Microplastics in settled indoor dust: Implications for human exposure

Airborne transmission is one of the environmental dissemination pathways of antibiotic resistance genes (ARGs), and has critical implications for human exposure through inhalation. In this study, we focused on three regions of China to reveal some unique spatiotemporal features of airborne bacteria and ARGs in fine aerosols (PM2.5): (1) greater seasonal variations in the abundance of bacteria and ARGs in temperate urban Beijing than in the subtropical urban areas of the Yangtze River Delta (YRD) and Pearl River Delta (PRD) regions, with regional disparities in bacterial communities; (2) geographical fingerprints of ARG profiles independent of seasonal cycles and land-use gradients within each region; (3) region-independent associations between the targeted ARGs and limited bacterial genera; (4) common correlations between ARGs and mobile genetic elements (MGEs) across regions; and (5) PM2.5 at the higher end of ARG enrichment across various environmental and human media. The spatiotemporally differentiated bacterial communities and ARG abundances, and the compositions, mobility, and potential hosts of ARGs in the atmosphere have strong implications for human inhalational exposure over spatiotemporal scales. By comparing other contributing pathways for the intake of ARGs (e.g., drinking water and food ingestion) in China and the U.S.A., we identified the region-specific importance of inhalation in China as well as country-specific exposure scenarios. Our study thus highlights the significance of inhalation as an integral part of the aggregate exposure pathways of environmentally disseminated ARGs, which, in turn, may help in the formulation of adaptive strategies to mitigate the exposure risks in China and beyond.

Microplastic contamination in seafood has emerged as a significant concern for public health and food safety. Bivalve molluscs are especially vulnerable because of their filter-feeding behaviour, leading to the accumulation of different substances in seawater, including contaminants like microplastics. This study examines microplastic contamination by comparing commercially available ready-to-cook frozen and deep-frozen clams, assessing particle morphologies, dimensions, colours, and chemical identities. The Polymer Hazard Index (PHI) derived from the proportions of polymers in the samples and their hazard scores, whereas the Estimated Average Daily Intake (EADI) was determined based on per capita consumption and microplastic counts. The results indicated a significantly higher prevalence of microplastics in deep-frozen clams compared to frozen clams, with 2.58 ± 0.87 and 0.43 ± 0.13, respectively. EADI was estimated at 0.47 and 0.76 MP/kg(bw)/day for deep-frozen clams and frozen clams, respectively (before cooking). Our findings highlight the influence of industrial processing on microplastic contamination, other than the environmental contribution, with considerable implications for human exposure, underscoring the necessity for monitoring initiatives and regulatory policies to reduce microplastic exposure in seafood, thereby safeguarding food safety and public health.

Particle size: A missing factor in risk assessment of human exposure to toxic chemicals in settled indoor dust

Contaminants in settled indoor dust are potentially health hazardous to human. Thus, identification and quantification of toxic chemicals in settled indoor dust is of great concern. In this study, the levels of major anions ([Formula: see text]), trace metals (Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, As and Pb) and polybromodiphenyl ethers (PBDEs) in settled office and home dust were determined and correlations between the contaminants investigated. Depending on the available materials in both microenvironments, the most possible sources were identified. The results showed that the settled office dusts (n = 6 pooled samples from 85 offices) were more contaminated than home dusts (n = 8 homes). For anions, [Formula: see text] and Cl(-) accounted for 87 and 97% of the total office and home dust contaminants, respectively. For trace metals, Fe, Cu, Zn and Mn, accounted for 98% of the contaminants in both office and home dust samples. Fe exhibited the highest percentage of 76.7 and 87.3% in office and home dust samples, respectively. For PBDEs, the mean concentrations detected in office and home dust ranged between 5.8-86.3 and 1.5-20.6 ng g(-1), respectively. The log-transformed correlation between the total concentrations of trace metals and major anions detected in offices and homes was positive for offices and negative for homes with a statistically significant values (r = 0.73, p < 0.01; r = -0.22, p < 0.01, respectively). The daily exposure rates determined for the most hazardous such as As, Cd, Pb and PBDEs congeners, relative to the individual concentrations reported in the literature in settled indoor dust, were found very lower. Therefore, maybe it is possible to expect less potential health risk. Investigation of formation of coordination compounds between trace metals and PBDEs congeners is possible; however, this requires further study.

A review of organophosphate esters in indoor dust, air, hand wipes and silicone wristbands: Implications for human exposure

Corrigendum to "A review of organophosphate esters in indoor dust, air, hand wipes and silicone wristbands: Implications for human exposure" [Environ. Int. 146 (2021) 106261

Organophosphate di- and tri-esters in indoor and outdoor dust from China and its implications for human exposure

