Estimation of multi-route exposures to various chemicals during Children's clay toy use.

Clay toys have been used as play materials and educational tools for children. Clay toys exhibit adherent properties, and may facilitate chemical ingestion via dermal absorption and oral (hand-to-mouth, HTM) exposures. Inhalation exposure also be considered when contain volatile chemicals. The purpose of this study was to estimate the exposure dose for chemicals in clay toys via three exposure routes, and to evaluate the relationship between the exposure contribution of each route considering both the chemical properties and children's age. Chemical analysis was conducted for 9 semi-volatile organic compounds (SVOCs), 17 volatile organic compounds (VOCs), and 7 metal elements in clay toys (n = 66) purchased from Korean market. Exposure factors for usage pattern of clay toys were conducted based on a nationally representative survey in Korea. A total of 12,144 (60.7%) children responded positively to playing with clay toys. Exposure to SVOCs and VOCs in clay toys via HTM, inhalation, and dermal absorption were estimated. The exposure level was the highest in styrene with 5.2 × 10-3 mg/kg-bw/day (95th percentile population), which was approximately 13% of the acceptable daily dose for styrene. In 3-year-old children, dermal absorption route contributed the highest at 59.2-100%. Chemicals with higher octanol-water partition coefficient (Kow) had the greater the contribution of the dermal absorption route and the weaker the contribution of the HTM route. In infants (0-2 years), the contribution via HTM exposure was higher than that in the other age groups. The contribution of inhalation exposure differed depending on the volatility of the chemicals. Furthermore, the exposure route contribution significantly differed due to age-dependent behavioral changes in children. These results suggest that the exposure assessments for children could be considered with multiple exposure routes related to chemical properties.

Effect-directed analysis of toxic organics in PM2.5 exposure to the cellular bioassays in vitro: Application in Shanxi of China.

To optimize the effect-directed analysis (EDA) approach to identify the fine particulate matter (PM2.5) bound organic toxicants, Jinzhong city, in the Shanxi Province of China, was selected as the object of our study. First, PM2.5 samples were collected and their organic extracts were separated out in 9 fractions (F1-F9) using reversed-phase high performance liquid chromatography after purification using gel permeation chromatography. Second, the toxicity effects of each fraction were measured by human bronchial epithelial cells (BEAS-2B) in vitro. And toxicity effects included antioxidant stress (ROS, LDH, and CAT) and an inflammatory response (IL-6, IL-1ß, and TNF-α). The results showed that the scores of the toxicity effects on multiple lines of evidence were the highest in the F3 and F4 fractions compared with those of the control. Subsequently, the main poisons, o-cymene, p-cymene, benzene, ethylbenzene, xylene, and styrene, were identified using GC×GC-TOF/MS. Finally, to confirm the above possible candidates, (1) the levels of o-cymene, p-cymene and BTEXS in daily PM2.5 were measured using GC-MS in November 2020, and the rates of detection of these pollutants were 100% in PM2.5. Among them, o-cymene and p-cymene were first reported as the key toxic substances of PM2.5, and their average concentration values were 0.16 ± 0.11 and 0.18 ± 0.15 ng‧m-3, respectively. (2) the toxicity of p-cymene may be no less than that of other benzene derivatives according to their LC50 in Daphnia magna. (3) based on canonical correlation analysis, the exposure to p-cymene, benzene, and styrene in PM2.5 was most likely associated with the toxicity effects (CAT, IL-6, and TNF-α), which in turn caused the observed toxicity. In conclusion, p-cymene, benzene, and styrene were found to be the key toxic organics in PM2.5 for cells in vitro. EDA technology avoids the limitations of chemical analysis and uncertainty of the biological testing and adds new toxicants to the control list of PM2.5, contributing to this study field. However, the application of EDA to PM2.5 still faces challenges such as the selection of biological effects, loss of toxicity with the separation process, influence of the dosing method, and identification of the unknown effects of pollutants.

Perioperative exposure to volatile organic compounds in neonates undergoing cardiac surgery.

