First evidence of microplastic contamination in ready-to-use packaged food ice cubes.

Concern over microplastics has grown tremendously, and they have been found in all environmental compartments; yet, much remains unknown regarding their impact on a variety of human-consuming food products. Here, we contribute to ongoing research by screening the 15 most popular commercial brands of packaged food ice cubes in Mexico City for microplastics. Microplastics were detected in 100% of the samples evaluated, with concentrations ranging from 19 ± 4 to 178 ± 78 L-1. There was a significant difference in the microplastic concentration across samples. The mean microplastic concentration was 79 ± 47 L-1, and the main types were polypropylene, polyethylene, polyvinyl alcohol, tygon polymer, sealing ring gardena 2824 large, polyamide 6, and cellophane. Moreover, microplastics that are fibrous (87%), non-colored (54%), and less than 300 µm in size (63%), were found to be more prevalent. The SEM-EDX analysis showed heterogeneous structural and morphological characteristics of microplastics, as well as traces of Si, S, Ti, Ca, Al, and Na. Furthermore, we estimate that ice cube consumption in Mexico City can result in the inadvertent ingestion of 4.9 × 102 ± 3.4 × 102-1 × 104 ± 7.2 × 103 microplastics annually. The findings of the study revealed that microplastics were identified in ice cubes and can be conveyed to humans, stressing the need of managing and eradicating such contamination from our food.

Free, but not microplastic-free, drinking water from outdoor refill kiosks: A challenge and a wake-up call for urban management.

Free refill drinking water kiosks are an essential sustainable water supply system for people in metropolitan areas worldwide. Despite their importance in urban settings, the impact of microplastic contamination remains elusive. Here, we investigated the occurrence and characteristics of microplastics in drinking-water samples collected from 22 self-distributed refill kiosks located in 14 multiuse urban parks spread across nine municipalities in Mexico City (Mexico). The results showed that microplastics were detected in all the samples, with an overall mean concentration of 74.18 ± 48.76 microplastics L-1. The abundance of microplastics was significantly different between sampled kiosks, ranging from 23 ± 11.31 to 202 ± 28.39 microplastics L-1. There were more fibrous microplastics (88%) than fragments (9%) and films (3%), with the majority (56%) being <200 µm in length. They were predominantly transparent (85%), with only a few being colored (15%; blue, red, green, and brown). Attenuated Total Reflection-Fourier-transform infrared spectroscopy further revealed microplastics of various polymer types, including polyvinyl alcohol, high-density polyethylene, polypropylene, polyvinyl acetate, ethylene vinyl alcohol, acrylic, alkyd resin, and viscose. Based on our findings, drinking water from urban refill kiosks exposes children more than adults to microplastics. Furthermore, the steps that should be taken at urban refill kiosks to prevent microplastic pollution while offering recreational services to people have been highlighted. Therefore, this first study serves as a wake-up call to urban water management to improve the safety of water from emerging pollutants like microplastics in the infrastructure of refill kiosks.

Toward a unified framework for investigating micro(nano)plastics in packaged beverages intended for human consumption.

The continuously increasing presence of micro- and nanoplastics contamination in numerous food products for human consumption is threatening and their potential health effects towards humans remain uncertain. At present, investigations on packaged beverages (e.g. bottled drinking water, beer, milk and refreshments) have received scientific attention and represent an important part of microplastic research as humans are orally exposed to these anthropogenic contaminants every day. Rapid and effective detection methods are important to quantify micro- and nanoplastic particles with a great accuracy as well as to identify their sources and characteristics. A number of methods are currently in use to assess microplastics in packaged beverages; however, the great variations in methods and data acquisition render difficulties when comparing the results and developing the protocols. Based on the challenges, this paper aims to provide a comprehensive understanding of emerging technological approaches, points out the current limitations from sample preparation to quantification and present recommendations. From the results of our analysis, we postulate an example framework that can be applied to different types of drinking products for investigating micro- and nanoplastics. Overall, this review will serve as a first step towards harmonization of micro- and nanoplastic monitoring efforts and a point of reference to help direct future researches focusing on drinking products intended for human consumption.

Impacts of the COVID-19 lockdown on air quality and its association with human mortality trends in megapolis Mexico City.

Mexico City is the second most populated city in Latin America, and it went through two partial lockdowns between April 1 and May 31, 2020, for reducing the COVID-19 propagation. The present study assessed air quality and its association with human mortality rates during the lockdown by estimating changes observed in air pollutants (CO, NO2, O3, SO2, PM10 and PM2.5) between the lockdown (April 1-May 31) and prelockdown (January 1-March 31) periods, as well as by comparing the air quality data of lockdown period with the same interval of previous 5 years (2015-2019). Concentrations of NO2 (- 29%), SO2 (- 55%) and PM10 (- 11%) declined and the contents of CO (+ 1.1%), PM2.5 (+ 19%) and O3 (+ 63%) increased during the lockdown compared to the prelockdown period. This study also estimated that NO2, SO2, CO, PM10 and PM2.5 reduced by 19-36%, and O3 enhanced by 14% compared to the average of 2015-2019. Reduction in traffic as well as less emission from vehicle exhausts led to remarkable decline in NO2, SO2 and PM10. The significant positive associations of PM2.5, CO and O3 with the numbers of COVID-19 infections and deaths, however, underscored the necessity to enforce air pollution regulations to protect human health in one of the important cities of the northern hemisphere. Graphical abstract.

