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BACKGROUND Commercially formulated pesticide products are complex mixtures of one or more active ingredients and several co-ingredients. However, the modifying effect of co-ingredients on skin uptake and glove barrier protection has been poorly studied. The aim of this study was to understand the role of formulation co-ingredients in skin and glove barrier protection performance against organophosphate insecticides. RESULTS We adapted standard in vitro diffusion cell methods to test permeation kinetics of two commonly used organophosphate insecticides: dimethoate and omethoate. For spray dilutions, dimethoate and omethoate did not reach breakthrough glove permeation rate (1 μg·cm-2 ·min-1 ) and no or little skin permeation was observed for up to 8 h, regardless of formulation. For exposure conditions involving highly concentrated products, significant differences in glove permeation were observed between different formulations of dimethoate (about 1.5-fold, P 0.05) was observed between formulations in terms of skin permeation. CONCLUSION These results suggest that co-ingredients play a critical role in glove barrier protection against undiluted organophosphate insecticides, whereas their influence on skin uptake was insignificant within the exposure time tested. This implies that dermal exposure risk may vary between handling different formulated products of the same active ingredient hence recommending a common glove material for different formulations of the same chemical without careful consideration of co-ingredients and their permeation properties may not necessarily be appropriate.

The growing interest in regulating flavored E-liquids must incorporate understanding of the “flavoring profile” of each E-liquid—which flavorings (flavoring chemicals) are present and at what concentrations not just focusing on the flavor on the label. We investigated the flavoring profile of 10 different flavored E-liquids. We assessed bronchial epithelial cell viability and apoptosis, phagocytosis of bacteria and apoptotic cells by macrophages after exposure to E-cigarette vapor extract (EVE). We validated our data in normal human bronchial epithelial cells (NHBE) and alveolar macrophages (AM) from healthy donors. We also assessed cytokine release and validated in the saliva from E-cigarette users. Increased necrosis/apoptosis (16.1–64.5% apoptosis) in 16HBE cells was flavor dependent, and NHBEs showed an increased susceptibility to flavors. In THP-1 differentiated macrophages phagocytosis was also flavor dependent, with AM also showing increased susceptibility to flavors. Further, Banana and Chocolate were shown to reduce surface expression of phagocytic target recognition receptors on alveolar macrophages. Banana and Chocolate increased IL-8 secretion by NHBE, whereas all 4 flavors reduced AM IL-1β secretion, which was also reduced in the saliva of E-cigarette users compared with healthy controls. Flavorant profiles of E-liquids varied from simple 2 compound mixtures to complex mixtures containing over a dozen flavorants. E-liquids with high benzene content, complex flavoring profiles, high chemical concentration had the greatest impacts. The Flavorant profile of E-liquids is key to disruption of the airway status quo by increasing bronchial epithelial cell apoptosis, causing alveolar macrophage phagocytic dysfunction, and altering airway cytokines.

Hands and forearms are the principal sites of dermal exposure to organophosphate insecticides, which makes glove use one of the most important components of an exposure control strategy. However, the selection of suitable gloves depends on issues such as task, type, and concentration of organophosphate as well as cost. In addition, chemical protection performance of gloves may be temperature dependent, which is of increasing concern in a warming climate. Two recommended reusable glove materials (polyvinylchloride and nitrile butadiene rubber) and one single-use glove (nitrile/neoprene) were tested for permeation resistance to actual formulations of organophosphate insecticides with active ingredients dimethoate and malathion. Chemical resistance parameters were measured using American society for testing and materials permeation test cells and compared across glove, organophosphate type, and temperature. The three gloves demonstrated comparable and adequate chemical resistance (less than one µg cm

The popularity of engineered stone (ES), alternatively known as artificial stone, as a building material for kitchen and bathroom benchtops in residential houses has expanded rapidly over the last decade. This has been associated with a global increase in occupational lung disease in workers exposed to the respirable dust produced during fabrication of ES products. In this study, we evaluated the reactivity and subsequent oxidative reduction potential of ES dusts generated by dry-cutting different ES materials using a common fabrication tool in a controlled environment and subsequently applying these freshly generated dusts to a cell-free deoxyguanosine hydroxylation assay to assess the potential for oxidative DNA damage. The objectives of this study were to (1) compare the potential for oxidative damage by (i) engineered vs. natural stones, (ii) settled vs. respirable stone dust fractions and (2) assess the effect of ageing on the reactivity of freshly-generated stone dust. Engineered stone dust was found to exhibit a higher relative reactivity than the majority of natural stones tested. Respirable dust fractions were found to be significantly more reactive than their corresponding settled fraction (p

