Our study shows that site-specific estimates of dermal exposure to selected polycyclic aromatic hydrocarbons contained in contaminated gasworks soil result in lower average daily exposure and risk to human health when compared to the generic assumptions used in risk assessment software. We use site specific in vitro dermal bioavailability flux (μg/cm2/h) for benzo[a]pyrene measured by earlier research published by the authors, where dermal flux provides an analogue of diffusion through the skin and into systemic circulation. We used measured in vitro dermal flux for gasworks contaminated soil containing 150 mg/kg of benzo[a]pyrene to estimate average daily exposure and risk using the Contaminated Land Exposure Assessment (CLEA) framework. Site-specific flux (0.00237 ng/cm2/hour) was used to calculate an uptake of 23.7 ng benzo[a]pyrene/m2 skin/hour, resulting in an average daily exposure (ADE) ranging from 20.7 to 37.3 ng benzo[a]pyrene/kg bw/day for the first six years of a female child's life. The average ratio of average daily exposure to the Health Criteria Value (Index Dose) was 0.54, where a soil concentration of 278.4 mg/kg is equivalent to a ratio of ADE to Index Dose of one. The results show that for the dermal pathway only, the risk to human health calculated using site-specific dermal flux is lower than using default values used in CLEA. In our discussion we highlight that dermal bioavailability varies between sites and PAH and that differences are likely to be influenced by the source of contamination and the physico-chemical properties of soil. Our findings support an evidence-based shift toward sample-specific parameters in regulatory risk assessment frameworks, but the scalability, inter-laboratory reproducibility, range and contaminants tested and the cost-effectiveness of in vitro flux testing need to be researched further before broader regulatory adoption.

An enhanced in vitro human dermal bioavailability method was developed to measure the release of twenty parent and seven alkylated high molecular weight (HMW) polycyclic aromatic hydrocarbons (PAHs) from contaminated soils collected from five former manufactured Gas Plants (MGP) in England. GC-MS/MS was used to quantify HMW PAHs in soil, Strat-M artificial membrane representing skin, and synthetic receptor solution (RS) representing systemic circulation at 1-h, 10-h, and 24-h timesteps. Fluoranthene and pyrene exhibited the highest fluxes from soils to membrane (ranging from 9.5 - 281 ng/cm 2 /h) and soil to RS ( 16.9 ng/cm 2 / h). Chrysene, benzo[ a ]anthracene, benzo[ b ]fluoranthene and the alkylated C1-fluoranthene/pyrene homologue series demonstrated fluxes higher than other HMW PAHs. The dermal fluxes were generally lower than those reported in previous investigations and suggests that dermal absorption varies between both HMW parent and alkylated PAHs and individual PAHs. The utilisation of real -world contaminated soils allowed for a more realistic representation; this is important because current risk assessment guidance is baseed on results from experiments that used artificially spiked soils. This research shows that the the ranges of dermal fluxes are PAH dependent and impact the mass of absorbed from soil after dermal exposure and therefore the potential risk contaminated soil poses to human health.

Soils sampled from 10 former manufactured gas plants (MGP) in the UK were investigated using gas chromatography mass spectrometry (GC-MS/MS) and Rock-Eval (6) Pyrolysis (RE). RE is a screening tool used to characterise bulk organic matter in soils via the release of carbon compounds during pyrolysis and oxidation. Both the distributions and concentrations of 30 parent and 21 alkylated polycyclic aromatic hydrocarbons (PAHs) and the parameters of RE were analysed to establish relationships between soils and the MGP processes history. Principal component analysis (PCA) using the PAHs distributions and RE parameters can assist with differentiating between MGP processes. MGP processes utilizing oil provided the clearest results, attributed to petrogenic signatures with high proportions of low molecular weight PAHs. Processes using lower temperature processes were distinguished by higher proportions of high molecular weight PAHs. RE parameters alone were unable to distinguish MGP processes but showed potential in estimating the lability and thus the amount of PAH that could be released from soils. This research provides new insights that may be useful in understanding and characterising the risks posed to human health from PAHs in soils.

