Organophosphate flame retardants in the indoor air and dust in cars in Japan

Concentrations of potentially endocrine disrupting chemicals in car cabin air and dust - Effect of temperature and ventilation

Materials in car cabins contain performance-enhancing semi-volatile organic compounds (SVOCs). As these SVOCs are not chemically bound to the materials, they can emit from the materials at slow rates to the surrounding, causing human exposure. This study aimed at increasing the understanding on abundance of SVOCs in car cabins by studying 18 potential endocrine disrupting chemicals in car cabin air (gas phase and airborne particles) and dust. We also studied how levels of these chemicals varied by temperature inside the car cabin along with ventilation settings, relevant to human exposure. A positive correlation was observed between temperature and SVOC concentration in both the gas and the particle phase, where average gas phase levels at 80 °C were a factor of 18-16,000 higher than average levels at 25 °C, while average particle phase levels were a factor of 4.6-40,000 higher for the studied substances. This study also showed that levels were below the limit of detection for several SVOCs during realistic driving conditions, i.e., with the ventilation activated. To limit human exposure to SVOCs in car cabins, it is recommended to ventilate a warm car before entering and have the ventilation on during driving, as both temperature and ventilation have a significant impact on SVOC levels.

Flame Retardant Exposure in Vehicles Is Influenced by Use in Seat Foam and Temperature

Flame retardants (FRs) are added to vehicles to meet flammability standards, such as US Federal Motor Vehicle Safety Standard FMVSS 302. However, an understanding of which FRs are being used, sources in the vehicle, and implications for human exposure is lacking. US participants (n = 101) owning a vehicle of model year 2015 or newer hung a silicone passive sampler on their rearview mirror for 7 days. Fifty-one of 101 participants collected a foam sample from a vehicle seat. Organophosphate esters (OPEs) were the most frequently detected FR class in the passive samplers. Among these, tris(1-chloro-isopropyl) phosphate (TCIPP) had a 99% detection frequency and was measured at levels ranging from 0.2 to 11,600 ng/g of sampler. TCIPP was also the dominant FR detected in the vehicle seat foam. Sampler FR concentrations were significantly correlated with average ambient temperature and were 2-5 times higher in the summer compared to winter. The presence of TCIPP in foam resulted in ∼4 times higher median air sampler concentrations in winter and ∼9 times higher in summer. These results suggest that FRs used in vehicle interiors, such as in seat foam, are a source of OPE exposure, which is increased in warmer temperatures.

Dust dynamics: distribution patterns of semi-volatile organic chemicals across particle sizes in varied indoor microenvironments

An extensive analysis of the distribution patterns of three distinct classes of semi-volatile organic chemicals (SVOCs)-phthalates (PAEs), organophosphate flame retardants (OPFRs), and polycyclic aromatic hydrocarbons (PAHs)-across four distinct size fractions of dust (25, 50, 100, and 200 μm) was conducted. The dust samples were sourced from AC filter, covered car parking lots, households, hotels, mosques, and car floors. To generate the four fractions, ten dust samples from each microenvironment were pooled and sieved utilizing sieving apparatus with the appropriate mesh size. Selected SVOCs were quantified utilizing gas chromatography-mass spectrometry in electron impact (EI) mode. Results unveiled diverse contamination levels among dust fractions, showcasing car parking lot dust with the lowest chemical contamination, while car floor dust displayed the highest levels of PAHs and OPFRs, peaking at 28.3 µg/g and 43.2 µg/g, respectively. In contrast, mosque and household floor dust exhibited the highest concentrations of phthalates, with values of 985 µg/g and 846 µg/g, respectively. Across the analyzed microenvironments, we observed a trend where concentrations of SVOCs tended to rise as dust particles decreased in size, forming a visually striking pattern. This phenomenon was particularly pronounced in dust samples collected from car floors and parking lots. Among SVOCs, PAEs emerged as the predominant contributors with > 90% followed by OPFRs and PAHs. The high levels of OPFRs in car floor dust align logically with the fact that numerous interior components of cars are treated with OPFRs, within a compact indoor microenvironment, to comply to fire safety regulations. Furthermore, petroleum products are a major source of PAHs in the environment and all the sampled cars in the study had combustion engines. Consequently, car dust is more likely to be polluted with PAHs stemming from petroleum combustion. Although previous investigations have noted an increase in heavy metals and brominated flame retardants with decreasing dust particles, this is the first study analyzing these SVOCs in different fractions of dust from various microenvironments. However, aside from two specific microenvironments, the observed pattern of escalating SVOC concentrations with smaller dust particle sizes was not corroborated among the examined microenvironments. This divergence in concentration trends suggests the potential involvement of supplementary variables in influencing SVOC distributions within dust particles.