OBJECTIVE: Volatile organic compounds (VOCs) are used in the sterilization and manufacture of medical equipment. These compounds have high vapor pressures with low water solubility and are emitted as gases from solids or liquids. They can be mutagenic, neurotoxic, genotoxic, and/or carcinogenic. Safe limits of exposure are not known for neonates. This study examined determinants of exposure in newborns undergoing cardiac surgery. METHODS: Twenty metabolites of 16 VOCs (eg, xylene, cyanide, acrolein, acrylonitrile, N, N-dimethylformamide, 1,3-butadiene, styrene, and benzene) were measured as metabolites in daily urine samples collected from 10 neonates undergoing cardiac operations (n = 150 samples). Metabolites were quantified using reversed-phase ultra-high performance liquid chromatography and electrospray ionization tandem mass spectrometry. Repeated measures analysis of covariance was performed for each metabolite to examine associations with use of medical devices. RESULTS: At least 3 metabolites were detected in every sample. The median number of metabolites detected in each sample was 14 (range, 3-15). In a model controlling for other factors, the use of extracorporeal membrane oxygenation was associated with significantly (P ≤ .05) greater metabolite levels of acrolein, acrylonitrile, ethylene oxide, propylene oxide, styrene, and ethylbenzene. Patients breathing ambient air had greater levels of metabolites of acrolein, xylene, N,N-dimethylformamide, methyl isocyanate, cyanide, 1,3-butadiene (all P ≤ .05). CONCLUSIONS: Exposure to volatile organic compounds is pervasive in newborns undergoing cardiac surgery. Sources of exposure likely include medical devices and inhalation from the air in the intensive care unit. The contribution of VOC exposure during cardiac surgery in newborns to adverse outcomes warrants further evaluation.

A new pre-concentration procedure based on poly(styrene-co-maleamide and imide) copolymers modified with 2-hydrazinobenzothiazole prior to spectrophotometric monitoring of inorganic as (as As(III)) in edible vegetable oils.

This study describes the development of 2-hydrazinobenzothiazole modified-amide/imide co-polymers for the extraction/pre-concentration of trace As(III), from edible vegetable oils. Their characterization was realized by help of instrumental techniques. The method is based on pH-dependent complexation between As(III) and co-polymeric chelators in presence of 35-fold excess As(V), their selective extraction into the mixed micellar phase, and detected at pH 2.0 and 6.0 by UV-vis spectrophotometer. The variables affecting extraction efficiency were optimized. From pre-concentration of 20-mL sample, the good linear relationships were obtained in range of 1-40 and 3-75 µg/L with DLs of 0.32 and 1.00 µg/L. The accuracy was verified by analysis of a certified sample without and with spiking. The method was applied into the analysis of iAs levels of samples. The results show that the functional co-polymers are efficient chelators, and exhibit great potential for the selective extraction of As(III) from edible vegetable oils.

Prerequisite for Imputing Non-detects among Airborne Samples in OSHA's IMIS Databank: Prediction of Sample's Volume.

INTRODUCTION: The US Integrated Management Information System (IMIS) contains workplace measurements collected by Occupational Safety and Health Administration (OSHA) inspectors. Its use for research is limited by the lack of record of a value for the limit of detection (LOD) associated with non-detected measurements, which should be used to set censoring point in statistical analysis. We aimed to remedy this by developing a predictive model of the volume of air sampled (V) for the non-detected results of airborne measurements, to then estimate the LOD using the instrument detection limit (IDL), as IDL/V. METHODS: We obtained the Chemical Exposure Health Data from OSHA's central laboratory in Salt Lake City that partially overlaps IMIS and contains information on V. We used classification and regression trees (CART) to develop a predictive model of V for all measurements where the two datasets overlapped. The analysis was restricted to 69 chemical agents with at least 100 non-detected measurements, and calculated sampling air flow rates consistent with workplace measurement practices; undefined types of inspections were excluded, leaving 412,201/413,515 records. CART models were fitted on randomly selected 70% of the data using 10-fold cross-validation and validated on the remaining data. A separate CART model was fitted to styrene data. RESULTS: Sampled air volume had a right-skewed distribution with a mean of 357 l, a median (M) of 318, and ranged from 0.040 to 1868 l. There were 173,131 measurements described as non-detects (42% of the data). For the non-detects, the V tended to be greater (M = 378 l) than measurements characterized as either 'short-term' (M = 218 l) or 'long-term' (M = 297 l). The CART models were complex and not easy to interpret, but substance, industry, and year were among the top three most important classifiers. They predicted V well overall (Pearson correlation (r) = 0.73, P < 0.0001; Lin's concordance correlation (rc) = 0.69) and among records captured as non-detects in IMIS (r = 0.66, P < 0.0001l; rc = 0.60). For styrene, CART built on measurements for all agents predicted V among 569 non-detects poorly (r = 0.15; rc = 0.04), but styrene-specific CART predicted it well (r = 0.87, P < 0.0001; rc = 0.86). DISCUSSION: Among the limitations of our work is the fact that samples may have been collected on different workers and processes within each inspection, each with its own V. Furthermore, we lack measurement-level predictors because classifiers were captured at the inspection level. We did not study all substances that may be of interest and did not use the information that substances measured on the same sampling media should have the same V. We must note that CART models tend to over-fit data and their predictions depend on the selected data, as illustrated by contrasting predictions created using all data vs. limited to styrene. CONCLUSIONS: We developed predictive models of sampled air volume that should enable the calculation of LOD for non-detects in IMIS. Our predictions may guide future work on handling non-detects in IMIS, although it is advisable to develop separate predictive models for each substance, industry, and year of interest, while also considering other factors, such as whether the measurement evaluated long-term or short-term exposure.

