Local exhaust ventilation and exposure to nitrous oxide in ambulances.

Under extreme conditions, ambulance attendants and drivers could be exposed to nitrous oxide administered to transported patients in concentrations causing acute effects. Special arrangements are necessary to prevent such exposure, which is influenced by travelling speed, local exhaust ventilation and the use of an excess gas transfer tube evacuating expired air and overflow gas from the face mask to the outside. The separate eliminative effects of travelling speed and local exhaust varied considerably with the experimental conditions. The excess gas transfer tube reduced the levels of nitrous oxide in the air by 86 to 97% inside the ambulance at different experimental conditions. The combination of excess gas transfer tube and local exhaust resulted in a relatively constant reduction of the airborne nitrous oxide levels by about 98% when the ambulance was at a standstill and 99% when it was running.

Laser Doppler flow-meter assessment of iontophoretically applied norepinephrine on human finger skin circulation.

A miniaturized technique to administer vasoactive substances iontophoretically into the human finger skin and to continuously assess the resulting reaction of the vessels is described. Cutaneous blood flow is measured with a laser Doppler flow-meter. The technique has been used in 9 healthy volunteers with norepinephrine as test substance. The described method is a convenient way to evaluate the effects of transdermally applied vasoactive substances in a semiquantitative way without risking central effects of the substance to influence the registered blood flow.

Buckwheat allergy: health food, an inhalation health risk.

Thirteen out of 28 persons (14 men and 14 women) employed in a company which imports, prepares and distributes plant products used in spices and as ingredients in so-called health food, had developed work-related symptoms in the form of rhinitis, conjunctivitis, asthma, itch or urticaria. The symptoms occurred in connection with specific work operations, especially in the grinding and packaging of buckwheat. Seven out of 25 examined persons (28%) had at least one positive allergy test (prick test or RAST) against buckwheat. Furthermore, one person had positive RAST against extract from castor-oil bean. The correlation between positive allergy tests and work-related symptoms is significant. Fourteen persons were also patch tested. All were negative except one person who had a positive patch test against nickel. The nickel allergy was diagnosed before this study was done and had no relation to the work. The levels of airborne dust in the breathing zones of the workers when they performed dust-forming work were around and below 5 mg/m3. When buckwheat flour was packaged, the airborne dust levels were about 1-2 mg/m3. Thus, exposure to comparatively low levels of buckwheat dust may induce a definite risk of rapidly ensuing allergy. It is also obvious that persons without atopic stigmata, such as an earlier history of allergy or the occurrence of allergic diseases in relatives, risk becoming allergic. A conclusion is that health food could be a danger, when it is inhaled.

Nitrous-oxide analgesia during ambulance transportation. Airborne levels of nitrous oxide.

A model experiment was performed for studying nitrous-oxide levels in the breathing zones of the different members of an ambulance team, viz. the anesthetist, the accompanying person in the ambulance coupé, and the ambulance driver. Without a functioning local exhaust coupled to the exhalation valve, the integrated average level of nitrous oxide in the breathing zone of the anesthetist was 650-1,700 ppm, with top concentrations up to 7,500 ppm. Under the same conditions, the accompanying person in the ambulance coupé was exposed to average concentrations of 58-280 ppm, with top concentrations up to 660 ppm. The mean exposure of the driver was 9-45 ppm (max. 81 ppm). However, the exposure to nitrous oxide was considerably decreased in all parts of the ambulance by an effective local exhaust system. A prerequisite for nitrous-oxide analgesia in ambulances is an effective local exhaust coupled to the exhalation valve or face mask. The ambulance coupé ought to be equipped with a motor-driven exhaust fan in the roof, the ordinary inlet fan of the ambulance should be switched on at maximum speed, and any additional heater or fan in the ambulance coupé should be placed inside the coupé and not behind the driver's seat.

Effects of tobacco and tobacco smoke constituents on cell multiplication in vitro.

Ascites sarcoma BP8 cells, cultured in suspension in vitro were used as a general toxicity test system for tobacco and tobacco smoke constituents. Some 250 compounds, representative of these materials, were examined by exposing cells to different concentrations of these constituents and measuring the inhibition of culture growth, which was related to corresponding effects encountered for positive standards. When employing the present cell toxicity test system possible effects of factors such as penetration, distribution and microsomal metabolism of the compounds studied, are not taken into account. The most active constituents were found to be unsaturated aldehydes and ketones, phenols and indoles. The good correlation obsered between functional groups and toxicity permits, within the range of functionalities studied, prediction of the toxicity for a compound of known structure.