Occurrence and Release of Organophosphite Antioxidants and Novel Organophosphate Esters from Plastic Food Packaging

Organic phosphite antioxidants (OPAs) are widely added in plastic products and can be oxidized to generate oxidized derivatives (OPAs = O), namely organic phosphate esters (OPEs), during production and use processing. Herein, the occurrence of OPEs and OPAs in five plastic food packages was detected by liquid chromatography-tandem mass spectrometry. Three OPEs (TPhP, TCEP, and AO168 = O) and three OPAs (TPhPi, TCEPi, and AO168) were found in the plastic packages, with concentrations of <MQL-124 ng/g (∑₃OPAs) and 196-831 ng/g (∑₃OPEs), respectively. The migration potential of OPAs and OPEs to food was measured by simulation experiments. OPAs and OPEs in plastic can efficiently migrate to oily simulants, alkaline simulants, and acidic simulants. After 14 days, the total concentration of all OPAs and OPEs in the food simulants reached <MQL-1.21 (acidic food simulants), <MQL-0.32 (alkaline food simulants), and 11.4-31.4 ng/mL (oily food simulants), respectively. OPAs and OPEs in 12 kinds of plastic-packaged foods were detected, with high concentrations in dairy food (∑₃OPAs + ∑₃OPEs: 18.3-28.9 ng/mL) and in oils (∑₃OPAs + ∑₃OPEs: 32.7-60.9 ng/mL). Accordingly, the estimated ingestion of OPAs and OPEs through plastic-packaged food can reach 2.6 and 32.7 ng/kg in children and 1.1 and 6.5 ng/kg in adults, indicating a non-negligible exposure risk of organic phosphorus pollutants.

Partial dust removal in vehicles does not mitigate human exposure to organophosphate esters

Organophosphate esters (OPEs) have been detected within car interior dust, suggesting that the indoor microenvironment of vehicles may represent a potential route of human exposure to OPEs. We recently showed that people with longer commutes are exposed to higher concentrations of tris(1,3-dichloro-2-isopropyl)phosphate (TDCIPP) - a widely used OPE - and other studies have suggested that dust removal may lead to lower exposure to chemicals. Therefore, the overall objective of this study was to determine if a decrease in interior car dust results in mitigation of personal OPE exposure. Participants (N = 49) were asked to wear silicone wristbands, and a subset of them wiped interior parts at the front of their vehicles prior to one study week (N = 25) or both study weeks (N = 11). There were no significant differences in total OPE concentrations (77.79-13,660 ng/g) nor individual OPE concentrations (0.04-4852.81 ng/g) across the different wiping groups nor in relation to participant residence ZIP codes and AC/Heater usage. These findings suggest that higher exposure to TDCIPP for participants with longer commutes may be independent of dust located on interior parts at the front of the vehicle. Therefore, our study demonstrates that there is a need for research on the potential contribution of other sources of TDCIPP exposure within car interiors.

Fast and Environment-Friendly GC-MS Method for Eleven Organophosphorus Flame Retardants in Indoor Air, Dust, and Skin Wipes

Organophosphorus based flame retardants (OPFRs) extensively used as alternatives to banned polybrominated diphenyl ethers and hexabromocyclododecane have been garnering interest due to the possibility that these compounds may have less significant impact on human and environmental health. Long pretreatment time, larger consumption of organic solvents, matrix interferents, and cross-contamination were found in previous studies while assessing OPFRs in indoor environments. We developed and optimized the extraction methods and simultaneous analysis of 11 OPFRs in indoor air, dust and skin wipe samples using the GC-MS approach. The proposed methods were validated using a standard addition approach, dust SRM 2585 and the real samples. Our procedures enabled the analyst to effectively limit coextracted interferences and simultaneous analytical methods of 11 target OPFRs for three matrices were achieved. The validation was performed according to standard guidelines (relative errors were identified by the analytes: −19% to 18% for indoor air, −11% to 14% for house dust, −15% to 16% for skin wipe). Good practices for quality assurance and quality control were well stated. The current high-Eco-scored methods could be categorized as “an excellent green analysis”. All analytes for the target OPFRs were detected in the real samples of indoor air, house dust and skin wipe collected from ten Taiwanese homes. Tris(2-butoxyethyl) phosphate, tris(1,3-dichloro-2-propyl)phosphate and tris(chloroisopropyl) phosphate were the most abundant OPFRs. Rapid, green and cost-effective GC-MS methods were developed and validated for the analysis of eleven OPFRs in indoor air, house dust and skin wipes.

Assessing exposure of semi-volatile organic compounds (SVOCs) in car cabins: Current understanding and future challenges in developing a standardized methodology

Semi-volatile organic compounds (SVOCs) can be found in air, dust and on surfaces in car cabins, leading to exposure to humans via dust ingestion, inhalation, and dermal contact. This review aims at describing current understanding concerning sampling, levels, and human exposure of SVOCs from car cabin environments. To date, several different methods are used to sample SVOCs in car cabin air and dust and there are no standard operating procedures for sampling SVOCs in cars detailed in the literature. The meta-analysis of SVOCs in car cabin air and dust shows that brominated flame retardants (BFRs) and organophosphate flame retardants (OPFRs) have been most frequently studied, primarily focusing on concentrations in dust. In dust, detected concentrations span over three to seven orders of magnitude, with highest median concentrations for OPFRs, followed by BFRs and, thereafter, polychlorinated biphenyls (PCBs). In air, the variation is smaller, spanning over one to three orders of magnitude, with phthalates and siloxanes having the highest median concentrations, followed by OPFRs, fluorotelomer alcohols (FTOHs) and BFRs. Assessments of human exposures to SVOCs in cars have, so far, mainly focused on external exposure, most often only studying one exposure route, primarily via dust ingestion. In order to perform relevant and complete assessments of human exposure to SVOCs in cars, we suggest broadening the scope to which SVOCs should be studied, promoting more comprehensive external exposure assessments that consider exposure via all relevant exposure routes and making comparisons of external and internal exposure, in order to understand the importance of in-car exposure as a source of SVOC exposure. We also suggest a new sampling approach that includes sampling of SVOCs in both car cabin air and dust, aiming to reduce variability in data due to differences in sampling techniques and protocols.

