Adequacy of iodisation of salt at the household level and its associated factors in a rural sub-centre area of Bangalore Urban District, Karnataka, India: a cross-sectional study

Background: Consumption of iodised salt is a simple, e?ective and inexpensive preventive measure to prevent iodine de?ciency disorders. Lack of awareness, faulty practices in storage as well as poor production quality lead to decreased availability of iodine at consumer level. The objective of the study was to estimate the proportion of households using adequately iodised salt and to assess their awareness and practices regarding iodised salt consumption in a subcentre region of Sarjapur PHC area in Bangalore Urban District.Methods: A cross-sectional study was done in 382 households selected by two stage method involving proportional allocation based on village size followed by systematic random sampling at village level. MBI salt testing kit was used to check for iodisation level.Results: Of the 382 households, 22.3% used inadequately iodised salt. Out of the 382 individuals interviewed, 72% were females and only 21% were aware about iodised salt. Majority of the households purchased salt from a general store, was stored in tightly closed plastic containers and kept on shelves. Only 5% looked for the iodine logo on the packets before purchase of salt. Individuals with poor awareness, purchase of salt at public distribution system store, storage of salt on the floor, use of crystal salt were significantly associated with presence of inadequately iodised salt at the household.Conclusions: Nearly 30% of the salt packets used by households were inadequately iodised. Awareness regarding iodised salt was poor which contributed to the presence of inadequately iodised salt at household level.

Innovations in Measurement: visual Analog Scales and Retrospective Pretest Self-Report Designs

The authors discuss limitations of two popular measurement procedures, the Likert scale and conventional pretest-posttest self-report design. Both techniques have limits and yet are often combined, leading to restricted fidelity for measuring change. The authors go on to discuss two innovations in measurement that provide researchers with greater assessment fidelity: Visual analog scales and the retrospective pretest design. Moreover, when used in combination, these innovations measurement techniques provide dramatic increases in the power to detect and quantify change.

Se discuten las limitaciones de dos procedimientos de medición extremadamente populares; la escala Likert y los diseños pre-post tradicionales. Ambos métodos tienen limitaciones; estos métodos son comúnmente combinados obteniendo como resultado una fidelidad limitada para la medición del cambio. Se discute sobre dos innovaciones en medición que proveen al investigador una mayor fidelidad: escalas visuales análogas y el diseño pre-test retrospectivo. Además, cuando se usan de manera combinada, estas innovaciones en medición proveen notables incrementos en el poder de detección y la cuantificación de cambios.

Alternatives to Randomized Control Trials: A Review of Three Quasi-experimental Designs for Causal Inference

The Randomized Control Trial (RCT) design is typically seen as the gold standard in psychological research. As it is not always possible to conform to RCT specifications, many studies are conducted in the quasi-experimental framework. Although quasi-experimental designs are considered less preferable to RCTs, with guidance they can produce inferences which are just as valid. In this paper, the authors present 3 quasi-experimental designs which are viable alternatives to RCT designs. These designs are Regression Point Displacement (RPD), Regression Discontinuity (RD), and Propensity Score Matching (PSM). Additionally, the authors outline several notable methodological improvements to use with these designs.

Los diseños de Pruebas Controladas Aleatorizadas (PCA) son típicamente vistas como el mejor diseño en la investigación en psicología. Como tal, no es siempre posible cumplir con las especificaciones de las PCA y por ello muchos estudios son realizados en un marco cuasi experimental. Aunque los diseños cuasi experimentales son considerados menos convenientes que los diseños PCA, con directrices estos pueden producir inferencias igualmente válidas. En este artículo presentamos tres diseños cuasi experimentales que son formas alternativas a los diseños PCA. Estos diseños son Regresión de Punto de Desplazamiento (RPD), Regresión Discontinua (RD), Pareamiento por Puntaje de Propensión (PPP). Adicionalmente, describimos varias mejorías metodológicas para usar con este tipo de diseños.

Risk Assessment of the Dietary Exposure to Contaminants and Pesticide Residues in Young Children in the Netherlands.

