International journal on injury control and safety promotion
Paginering:
Jaargang 3 (1996) nr. 3 pagina's 153-164
Jaar:
1996-09-01
Inhoud:
Aspiration is the entry of liquid or solid materials through the oral or nasal cavity into the trachea and lower respiratory structures. It is initiated at the moment of inspiration, as the causative material lodges at the crossroad of the upper respiratory and digestive tracts. Two major categories of consumer products present a risk of aspiration. They are, on the one hand, petroleum aliphatic hydrocarbons such as kerosene and gasoline, and on the other, lipid and fat-like materials such as mineral and vegetable oils, The hazard of aspiration and its pathological consequences are determined by physical chemical characteristics of a consumer product, and by physiological mechanisms of the respiratory and upper digestive tracts. The former are referred to as intrinsic factors and the latter as extrinsic factors pertaining to the subject at risk. Viscosity and surface tension are the most important intrinsic factors to consider in assessing potential aspiration of consumer products. At the same time, evaluating the conditions of operation of reflex mechanisms, as well as the actual level of consciousness, can help identify individuals at higher than average risk. The present evaluation of the intrinsic and extrinsic factors which determine the occurrence of aspiration provides a rationale for considering this phenomenon as part of a hazard-based criteria scheme for regulating consumer products. This is most feasible through labelling, and a two-tier scheme is proposed to address the regulatory concerns for aspiration hazards. Both tiers are primarily based on viscosity and surface tension. In the absence of professional judgement, the first tier could be used to label and warn the consumer against the hazard of aspiration of liquid substances which have a viscosity of less than 14 mm2/sec at 38°C (14 centiStokes = 73.4 Saybolt Universal Seconds) and/or a surface tension of less than 29 dynes/cm (mN/m) When appropriate expertise is available, the second tier would be the same as the first, except to exempt from labelling products which do not present an aspiration hazard, based on the following guidelines: (1) a boiling point lower than 50°C, hydrosolubility and the absence of nauseous or emetic properties do not favor completion of the aspiration process; (2)substances which contribute to an increase in the viscosity and surface tension of a consumer product mixture tend to decrease the potential for aspiration; (3) the aspiration risk is lower for adults who are not challenged with pathological conditions in reflex mechanisms of the respiratory and upper digestive tracts as well as with neurological abnormalities capable of causing loss of consciousness. The first tier would be improved if it also offered, through expert judgement, a list of substances not conforming to the adopted viscosity/surface tension cut-off guideline.
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