Quantification of microplastic by particle size down to 1.1 µm in surface road dust in an urban city, Japan.

The impact of microplastics (MPs, plastic particles ≤5 mm) on ecosystems is of great concern. Road surfaces represent a significant source of MPs where plastic fragments are physically and chemically reduced to MPs. However, the literature lacks information on fragmentation tendencies below 11 µm. This study aimed to characterize the occurrence of MPs in road dust in different size fractions down to 1.1 µm. Road dust was collected at five sites near a major road in Kusatsu city, Japan, and partitioned by size into 13 fractions (1.1-850 µm). The coarser fractions accounted for a greater proportion of the dust. The percentage of organic matter, determined by loss on ignition, increased as the fractions became finer. Pyrolysis-gas chromatography-mass spectrometry was used to quantify 12 types of polymers in each fraction. The dust was found to contain nine types of MP, namely, polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), polystyrene (PS), styrene/butadiene rubber (SBR), acrylonitrile/butadiene/styrene resin (ABS), polycarbonate (PC), polymethylmethacrylate (PMMA), and polyamide 66 (PA66). The total MP concentration in road dust particles by particle size fraction (concentrationf) began to increase from the 125-250 µm fraction and remained elevated in finer fractions down to 1.1 µm, indicating that MPs in the road dust micronized to at least 1.1 µm. However, for individual polymer types, the tendency for concentrationf to increase or decrease with particle size fraction varied: the concentrationf of some polymers, such as PE and PVC, remained elevated in fractions down to 1.1 µm; the concentrationf of SBR, a rubber-MP, showed a stable or decreasing trend in fractions of 7.0-11 µm and finer. Particles of PE, PVC, and some other plastics might become increasingly finer, even down to 1.1 µm. Further research is needed to understand the comminution limits of these polymers under pertinent environmental conditions.

Single-chemical and mixture effects of multiple volatile organic compounds exposure on liver injury and risk of non-alcoholic fatty liver disease in a representative general adult population.

Evidence on liver injury and non-alcoholic fatty liver disease (NAFLD) from volatile organic compounds (VOCs) exposure is insufficient. A cross-sectional study including 3011 US adults from the National Health and Nutrition Examination Survey was conducted to explore the associations of urinary exposure biomarkers (EBs) for 13 VOCs (toluene, xylene, ethylbenzene, styrene, acrylamide, N,N-dimethylformamide, acrolein, crotonaldehyde, 1,3-butadiene, acrylonitrile, cyanide, propylene oxide, and 1-bromopropane) with liver injury biomarkers and the risk of NAFLD by performing single-chemical (survey weight regression) and mixture (Bayesian kernel machine regression [BKMR] and weighted quantile sum [WQS]) analyses. We found significant positive associations of EBs for toluene and 1-bromopropane with alanine aminotransferase (ALT), EBs for toluene, crotonaldehyde, and 1,3-butadiene with asparate aminotransferase (AST), EBs for 1,3-butadiene and cyanide with alkaline phosphatase (ALP), EBs for xylene and cyanide with hepamet fibrosis score (HFS), EBs for the total 13 VOCs (except propylene oxide) with United States fatty liver index (USFLI), and EBs for xylene, N,N-dimethylformamide, acrolein, crotonaldehyde, and acrylonitrile with NALFD; and significant inverse associations of EBs for ethylbenzene, styrene, acrylamide, acrolein, crotonaldehyde, 1,3-butadiene, acrylonitrile, cyanide, and propylene oxide with total bilirubin, EBs for ethylbenzene, styrene, acrylamide, acrolein, 1,3-butadiene, acrylonitrile, and cyanide with albumin (ALB), EBs for ethylbenzene, styrene, acrylamide, N,N-dimethylformamide, acrolein, crotonaldehyde, 1,3-butadiene, acrylonitrile, cyanide, and propylene oxide with total protein (TP), and EB for 1-bromopropane with AST/ALT (all P-FDR<0.05). In BKMR and WQS, the mixture of VOC-EBs was significantly positively associated with ALT, AST, ALP, HFS, USFLI, and the risk of NAFLD, while significantly inversely associated with TBIL, ALB, TP, and AST/ALT. VOCs exposure was associated with liver injury and increased risk of NAFLD in US adults. These findings highlight that great attention should be paid to the potential risk of liver health damage from VOCs exposure.