Background: Prevention of negative health effects due to pesticide residues and contaminants in food is an important world-wide issue. It has been recognized that especially children may be a potentially vulnerable subgroup in this respect due to their higher consumption levels per kg body weight and differences in physiology compared to adults. Aim: To assess the dietary exposure and the related possible health risk to a selected number of compounds in young Dutch children in the Netherlands. Approach: Recent food consumption data of the Dutch National Food Consumption Survey-Young Children 2005/2006 were linked to recent monitoring concentration data. To assess both acute and chronic dietary exposure, the data were combined using advanced statistical models. The acute dietary exposure was calculated for the group of organophosphorus pesticides, and the chronic dietary exposure for acrylamide, dioxins (including dioxin-like PCBs), a number of mycotoxins (aflatoxin B1, deoxynivalenol, fumonisin B1, ochratoxin A and patulin) and nitrate. For the risk assessment the 99th percentile of exposure was compared to the health based limit value for chronic toxicity for all chemicals, except organophosphorus pesticides. For this group of pesticides, the99.9th percentile of exposure was compared to the health based limit value for acute toxicity. If the level of exposure exceeded the health based limit value, the percentage of children exceeding this limit was estimated. For acrylamide and aflatoxin B1, possible carcinogenic compounds with a genotoxic mechanism, a margin of exposure was derived. When the exposure exceeded the health based limit value or resulted in a relatively low margin of exposure, the available toxicity database was further reviewed with special attention to children to re-assess the risk. Results: According to the present findings the diet of young children in the Netherlands is safe regarding the exposure to fumonisin B1, deoxynivalenol, patulin, nitrate and organophosphorus pesticides present in food. For dioxins, there is a limited probability that an adverse health effect will occur. For acrylamide there is also a probability of an adverse health effect occurring in young children, although the extent to which this could happen is as yet unclear. This is due to in consistent results from epidemiology studies concerning the carcinogenicity of this compound. For aflatoxin B1and ochratoxin A, it was not feasible to determine whether or not an adverse health effect will occur, due to the use of (partly) targeted concentration data for these compounds. Conclusion: The diet of children aged 2 to 6 years in the Netherlands is safe regarding the exposure to fumonisin B1,deoxynivalenol, patulin (toxic compounds produced by fungi), nitrate and organophosphorus pesticides. For acrylamide, aflatoxin B1, dioxins and ochratoxin A, more research is needed to refine the risk assessment. The most important requirements for this purpose are the generation of representative concentration data for aflatoxin B1 and ochratoxin A and a better understanding of the toxicological effect of acrylamide. The complete report can be downloaded for free from http://www.rivm.nl/dsresource?objectid=rivmp:13714&type=org&disposition=inline&ns_nc= 1. Full report is also available as ‘Supplementary File’.

Dietary Habits and Exposure to Pesticides in Dutch Infants.

Background: Children are known to have higher dietary exposure levels to pesticide residues than adults due to higher consumption levels per kilogram bodyweight. Also social concern exists on the effects of these residues in young children, who are growing rapidly. To assess whether a certain compound may pose a risk for young children, it is important to have consumption levels of the foods that may contain the compound of interest in this age group. In the Netherlands food consumption data are available of children from 1 year onwards. However, the majority of children (if not all) already consume solid foods before age 1. Aims: Performance of a food consumption survey among Dutch infants aged 8 - 12 months gathering data on food consumption levels, and measuring and estimating the dietary exposure to selected pesticide residues Approach: Food consumption data were collected using a 1-daydietary record method. Weighing scales were provided, so that the amount consumed could be quantified accurately. During the study also duplicate portions of all the foods consumed by the children during the study day were collected. These duplicate portions were analysed for 19pesticides at the RIKILT - Institute of Food Safety to estimate the real intake of pesticides. Results: In total 373 infants (186 girls and 187 boys) were included. The fruit most eaten by this age group was banana (58%), followed by apple (34%), pear (28%) and kiwi (20%). Carrot (18%) was the most favorite vegetable, followed by broccoli (9%) and green beans (8%). Potato was also consumed frequently (49%). Of all the fruits and vegetables consumed by the children large portion sizes (LPs) were calculated at the level of the raw agricultural commodity. These LPs can be used in the point estimate approach to assess the acute dietary intake of toxic pesticide residues in the field of pesticide regulation. The infant food consumption database can also be used for probabilistic modelling of acute dietary exposure. Of 250 infants the duplicate portions were analysed for 19 pesticides. Of these samples a significant percentage (11%) had a low exposure to one or more pesticides. None of the exposures exceeded the toxicological reference level (acceptable daily intake (ADI) or acute reference dose (ARfD)). Conclusion: This study among infants resulted in a first impression of actual intake levels of pesticide residues by this age group in the Netherlands via the diet, an estimate of the LPs of fruits and vegetables consumed by young children for use in the point estimate approach and a database with consumption levels useful for probabilistic exposure assessments. Furthermore the duplicate portions collected can be used for the analysis of other compounds that may affect the development of young growing children (e.g. deoxynivalenol (DON), acrylamide, heavy metals). The complete report can be downloaded for free from http://edepot.wur.nl/44408. Full report is also available as ‘Supplementary File’.

Estimation of the Acute Dietary Exposure to Pesticides Using the Probabilistic Approach and the Point Estimate Methodology.