Engineered stones are novel construction materials associated with a recent upsurge in silicosis cases among workers in the stonemason industry. In order to understand the hazard for the short latency of lung disease among stonemasons, we simulated real-time dust exposure scenario by dry-machining engineered stones in controlled conditions, capturing and analysing the respirable dust generated for physical and chemical characteristics. Natural granite and marble were included for comparison. Cutting engineered stones generated high concentrations of very fine particles ( 80% respirable crystalline silica content, in the form of quartz and cristobalite. Engineered stones also contained 8–20% resin and 1–8% by weight metal elements. In comparison, natural stones had far lower respirable crystalline silica (4- 30%) and much higher metal content, 29–37%. Natural stone dust emissions also had a smaller surface area than engineered stone, as well as lower surface charge. This study highlighted the physical and chemical variability within engineered stone types as well as between engineered and natural stones. This information will ultimately help understand the unique hazard posed by engineered stone fabrication work and help guide the development of specific engineering control measures targeting lower exposure to respirable crystalline silica.

Background and objective E-cigarettes are often marketed and thought of as emitting harmless vapour; however, verification of their safety for non-smokers is scarce. We have previously shown that E-cigarettes cause decreased phagocytosis of bacteria by macrophages via reductions in surface bacterial recognition receptors. This study assessed the effect of E-cigarette constituents, 3 E-liquid apple flavours, nicotine, vegetable glycerine and propylene glycol, on bronchial epithelial cell viability, apoptosis and cytokine secretion and macrophage phagocytosis of apoptotic airway cells and phagocytic recognition molecules. Methods Cell necrosis and apoptosis were measured by Sytox Green stain and Annexin V. Efferocytosis was measured by internalization of pHrodo Green labelled apoptotic airway cells by macrophages. Expression of macrophage cell surface apoptotic cell receptors was measured by flow cytometry. Cytokine release by E-cigarette-exposed airway cells was measured by cytokine bead array. Results E-cigarette vapour increased primary bronchial epithelial necrosis and apoptosis. E-cigarette vapour reduced efferocytosis (lowest flavour 12.1%) versus control (20.2%, P = 0.032). The efferocytosis receptor CD44 was reduced by one flavour (MFI 1863 vs 2332 control, P = 0.016) and all components reduced expression of CD36, including the glycol bases (MFI 1067-12 274 vs 1415 control). Reduced secretion of TNF-α, IL-6, IP-10, MIP-1α and MIP-1β was observed for all flavour variants. Conclusion E-cigarettes can cause bronchial epithelial apoptosis and macrophage efferocytosis dysfunction via reduced expression of apoptotic cell recognition receptors. These data further show that E-cigarettes should not be considered harmless to non-smokers and their effects may go far beyond cytotoxicity to cells.

The toxic release of aldehyde vapours during a hazardous material (HAZMAT) incident primarily results in respiratory concerns for the unprotected public. However, skin absorption may be an important concurrent exposure route that is poorly understood for this scenario. This study provides experimental data on the skin absorption properties of common aldehydes used in industry, including acetaldehyde, acrolein, benzaldehyde and formaldehyde, in gaseous or vapour form using an adapted in vitro technique. Two of the four tested aldehydes were found to penetrate the skin in appreciable amounts following 30-min exposure at HAZMAT relevant atmospheric concentrations: acetaldehyde (5.29 ± 3.24 µg/cm2) and formaldehyde (3.45 ± 2.58 µg/cm2). Whereas only low levels of acrolein (0.480 ± 0.417 µg/cm2) and benzaldehyde (1.46 ± 0.393 µg/cm2) skin penetration was noted. The aldehydes demonstrated differing levels of interaction with fabric. Formaldehyde and acetaldehyde adsorbed strongly to denim, whereas benzaldehyde and acrolein displayed no sink properties. However, denim was shown to be an initial protective barrier and reduced penetration outcomes for all aldehydes. This study provides important information to assist first responders and confirms the relevance of using physicochemical properties (e.g. solubility, molecular weight, partition coefficient) to predict skin permeation potential in the absence of empirical data during HAZMAT incidents involving different types of aldehydes.