[Determination of o-chlorostyrene in the air of workplace by gas chromatography].

OBJECTIVE: To establish a rapid gas chromatographic method for determination of o-chlorostyrene in the air of workplace. METHOD: The air samples were collected by syringes, injected directly to the GC system, and then separated by a FFAP capillary column (30 m × 0.53 mm × 0.25 µm), finally determined by a Flame Ionization Detector. RESULTS: A good linear correlation was showed within a range of 0 ∼ 1200 µg/L, with regression formula Y = 14 030 + 7 207X (r = 0.9999). The air sample could be stably stored in the syringe for 5 hrs. The relative standard deviation (RSD) of repeated injection of o-chlorostyrene standard solutions at three different concentration by six times was 1.28% ∼ 1.97%. The minimum detectable concentration was calculated to be 5.2 mg/m(3). Other coexistent violative organic compounds such as styrene, p-chlorostyrene, and m-chlorostyrene didn't interfere with the determination under the experimental conditions of this method. CONCLUSION: This method meets the requirement of "Guide for establishing occupational health standards-Part 4: Determination methods of air chemicals in workplace". It is applicable for determination of o-chlorostyrene in the air of workplace.

Dissipation and dietary risk assessment of tristyrylphenol ethoxylate homologues in cucumber after field application.

The potential for tristyrylphenol ethoxylates (TSPEOs) residues to contaminate crops or be released into the environment is of increasing concern, as they are toxic to living organisms. This study determined the dissipation of TSPEO homologues in cucumber under field conditions. TSPEOn (n = 6-29) dissipated more rapidly in cucumber than in soil samples, with half-lives of 1.80-4.30 d and 3.73-6.52 d, respectively. Short-chain TSPEOn (n = 6-11) persisted for longer than other oligomers in soil. Concentrations of the final residues (∑TSPEOs) in cucumber and soil were 24.3-1349 µg/kg and 47.3-1337 µg/kg, respectively. TSP15EO or TSP16EO was the dominant oligomer, with concentrations of 2.30-150 µg/kg. The risk assessment showed that the acute and chronic dietary exposure risks of ∑TSPEOs in cucumber were 0.03-0.57% and 0.05-0.39%, respectively, suggesting little or no health risk to Chinese consumers.

Levels of Octachlorostyrene in Mothers' Milk and Potential Exposure Among Infants in Sendai City, Japan 2012.

Persistent organic pollutants can accumulate inside the human body, including in mothers' milk, which may affect infant development. This cross-sectional study aimed to examine selected persistent organic pollutants in the milk of 100 mothers in Sendai city, Miyagi Prefecture, Japan. We used gas-chromatography-electron capture negative chemical ionization-mass spectrometry to check for octachlorostyrene, dechlorane (Dec) plus, Dec 602, Dec 603, and Dec 604. Octachlorostyrene was detected in 86 samples at more than the method detection limit (84 pg g-lipid-1) but no dechloranes were above the method detection limit (1 ng mL-1 for dechlorane plus, Dec 602, and Dec 603; 20 ng mL-1 for Dec 604). The mean octachlorostyrene concentration was 461 pg g-lipid-1, the median was 337 pg g-lipid-1, and the standard deviation 450 pg g-lipid-1. No baseline characteristics were associated with octachlorostyrene level except for mother's occupation (stay-at-home mother, 353 ± 327 pg g-lipid-1; others, 531 ± 509 pg g-lipid-1). Octachlorostyrene was also significantly negatively correlated with lipid content (r = -0.35, p = 0.0004). However, the maximum intake of octachlorostyrene among infants in this study (3.5 ng/kg/day) was under the acceptable daily intake (30 ng/kg/day, derived from 12-month study in rats), and is therefore unlikely to pose a health risk.