Spatial pattern analysis reveals multiple sources of organophosphorus flame retardants in coastal waters

Organophosphorus flame retardants (PFRs) are a group of emerging contaminants which have been detected in worldwide waters. However, source of various PFRs in the large-scale area like coastal water environment have not been clearly revealed. In this study, fifteen PFRs in coast of Guangdong-Hong Kong-Macao Greater Bay area (GBA), China were investigated, and a method of spatial pattern analysis was firstly used for pollution source identification. Seawater samples from different segments of GBA coast were analyzed and thirteen PFRs were quantified with total concentrations ranging from 32.7 to 1032.7 ng L^-1. GBA coasts have been seriously polluted by PFRs. A hierarchical cluster analysis of the PFR concentrations in different GBA sites showed significant spatial distributions for different types of PFRs. A series of correlation analysis between PFRs distributions and spatial pattern of GBA socio-economic indicators were performed, and multiple sources including human settlement, wastewater, manufacture, construction industry, vehicles, and shipping transport were found to be correlated to PFRs pollutions in the coasts. This study indicates that spatial pattern analysis based on statistical analysis would be a promising method of analyzing environmental data and exploring pollution source in large-scale area.

ATR-FTIR and LC-Q-ToF-MS analysis of indoor dust from different micro-environments located in a tropical metropolitan area

Indoor dust is an important matrix that exposes humans to a broad spectrum of chemicals. The information on the occurrence of contaminants of emerging concern (CECs), their metabolites, and re-emerging contaminants in indoor dust is rather limited. As the indoor environment is exposed to various chemicals from personal care products, furniture, building materials, machineries and cooking/cleaning products, there is a high chance of the presence of hazardous contaminants in indoor dust. In the present study, dust samples were collected from four different micro indoor environments (photocopying centres, residential houses, classrooms, and ATM cabins) located in an urban environment located in India's southwestern part. The collected samples were subjected to ATR - FTIR and LC-Q-ToF-MS analyses. The ATR - FTIR analysis indicated the presence of aldehydes, anhydrides, carboxylic acids, esters, sulphonic acids, and asbestos - a re-emerging contaminant. A total of 19 compounds were identified from the LC-Q-ToF-MS analysis. These compounds belonged to various classes such as plasticisers, plasticiser metabolites, photoinitiators, personal care products, pharmaceutical intermediates, surfactants, and pesticides. To the best of our knowledge, this is the first report regarding the presence of CECs in indoor environments in Kerala and also the suspected occurrence of pesticides (metaldehyde and ethofumesate) in classroom dust in India. Another important highlight of this work is the demonstration of ATR-FTIR as a complementary technique for LC-Q-ToF-MS in the analysis of indoor pollution while dealing with totally unknown pollutants. These results further highlight the occurrence of probable chemically modified metabolites in the tropical climatic conditions in a microenvironment.

Evaluation of a four-zone indoor exposure model for predicting TCPP concentrations in a low-energy test house

Numerous chemicals have been detected in indoor environments that have potential impacts on occupant health and comfort. However, due to limited resources, it's infeasible to assess indoor exposure of each chemical for all indoor conditions through measurements alone. Hence, indoor exposure models have been developed to predict time-varied exposure for a wide range of sources and chemicals under different conditions. The Indoor Environmental Concentrations in Buildings with Conditioned and Unconditioned Zones (IECCU) model was developed by the United States Environmental Protection Agency. This study evaluated the predictive ability of the IECCU by comparing airborne tris(1-chloro-2-propyl) phosphate (TCPP) concentrations measured from 2013 to 2018 in a test house to modeled predictions. Inputs to IECCU included building and environment (i.e., air zone configuration and geometry, interzonal airflow rates and air temperature in each zone), parameters for both source (spray polyurethane foam (SPF)) and sinks (gypsum and wallboard), and simulation conditions. Simulations were conducted using three sets of inputs. Simulation 1 and 2 differed in using quantified versus design inputs for temperatures and airflow rates. Simulation 1 and 3 differed in the configured air zones in the IECCU model. Given the best available inputs (Simulation 1), IECCU predicted basement concentrations that were generally higher but within a factor of three of the measurements. The basement prediction/measurement ratios for all three simulations ranged from 0.5 to 8.3 and the average was 2.9, while the predicted concentrations in the living zone were generally lower but still within an order of magnitude of the measurements. The prediction accuracy decreased with time. For Simulation 1, predicted basement concentrations were on average 1.4 times higher than measurements in 2013 and 2014. However, the ratio increased to 4.7 in 2018. The design inputs of Simulation 2 resulted in greater discrepancy between measurements and predictions than the measured inputs of Simulation 1. In addition, Simulation 2 did not capture diurnal variation as well as Simulation 1. Comparisons of Simulation 1 and 2 demonstrate the importance of using accurate temperature and airflow model inputs for more accurately predicting concentrations. Furthermore, a sensitivity analysis indicated that to improve the accuracy of IECCU predictions for TCPP emission from SPF, efforts are needed to accurately measure the mass transfer parameters for SPF, especially the SPF/air partition coefficient and the initial TCPP concentration in SPF.

