HC Deb 09 June 1986 vol 99 cc77-8W
Dr. Roger Thomas

asked the Minister of Agriculture, Fisheries and Food if he will give detailed figures of the concentration of (a) inorganic heavy metals, particularly mercury and cadmium, (b) organic compounds, particularly polychlorinated biphenyls and dieldrin and (c) man-made synthetic contaminants in samples of sewage sludge dumped in the coastal waters of the United Kingdom, with particular reference to the Thames estuary, the Clyde estuary, Liverpool bay and Merseyside, and the Severn estuary.

Mr. Gummer

Specific information on levels of mercury, cadmium, polychlorinated biphenyls and dieldrin found in sewage sludges produced by the water

Mr. Lamont Lamont

[pursuant to his reply, 4 June 1986]: The table shows income tax plus national insurance contributions (less child benefit where appropriate) as a percentage of gross income for the family types and years affected by the Budgets specified. National insurance contributions have been taken to be at contracted-in rates and for the married couples it is assumed that only the husband is earning. Negative figures in the table indicate cases where child benefit exceeds liability to income tax and national insurance contributions.

authorities which use the sites in question is set out in the table. All sewage sludges contain very small traces of a wide range of man-made synthetic contaminants.

(parts per million, dry weight)
Site Total mercury Total cadmium Polychlorinated biphenyls Dieldrin
Thames estuary 4.8 19.0 0.15 0.12
Clyde estuary 3.2 8.0 0.32 0.14
Liverpool bay 5.0 12.5 0.13 0.09
Severn estuary 4.6 10.0 0.08 0.24


1. Figures are for total mercury and cadmium as separate data on inorganic mercury and cadmium are not available.

2. Total mercury and total cadmium levels are based on concentrations in sewage sludges licensed for disposal in the areas shown in 1985 and 1986.

3. For polychlorinated biphenyls and dieldrin, the figures are based on levels found in the last (1981–82) survey of sewage sludges produced by the relevant water authorities, except for those for the Clyde which relate to sludges licensed for disposal in 1985–86.

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