Piece-by-piece analysis of additives and manufacturing byproducts in plastics ingested by seabirds: Implication for risk of exposure to seabirds.

The risk of marine organisms ingesting plastics has become a growing concern due to hazard chemicals in plastics. To identify compounds to which seabirds potentially have substantial exposure, 194 plastics fragments and pellets ingested by seabirds, i.e., northern fulmars from the Faroe Islands, and laysan albatross and black-footed albatross from Mukojima Island, were analyzed piece by piece. Four kinds of UV stabilizers, 2 brominated flame retardants, and styrene oligomers were detected at detection frequencies of 4.6%, 2.1%, and 2.1%, respectively. Concentrations ranging from not detected (n.d.) - 1700 µg/g were measured for UV stabilizers, n.d. - 1100 µg/g for flame retardants, and n.d. - 3200 µg/g for styrene oligomers. We found that these chemicals could be retained in plastics during drifting and fragmentation in the ocean and transported to seabirds. This type of transport via plastics can be direct pathway that introduces hazardous compounds to marine organisms.

Effect of casein on pure lecithin liposome: Mixed biomacromolecular system for providing superior stabilization to hydrophobic molecules.

Formulation of new liposoma-based systems can always be in the spotlight for their unique utilization as carriers. Some changes in the composition of lipids may give rise to new mixed liposomes exhibiting modified size and physico-chemical characteristics. Consequently, these display different encapsulating properties toward various molecules. In this work, we have explored the variations in the model lecithin liposomes with casein additive from their size, shape, microenvironment and dynamics in solution. It is observed that with introduction of casein, the size of the liposome is substantially reduced due to incorporation of the additive in its bilayer. Strong interaction between the hydrophobic side chains of casein and lipid bilayer, and electrostatic repulsion of head groups of lipid are responsible to result small casein-mixed liposomes. Spectral properties of coumarin-153 disclose that the microenvironment of the bi-layer of mixed system is predominantly hydrophobic in nature and much rigid too. Fluorescence-lifetime-imaging-microscopy indicates that casein mixed systems exhibit wider lifetime distribution than pure liposomes with predominance of longer lifetimes, entirely arising from the outer bilayer. This indicates that casein gets incorporated in the bilayer of the vesicle to cater rigid and more hydrophobic microenvironment with an effective decrease in size. It is found that such mixed system is very efficient to stabilize the hydrophobic drugs (curcumin and ß-carotene) for prolonged period than the pure liposome or casein-only. The findings are indeed important from the perspective of drug stabilization by liposomes, and is suggestive of possible utilization in oral drug delivery applications involving such size-reduced nano-encapsulates.

Detection of filamentous tau inclusions by the fluorescent Congo red derivative FSB [(trans,trans)-1-fluoro-2,5-bis(3-hydroxycarbonyl-4-hydroxy)styrylbenzene].

Filamentous inclusions made of the microtubule-associated protein tau in a hyperphosphorylated state are a defining feature of a large number of human neurodegenerative diseases. Here we show that (trans,trans)-1-fluoro-2,5-bis(3-hydroxycarbonyl-4-hydroxy)styrylbenzene (FSB), a fluorescent Congo red derivative, labels tau inclusions in tissue sections from a mouse line transgenic for human P301S tau and in cases of familial frontotemporal dementia and sporadic Pick's disease. Labelling by FSB required the presence of tau filaments. More importantly, tau inclusions in the spinal cord of human P301S tau transgenic mice were labelled following a single intravenous injection of FSB. These findings indicate that FSB can be used to detect filamentous tau in vivo.

Cyclic voltammetric analysis of 2-styrylchromones: relationship with the antioxidant activity.