The popularity of engineered stone (ES) has been associated with a global increase in occupational lung disease in workers exposed to respirable dust during the fabrication of benchtops and other ES products. In this study, the reactivity and subsequent oxidative reduction potential of freshly generated ES dusts were evaluated by (i) comparing different engineered and natural stones, (ii) comparing settled and respirable stone dust fractions and (iii) assessing the effect of ageing on the reactivity of freshly generated stone dust. An established cell-free deoxyguanosine hydroxylation assay was used to assess the potential for oxidative DNA damage. ES dust exhibited a higher relative reactivity than two of the three natural stones tested. Respirable dust fractions were found to be significantly more reactive than their corresponding settled fraction (ANOVA, p < 0.05) across all stone types and samples. However, settled dust still displayed high relative reactivity. The lower reactivity of the settled dust was not due to decay in reactivity of the respirable dust when it settled but rather a result of the admixture of larger nonrespirable particles. No significant change in respirable dust reactivity was observed for three ES samples over a 21-day time period, whereas a significant decrease in reactivity was observed in the natural stone studied. This study has practical implications for dust control and housekeeping in industry, risk assessment and hazard management.

Dichlorvos is a toxic organophosphate insecticide that is used in agriculture and other insecticide applications. Dermal uptake is a known exposure route for dichlorvos and chemical protective gloves are commonly utilized. Chemical handling and application may occur in a variety of thermal environments, and the rates of both chemical permeation through gloves and transdermal penetration may vary significantly with temperature. There has been no published research on the temperature-dependent kinetics of these processes for dichlorvos and thus, this study reports on the effects of hot conditions for the concentrated and application strength chemical. Dichlorvos breakthrough times for non-disposable polyvinyl chloride (PVC) gloves at 60 &deg, C were approximately halved compared to 25 &deg, C for the concentrate (2 vs. 4 h) and more than halved at application strength (3 vs. &gt, 8 h). From permeation experiments covering 15&ndash, 60 &deg, C, there was a 460-fold increase in cumulative permeation over 8 h for the concentrated dichlorvos and the estimated activation energy halved. Elevated temperature was also shown to be a significant factor for human skin penetration increasing the cumulative penetration of concentrate dichlorvos from 179 &plusmn, 37 to 1315 &plusmn, 362 &micro, g/cm2 (p = 0.0032) and application strength from 29.8 &plusmn, 5.7 to 115 &plusmn, 19 &micro, g/cm2 (p = 0.0131). This work illustrates the important role temperature plays in glove performance and health risk via dermal exposure. As such, it is important to consider in-use conditions of temperature when implementing chemical hygiene programs.

Greenhouses are enclosed structures which have various characteristics that enhance crop productivity, but the implications for workers' pesticide exposure and uptake are not well understood. A narrative literature review was conducted to explore the mechanism/s of interactions between greenhouse characteristics and occupational pesticide exposure. Using a "work", "worker" and "workplace" conceptual framework, the greenhouse environment (hot and humid microclimate, limited space and dense crop arrangements) combines with work characteristics (high work and pesticide use intensity, multi-tasking, predominantly manual spraying techniques and quick reentry to treated farms) to potentially increase occupational pesticide exposure, compared with open field farming. Greenhouse environments, are variable but have been shown to influence pesticide availability, route, pathways and frequency of exposure, deposition and distribution on a worker's body as well as use and performance of exposure control methods. Training programs can emphasize the differences in exposure potential between greenhouse and open field farming. Development of tailored guidelines for exposure control strategies to better suit the level of uniqueness of greenhouse agriculture seems warranted.

BACKGROUND Cyanogen is a toxic flammable gas used as a fumigant in numerous industries. Occupational exposure to cyanogen can occur during its production and use. The most serious human health risk from exposure to cyanogen is via the respiratory system. However, there is also potential for skin exposure in many workplace situations. The extent of skin absorption under occupational exposure scenarios has not been directly assessed. Understanding skin uptake potential may inform risk assessment and exposure control measures. RESULTS We describe an in vitro experimental system using human epidermis and dynamic atmosphere exposure to cyanogen to mimic potential workplace exposures. The influence of clothing and ventilation on skin permeation outcomes were also assessed. No evidence of transdermal permeation was found at 100 or 1000 ppm exposures, while permeation of 0.99 ± 0.38 μg cm-2 was observed after 60 min exposure to 10 000 ppm. Fabric on skin and skin ventilation had no additional influence on transdermal permeation compared with naked skin, but fabric provided a reservoir for potential secondary exposures. CONCLUSION Results show dermal uptake following cyanogen exposure is possible, but only at very high atmospheric concentrations (10 000 ppm after >15 min exposure). Importantly, this could have implications for fumigant applicators who may only be wearing personal respiratory protection. These empirical data may be used in conjunction with other relevant toxicological information in determining whether a Skin Notation is warranted for Workplace Exposure Standard setting. © 2019 Society of Chemical Industry.

