Chemical flame retardants (FRs) such as polybrominated diphenyl ethers (PBDEs) and chlorinated organophosphates (e.g. tris (2-chloroisopropyl)phosphate – TCIPP) have been used extensively in a wide range of applications worldwide. Substantial evidence exists that this has led to environmental contamination following emissions during their manufacture, incorporation into products and materials, as well as during their use and disposal. However, while a small number of studies have characterised the presence of PBDEs in urban and rural soils and sediments in the UK; very little is known about the existence of hotpots of FR contamination that may present specific local human exposure hazards. Moreover, very little information exists about the extent to which human contact with such contaminated land may influence concentrations in the body. This project thus has two principal objectives. The first is to characterise a range of FRs in soil from a range of potentially contaminated sites across the UK. These will include: landfills, e-waste processing facilities, and facilities where FRs are incorporated into goods, such as furniture foam manufacturers etc. These data will be placed in context against previous surveys of soil contamination in the UK and elsewhere, augmented where needed by fresh measurements in soils from “control” locations in the UK. The second objective is optimise and apply in vitro bioaccessibility/bioavailability models to evaluate human uptake from contaminated soil. At the University of Birmingham, we will use cultured human skin equivalent models to study dermal uptake, while at BGS, the (Fed ORganic Estimation human Simulation Test- FOREhST) gut bioaccessibility model will be applied to evaluate uptake via ingestion of soil. Data generated in addressing these objectives will be combined with information on human health impacts, to aid assessment of the risk arising from human exposure arising from the presence of FRs in soil.
We will test the hypothesis that hotspots of FR contamination of soil exist and represent a human exposure hazard. To do so, we will measure concentrations of halogenated FRs in topsoil from locations potentially impacted by putative source activities such as waste treatment facilities. We hypothesise that concentrations in soils from these sites will exceed significantly those in soils taken from locations not directly impacted by such activities. We will then use in vitro models to evaluate the efficiency of uptake of FRs from contaminated soil as a result of intake via dermal contact and ingestion. This work will test hypotheses about the influence on contaminant uptake efficiency, of various parameters including properties of the contaminants, environment, and soil. Data produced will be input into existing models of human exposure to contaminated land (e.g. CLEA) and interpreted in the context of prevailing exposure guidelines to evaluate the potential risk to human health.
Training and Skills
CENTA students are required to complete 45 days training throughout their PhD including a 10 day placement. In the first year, students will be trained as a single cohort on environmental science, research methods and core skills. Throughout the PhD, training will progress from core skills sets to master classes specific to the student's projects and themes.
The project has a strong multidisciplinary component, combining aspects of analytical science, environmental chemistry, in vitro testing, as well as exposure and risk assessment. Consequently, subject-specific training will be offered in each of these areas. It will comprise a mix of appropriate postgraduate level training (e.g. Pollution Management and Control, Environmental Analysis and Modelling), “hands-on” training in the in vitro models used, and external training courses. Examples of the latter include those run by Marie Curie Initial Training Network projects headed by Harrad that address aspects specific to the environmental analysis of pollutants including FRs.
Year 1: Familiarisation with literature, training in generic research techniques (e.g. research ethics, project planning, lab safety), and subject-specific training in trace analysis and soil sampling techniques; development and validation of analytical chemistry methods for the determination of halogenated FRs in soils; identification of sampling locations and collection of first soil samples.
Year 2: Continued field sampling of soils from UK sites; determination of concentrations of halogenated FRs in soil samples; write-up of data on FR concentrations in soils from source-impacted locations for international conference presentation towards end of year 2; training in use of: (a) cultured human skin equivalent models for assessing dermal uptake, and (b) in vitro gut bioaccessibility models for evaluating uptake across the gastrointestinal tract.
Year 3: Application of in vitro models to evaluating human uptake of halogenated FRs from contaminated soil; assessment of human exposure and risk arising from soils contaminated with halogenated FRs; write research papers and thesis; make second presentation at international conference towards end of year 3
Partners and collaboration (including CASE)
The project is a new collaboration between the POPs research group led by Harrad and the teams of Vane and Cave at BGS. We envisage additional collaboration with potential CASE partners such as the Environment Agency, waste treatment companies (e.g. Veolia) and others with interest in characterising and assessing risks arising from contaminated land.
For further information, please contact either Professor Stuart Harrad, School of Geography, Earth & Environmental Sciences (S.J.Harrad@bham.ac.uk; 0121 414 7298; Webpage) or Dr. Christopher Vane, BGS Keyworth, (firstname.lastname@example.org; 0115 936 3017; Webpage)