Search Results (9)

As polybrominated diphenyl ethers were phased out as flame retardants and plasticizers, increasing quantities of organophosphate triesters (OPEs) have been used as replacements. Despite a surge in reports on levels and profiles of OPEs, especially in indoor environments, and the potential exposure, there are still understudied areas with no data on the levels of these chemicals. We carried out the first study investigating levels and profiles of OPEs in indoor dust from such an area, the Tampa Bay (Florida) area. ∑₁₃OPEs measured at each site ranged from 545 to 502,086 ng g⁻¹, with overall medians and means over 64 sites of 15,447 and 36,135 ng g⁻¹, respectively. Alkyl OPEs were predominant, with lesser levels of chlorinated and aryl OPEs. Median levels were highest for tris (2-butoxyethyl) phosphate (TBOEP) and triphenyl phosphate (TPHP) at 4641 and 1046 ng g⁻¹, respectively; lower for tris(1,3–dichloro-2-propyl) phosphate (TDCIPP), tris(2-chloropropyl) phosphate (T2CPP), and tris (2-chloroisopropyl) phosphate (TCIPP) at 530, 458, and 360 ng g⁻¹, respectively; with others ranging from 2 to 85 ng g⁻¹. There were differences in levels in different microenvironments (urban versus suburban; non-residential versus residential; apartments versus single-family homes; daycares versus residences and university rooms; building age; and rooms with different floor material). Estimated daily intakes for median and higher exposure scenarios for ∑₁₃OPEs (in ng kg⁻¹ bw day⁻¹) were 12 and 552 for toddlers and 6 and 451 for adults, respectively. TBOEP accounted for 30% of total intake for toddlers and adults in a mean exposure scenario but 90% for high exposure scenario. Full article

Tris(2-chloroethyl) phosphate (TCEP) is a representative chlorinated organophosphate flame retardant (OPFR) that demonstrates greater persistence than other non-halogenated alkyl or aryl OPFRs. Although TCEP has been shown to accumulate significantly in the environment and contribute to testicular toxicity and spermatogenic dysfunction, the precise underlying factors and mechanisms of action remain unclear. Herein, male ICR mice were gavaged with corn oil, 50 mg/kg body weight (bw) TCEP, or 100 mg/kg bw TCEP from postnatal day (PND) 22 to PND 35. TCEP exposure resulted in the disruption of blood-testis barrier (BTB) integrity and in abnormal testicular development. Considering that Sertoli cells constitute the primary target of toxicants and that TCEP induces oxidative stress in the testis and other organs, we focused on ferroptosis in Sertoli cells. Our findings revealed a significant increase in ferroptosis in the testes and Sertoli cells following TCEP exposure, and we observed functional restoration of Sertoli cell junctions upon treatment with the ferroptosis inhibitor ferrostatin-1. Furthermore, ferritin heavy chain 1 (FTH1) was markedly reduced in TCEP-exposed testes and Sertoli cells. Since nuclear receptor coactivator 4 (NCOA4)-mediated ferritinophagy is essential for the degradation of FTH1, we assessed ferritinophagic activity and found significant upregulation of NCOA4, ATG5, ATG7, and LC3B II/I in TCEP-exposed testes and Sertoli cells. These results strongly suggest that TCEP triggers Sertoli cell ferroptosis by activating ferritinophagy that leads to reduced expression of BTB-associated proteins, ultimately causing BTB disruption and testicular developmental toxicity. Full article

Insecticides reduce the spread of mosquito-borne disease. Over the past century, mosquito control has mostly relied on neurotoxic chemicals—such as pyrethroids, neonicotinoids, chlorinated hydrocarbons, carbamates and organophosphates—that target adults. However, their persistent use has selected for insecticide resistance. This has led to the application of progressively higher amounts of insecticides—known as the pesticide treadmill—and negative consequences for ecosystems. Comparatively less attention has been paid to larvae, even though larval death eliminates a mosquito’s potential to transmit disease and reproduce. Larvae have been targeted by source reduction, biological control, growth regulators and neurotoxins, but hurdles remain. Here, we review methods of mosquito control and argue that photoactive molecules that target larvae—called photosensitive insecticides or PSIs—are an environmentally friendly addition to our mosquitocidal arsenal. PSIs are ingested by larvae and produce reactive oxygen species (ROS) when activated by light. ROS then damage macromolecules resulting in larval death. PSIs are degraded by light, eliminating environmental accumulation. Moreover, PSIs only harm small translucent organisms, and their broad mechanism of action that relies on oxidative damage means that resistance is less likely to evolve. Therefore, PSIs are a promising alternative for controlling mosquitoes in an environmentally sustainable manner. Full article