This paper presents the first empirical experimental data on the skin absorption of methyl chloride gas using an in vitro technique and human skin. Methyl chloride is a commonly used industrial agent that is known to be an inhalational hazard but is also reported to be absorbed through human skin in amounts that contribute substantially to systemic intoxication. As a result is has been assigned a skin notation by the ACGIH. Other than predictive models, there is a general paucity of experimental data on the skin absorption of methyl chloride and therefore a distinct lack of empirical evidence in the open literature to support the assignment of a skin notation for this chemical. This study found that methyl chloride permeates through human epidermis when exposed at high atmospheric concentrations within relatively short timeframes. Therefore, providing important initial empirical evidence in support of the assignment of a skin notation.

Owing to their volatility, the most important occupational exposure route for low-molecular-weight amines is considered to be inhalation. However, dermal exposure is also possible in many workplace situations. There are limited data available on the dermal uptake of these amines through human skin, and existing exposure standard skin notations are typically based on acute toxicity animal studies or by chemical analogy. This gap in knowledge is in part due to a lack of standardized approach for assessing dermal uptake. We describe a relatively simple protocol for the determination of permeation of low-molecular-weight amines through human skin in vitro. Using isopropylamine as a test amine, it was found that isopropylamine vapour has limited capacity to absorb into, or penetrate through, the epidermal layer of human skin, even at lethal atmospheric concentrations. This protocol can be adapted for a range of exposure scenarios, including clothing effects, and may be used to determine whether skin notations are warranted.

Capacitively coupled contactless conductivity detection (C4D) and its integration with Lab-on-a-Chip (LOC) systems has been well studied. However, most reported methods require multi-step electrode patterning/fabrication processes which in turn leads to difficulty in consistently aligning detection electrodes. These limitations have the potential to compromise analytical performance of the electrodes and increase the time and cost of device production. We have previously demonstrated a simplified approach for C4D electrode integration with poly(dimethylsiloxane) electrophoresis LOC devices by utilizing ‘injected’ gallium electrodes.1 The developed fabrication process is fast, highly reproducible, and eliminates difficulties with electrode alignment. Using this approach C4D can be readily achieved in any microchip by simply adding extra ‘electrode’ channels to the microchip design. This design flexibility allows for straightforward optimization of electrode parameters. Here, we present the optimization of physical electrode parameters including orientation, length and distance from separation channel. The suitability of the optimized system for on-chip C4D detection was demonstrated through the excellent intra- and inter-day repeatability (< 4 %RSD) of electrophoretically separated lithium, sodium and potassium ions.

We demonstrate the use of injected gallium electrodes for capacitively coupled contactless conductivity detection (C(4)D) within a microchip electrophoresis device. Evaluation of the electrodes for quantitative detection of electrophoretically separated lithium, sodium and potassium ions showed the system offers competitive detection limits of 6.1 × 10(-6) M, 6.7 × 10(-6) M and 8.5 × 10(-6) M, respectively. The fabrication process is fast, highly reproducible, and eliminates difficulties with electrode alignment. Using this approach C(4)D can be readily achieved in any microchip by simply adding extra 'electrode' channels to the microchip design.

Herein, we describe the development of a novel primer system that allows for the capture of double-stranded polymerase chain reaction (PCR) amplification products onto a microfluidic channel without any preliminary purification stages. We show that specially designed PCR primers consisting of the main primer sequence and an additional “tag sequence” linked through a poly(ethylene glycol) molecule can be used to generate ds-PCR amplification products tailed with ss-oligonucleotides of two forensically relevant genes (amelogenin and human c-fms (macrophage colony-stimulating factor) proto-oncogene for the CSF-1 receptor (CSF1PO). Furthermore, with a view to enriching and eluting the ds-PCR products of amplification on a capillary electrophoretic-based microfluidic device we describe the capture of the target ds-PCR products onto poly(dimethylsiloxane) microchannels modified with ss-oligonucleotide capture probes.