Review of current trends, advances and analytical challenges for microplastics contamination in Latin America.

Microplastics accumulation is an emerging environmental issue and a threat to marine life and human health. There is a growing number of investigations on the abundance and distribution of microplastics in different water bodies and biota worldwide, with relatively few studies conducted in Latin America, however, the current knowledge of microplastics sources, occurrence, transport, fate and potential impacts remains largely unexplored. This review presents the current trends and advances of microplastics on a lesser known region of the world by compiling the research performed to date in different environmental compartments. The sampling techniques and methods for microplastics extraction in the existing literature data are also summarized. Among 78 published studies reviewed, 34% of studies were from Brazil and 46% of studies have mainly focused on biota. The main findings showed that microplastics are not negligible across Latin America significantly varying in their distribution, with the prevalence of fibers comprising 62% of the total. Polyethylene, polypropylene, polyethylene terephthalate and polystyrene have been identified as the most common polymer types, accounting for 80% of the total. Limited studies and lack of standardized methodologies render difficulties to establish fundamental information on microplastics abundance and types in most countries of this region. Therefore, this review will primarily serve as a baseline when evaluating the environmental relevance of microplastics in Latin America and would stimulate discussions focusing on this topic, calling for more research in future.

Identification and characterization of single use oxo/biodegradable plastics from Mexico City, Mexico: Is the advertised labeling useful?

The compositional characterization of single-use plastics (SUPs), often advertised as biodegradable (B) and oxo-biodegradable (OB), is an important step towards plastic pollution mitigation through the formulation of appropriate (re) use and disposal strategies. We present here the very first study to screen daily SUPs in Mexico through comprehensive characterizations of 33 randomly collected samples (B and OB) of high consumption, with or without food contact, from the markets (n = 80), bakeries (n = 5), pharmacies (n = 5) and near public transportation systems (n = 2) across 16 municipalities of Mexico City, using the polymer composition, metal contents and thermal properties. These SUPs are composed of 85% high-density polyethylene and 15% low-density polyethylene, with significant inorganic additives, and all of them show variable thermal degradation behavior. Among the twenty five different metals identified, most of the SUPs exceed the standard international norms (94/62/EC; EN 13432; 2016/1416; ASTM D6400-04) for Cu, Cr, Mo, Zn, Fe and Pb with the maximum concentrations of 1898 mg/kg, 1586 mg/kg, 95 mg/kg, 1492 mg/kg, 1900 mg/kg and 7528 mg/kg, respectively. Our findings uncovered that the collected SUPs from Mexico City did not have the suitable physicochemical characteristics and they might end up adding to the exponentially growing solid waste in the immediate future. Hence, we recommend the implementation of strict norms to certify the SUPs.

First study of its kind on the microplastic contamination of soft drinks, cold tea and energy drinks - Future research and environmental considerations.

Investigating wide range of food products of direct human consumption for microplastics is critical to understand the routes of contamination and assess the risks in microplastics uptake by humans. However, microplastics knowledge for many beverage products excluding beers is still lacking. Here, common beverages (n = 57; 27 brands) such as soft drinks (n = 19), energy drinks (n = 8), cold tea (n = 4) and beer (n = 26) were targeted for microplastics occurrences in Mexico and their shape, size, surface morphology and polymer composition were analyzed. Microplastics were detected in 48 out of 57 samples tested. The results identified microplastics of various forms (fibers and fragments) and sizes (0.1-3 mm) of colors (blue, red, brown, black and green), in amounts ranging from not detected to 28 ± 5.29 particles/L. Micro-Raman spectroscopy identified particles as polyamide, poly(ester-amide), acrylonitrile-butadiene-styrene and poly(ethylene-terephthalate) indicating microplastics contamination of synthetic textiles and packaging origin in the beverage products. Finally, this paper discusses that human excreta could act as a vehicle for the dispersion and accumulation of microplastics into terrestrial and aquatic environments. Combined, it is the first study to investigate microplastics contamination on soft drinks, energy drinks and cold tea and to document the material composition of microplastics from beverage products.

Branded milks - Are they immune from microplastics contamination?

The widespread dispersal of microplastic (plastic particle <5 mm) contamination in human food chain is gaining more attention in the public arena and scientific community. Better assessment of diversified consumer products is a key for combating problems related to microplastic contamination. To the best of our knowledge, no study has been conducted on dairy milk products, and the current research status of microplastics is lacking. Here, a total of 23 milk samples (22 adult and 1 kid) from 5 international and 3 national brands of Mexico was collected and tested for the occurrence of microplastics. Results confirmed the ubiquity of microplastics in the analyzed samples and showed variability ranging between 3 ± 2-11 ± 3.54 particles L-1 with an overall average of 6.5 ± 2.3 particles L-1 which are lower than any reported levels in liquid food products. Microplastic particles exhibited variety of colors (blue, brown, red and pink), shapes (fibers and fragments) and sizes (0.1-5 mm). Among which, blue colored fibers (<0.5 mm) were predominant. Micro-Raman identification results revealed that thermoplastic sulfone polymers (polyethersulfone and polysulfone) were common types of microplastics in milk samples, which are highly used membrane materials in dairy processes. Thus, this study findings developed a baseline outlook for microplastics contamination in dairy products and posed a great deal to take necessary controls and preventive measures to avoid them.