Exhaustive characterization of (semi-)volatile organic contaminants in car dust using comprehensive two-dimensional gas chromatography ‒ Time-of-flight mass spectrometry

This work represents the first reported effort to build an extensive database of the organic volatile and semi-volatile contaminants present in car dust as a result of migration from materials used in auto-manufacturing. Untargeted analysis of car dust samples has been performed using comprehensive two-dimensional gas chromatography combined with time-of-fight mass spectrometry (GC×GC ‒ToF MS) after generic sample preparation. The enhanced separation power and structural confirmation capabilities provided by this technique have been used for the either positive or tentative identification of 245 GC-amenable compounds, a number of them being identified for the first time in this type of matrix. Information concerning 5 compounds remaining unidentified has also been provided. Results have been summarised in a searchable database containing chromatographic, mass spectral and normalised abundances calculated for the detected analytes in the ten investigated car dusts used to discuss the main findings of the study. Results are expected to serve other researcher to take decisions concerning priority analytes for further evaluation in this research field and for car manufacturers who might search for safer materials.

Organophosphate esters in airborne particles from subway stations

For the first time, the concentrations of 19 organophosphate esters (OPEs) were measured in airborne fine particulate matter (PM2.5) from subway stations in Barcelona (Spain) to investigate their occurrence, contamination profiles and associated health risks. OPEs were detected in all PM2.5 samples with levels ranging between 1.59 and 202 ng/m³ (mean value of 39.9 ng/m³). Seventeen out of 19 tested analytes were detected, with TDClPP, TClPP and TCEP being those presenting the highest concentrations. OPE concentrations are not driven by the same factors that determine the ambient PM2.5 concentrations of other constituents in the subway. Newer stations presented higher OPE levels, probably due to the materials used in the design of the platforms, with greater use of modern plastic materials versus older stations with tiles and stones. Estimated daily intakes via airborne particles inhalation during the time expended in subway stations were calculated, as well as the carcinogenic and non-carcinogenic health risks (CR and non-CR), all being much lower than the threshold risk values. Thus, subway inhalation exposure when standing on the platform to OPE's per se is not considered to be dangerous for commuters.

Inhalation of two Prop 65-listed chemicals within vehicles may be associated with increased cancer risk

Chemicals are listed on California's Proposition 65 (Prop 65) for their potential to cause cancer, birth defects or other reproductive harm, and certain chemicals from this list are often detected within interior vehicle dust and air. Therefore, this study examined the potential risk associated with five Prop 65-listed chemicals detected within vehicle interiors: benzene, formaldehyde, di (2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), and tris(1,3-dichloro-2-propyl)phosphate (TDCIPP). Exposure estimates based on time spent within a vehicle were derived from a meta-analysis of estimated concentrations from the literature. Regulatory levels established by the California Office of Environmental Health Hazard Assessment (OEHHA) were then used to generate percent reference doses (%RfDs) for chemical-specific daily doses as well as determine the probability of risk (exceedance probability) as a function of %RfD for each chemical-specific daily dose. Based on our meta-analysis, benzene and formaldehyde were detected in vehicle interior air whereas DEHP, DBP and TDCIPP were detected in vehicle interior dust. Benzene and formaldehyde were the only two chemicals with an estimated %RfD > 100 across any of the commute times. For commute times of 20 min or longer, the %RfD was > 100 for maximum exposures based on the "maximum allowable daily level" for benzene, and for 95th-percentile exposures based on the "no significant risk level" for benzene and formaldehyde. Furthermore, the probability of exceeding 100% RfD was highest for cancer risks associated with benzene, followed by cancer risks associated with formaldehyde and the risk of reproductive and developmental toxicity associated with benzene. Lastly, within the entire state of California, the percent of commuters with a 10% probability of exceeding cancer risk associated with benzene or formaldehyde exposure was 78% and 63%, respectively. Overall, our study raises concerns about the potential risk associated with inhalation of benzene and formaldehyde for people who spend a significant amount of time in their vehicles, an issue that is especially pertinent to traffic-congested areas where people have longer commutes.

Tris(2-chloroethyl) Phosphate (TCEP) Elicits Hepatotoxicity by Activating Human Cancer Pathway Genes in HepG2 Cells

Tris(2-chloroethyl) phosphate (TCEP) is one of the organophosphorus flame retardants (OPFRs) used in consumer commodities and have been detected in human body fluids. Research on TCEP-induced transcriptomic alterations and toxicological consequences in liver cells is still lacking. Herein, human hepatocellular (HepG2) cells were treated with 100, 200, and 400 μM TCEP for 3 days to quantify hepatotoxicity by MTT, NRU, and comet assays. Apoptosis, mitochondrial membrane potential (ΔΨm), oxidative stress, and Ca²⁺ influx were measured by flow cytometry. A qPCR array was employed for transcriptomic analysis. MTT and NRU data showed 70.92% and 75.57% reduction in cell survival at 400 μM. In addition, 20-fold greater DNA damage was recorded at 400 μM. Cell cycle data showed 65.96% subG1 apoptotic peak in 400 μM treated cells. An elevated level of oxidative stress, esterase, Ca²⁺ influx, and ΔΨm dysfunction were recorded in TCEP-treated cells. Out of 84 genes, the qPCR array showed upregulation of 17 genes and downregulation of 10 key genes belonging to human cancer pathways. Our study endorses the fact that TCEP possesses hepatotoxic potential at higher concentrations and prolonged exposure. Hence, TCEP may act as a cancer-inducing entity by provoking the gene network of human cancer pathways.

