RESUMO
OBJECTIVE: Iron fortification of wheat flour is widely used. In most cases, elemental iron powders are utilized as fortificants due to their lower cost and few, if any, sensory problems. However, their bioavailability is unknown. We aimed to measure the bioavailability of H(2)-reduced elemental iron powder in white wheat bread made from 72% extraction flour. DESIGN: A stable isotope of H(2)-reduced iron powder (mean particle size 15 microm) was used as fortificant in bread prepared from unfortified wheat flour. In all, 12 5- to 7-y-old children were fed bread with 4 mg of H(2)-reduced (58)Fe /100 g of flour. The next day (57)Fe ascorbate was given as reference dose. After 14 days, erythrocytes were analyzed for isotopic enrichment using mass spectrometry. RESULTS: When normalized to 40% absorption of the reference dose, the geometric mean (+/-range of 1 s.d.) bioavailability of reduced (58)Fe in wheat bread rolls was 6.5% (3.7-11.8). CONCLUSIONS: When compared to previous radioiron studies of ferrous sulfate showing 10% absorption from an identical meal in adult women, the relative bioavailability can be estimated at about 65%. However, the bioavailability of this smaller particle size (58)Fe (15 microm) is likely to be higher than that of commercial iron powder (45 microm) although the precise difference cannot be ascertained with current methods. Thus, the bioavailability of commercial elemental iron powders currently used in fortification programs is likely to be substantially lower than that of ferrous sulfate. SPONSORSHIP: This work was funded in part by Grant No 910313 by Micronutrient Initiative, IDRC, Ottawa, Canada.
Assuntos
Pão , Eritrócitos/química , Alimentos Fortificados , Ferro/farmacocinética , Disponibilidade Biológica , Pão/análise , Criança , Pré-Escolar , Deutério , Feminino , Compostos Ferrosos/sangue , Compostos Ferrosos/metabolismo , Compostos Ferrosos/farmacocinética , Farinha , Humanos , Absorção Intestinal , Ferro/sangue , Ferro/metabolismo , Isótopos de Ferro , Masculino , Espectrometria de Massas , Tamanho da Partícula , TriticumRESUMO
BACKGROUND: A number of studies have reported associations between indoor biofuel air pollution in developing countries and chronic obstructive lung disease (COLD) in adults and acute lower respiratory infection (ALRI) in children. Most of these studies have used indirect measures of exposure and generally dealt inadequately with confounding. More reliable, quantified information about this presumed effect is an important pre-requisite for prevention, not least because of the technical, economic and cultural barriers to achieving substantial exposure reductions in the world's poorest households, where ambient pollution levels are typically between ten and a hundred times higher than recommended standards. This study was carried out as part of a programme of research designed to inform the development of intervention studies capable of providing quantified estimates of health benefits. METHODS: The association between respiratory symptoms and the use of open fires and chimney woodstoves ('planchas'), and the distribution of confounding factors, were examined in a cross-sectional study of 340 women aged 15-45 years, living in a poor rural area in the western highlands of Guatemala. RESULTS: The prevalence of reported cough and phlegm was significantly higher for three of six symptom measures among women using open fires. Although this finding is consistent with a number of other studies, none has systematically examined the extent to which strong associations with confounding variables in these settings limit the ability of observational studies to define the effect of indoor air pollution adequately. Very strong associations (P < 0.0001) were found between the type of fire and a number of household and socioeconomic factors including the arrangement of rooms, floor type, and possession of a radio and television. The spouse's economic activity type was also significantly associated (P < 0.05). Thus, while 82% of open fire users had dirt floors and only 18% cement or tile floors, the situation was reversed for plancha users, only 16% of whom had dirt floors. CONCLUSIONS: Confounding presents a substantial problem for observational studies of indoor air pollution and health, although there is a reasonable case for believing that the observed association is causal. Intervention studies are required for stronger evidence of this association, and more importantly, to determine the size of health benefit achievable through feasible exposure reductions.
PIP: The authors investigated the association between respiratory symptoms and the use of open fires and chimney woodstoves, as well as the distribution of confounding factors, in a cross-sectional study of 340 women aged 15-45 years living in a poor rural area in the western highlands of Guatemala, and found a significantly higher prevalence of reported cough and phlegm for 3 of 6 symptom measures among women using open fires. When considering confounding factors, very strong associations were found between the type of fire and a number of household and socioeconomic factors including the arrangement of rooms, floor type, and possession of a radio and television. The spouse's economic activity type was also significantly associated. 82% of open fire users had dirt floors, with the remaining 18% having cement or tile floors, while only 16% of chimney woodstove users had dirt floors.
Assuntos
Poluição do Ar em Ambientes Fechados/efeitos adversos , Países em Desenvolvimento , Calefação , Pneumopatias Obstrutivas/epidemiologia , População Rural/estatística & dados numéricos , Madeira , Adolescente , Adulto , Poluição do Ar em Ambientes Fechados/estatística & dados numéricos , Causalidade , Feminino , Guatemala , Humanos , Pneumopatias Obstrutivas/etiologia , Pessoa de Meia-Idade , Pobreza/estatística & dados numéricos , Fatores de RiscoRESUMO
The use of the t Student and Cochran tests to evaluate central tendency measures, as well as the F test to evaluate variability and correlation analysis, have been incorrectly used for the evaluation of concordance between thyroid examiners. This paper presents the intraclass Kappa test (Bloch & Kraemer, 1989), as well as the experience of its use in Central America to standardize thyroid examiner personnel who participated in national surveys carried out during 1990 to determine goiter prevalence.