Aim: This report deals with the generation of work examples using food consumption data from the Netherlands and Sweden to facilitate the understanding of probabilistic modeling of dietary exposure to pesticides by risk managers. Imaginary field trial residue data were invented to be as useful as possible to show the potential of probabilistic modeling. Via seven work examples different aspects of acute dietary exposure assessment to pesticides and the use of the probabilistic approach were addressed. Approach and Results: In work example 1 the point estimate approach was compared with the probabilistic approach using the same input data. This work example showed that the point estimate resulted in higher estimations of exposure compared to the probabilistic approach, resulting from the conservative assumptions underlying the point estimate (one high level for both consumption and residue and a high default variability factor). It was demonstrated that with the probabilistic approach all consumption levels and field trial residue levels available could be used in one analysis, resulting in a better use of the available data. Also all foods contributing to the exposure could be addressed simultaneously in one analysis, as opposed to only one food at a time in the point estimate. In this way a more holistic approach to risk is possible. Work example 2 addressed the concept of ‘consumers only’. The example showed that, when exposure could occur via the consumption of more than one food, this concept could result in risk estimates that are difficult to interpret in probabilistic modeling, because the underlying database contains both consumers and non-consumers of the specific food items. This may hamper a clear risk management decision. It was also shown, when addressing only the consumers, that the exposure was influenced by the percentage of the population that consumes such a product. When that percentage was very low the exposure increased more compared to the situation where the whole population (consumers and non-consumers) was considered (e.g. kiwi fruit) than when the food was consumed by a large majority of the population (e.g. apple in The Netherlands or apple/pear in Sweden). The effect of processing on the acute exposure assessment was demonstrated in work example 3, showing clearly that processing influenced the level of exposure. It was demonstrated that with the probabilistic approach the risk assessor can address different types of food processing simultaneously with each food item being linked to the correct variability factor (e.g. variability applied when addressing apples and pears eaten whole, but not when addressing apples and pears mixed in juices and nectars). This is not possible with the point estimate. In work example 4 the effect of introducing variability in different ways into the probabilistic exposure assessment was studied. This resulted in different outcomes. The beta assumption on distribution reflects best what happens in real life (residue levels of individual units can be lower, equal or higher than the corresponding composite sample level) and the maximum residue level to be sampled is bounded at an upper level. The meaning of different endpoints in the acute exposure distribution created by probabilistic assessment was addressed in work example 5. It was argued that when a certain critical percentile of exposure exceeds the acute reference dose (ARfD) a critical examination of the exposures contributing to this, by studying for example the highest ten exposure levels with their corresponding consumption and residue levels, would be very useful, giving the risk manager an insight in the reliability of the upper percentiles. Related to this it was argued that the uncertainty factors used to derive an ARfD should be considered in relation to the occurrence probability of the exposure exceeding the ARfD. When this probability is very low (e.g. lower than 10-4 or 10-5) one can argue whether such a risk is acceptable or not. In the last two work examples the stability of the tail of the distribution was examined. In work example 6 this was done by examining the effect of the number of iterations on the upper percentiles of the exposure distribution. The results showed that the number of iterations should be sufficient for making a confident estimation of a certain percentile. The number of iterations depends on the amount of consumption data and residue levels available, and on the percentile of interest. The more data available the more combinations will be possible of food consumption and residue levels, resulting in a need for a higher number of iterations to describe the exposure within a population adequately. Also more iterations will be necessary to reliably estimate higher percentiles of the exposure distribution (≥ P99.9). In work example 7 the stability of the tail was examined by studying the effect of the presence in the food consumption database of consumers with an extreme food consumption pattern (e.g. an infant consuming 2 kg of apples) or the presence of an outlier in the residue database. It was evident that an outlier (high consumption or residue level) affected the result of an exposure assessment depending on the magnitude of the outlier compared to the other data present in the data set and on the largeness of the data set available. The effect was more evident on the P99.99 and maximum exposure level simulated than on the P99.9. It was argued that when outliers are present in the data, it is always important to visualise them (quality check on the data, for example related to reporting mistakes in the food consumption database), and to discuss the meaning of these outliers on a possible decision about the compound addressed. For example, it can be argued to what extent individuals with extreme dietary habits should be protected or that general advices concerning healthy eating habits should suffice. Conclusion: This report demonstrates clearly the potential of the probabilistic approach when dealing with acute dietary exposure assessment of pesticide residues compared to the current methodology used. The probabilistic approach to assess dietary exposure is also applicable to data from other countries, and, more importantly, others can be trained to perform risk assessments with the same model using their own data. Different aspects of an exposure assessment were addressed to help risk managers to understand better how exposures are calculated and to interpret the results of a probabilistic exposure assessment. The complete report can be downloaded for free from http://edepot.wur.nl/28647. Full report is also available as ‘Supplementary File’.

Silver staining nucleolar organiser region (AgNOR) study in melanocytic skin tumours.

Silver staining nucleolar organiser regions (AgNORs) were studied in 35 cases of melanocytic skin tumours. In the 23 cases of benign melanocytic naevi AgNORs per nucleus were between 1.06 and 3.43 with a mean of 2.05. In the 12 cases of malignant melanoma the AgNORs ranged from 4.26 to 10.66 (mean 7.43). Since statistically significant difference in AgNOR counts between benign and malignant melanocytic skin tumours was noted, this technique may serve as a useful adjunct to routine histopathology.