In vitro oxidative stress, mitochondrial impairment and G1 phase cell cycle arrest induced by alkyl-phosphorus-containing flame retardants

Phosphorus-containing flame retardants (PFRs) have been frequently detected in various environmental samples at relatively high concentrations and are considered emerging environmental pollutants. However, their biological effects and the underlying mechanism remain unclear, especially alkyl-PFRs. In this study, a battery of in vitro bioassays was conducted to analyze the cytotoxicity, oxidative stress, mitochondrial impairment, DNA damage and the involved molecular mechanisms of several selected alkyl-PFRs. Results showed that alkyl-PFRs induced structural related toxicity, where alkyl-PFRs with higher logKow values induced higher cytotoxicity. Long-chain alkyl-PFRs caused mitochondrial and DNA damage, resulting from intracellular reactive oxygen species (ROS) and mitochondrial superoxide overproduction; while short-chain alkyl-PFRs displayed adverse outcomes by significantly impairing mitochondria without obvious ROS generation. In addition, alkyl-PFRs caused DNA damage-induced cell cycle arrest, as determined by flow cytometry, and transcriptionally upregulated key transcription factors in p53/p21-mediated cell cycle pathways. Moreover, compared to the control condition, triisobutyl phosphate and trimethyl phosphate exposure increased the sub-G1 apoptotic peak and upregulated the p53/bax apoptosis pathway, indicating potential cell apoptosis at the cellular and molecular levels. These results provide insight into PFR toxicity and the involved mode of action and indicate the mitochondria is an important target for some alkyl-PFRs.

Monitoring the levels of brominated and organophosphate flame retardants in passenger cars: Utilisation of car air filters as active samplers

Filters in residential and office air conditioning (A/C) systems have been used as sampling devices for monitoring different pollutants. However, cabin air filters (CAFs) in the A/C system of passenger cars have not been utilised for this purpose. In this study, we collected 22 used CAFs from passenger cars in Hanoi, Vietnam to analyse for 8 polybrominated diphenyl ethers (PBDEs) and 10 organophosphate esters (OPEs). All the analytes were detected in more than 50% of samples with the exception of BDE153 and BDE154. The average concentrations of ∑₁₀OPEs and ∑₈BDEs in the captured dust were 2600 and 40 ng/g, respectively with Tris (1-chloro-2-propyl) phosphate (TCIPP) and BDE209 as the dominant congener in OPE and BDE groups, respectively. CAFs are a potential tool to qualitatively assess the levels of semi-volatile chemicals in suspended dust in cars as a screening step for exposure assessment of those chemicals.

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

Organophosphate (OP) esters are emerging environmental contaminants, but little is known about their occurrence in dust. In this study, 19 OP triesters and their 11 diester degradation products were measured in indoor dust and outdoor dust collected from China. ∑OP triester concentrations in indoor dust (median: 2380 ng/g dry weight [dw]) were an order of magnitude higher than those in outdoor dust (446 ng/g dw). The median concentrations of ∑OP diesters in indoor and outdoor dust were 260 and 96.8 ng/g dw, respectively. Dust samples collected from eastern and southern China contained higher concentrations of ∑OP di- and tri-esters than those from the other regions. Dust from the most urbanized areas in China including Beijing, Shanghai, and Guangzhou exhibited the highest concentrations of ∑OP di- (>1000 ng/g dw) and triesters (>4000 ng/g dw). We also found notable concentrations of emerging aryl-OP triesters in dust (3.85-10.6 ng/g dw). Significant correlations existed between the concentrations of bis(2-ethylhexyl) phosphate (BEHP) and tris(2-ethylhexyl) phosphate (TEHP) (rho = 0.672-0.691, p < 0.01), as well as DPHP and triphenyl phosphate (TPHP) (rho = 0.537-0.766, p < 0.01) in dust samples, indicating that OP diesters originated from the degradation of triesters. High molar concentration ratios of DEP to triethyl phosphate (TEP) and DPHP to TPHP/ethylhexyl diphenyl phosphate (EHDPP) suggested that these OP triesters degrade readily. Significant correlations were found between the concentrations of ∑OP di- (R² = 0.390, p < 0.05) and tri-esters (R² = 0.475, p < 0.01) in paired indoor-outdoor dust samples, which suggested that indoor dust was the source of OP esters to the outdoor environment. The estimated daily intake (EDI) of ∑OP diesters through dust ingestion was 0.21 ng/kg bw/d for adults and 2.59 ng/kg bw/d for children. The exposure levels of OP diesters, DEP and DPHP, were comparable to those of their parent triester compounds.

A review of organophosphorus flame retardants (OPFRs): occurrence, bioaccumulation, toxicity, and organism exposure

Organophosphorus flame retardants (OPFRs) are increasingly being applied as flame retardants due to their unique properties. OPFRs are commonly detected in various environmental matrices, and organisms are extensively exposed to them. Considering the adverse effects of OPFRs, many researchers have devoted their attention to environmental risk assessments. This review outlines the current knowledge regarding the toxicity of OPFRs based on both in vitro and in vivo experiments in various environmentally relevant test species. The production, absorption, bioaccumulation, and biomagnification of OPFRs in animals and humans are also described. The joint effects of OPFRs and their coexisting characteristics are also discussed based on the limited available data and results. Finally, knowledge gaps and perspectives for future exposure studies of OPFRs in animals and humans are identified.