The current research builds on the findings of a systematic literature review by the authors which recommends the need to work towards a standardised method for measuring the in vitro dermal absorption of HMW-PAH in soils. One part of the method is understanding the partitioning of the high molecular weight polycyclic aromatic hydrocarbons (HMW-PAH) from soil to sebum found in skin. In vitro HMW-PAH soil-sebum partition coefficients (KSS) were measured for twelve soils collected from former UK gasworks. Concentrations of ∑16 USEPA PAH in the soils ranged from 51 to 1440 mg/kg, benzo[a]pyrene ranged from 3.2 to 132 mg/kg. Time series extractions (0.5, 1, 2, 4, 8 and 24 h) at skin temperature (32°C) of HMW-PAH from sebum to soil for two samples were conducted to determine the maximum release time-step. The maximum HMW-PAH release time-step was determined as 4 h, which was subsequently used as the extraction time for the remaining samples. Evaluation of KSS data for the 4 h extractions showed that soil type and selected HMW-PAH properties (literature based molecular weight and octanol-carbon partition coefficients) affect the amount of HMW-PAH released from soil into sebum. Characterisation of soil properties was limited to total organic carbon, which showed no relationship to KSS. Selected soils showed distinctly higher K¬SS than others. The relationship between MW and KSS was statistically significant while the relationship between KOC and KSS was not statistically significant. Further research effort is required to improve our understanding of which soil and HMW-PAH properties affect the release of HMW-PAH from soil into sebum and the reasons why.

Polycyclic aromatic hydrocarbons (PAHs) are a group of organic compounds consisting of two or more fused aromatic rings and are probably one of the most studied groups of organic chemicals in environmental research. PAHs originate mainly from anthropogenic processes, particularly from incomplete combustion of organic fuels. PAHs are distributed widely in particulate matter. Due to widespread sources and persistent characteristics, PAHs disperse through atmospheric transport and exist almost everywhere. Human beings are exposed to PAH mixtures in gaseous or particulate phases in ambient air. Long-term exposure to high concentrations of PAHs is associated with adverse health problems. This review identifies the main research and development themes in the measurement and occurrences of PAHs in dusts and particulates using a new approach to carrying out a literature review where many peer-review publications have been produced. The review extracts the most important research themes from a literature search using a combination of text mining and a more detailed review of selected papers from within the identified themes.

12 Creosote is a distillation product of coal tar and is widely used as wood preservative 13 for railway sleepers, utility poles and for other applications. Creosote can have 14 potentially negative effects on the environment and many of the components are toxic. 15 This study presents the analysis of a Creosote sample from a former wood 16 impregnation plant located in the UK. The sample was analysed using two 17 dimensional gas chromatography time-of-flight mass spectrometry (GCxGC-TOFMS) 18 and a database of compounds that could be detected was produced. The GCxGG19 TOFMS was capable of detecting 1505 individual compounds, which is far more than 20 previous estimates for the number of compounds present within Creosote. Post 21 extraction derivatization using BTSFA with 1% TMCS was employed to increase the 22 potential number of compounds detected with 255 derivatized compounds detected, 23 231 of which would not have been detected without prior derivatization. Selected 24 derivatized compounds were quantified with limits of detection ranging from 25

Creosote is a distillation product of coal tar and is widely used as wood preservative for railway sleepers, utility poles and for other applications. Creosote can have potentially negative effects on the environment and many of the components are toxic. This study presents the analysis of a Creosote sample from a former wood impregnation plant located in the UK. The sample was analysed using two dimensional gas chromatography time-of-flight mass spectrometry (GCxGC-TOFMS) and a database of compounds that could be detected was produced. The GCxGG-TOFMS was capable of detecting 1505 individual compounds, which is far more than previous estimates for the number of compounds present within Creosote. Post extraction derivatization using BTSFA with 1% TMCS was employed to increase the potential number of compounds detected with 255 derivatized compounds detected, 231 of which would not have been detected without prior derivatization. Selected derivatized compounds were quantified with limits of detection ranging from 0.6 mg/kg to 1.6 mg/kg from a concentrated dense non-aqueous phase liquid (DNAPL). This work presents the first published full analysis of a Creosote using GCxGC-TOFMS combined with derivatization.