SHE-Net

Overview

The aim of SHE-Net is to improve our estimates of human exposure to toxic organic chemicals in soil through the consumption of home grown and allotment produce and consequently improve the protection of public health. The largest area of concern in the risk assessment process for contaminated soils is the oral ingestion pathway, specifically the plant uptake of organic pollutants, where knowledge is currently lacking. SHE-Net is unique in that it assembles national and international experts in the areas of plant science, toxicology and risk assessment to address these issues. SHE-Net will produce a series of authoritative recommendations to help improve predictions of the health risks from chemical contamination of soils resulting in improved public health protection. The outputs from the network will be of direct benefit to the Environment Agency, Food Standards Agency, Health Protection Agency and local authorities when providing guidance on land affected by chemical contamination and estimating of dietary intakes when assessing the implications of such land for food safety.

Objectives

The overarching objective of SHE-Net is to comprehensively review the current understanding and methods for the assessment of human exposures to organic pollutants in soils via the foodchain by using a holistic approach to address the current shortcomings of the risk assessment process. To address this SHE-Net is organising three workshops with the objective of addressing the three components of the risk assessment for human exposure to soils containing organic pollutants: 1) Transfer of organic pollutants from soil to plants 2) Human health and organic pollutants 3) Risk assessment procedures for contaminated soils and the foodchain. Collectively these objectives address the aim of SHE-Net to improve the protection of human health from contaminated soils.

The network

SHE-Net will provide the first forum to specifically address the transfer of organics pollutants into the foodchain from contaminated land. The network is a combination of researchers and practitioners across the disciplines of plant science, human toxicology and risk assessment and includes representatives of academia, regulatory agencies and local government who are all stakeholders in this area (Link Network members). It therefore has the necessary range, knowledge and representation to deliver its task of improving our understanding of these processes, notably how they interact with one another and how research capacity can be built to address future requirements and thereby improve human health protection. The lead partners are all from internationally recognised research groups within the three key themes of the network, with support from the responsible regulatory agencies.

Specific issues addressed by the network

The network will convene at three workshops; each organised to address a specific theme. will attend workshops based on their expertise. Other interested parties who can contribute will be welcome.

Workshop 1

Transfer of organic pollutants from soils to plants. (25th -26th Sept 2007, Reading University). Read more about Workshop 1

Plant uptake of organic pollutants (including attached soil particles) is often the main pathway of concern for risk assessments for contaminated sites containing organic pollutants. The modelling of this process is subject to a number of uncertainties. The uptake from the soil to the root is reasonably well understood although the algorithms describing this were not developed using crops representative of the UK diet. Larger uncertainties are associated with the transfer from the root to the shoot of edible crops, the shoot uptake of vapours emanating from the contaminated soil and the rate and products of metabolism within the plant. Workshop sessions will include: quantifying uptake pathways, potential for plant metabolism of pollutants, estimating the loading of soil particles on vegetation.

Workshop 2

Human health and organic pollutants. (29th – 31st January 2008, Newcastle University).  Read more about Workshop 2

Persistent Organic Pollutants (POPs) are often found in contaminated soils and illustrate some of the research problems associated with organic chemicals. POPs are toxic, recalcitrant, and can bio-magnify up the food chain; they have been linked to adverse effects such as cancer and reproductive disorders. Large interspecies differences in the susceptibility to POPs exist. The magnitude of effect from POPs on human exposure and health is therefore still a matter of debate. Extrapolations from high accidental exposures and their association with health outcomes to lower level exposures in wider populations, have resulted in large levels of uncertainties attached to exposure assessments. Workshop sessions will include: relevant pathways linking soil contamination and human body burden; review of data linking environmental exposures and low level long term exposure to human health outcomes.

Workshop 3

Risk assessment from contaminated soils to humans via the foodchain. (Easter 2008, University of Nottingham)

Over the last 10 years quantitative risk assessment (QRA) has been widely adopted as a formalised, quantitative and defensible methodology in the assessment of chronic health risks resulting from exposure to pollutants in the environment. Inverse modelling using QRA procedures is now commonly used to determine contaminant concentrations which give rise to pre-determined exposure/risk thresholds. In the UK the CLEA model currently provides the basis for risk assessments and for the determination of soil guideline values (SGVs) to protect human health and similar approaches are used abroad (e.g. CALTox , USA; CSOIL, NL). Even though the rigorous methodology of QRA can establish objective 'safety' thresholds for contaminants, there are still uncertainties associated with these values resulting from an imperfect understanding of environmental pathways and mechanisms, such as plant uptake identified here, as well as the toxicology of many of the substances of concern. Workshop sessions will include: review of existing risk assessment models, probabilistic vs. deterministic computational approaches, review of data availability and quality requirements.

Workshop management

Each workshop will be lead and managed by one of the Investigators with the support of the relevant regulatory agency, they will also summarise the workshop findings. The workshop venue will be at the investigator's institution. In all cases these are easily accessible and have the necessary infrastructure. Individual sessions will be lead by a nominated member of the network. The workshop themes, attendance details, reports and recommendations will all be placed on the SHE-Net website.

Individual

Organisation

Expertise

Role

Prof. Chris Collins

University of Reading

Plant uptake and modelling of organic pollutants

PI, organiser of workshop 1, webmaster.

Prof Tanja Pless-Mulloli

Newcastle University

Public health, environmental epidemiology, risk perception.

CoI and organiser of workshop 2.

Prof. George Shaw

Nottingham University

Quantitative risk assessment, exposure models and data.

CoI and organiser of workshop 3.

Dr. David Mortimer

Food Standards Agency

Food contamination

Supporting workshop 1

Dr. Mike Waring

Health Protection Agency

Toxicology.

Supporting workshop 2

Ian Martin

Environment Agency

Exposure modelling

Supporting workshop 3

Outputs and Outcomes

The workshop managers will produce a report from each workshop which will be circulated within the network with further disseminated by the individual members and placed on the SHE-Net website. The final report produced by SHE-Net will describe the outcomes of each meeting in detail and make practical recommendations for improvement of health protection of UK consumers with respect to organic soil contaminants. Gaps in understanding which currently limit our ability to provide such protection will be identified and prioritised. Finally, recommendations for future research to close these gaps will be made. The report will form the basis of a position paper to be sent to the policy section of Environmental Science and Technology, the leading journal in the field.

SHE-Net directly addresses the aims of the NERC EHH programme to:

inform development of more effective policy and practice to improve human health and an increase in scientific knowledge regarding environment and human health issues.

It will also clearly:

create working relationships between academics of different disciplines that can be built on for future research.

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