Indoor Air Pollution in Cars: An Update on Novel Insights

From a global viewpoint, a lot of time is spent within the indoor air compartment of vehicles. A German study on mobility has revealed that, on average, people spend 45 minutes per day inside vehicles. In recent years the number of cars has increased to around 43 million vehicles in private households. This means that more than one car can be used in every household. The ratio has been growing, especially in eastern Germany and rural areas. "Overall and especially outside the cities, the car remains by far number one mode of transport, especially in terms of mileage". Therefore, numerous international studies have addressed different aspects of indoor air hygiene, in the past years. In this paper, meaningful original studies on car indoor air pollution, related to VOCs, COx, PMs, microbials, BFRs, OPFRs, cigarettes, electronic smoking devices, high molecular weight plasticizer, and NOx are summarized in the form of a review. This present review aimed to summarize recently published studies in this important field of environmental medicine and points to the need for further studies with special recommendations for optimizing the interior air hygiene.

Dermal exposure to plasticizers in nail polishes: An alternative major exposure pathway of phosphorus-based compounds

Phosphorus-based compounds are used as plasticizers in the manufacture of many products found in the indoor environment. Here we quantitatively investigated dermal exposure to phosphorus-based compounds contained in 45 nail polishes purchased in Japan. The alternative plasticizer triphenyl phosphate (TPhP) was detected in some samples of the nail polishes made in the USA (concentration, 1.1-1.8 wt%). The potential dermal exposure rates for TPhP, estimated using ConsExpo (version 5.0; Dutch National Institute for Public Health and the Environment), were in the range 200 (5%ile)-1700 (50%ile)-5000 (95%ile) ng kg-bw^-1 day^-1, which is more than 1400 times the reported values for exposure via dust ingestion and inhalation. Thus, dermal exposure via nail polish may be a major route of exposure to TPhP. The margin of exposure range for TPhP was 3.6 × 10⁵-4.1 × 10⁴-1.4 × 10⁴. For comparison, the potential dermal exposure rate range for the conventional plasticizer dibutyl phthalate and the alternative plasticizer acetyl tributyl citrate was 360-3500-14,000 and 430-4100-17,000 ng kg-bw^-1 day^-1, respectively, and the margin of exposure range was 4.1 × 10³-4.2 × 10²-1.1 × 10² and 2.3 × 10⁵-2.4 × 10⁴-5.9 × 10³, respectively.

A nationwide survey of 19 organophosphate esters in soils from China: Spatial distribution and hazard assessment

Organophosphate esters (OPEs) are ubiquitous in the environment, but little is known about their distribution in soils. In this study, we measured 19 OPEs in soil samples collected nationwide in China for the first time. Concentrations of 19 OPEs (∑OPEs) in soils ranged from 4.50 to 430 ng/g dry weight (dw), with a median value of 36.6 ng/g dw. ∑OPE concentrations in soils were significantly higher in Northeastern (90.6, 19.1-180 ng/g dw; median, range) and Eastern/Southern China (57.4, 7.23-430 ng/g dw), areas with high population density and economic development, than those in Central (35.8, 4.80-417 ng/g dw) and Western China (29.7, 4.50-228 ng/g dw). High concentrations of ∑OPEs were found in soils collected from sites located in the most urbanized areas of China including Beijing (126 ng/g dw), Shanghai (388 ng/g dw), and Guangzhou (430 ng/g dw). Chlorinated (Cl-) OPEs were the predominant compounds, accounting for over 74.0% of ∑OPE concentrations in soils from China. In soil samples from Northeastern and Eastern/Southern China, Cl-OPEs accounted for 84.3% and 92.1% of ∑OPE concentrations, respectively. Cresyl diphenyl phosphate (CDPP) and isodecyl diphenyl phosphate (IDDP), which have been less studied thus far, were also found at measurable concentrations (0.15-0.40 ng/g dw) in soils. The Spearman's rank correlations among major aryl-OPEs in soils were significant (Rho = 0.582-0.747, p < 0.01), which suggested similar sources of environmental release of these compounds. Total organic carbon (TOC) content was not correlated with the concentrations of ∑OPE in soils (Rho = 0.036, p > 0.05). A hazard assessment for ten OPEs in soils suggested a notable risk from tris(2-ethylhexyl) phosphate (TEHP) and trimethylphenyl phosphate (TMPP). Further studies are needed to elucidate the fate of TMPP in soils.