2-Styrylchromones (2-SC) are a chemical family of oxygen heterocyclic compounds, vinylogues of flavones (2-phenylchromones), whose occurrence in nature has been reported. Recently, several 2-SC derivatives were demonstrated to have antioxidant properties, namely, xanthine oxidase inhibition, hepatoprotection against pro-oxidant agents in cellular and non-cellular systems and scavenging activity against reactive oxygen and reactive nitrogen species (ROS and RNS). Considering these antioxidant properties, it may be hypothesised that the electrochemical redox behaviour of 2-SC contributes significantly to their activity. To test this hypothesis, the electrochemical behaviour of different 2-SC was studied, together with a number of flavonoids with well-known antioxidant activities, by cyclic voltammetry, and the results correlated to their ability to scavenge ROS and RNS. The results obtained showed that 2-SC with a catecholic B-ring have a low oxidation peak potential corresponding to the oxidation of the 3',4'-OH (catechol) moiety. The compounds with a phenolic B-ring have a common peak, with oxidation potential values of about +0.4/+0.5 V versus Ag/AgCl, corresponding to the oxidation of the 4'-OH. The oxidation of the hydroxyl substituents in the A-ring generated peaks of higher potentials (+0.7/+0.8 V vs Ag/AgCl). The results from the scavenging assays were in agreement with those obtained from the cyclic voltammetry, that is, higher scavenging effects corresponded to lower values of oxidation potentials, with significant correlation coefficients. The values obtained for the studied flavonoids are in accordance with the literature, and reflect their relative antioxidant activity, when compared to the studied 2-SC. Thus, in this family of compounds, oxidation potentials obtained by cyclic voltammetry seem to be applicable as a general indicator of radical scavenging activity.

Ecotoxicological evaluation of octachlorostyrene in fourth instar larvae of Chironomus riparius (Diptera, Chironomidae).

The ecotoxicological effects of octachlorostyrene (OCS) on the aquatic larvae of the nonbiting midges Chironomus riparius (Diptera, Chironomidae) were investigated by evaluating their responses in various biological organizations, from the molecular and biochemical to the ecophysiological levels. The results of the 24-h lethality test of OCS on C. riparius suggest that this compound has a low acute toxic potential with respect to this species. The OCS exhibited serious chronic toxicity in C. riparius, however, especially on the species' development (pupation and emergence failure), the sex ratio of the emerged adults (high female to male ratio), and the adults' reproduction (oviposition failure). As the basic premise that changes in the gene expression can be harnessed to diagnose the exposure and effects of environmental chemicals is currently receiving significant attention, the increase in the expression of the heat shock protein and hemoglobin genes suggests that altered molecular-level parameters could be interpreted as early warning biomarkers of chemical stress. The establishment of a causal relationship between molecular and organism or population indicators is important, however, from the ecotoxicological point of view, although it is difficult to perform. The experimental evidence generated in the present study, especially at the molecular and biochemical levels, is not sufficient to demonstrate a plausible mechanistic linkage among responses across biological levels. Had more parameters at the molecular and biochemical levels been investigated, the mechanistic linkage might have been better identified. A mechanistic study appears to be necessary to understand causal relationships between gene expression and higher-level consequences, such as development and reproduction. The results of the present study may constitute an important contribution to knowledge on the ecotoxicology of OCS in aquatic organisms, about which little data is available.

Qualitative assessment to determine internal and external factors influencing the origin of styrene oligomers pollution by polystyrene plastic in coastal marine environments.

The objective of this study is to investigate the qualitative contribution of internal and external factors of the area contaminated by polystyrene (PS) in coastal marine environments. This study is based on the extensive results of monitoring the styrene oligomers (SOs) present in sand and seawater samples along various coastlines of the Pacific Ocean. Here, anthropogenic SOs is derived from PS during manufacture and use, and can provide clues about the origin of SOs by PS pollution. The monitoring results showed that, if the concentration of SOs in water is higher than those concentrations in beach sand, this area could be affected by PS plastic caused by an external factor. On the other hand, if the concentration of SOs is higher in the beach sand, the region can be mainly influenced by PS plastic derived from its own area. Unlike the case of an external factor, in this case (internal influence), it is possible to take policy measures of the area itself for the PS plastic problem. Thus, this study is motivated by the need of policy measures to establish a specific alternative to the problems of PS plastic pollution in ocean environments.

Synthesis, spectra, delivery and potentiometric responses of new styryl dyes with extended spectral ranges.