Human exposure to organophosphate esters (OPEs) is more pervasive in industrial areas manufacturing OPE-related products. OPE exposure is of great concern due to its associations with adverse health effects, while studies on OPE exposure in industrial districts are scarce. This study aimed to assess human exposure to OPEs in a typical industrial area producing large amounts of OPE-related products in Shenzhen, China. Tris (2-chloroethyl)-phosphate (TCEP), tris (2-chloroisopropyl) phosphate (TCPP) and other common OPEs were analyzed in urine (n = 30) and plasma (n = 21) samples. Moreover, we measured five OPE metabolites (mOPEs) in plasma samples (n = 21). The results show that TCPP and TCEP are dominant compounds, with moderate to high levels compared with those reported in urine and plasma samples from other regions. In addition, di-n-butyl phosphate (DnBP) and diethyl phosphite (DEP) were frequently detected in plasma samples and could be considered as biomarkers. Risk assessment revealed a moderate to high potential health risk from TCEP exposure. Our results provide basic data for human exposure to OPEs in industrial areas and call for the prevention and mitigation of industrial chlorinated OPE pollution. Full article

Organophosphate esters (OPEs) are widely used as flame retardants and plasticizers. OPEs have been released into various environments (e.g., water, sediments, dust and air, and soil). To investigate the occurrence and distribution of OPEs in various environments in China, this review collects and discusses the published scientific studies in this field. Chlorinated OPEs, as flame retardants, are the predominant OPEs found in the environment. The analysis of data revealed large concentration variations among microenvironments, including inflowing river water (range: 0.69–10.62 µgL⁻¹), sediments (range: 0.0197–0.234 µg/g), dust (range: 8.706–34.872 µg/g), and open recycling sites’ soil (range: 0.122–2.1 µg/g). Moreover, OPEs can be detected in the air and biota. We highlight the overall view regarding environmental levels of OPEs in different matrices as a starting point to monitor trends for China. The levels of OPEs in the water, sediment, dust, and air of China are still low. However, dust samples from electronic waste workshop sites were more contaminated. Human activities, pesticides, electronics, furniture, paint, plastics and textiles, and wastewater plants are the dominant sources of OPEs. Human exposure routes to OPEs mainly include dermal contact, dust ingestion, inhalation, and dietary intake. The low level of ecological risk and risk to human health indicated a limited threat from OPEs. Furthermore, current challenges and perspectives for future studies are prospected. A criteria inventory of OPEs reflecting the levels of OPEs contamination association among different microenvironments, emerging OPEs, and potential impact of OPEs on human health, particularly for children are needed in China for better investigation. Full article

Chlorpyrifos (CP) is a pesticide used extensively in agricultural crops. Residual CP has been found in a variety of soils, vegetables and fruits indicating a serious danger to humans. Therefore, it is necessary to restrict its entry into agricultural products for food safety. A wire-house pot experiment was conducted with maize plants in biochar- and compost-amended soil (at 0.25% and 0.50%, respectively, in weight-by-weight composition) contaminated with 100 and 200 mg kg⁻¹ of CP, respectively. Results indicated toxicity at both CP levels (with 84% growth reduction) at CP 200 mg kg⁻¹. However, application of compost and biochar at the 0.50% level improved the fresh weight (2.8- and 4-fold, respectively). Stimulated superoxide dismutase (SOD) and peroxidase (POX) activities and depressed catalase (CAT) activity were recorded in response to CP contamination and were significantly recovered by the amendments. Both amendments significantly decreased the CP phytoavailability. With biochar, 91% and 76% reduction in the CP concentration in maize shoots and with compost 72% and 68% reduction was recorded, at a 0.50% level in 100 and 200 mg kg⁻¹ contaminated treatments respectively. Compost accelerated the CP degradation in postharvest soil. Therefore, biochar and compost amendments can effectively be used to decrease CP entry in agricultural produce by reducing its phytoavailability. Full article