A Review of a Class of Emerging Contaminants: The Classification, Distribution, Intensity of Consumption, Synthesis Routes, Environmental Effects and Expectation of Pollution Abatement to Organophosphate Flame Retardants (OPFRs)

Organophosphate flame retardants (OPFRs) have been detected in various environmental matrices and have been identified as emerging contaminants (EC). Given the adverse influence of OPFRs, many researchers have focused on the absorption, bioaccumulation, metabolism, and internal exposure processes of OPFRs in animals and humans. This paper first reviews the evolution of various types of flame retardants (FRs) and the environmental pollution of OPFRs, the different absorption pathways of OPFRs by animals and humans (such as inhalation, ingestion, skin absorption and absorption), and then summarizes the environmental impacts of OPFRs, including their biological toxicity, bioaccumulation, persistence, migration, endocrine disruption and carcinogenicity. Based on limited available data and results, this study also summarizes the bioaccumulation and biomagnification potential of OPFRs in different types of biological and food nets. In addition, a new governance idea for the replacement of existing OPFRs from the source is proposed, seeking environmentally friendly alternatives to OPFRs in order to provide new ideas and theoretical guidance for the removal of OPFRs.

Organophosphate Esters in Road Dust from a Suburban Area of Chongqing, China: Characterization of Particle Size Distribution and Human Exposure

Four types of road dust, including main road, industrial road, campus road, and campus walking street dust, were analyzed in a suburban area of Chongqing, western China. The organophosphate esters (OPEs) concentrations varied from 3.69 to 1600 ng/g dry weight, with a median of 292, 476, 203, and 48.8 ng/g dw in main road, industrial road, campus road, and campus walking street dust, respectively. The industrial sources should be responsible for the elevated OPEs concentrations in industrial road dust, while the vehicle emissions may play a role in the OPEs distribution in main road dust. Semblable OPEs composition patterns were observed among different types of road dust; tributyl phosphate predominated followed by tris(methylphenyl) phosphate. Significantly positive correlations were obtained between industrial road dust and campus road dust and main road dust, respectively, and statistical correlations also were found between main road dust and other road dust. An increasing trend of OPEs was displayed with the descending particle size in industrial road dust, whereas highest values were at F3 (90-150 μm) (340 ng/g dw) and F5 (< 75 μm) (305 ng/g dw), with a peak value at F3 in main road dust. This result may suggest that OPEs are prone to accumulate in finer particles. The estimated daily intake values for toddlers were approximately two times greater than those for adults in each region, implying that toddlers may be more vulnerable to OPEs intake via road dust.

Comparison of rates of direct and indirect migration of phosphorus flame retardants from flame-retardant-treated polyester curtains to indoor dust

In this study, the pathways for migration of phosphorus flame retardants (PFRs), tris(1,3-dichloroisopropyl) phosphate (TDCPP) and tricresyl phosphate (TCsP) which were detected from curtains often, from flame-retardant-treated polyester curtains to indoor dust were investigated. Two possible migration pathways were compared quantitatively: (1) an indirect pathway in which the PFRs in the curtains first evaporate from the curtains and are then adsorbed onto indoor dust and (2) a direct pathway in which the PFRs are directly transferred to dust placed on the curtains. The contribution of the indirect pathway was evaluated by means of emission cell tests, which showed that the area-specific emission rates from curtains treated with PFRs were 0.044 (TDCPP, Curtain 5), 0.17 (TDCPP, Curtain 8), and 0.060 (TCsP, Curtain 12) μg m^-2 h^-1 at 20 °C (averaged during 24 h). The contribution of the direct pathway was evaluated by measurement of the time dependence of PFR concentrations on the indoor dust placed on the curtains. These measurements indicated that PFR concentrations on the dust increased with time and that the direct migration rates of PFRs from curtains treated with PFRs were 4.4 (TDCPP, Curtain 5), 12 (TDCPP, Curtain 8), and 7.0 (TCsP, Curtain 12) μg m^-2 h^-1 at 20 °C (averaged during 24 h), or 71-120 times the indirect migration rate. This result suggests that the direct pathway can be expected to predominate.

Enhanced emissions of brominated flame retardants from indoor sources by direct contact with dust

The emissions of brominated flame retardants (BFRs) from consumer products have been considered the major to the ubiquitous occurrence of contaminants in indoor environments. Direct contact with dust covering the surface of source materials in a real environment could introduce significant uncertainty. This study investigated the effects of dust coverage on the emissions of four BFRs, including 1, 2, 5, 6, 9, and 10-hexabromocyclododecane (HBCD), bis(2-ethyl-1-hexyl) tetrabromophthalate (BEHTBP), tetrabromobisphenol A (TBBPA), and hexabromobenzene (HBBZ), from decorative laminate, cotton sound insulation, PVC floor, and carpet. Direct contact with dust was confirmed to increase the total emissions by 30.8-98.1% compared with the emissions in the non-dust group. The emissions of HBCD, TBBPA, and HBBZ from cotton sound insulation were obviously enhanced by dust with smaller particles but did not linearly increase along with the dust amounts. Thus, these findings have practical implications in that the frequent removal of dust could be important to minimize the exposure risk from indoor emissions of BFRs.

Concentrations and Dietary Exposure to Organophosphate Esters in Foodstuffs from Albany, New York, United States

Organophosphate esters (OPEs) are ubiquitous contaminants in the environment, but little is known about their occurrence in foodstuffs, an important source of human exposure. In this study, 15 OPEs were measured in foodstuffs and food-packing materials collected from local markets in Albany, New York, United States, for the first time. Among the foodstuffs analyzed, median concentrations of ∑OPEs (sum of 15 OPEs) in meat (6.76 ng/g wet weight; ww) and fish/seafood (7.11 ng/g ww) were higher than those in other food categories. ∑OPEs were found in food packaging at a median concentration of 132 ng/g. The estimated daily dietary intakes (EDIs) of OPE were of 37.9, 135, 56.6, 32.2, and 25.1 ng/kg body weight (bw)/day for infants, toddlers, children, teenagers, and adults, respectively. Meat was a major source (47%) of dietary OPEs exposure in adults, whereas dairy products accounted for 52% of OPE exposures in toddlers.

