Development of perfluorocarbon tracer technology for underground leak location.

A method has been developed for the atmospheric sampling and analysis of four perfluorocarbon tracer (PFT) compounds simultaneously at the parts per trillion (ppt) level. PFTs were pre-concentrated using adsorbent tube air sampling. Analysis was achieved by thermal desorption (TD) and gas chromatography (GC) with electron capture detection (ECD). Efficient separation of the PFTs from the other sample constituents was achieved by use of a capillary porous layer open tubular (PLOT) GC column without the need to cool the GC oven to sub-ambient temperatures using liquid coolants (M. de Bortoli and E. Pecchio, J. High Resolut. Chromatogr., 1985, 8, 422) or for a catalytic destruction step to remove interferents (T. W. D'Ottavio, R. W. Goodrich and R. N. Dietz, Environ. Sci. Technol., 1986, 20, 100). Results from test field trials with two volatile PFTs that were buried to simulate an underground leaking cable were successful. The PFTs were detected above ground level to pinpoint the leak position. The highest tracer concentrations were detected within 1 m of the simulated leak positions 2 days after tracer burial. The developed technology was applied to an oil leaking high voltage electricity cable. One PFT was added to the cable oil which enabled detection of the oil leak to within 3 m. The reported method has many advantages over currently used leak detection methods and could, in the future, be applied to the detection of underground leaks in a variety of cables and pipes.

A double-blind, placebo-controlled trial by the sublingual route of immunotherapy with a standardized grass pollen extract.

Fifty-eight patients with well-documented history of seasonal rhinoconjunctivitis caused by grass pollens were allocated randomly on a double-blind basis to receive either sublingual therapy with a solution of purified, standardized allergen preparation (Stallergènes) or a matched placebo for 17 weeks. The assessment of the effect of oral immunotherapy, done with drops of five-grass allergen extract, was on the clinical symptoms and on the medication score of the authorized rescue treatments. The actively treated patients had significantly (P < 0.05 to P < 0.01) fewer symptoms of rhinitis (sneezing and rhinorrhea) and of conjunctivitis (redness and tears) during the pollen season than the placebo group. Consumption of nasal solution of sodium cromoglycate and of betamethasone and dexchlorpheniramine was significantly less in the desensitized group (P < 0.01). Side-effects were negligible. This study concludes that perlingual immunotherapy with grass pollen extract in grass-pollen-sensitive seasonal hay fever and conjunctivitis patients is effective, easy to perform, inexpensive, and safe.

[Sublingual specific immunotherapy for rhinoconjunctivitis caused by grass pollens]. / Immunothérapie spécifique par voie sublinguale de la rhinoconjonctivite aux pollens de graminées.

Fifty eight patients with rhino-conjunctivitis caused by grass pollen were included in a double-blind study in which they received, by the sub-lingual route over 5 months, either a solution of purified and standardised allergen or a placebo. Assessment of the effect of this immunotherapy, which was done with drops of Stallergenes "5-grass pollen" was by clinical symptoms and the use of authorized drugs and treatments. Compared with the placebo group, the patients on active treatment showed significantly less (P = 0.05 to P = 0.01) rhinitis symptoms (sneezing and rhinorrhea) and conjunctivitis (reddening and tears) during the pollen season. Consumption of nasal cromoglycate solution, of betamethasone and dexchlorpheniramine was significantly lower (p = 0.01) in the desensitised group. Secondary effects were negligible. From this study, it can be concluded that immunotherapy with grass pollen extract, by the sub-lingual route, of patients with rhino-conjunctivitis who were sensitive to these allergens, is efficacious, easy to do, economic and sure.