) solve specific problems with remarkable results in several industrial and scientific areas. Among NMs, silver nanoparticles (AgNPs) have been extensively employed as drug carriers, medical diagnostics, energy harvesting devices, sensors, lubricants, and bioremediation. Notably, they have shown excellent antimicrobial, anticancer, and antiviral properties in the biomedical field. The literature analysis shows a selective cytotoxic effect on cancer cells compared to healthy cells, making its potential application in cancer treatment evident, increasing the need to study the potential risk of their use to environmental and human health. A large battery of toxicity models, both in vitro and in vivo, have been established to predict the harmful effects of incorporating AgNPs in these numerous areas or those produced due to involuntary exposure. However, these models often report contradictory results due to their lack of standardization, generating controversy and slowing the advances in nanotoxicology research, fundamentally by generalizing the biological response produced by the AgNP formulations. This review summarizes the last ten years’ reports concerning AgNPs’ toxicity in cellular respiratory system models (e.g., mono-culture models, co-cultures, 3D cultures, ex vivo and in vivo). In turn, more complex cellular models represent in a better way the physical and chemical barriers of the body; however, results should be used carefully so as not to be misleading. The main objective of this work is to highlight current models with the highest physiological relevance, identifying the opportunity areas of lung nanotoxicology and contributing to the establishment and strengthening of specific regulations regarding health and the environment.

2020 broke records for the most active fire year on the West Coast, resulting in the worst air quality observed in decades. Concurrently, the public health threat of COVID-19 caused over 1 million deaths in the United States (US) and Mexico in 2020 and 2021. Due to the effect of air pollution on respiratory diseases, wildfire-specific particulate matter is a hypothesized driver of COVID-19 severity and death. Capitalizing on wildfire smoke that hit the San Diego-Tijuana border region in September 2020, we applied synthetic control methods to explore its potential differential role in affecting COVID-19 mortality on both sides of the border. Daily data on COVID-19 cumulative deaths for US counties were obtained from the CDC COVID tracker and data for Mexican municipalities was obtained from the Mexican Secretary of Health. Counties and municipalities with wildfire smoke exposure were identified using the National Oceanic and Atmospheric Administration hazard mapping smoke product (HMS); a day where 90% of the area was covered by smoke was considered exposed for the main analyses. Unexposed counties/municipalities were considered as potential controls. The San Diego-Tijuana border region was covered by dense smoke by the 7th of September; 707 COVID-19 deaths had occurred in San Diego and 1367 in Tijuana. While a slight increase in cumulative mortality was observed in San Diego, no change was found in Tijuana; neither estimate indicated a strong precise effect of wildfire smoke on COVID-19 mortality. We hope this study will serve as an illustration of how border contexts can be used to investigate differential vulnerability to wildfire smoke for infectious diseases. Examining the interactive effect of COVID-19 and smoke can help in recognizing the implications of these dual health risks which will be increasingly important as wildfires become more frequent and severe in the context of climate change.

At US-Mexico border Ports of Entry, vehicles idle for long times waiting to cross northbound into the US. Long wait times at the border have mainly been studied as an economic issue, however, exposures to emissions from idling vehicles can also present an exposure risk. Here we present the first data on in-vehicle exposures to driver and passengers crossing the US-Mexico border at the San Ysidro, California Port of Entry (SYPOE). Participants were recruited who regularly commuted across the border in either direction and told to drive a scripted route between two border universities, one in the US and one in Mexico. Instruments were placed in participants' cars prior to commute to monitor-1-minute average levels of the traffic pollutants ultrafine particles (UFP), black carbon (BC) and carbon monoxide (CO) in the breathing zone of drivers and passengers. Location was determined by a GPS monitor. Results reported here are for 68 northbound participant trips. The highest median levels of in-vehicle UFP were recorded during the wait to cross at the SYPOE (median 29,692particles/cm3) significantly higher than the portion of the commute in the US (median 20,508particles/cm3) though not that portion in Mexico (median 22, 191particles/cm3). In-vehicle BC levels at the border were significantly lower than in other parts of the commute. Our results indicate that waiting in line at the SYPOE contributes a median 62.5% (range 15.5%-86.0%) of a cross-border commuter's exposure to UFP and a median 44.5% (range (10.6-79.7%) of exposure to BC inside the vehicle while traveling in the northbound direction. Reducing border wait time can significantly reduce in-vehicle exposures to toxic air pollutants such as UFP and BC, and these preventable exposures can be considered an environmental justice issue.