Methods for the analysis of organophosphorus flame retardants-Comparison of GC-EI-MS, GC-NCI-MS, LC-ESI-MS/MS, and LC-APCI-MS/MS

Organophosphorus flame retardants (PFRs) are extensively used as alternatives to banned polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD). In this study, we analyzed 14 PFRs by means of four mass-spectrometry-based methods: gas chromatography combined with electron-impact mass spectrometry (GC-EI-MS) or negative-chemical-ionization mass spectrometry (GC-NCI-MS) and liquid chromatography combined with tandem mass spectrometry using electrospray ionization (LC-ESI-MS/MS) or atmospheric pressure chemical ionization (LC-APCI-MS/MS). The limits of quantification (LOQs) for LC-ESI-MS/MS and LC-APCI-MS/MS (0.81-970 pg) were 1-2 orders of magnitude lower than the LOQs for GC-EI-MS and GC-NCI-MS (2.3-3900 pg). LC-APCI-MS/MS showed the lowest LOQs (mean = 41 pg; median = 3.4 pg) for all but two of the PFRs targeted in this study. For LC-APCI-MS/MS, the lowest LOQ was observed for tributyl phosphate (TBP) (0.81 pg), and the highest was observed for tris(butoxyethyl) phosphate (TBOEP) (36 pg). The results of this study indicate that LC-APCI-MS/MS is the optimum analytical method for the target PFRs, at least in terms of LOQ.

Legacy and emerging organophosphοrus flame retardants in car dust from Greece: Implications for human exposure

Organophosphorus flame retardants (PFRs) and emerging PFRs (ePFRs) are two groups of compounds used as replacements for brominated flame retardants (BFRs). They have already been detected in indoor dust (mainly in homes and offices). To date, few studies investigated the occurrence of FRs in car dust and the information of possible health risks is still limited. The present study reports on the investigation of the levels and profiles of eight target PFRs: tris(2-ethylhexyl) phosphate (TEHP), tris(2-chloroethyl) phosphate (TCEP), tris(2-butoxyethyl) phosphate (TBEP), triphenyl phosphate (TPHP), 2-ethylhexyl diphenyl phosphate (EHDPHP), tris(1-chloro-2-propyl) phosphate (TCIPP), tri cresyl phosphate (TCP), tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) and four target ePFRs; 2,2-bis(chloromethyl)propane-1,3-diyltetrakis(2-chloroethyl)bisphosphate (V6), isodecyl diphenyl phosphate (iDDPHP), resorcinol bis(diphenylphosphate) (RDP) and bisphenol A-bis(diphenyl phosphate) (BDP) in car dust from Greece. The samples were collected from the interior of 25 private cars in Thessaloniki, Greece, with different years of manufacture (1997-2015) and continents of origin. After ultrasonic extraction and Florisil fractionation, the PFR analysis was carried out by GC-EI/MS, whereas the ePFRs were analyzed by LC-MS/MS. Levels of Σ₈PFRs varied from 2000 to 190,000 ng g^-1, with mean and median concentrations of 20,000 and 11,500 ng g^-1, respectively. The concentrations of Σ₄ePFRs ranged from 44 to 8700 ng g^-1, with mean and median values at 1100 and 190 ng g^-1, respectively. Estimations of human exposure showed that toddlers are more exposed than adults to both PFRs and ePFRs. Yet, the intake via dust ingestion and dermal absorption was several orders of magnitude lower than the corresponding reference doses.

Potential Role of Pet Cats As a Sentinel Species for Human Exposure to Flame Retardants

Flame retardants are a wide group of chemicals used by the industry to avoid combustion of materials. These substances are commonly found in plastics, electronic equipment, fabrics, and in many other everyday articles. Subsequently, ubiquitous environmental contamination by these common chemical is frequently reported. In the present study, we have evaluated the level of exposure to polychlorinated biphenyls (PCBs), brominated diphenyl ethers (BDEs), and organophosphorous flame retardants (OPFRs) in pet cats through the analysis of their serum. We also analyzed the level exposure to such chemicals in a series of 20 cat owners, trying to disclose the role of pet cats as sentinel species of human exposure to FRs. Our results showed that PCBs, banned 40 years ago, showed the lowest levels of exposure, followed by BDEs—banned recently. Congeners PCB-138 and PCB-180 were detected in ≥50% of the series, while BDE-47 was detected in near 90% of the pet cats. On the other hand, the highest levels were that of OPFRs, whose pattern of detection was similar to that observed in humans, thus suggesting a potential role of cats as a sentinel species for human exposure to these currently used FRs. Six out of 11 OPFRs determined [2-ethylhexyldiphenyl phosphate, tributylphosphate, triisobutylphosphate, triphenylphosphate, tris (2-chloroethyl) phosphate, and tris (2-chloroisopropyl) phosphate] were detected in 100% of the samples. It will be interesting to perform future studied aimed to elucidating the potential toxicological effects of these highly detected chemicals both, in cats and humans.