§ Mr. WelshTo ask the Secretary of State for Scotland if he will make a statement on the levels of benzene emissions from tanker terminals in Scotland.
§ Sir Hector MonroBenzene is a commodity chemical that has well-recognised toxic and carcinogenic properties and transfers of the chemical itself into tankers of all sorts are undertaken using closed vapour handling systems to prevent emissions leading to unacceptable exposures to the process operators.
Benzene is also a constituent of petrol and its precursor component mixtures. Vapours given off by such materials contain only very low concentrations of benzene which is vented along with the displacement gases during tanker loading. The implementation of the stage 1 petrol vapour recovery directive, formally adopted by the European Union in December 1994, and intended primarily to reduce emissions of ozone precursors, will see the progressive installation of closed vapour handling systems at all road, rail and inland waterway terminals. For shiploading terminals such as Hound point and Braefoot 278W bay, the International Maritime Organisation is negotiating amendments to the MARPOL convention that, once implemented, will extend closed vapour handling systems to ships. An incidental benefit of these changes will be to reduce further the very low levels of benzene emissions arising currently during tanker loading.
Monitoring exercises in the Grangemouth area have detected benzene at levels consistently below 1 part per billion-14-day average. Some at least of this concentration can be attributed to tanker loading, but when compared with the 1ppb air quality target recommended by the expert panel on air quality standards, it is clear that the operation of the tanker terminals in the Grangemouth area has a negligible impact on air quality in that locality.
A recent monitoring exercise carried out around the Braefoot bay terminal during shiploading of natural gasoline, which contains low concentrations of benzene, and is used in petrol formulation, demonstrated that peak concentrations—eight-hour averages—in the Aberdour area were greater in numerical terms than the levels recommended by EPAQS for adoption as annual average air quality concentrations. The panel, in making its recommendation, noted that at concentrations occurring in the ambient atmosphere benzene does not have short-term, or acute, effects. In these circumstances, any carcinogenic effect is attributable to the total intake of the material over a lifetime and short-term peaks are of themselves of little import. Concentrations in the Aberdour area measured at times other than during shiploading of natural gasoline were found to be negligible.