Characteristics
Dioxins and furans organic compounds that are harmful to human health. Chemically they are classed as halogenated aromatic hydrocarbons and are commonly produced by combustion of fossil fuels and incineration of municipal waste. They are also produced as a by-product of pulp and paper bleaching as well as in the production of other chemicals. Gateshead is across the Tyne from the Byker incinerator. Ash, found to be contaminated with dioxins, from the Byker incinerator was spread on footpaths in allotments and other places in Newcastle leading to an Environment Agency prosecution in the early years of this century. Although studies showed dioxins from Byker ash were not present in Gateshead, other dioxin mixtures, dominated by furans, were discovered in Saltmeadows Riverside, Gateshead thought to be present waste materials produced by Gateshead alkali chemical industry.
Hazardous properties
Dioxins and dioxin-like compounds cause chloracne, immune system suppression, cancer, and reproductive and developmental toxicity. The potency of various dioxin congeners (compounds) can vary over orders of magnitude. Individual dioxins and furans are called congeners and are assigned a Toxic Equivalency Factor (TEF) based on comparison with the most potent congener, 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD). Environment Agency (2009).
Pathway
Harm to human health can occur by eating or touching soil contaminated with dioxins or eating fatty fish fed on a diet containing dioxins.
Occurrence
In the past, in Gateshead, the Saltmeadows area is a known source of dioxin contaminated soils. BGR_calc includes an area known or suspected to have been affected by dioxin contamination. The area is associated with Christian Allhusen’s chemical works that covered some 137 acres and had a kilometre-long river frontage. Allhusen’s was a leading manufacturer of soda ash and crystals, bleaching powder and later sulphuric and hydrochloric acid.
Natural occurrences
Dioxins are and by-product of chemical manufacturing and waste incineration. There is no evidence they occur naturally in Gateshead.
Site investigation
Desk study
An understanding of the historical industrial use of land and its vicinity is important in order to recognise the likelihood of dioxin soil contamination and to inform an appropriate soil sampling strategy. Sites within the BGR_calc dioxin affected area should be investigated for dioxin contamination by specialist consultants.
Walk over
Normal health and safety precautions should be taken. Dioxin contaminated soil is know identifiable by eye.
Intrusive investigation
Analysis of soil for dioxins is expensive, therefore carefully targeted sampling and analytical strategies are needed to ensure costs of investigation are controlled.
Foundations
Not relevant
Remediation
TBA
Pathway interruption
Isolating dioxin contaminated soils beneath a sufficiently thick and well-marked capping layer prevents human contact with the dioxins but does not prevent re-exposure of the soil by burrowing animals.
Source removal
Excavation and off-site disposal of dioxin contaminated soil is a simple and widely used remediation technique.
Waste disposal
Dioxin contaminated excavated soils would be classified as hazardous waste.
Regulatory aspects
No dioxin specific regulations are in place.
Glossary
- Dioxin: a harmful by-product of burning materials including chlorine or bromines in which two benzene rings are linked via two oxygen atoms.
- Furan: a harmful by-product of burning materials including chlorine or bromines in which two benzene rings are linked via one oxygen atom.
Saltmeadows Riverside – Contaminated land location plan
Environment Agency. 2009. Contaminants in soil: updated collation of toxicological data and intake values for humans Dioxins, furans and dioxin-like PCBs. Science report: SC050021/TOX 12
Borehole materials
Document contact
Dr. Darren Beriro, (darrenb@bgs.ac.uk)