Dust samples were collected in Beijing, China, from four different indoor microenvironments (office, hotel, kindergarten, and student dormitory) and one outdoor (road dust) microenvironment. These five composite samples were fractionated into 13 sequential size fractions and an individual fraction of <50 μm for further analysis. In the fractions of <50 μm, nine phosphorus flame retardants (∑PFRs), four novel brominated flame retardants (∑NBFRs), and two Dechlorane Plus isomers (DPs) showed the highest concentrations in hotel dust (124,000 ng g(-1)), dormitory dust (14,200 ng g(-1)), and kindergarten dust (231 ng g(-1)), respectively. Nevertheless, nine polybrominated diphenyl ethers (∑PBDEs) were the dominant flame retardants (FRs) (96% of total FRs) in road dust, with the maximum concentration of 23,700 ng g(-1), higher than in any indoor dust. The FR contamination varied strongly among different types of microenvironments, leading to high human exposure to various FRs. Concentrations of FRs did not increase constantly with a particle size decrease. Fractions with a particle size around 900, 100, and 10 μm could represent peak values, while valley values were commonly detected around fractions with a particle size around 40 μm. Large differences were found between indoor dust and road dust. In road dust, FRs were mainly enriched in fractions of <50 μm. The organic content of dust, FR application, and consequent abrasion processes of FR-containing materials might be the determinants of the FR concentrations. Volatilization and abrasion were considered to be important migration pathways for FRs. DPs and BDE-209 were sought to be mainly applied in abrasion-proof materials, while most phosphorus flame retardants (PFRs) were probably added in a large proportion in materials easy to wear.

Microplastic occurrence in settled indoor dust in schools

Occurrence of bisphenol A and its alternatives in paired urine and indoor dust from Chinese university students: Implications for human exposure

Per- and polyfluoroalkyl substances (PFASs) were analyzed in outdoor (n = 101) and indoor dust (n = 43, 38 paired with outdoors) samples across mainland China. From 2013 to 2017, the median concentration of ∑PFASs in outdoor dust tripled from 63 to 164 ng/g with an elevated contribution of trifluoroacetic acid and 6:2 fluorotelomer alcohol. In 2017, the indoor dust levels of ∑PFASs were in the range 185-913 ng/g, which were generally higher than the outdoor dust levels (105-321 ng/g). Emerging PFASs were found at high median levels of 5.7-97 ng/g in both indoor and outdoor dust samples. As first revealed by the total oxidized precursors assay, unknown perfluoroalkyl acid (PFAA)-precursors contributed 37-67 mol % to the PFAS profiles in indoor dust samples. A great proportion of C8 PFAA-precursors were precursors for perfluorooctanesulfonic acid, while C6 and C4 PFAA-precursors were mostly fluorotelomer based. Furthermore, daily perfluorooctanoic acid (PFOA) equivalent intakes of PFAAs (C4-C12) mixtures via indoor dust were first estimated at 1.3-1.5 ng/kg b.w./d for toddlers at high scenarios, which exceeds the derived daily threshold of 0.63 ng/kg b.w./d. from the European Food Safety Authority (EFSA). On this basis, an underestimation of 56%-69% likely remains without considering potential risks due to the biotransformation of unknown PFAA-precursors.

A review on organophosphate flame retardants in indoor dust from China: Implications for human exposure

In order to determine human exposure to the indoor toxicant, selection of dust fraction and understanding dust particle size distribution in settled indoor dust are very important. This study examined the influence of dust particle size on the concentration of polybrominated diphenyl ethers (PBDEs) congeners, assessed the distribution of dust particle size and characterized the main indoor emission sources of PBDEs. Accordingly, the concentrations of PBDE congeners determined in different indoor dust fractions were found to be relatively higher in the order of dust particle size: 45-106 μm>(<45 μm)>106-150 μm. The finding shows arbitrary selection of dust fractions for exposure determination may result in wrong conclusions. Statistically significant moderate correlation between the concentration of Σ9PBDEs and organic matter content calculated with respect to the total dust mass was also observed (r=0.55, p=0.001). On average, of total dust particle size <250 μm, 93.4 % (m/m%) of dust fractions was associated with less than 150 μm. Furthermore, of skin adherent dust fractions considered (<150 μm), 86 % (v/v%) is in the range of particle size 9.25-104.7 μm. Electronic materials treated with PBDEs were found the main emission sources of PBDE congeners in indoor environment. Based on concentrations of PBDEs determined and mass of indoor dust observed, 150 μm metallic sieve is adequate for human exposure risk assessment. However, research in this area is very limited and more research is required to generalize the fact.

The concentration of grass‐pollen allergens in settled dust was measured over a period of 11 weeks in ten homes, five situated in an urban area and five in a rural area, in southwestern Finland during the summer of 1995. Dust samples were collected once a week, using a vacuum cleaner equipped with a special collection device (ALK, Copenhagen) and with a replaceable glass‐fiber filter in a filter dish. All dust samples were analyzed by means of an IgG‐ELISA‐procedure using murine monoclonal antibodies. The allergenic activity of grass pollen in settled indoor dust was low compared with that of birch pollen previously analyzed in the same area. Counts of airborne pollen used in comparison were obtained from the Burkard sampling station in Turku. The grass pollen season is not continuous in this area, but has sporadic relatively low peaks, because a variety of grass species flower at different times. Airborne grass pollen counts in Turku exceeded the threshold value of abundant (> 30 grains per cubic metre of air, Rantio‐Lehtimaki et al. 1991) only six times during the investigation period. The highest concentration of indoor allergenic activity was found about 3 weeks after the grass pollen peak. The allergenic activity of settled outdoor dust intercorrelated with the activity in settled indoor dust. This study supports the assumption that grass pollen antigens are carried home by people and pets. The concentration of grass‐pollen antigens resuspended in the air from settled dust may sporadically reach a level which provokes symptoms in allergic persons.

Occurrence and fate of organophosphate ester flame retardants and plasticizers in indoor air and dust of Nepal: Implication for human exposure