RESUMO
To characterize the accumulated hazards associated with the inhalation of gases typical of combustion products, a time-integrated value known as the fractional effective dose (FED) is used. This FED is maintained by the International Organization for Standardization (ISO) and made publicly available as the Standard ISO 13571. The current FED calculation related to asphyxiant gases is based on non-human primate data to estimate the 50% probability of humans to be incapacitated or not being able to execute any escape paradigm from fires. The objective of this paper was to compare two to calculate FEDs of the most common mixture of asphyxiant fire gases CO, HCN, and CO2. The first was based on the current ISO 13571 (draft) standard, the alternative second method applied the conceptual principles established for the derivation of Acute Emergency Response Planning Guideline values. The alternative approach applied one third of the non-lethal threshold concentration (LC01) as the most suitable and robust Point of Departure (POD) to estimate the threshold characterizing 'impairment of escape' in the absence of post-exposure mortality. The hyperventilation correction factor for CO2 of ISO 13571 was replaced by a separate term that accounts for the inherent acute toxicity of CO2. This analysis supports the conclusion that the current ISO 13571 standard misjudges the impact of the acute toxicity elicited by concentrations of CO2 exceeding ≈6%. While underestimating the hazards attributable to CO2, the hyperventilation adjustment factor suggested by this standard is biased to markedly overestimate the hazards assigned to CO and HCN in fire effluents.
Assuntos
Asfixia/induzido quimicamente , Dióxido de Carbono/toxicidade , Incêndios , Gases/toxicidade , Animais , Asfixia/patologia , Monóxido de Carbono/toxicidade , Carboxihemoglobina/metabolismo , Humanos , Cianeto de Hidrogênio/toxicidade , Hiperventilação/fisiopatologia , Dose Letal Mediana , Ratos , Mecânica Respiratória/efeitos dos fármacos , Medição de Risco , Local de Trabalho/normasRESUMO
Cyanide toxicity is common after significant smoke inhalation. Two cases are presented that provide framework for the discussion of epidemiology, pathogenesis, presenting signs and symptoms, and treatment options of inhalational cyanide poisoning. An evidence-based algorithm is proposed that utilizes point-of-care testing to help physicians identify patients who benefit most from antidotal therapy.
Assuntos
Antídotos/uso terapêutico , Medicina de Emergência Baseada em Evidências , Intoxicação por Gás/tratamento farmacológico , Cianeto de Hidrogênio/toxicidade , Lesão por Inalação de Fumaça/complicações , Centros Médicos Acadêmicos , Algoritmos , Antídotos/efeitos adversos , Biomarcadores/sangue , Terapia Combinada/efeitos adversos , Árvores de Decisões , Bolsas de Estudo , Feminino , Intoxicação por Gás/complicações , Intoxicação por Gás/diagnóstico , Intoxicação por Gás/terapia , Humanos , Cianeto de Hidrogênio/antagonistas & inibidores , Hidroxocobalamina/efeitos adversos , Hidroxocobalamina/uso terapêutico , Masculino , Massachusetts , Testes Imediatos , Lesão por Inalação de Fumaça/sangue , Lesão por Inalação de Fumaça/terapia , Toxicologia/educação , Recursos HumanosRESUMO
Cassava (Manihot esculenta Crantz) leaves contained a high level of crude protein (29.3-32.4% dry weight) compared to a conventional vegetable, Amaranthus (19.6%). Ash was 4.6-6.4% in cassava leaf samples but 13.1% dry weight in Amaranthus. Dietary fibre was very high in all samples (26.9-39% dry weight) while HCN-potential was low (5.1-12.6 mg/100 g dry weight). Tannin was the highest in IITA red cassava leaves (29.7 mg/g) and the lowest in Amaranthus vegetable. In vitro digestibility was very low in oven dried samples (15.6-22.7%). Blanching increased protein content (except Amaranthus) and in vitro protein digestibility but decreased ash, minerals, dietary fibre and tannin, while HCN-potential was unchanged. Grinding reduced both HCN-potential and tannin by 84 and 71% respectively while oven drying only reduced the HCN content marginally. Preference studies showed that the highest percentage of respondents (25.3%) preferred Amaranthus vegetable, followed by Celosia (17.5%), Talinum (12.4%), garden egg (11.5%), with cassava leaves as the least (0.5%). Organoleptic evaluation rated cassava leaf soup inferior to Amaranthus in terms of appearance, colour and texture but equal in terms of taste and flavour and overall acceptability.
Assuntos
Manihot , Valor Nutritivo , Fibras na Dieta , Proteínas Alimentares/análise , Digestão , Temperatura Alta , Humanos , Cianeto de Hidrogênio/análise , Cianeto de Hidrogênio/toxicidade , Taninos Hidrolisáveis/análise , Manihot/química , Nigéria , Folhas de PlantaRESUMO
Toxic hazard in fire depends upon three factors: the fire growth curve (mass loss rate of materials, kg/min) and volume dispersal (kg/m3), the yields of toxic products (e.g. kg CO/kg fuel burned) and the toxic potency of the products (exposure dose needed to cause toxic effects, e.g. lethal dose of CO in ppm.min). The first and second sets of data are obtainable from large-scale tests or small-scale tests and mathematical modelling, the third and some information on the second are derived from toxicity studies of combustion products in small-scale tests or of individual fire gases. Small-scale toxicity test data on materials expressed as lethal mass loss exposure doses (LCt50 g min m-3) can be used in Fractional Effective Dose (FED) hazard assessments, providing the decomposition conditions of the test reproduce those in the fire being examined; principally either non-flaming oxidative, early well-ventilated flaming, or vitiated post-flashover. Although bioassays are needed for a full toxicity assessment, it is now possible to predict the toxic potency of materials to some extent from analytical data alone. The suitability of the small-scale test decomposition conditions are determined in terms of non-flaming or flaming behaviour, temperature (or radiant flux), CO2/CO ratio and oxygen concentration. Existing small-scale test methods provide reasonable models for materials under non-flaming oxidative and early flaming conditions, although the data base for the latter is poor. Only the DIN 53436 method is able to model vitiated post-flashover decomposition conditions, but data for this condition are almost non-existent.