Styryl dyes have been among the most widely used probes for mapping membrane potential changes in excitable cells. However, their utility has been somewhat limited because their excitation wavelengths have been restricted to the 450-550 nm range. Longer wavelength probes can minimize interference from endogenous chromophores and, because of decreased light scattering, improve recording from deep within tissue. In this paper we report on our efforts to develop new potentiometric styryl dyes that have excitation wavelengths ranging above 700 nm and emission spectra out to 900 nm. We have prepared and characterized dyes based on 47 variants of the styryl chromophores. Voltage-dependent spectral changes have been recorded for these dyes in a model lipid bilayer and from lobster nerves. The voltage sensitivities of the fluorescence of many of these new potentiometric indicators are as good as those of the widely used ANEP series of probes. In addition, because some of the dyes are often poorly water soluble, we have developed cyclodextrin complexes of the dyes to serve as efficient delivery vehicles. These dyes promise to enable new experimental paradigms for in vivo imaging of membrane potential.

An investigation of multiple biomarkers among workers exposed to styrene and styrene-7,8-oxide.

Investigations of cancer and cytogenetic damage among reinforced-plastics workers have produced contradictory results. In all studies, the focus has been on styrene rather than the carcinogen, styrene-7,8-oxide (SO), traces of which are generated during the manufacturing process. Because styrene is present at very high levels and is metabolized almost exclusively through SO, coexposures to SO have been discounted. This study investigated the relative contributions of airborne styrene and SO and of smoking toward several SO-specific biomarkers (DNA and albumin adducts) and sister chromatid exchanges in the blood of 48 reinforced-plastics workers. Among individual subjects, albumin and DNA adducts as well as sister chromatid exchanges were significantly correlated with styrene exposure. However, among the 20 subjects with measurements to both styrene and SO, albumin adducts were significantly correlated with exposure to SO but not to styrene. Finally, among the 10 job groups, surprisingly strong correlations (0.709 < or = r < or = 0.966) were found between all SO biomarkers and exposure to SO but not to styrene. Calculations suggest that SO was about 2000 times more effective than styrene in producing SO biomarkers. After accounting for the disparate exposures to the two chemicals, a typical worker received 71% of the systemic dose of SO via inhalation; nonetheless, 5 of the 20 subjects received the majority of the SO dose from styrene. Cigarette smoking increased levels of SO-albumin and SO-DNA adducts, suggesting that SO was a constituent of tobacco smoke. We conclude that inhalation of SO should be considered in any interventions to reduce health risks.

Voltage imaging from dendrites of mitral cells: EPSP attenuation and spike trigger zones.

To obtain a more complete description of individual neurons, it is necessary to complement the electrical patch pipette measurements with technologies that permit a massive parallel recording from many sites on neuronal processes. This can be achieved by using voltage imaging with intracellular dyes. With this approach, we investigated the functional structure of a mitral cell, the principal output neuron in the rat olfactory bulb. The most significant finding concerns the characteristics of EPSPs at the synaptic sites and surprisingly small attenuation along the trunk of the primary dendrite. Also, the experiments were performed to determine the number, location, and stability of spike trigger zones, the excitability of terminal dendritic branches, and the pattern and nature of spike initiation and propagation in the primary and secondary dendrites. The results show that optical data can be used to deduce the amplitude and shape of the EPSPs evoked by olfactory nerve stimulation at the site of origin (glomerular tuft) and to determine its attenuation along the entire length of the primary dendrite. This attenuation corresponds to an unusually large mean apparent "length constant" of the primary dendrite. Furthermore, the images of spike trigger zones showed that an action potential can be initiated in three different compartments of the mitral cell: the soma-axon region, the primary dendrite trunk, and the terminal dendritic tuft, which appears to be fully excitable. Finally, secondary dendrites clearly support the active propagation of action potentials.

Quantitative analysis of styrene monomer in polystyrene and foods including some preliminary studies of the uptake and pharmacodynamics of the monomer in rats.

A variety of food containers, drinking cups and cutlery, fabricated from polystyrene (PS) or polystyrene-related plastic, were analyzed for their styrene monomer content. Samples of yogurt, packaged in PS cups, were similarly analyzed and the leaching of styrene monomer from PS containers by some food simulants was also determined. Blood level studies with rats, dosed with styrene monomer by various routes, illustrated uptake phenomena that were dependent on the dose and route of administration and were also affected by the vehicle used to convey the styrene monomer.