Polyurea is a synthetic material made by the reaction of isocyanate and polymer blend-containing amines. Due to its outstanding mechanical properties and fast curing, polyurea-based coatings have found dozens of applications, including waterproofing and anti-corrosion coatings. Further development of this material can create a flame-retardant product, a good alternative for common products available on the market, such as intumescent coatings. To improve the flame retardancy of polyurea, several flame retardants were investigated. The influence of aluminum hydroxide, resorcinol bis(diphenyl phosphate) (RDP), and tris chloropropyl phosphate (TCPP) on flame retardancy and morphology was studied. The following methods were used: infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, limiting oxygen index, and tensile strength. The examinations mentioned above showed the improvement of flame-retardancy of polyurea for two products: chlorinated organophosphate and organophosphate. Nevertheless, using the chlorinated organophosphate additive caused a rapid deterioration of mechanical properties. Full article

Our aim was to find chlorine-substituted antidotes against organophosphate poisoning and compare their pharmacokinetics to their parent compound, K-203. White male Wistar rats were intramuscularly injected with K-203, K-867 or K-870. Serum, brain, kidneys, liver, lung, eyes, and testes tissues were taken after 5, 15, 30, 60, and 120 min and analyzed using reversed-phase high-performance liquid chromatography. K-203, K-867, or K-870 was present in every tissue that was analyzed, including the serum, the eyes, testes, liver, kidneys, lungs, and the brain. The serum levels of K-867 and K-870 (chlorine-substituted derivatives of K-203) were nearly constant between 15 and 30 min, while their parent compound (K-203) showed peak level at 15 min after the administration of 30 µmol/rat. Neither K-203, nor K-867 or K-870 were toxic at a dose of 100 µmol/200 g in rats. Chlorine-substitution of K-867 and K-870 produced limited absorbance and distribution compared to their parent compound, K203. Full article

Inhalation of halogenated flame-retardants (HFRs) released from consumer products is an important route of exposure. However, not all airborne HFRs are respirable, and thus interact with vascular membranes within the gas exchange (alveolar) region of the lung. HFRs associated with large (>4 µm), inhalable airborne particulates are trapped on the mucosal lining of the respiratory tract and then are expelled or swallowed. The latter may contribute to internal exposure via desorption from particles in the digestive tract. Exposures may also be underestimated if personal activities that re-suspend particles into the breathing zone are not taken into account. Here, samples were collected using personal air samplers, clipped to the participants’ shirt collars (n = 18). We observed that the larger, inhalable air particulates carried the bulk (>92%) of HFRs. HFRs detected included those removed from commerce (i.e., polybrominated diphenyl ethers (Penta-BDEs: BDE-47, -85, -100, -99, and -153)), their replacements; e.g., 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (TBB or EH-TBB); bis(2-ethylhexyl) 3,4,5,6-tetrabromophthalate (TBPH or BEH-TEBP) and long-produced chlorinated organophosphate-FRs (ClOPFRs): tris(2-chloroethyl)phosphate (TCEP), tris(1-chloro-2-propyl)phosphate (TCPP or TCIPP), and tris(1,3-dichloro-2-propyl)phosphate (TDCPP or TDCIPP). Our findings suggest estimates relying on a single exposure route, i.e., alveolar gas exchange, may not accurately estimate HFR internal dosage, as they ignore contributions from larger inhalable particulates that enter the digestive tract. Consideration of the fate and bioavailability of these larger particulates resulted in higher dosage estimates for HFRs with log K_oa < 12 (i.e., Penta-BDEs and ClOPFRs) and lower estimates for those with log K_oa > 12 (i.e., TBB and TBPH) compared to the alveolar route exposure alone. Of those HFRs examined, the most significant effect was the lower estimate by 41% for TBPH. The bulk of TBPH uptake from inhaled particles was estimated to be through the digestive tract, with lower bioavailability. We compared inhalation exposure estimates to chronic oral reference doses (RfDs) established by several regulatory agencies. The U.S. Environmental Protection Agency (EPA) RfD levels for several HFRs are considered outdated; however, BDE-99 levels exceeded those suggested by the Dutch National Institute for Public Health and the Environment (RIVM) by up to 26 times. These findings indicate that contributions and bioavailability of respirable and inhalable airborne particulates should both be considered in future risk assessments. Full article