Circadian changes and sex-related differences in fetal heart rate parameters

BACKGROUND: Previous researchers have studied circadian changes in the fetal heart rate (FHR) on small sample sizes and in a strictly controlled environment. This study was undertaken to investigate these changes during the late second and third trimesters, using a portable fetal electrocardiogram recording device (Monica AN24) in pregnant women in home and hospital environments with unrestricted mobility. METHODS: This was a prospective cohort study of 54 pregnant women with uncomplicated singleton pregnancies between 25 and 40 weeks gestation. FHR recordings were made up to 16 h at home or in the hospital setting in the United Kingdom. FHR data over 90 min periods were averaged and the day (7:00 am-11:00 pm) and night (11:00 pm-7:00 am) data from the same individual were compared. Data were examined for evidence of sex-related differences. RESULTS: During the night, there was a significant reduction in basal heart rate (bFHR) and a significant increase in short term variation (STV) and long term variation (LTV) (P < 0.05). Basal FHR decreased (P < 0.002), whereas LTV increased (P = 0.014) with advancing gestation. Male fetuses showed greater day: night variation than females regardless of gestation (P = 0.014). There was a higher bFHR in fetuses monitored during the day in hospital (P = 0.04). CONCLUSION: This study demonstrates that there are sex-, environment and time-related differences in the FHR parameters measured. These differences may need to be considered taken when interpreting FHR data

Variatie in berekende humane blootstelling. Vergelijk van berekeningen met zeven Europese modellen

Twintig scenario's die verschillen voor wat betreft bodemgebruik, bodem type en contaminant vormden de basis voor berekening van de humane blootstelling aan contaminanten in de bodem, met behulp van modellen afkomstig uit zeven Europese landen. (een model per land). Hiertoe werden de humane blootstelling van kinderen en volwassenen zoals berekend met deze modellen, vergeleken. Alle berekeningen werden in tweevoud uitgevoerd: eenmaal met een voorgeschreven set aan input parameters en eenmaal met de land-specifieke default input parameters. De blootstelling via de drie belangrijkste blootstellingsroutes, namelijk via grondingestie, gewasconsumptie en inhalatie binnenlucht, werd berekend . Bovendien werden de relevante concentraties in de contactmedia and in de bodemcompartimenten berekend. Evaluatie van de variaties in de berekende blootstelling voor elke belangrijkste blootstellingsroute en van de factoren die de variatie beinvloeden, leidde tot de volgende belangrijkste conclusies: De variatie in berekende blootstelling is groot voor blootstelling via inhalatie binnenlucht, substantieel voor blootstelling via gewasconsumptie en beperkt voor blootstelling via grondingestie. De variatie in berekende blootstelling wordt met name be6nvloed door de keuze van het blootstellingsmodel, in mindere mate door de selectie van de contaminant en type input parameter (gestandaardiseerd of default). De variatie in berekende bloostelling in nauwelijks afhankelijk van bodemgebruik en nog minder van bodem type. Mis-communicate is een (moeilijk te vermijden) bron voor variatie in berekende blootstelling. Bovendien werd een overzicht gegeven van de karakteristieken van de humane blootstellingsmodellen en van de waarden voor de default input parameters, zoals in de verschillende landen gebruikt. Een aanbeveling is op de langere termijn een toolbox te ontwikkelen voor gebruik op Europees niveau, met een gestandaardiseerde methode ter bepaling van de humane blootstelling, maar met ruimte voor flexibele (land-specifieke) elementen.Twenty scenarios, differing with respect to land use, soil type and contaminant, formed the basis for calculating human exposure from soil contaminants with the use of models contributed by seven European countries (one model per country). Here, the human exposures to children and children calculated by each of the models are compared. All calculations were performed twice: once with a prescribed set of parameters and once with the default data used in the different countries. Exposure via the three major exposure pathways of soil ingestion, crop consumption and indoor air inhalation was calculated in each case. Relevant concentrations in contact media and the soil compartments were also calculated. Evaluation of variations in the calculated exposure for each major exposure pathway, and factors affecting the variation, have led to the following main conclusions: The variation in calculated exposure is large for exposure via indoor air inhalation, substantial for exposure via crop consumption and limited for exposure via soil ingestion. The variation in calculated exposure is mainly influenced by the choice of exposure model and, to a lesser extent, by the selection of contaminant and type of input parameter (standardised or default). The variation in calculated exposure is scarcely dependent on soil use and even less on soil type. Miscommunication is a source (difficult to avoid) for variation in calculated exposure. Besides the above, characteristics of human exposure models and default values for the input parameters used in different countries have also been overviewed. One recommendation for the long term would be to construct a toolbox for use in the whole or part of Europe that would allow standardised assessment of human exposure, with the possibility of including flexible (country-specific) elements.DGM/BW

Variatie in berekende humane blootstelling. Vergelijk van berekeningen met zeven Europese modellen

Twenty scenarios, differing with respect to land use, soil type and contaminant, formed the basis for calculating human exposure from soil contaminants with the use of models contributed by seven European countries (one model per country). Here, the human exposures to children and children calculated by each of the models are compared. All calculations were performed twice: once with a prescribed set of parameters and once with the default data used in the different countries. Exposure via the three major exposure pathways of soil ingestion, crop consumption and indoor air inhalation was calculated in each case. Relevant concentrations in contact media and the soil compartments were also calculated. Evaluation of variations in the calculated exposure for each major exposure pathway, and factors affecting the variation, have led to the following main conclusions: The variation in calculated exposure is large for exposure via indoor air inhalation, substantial for exposure via crop consumption and limited for exposure via soil ingestion. The variation in calculated exposure is mainly influenced by the choice of exposure model and, to a lesser extent, by the selection of contaminant and type of input parameter (standardised or default). The variation in calculated exposure is scarcely dependent on soil use and even less on soil type. Miscommunication is a source (difficult to avoid) for variation in calculated exposure. Besides the above, characteristics of human exposure models and default values for the input parameters used in different countries have also been overviewed. One recommendation for the long term would be to construct a toolbox for use in the whole or part of Europe that would allow standardised assessment of human exposure, with the possibility of including flexible (country-specific) elements.Twintig scenario's die verschillen voor wat betreft bodemgebruik, bodem type en contaminant vormden de basis voor berekening van de humane blootstelling aan contaminanten in de bodem, met behulp van modellen afkomstig uit zeven Europese landen. (een model per land). Hiertoe werden de humane blootstelling van kinderen en volwassenen zoals berekend met deze modellen, vergeleken. Alle berekeningen werden in tweevoud uitgevoerd: eenmaal met een voorgeschreven set aan input parameters en eenmaal met de land-specifieke default input parameters. De blootstelling via de drie belangrijkste blootstellingsroutes, namelijk via grondingestie, gewasconsumptie en inhalatie binnenlucht, werd berekend . Bovendien werden de relevante concentraties in de contactmedia and in de bodemcompartimenten berekend. Evaluatie van de variaties in de berekende blootstelling voor elke belangrijkste blootstellingsroute en van de factoren die de variatie beinvloeden, leidde tot de volgende belangrijkste conclusies: De variatie in berekende blootstelling is groot voor blootstelling via inhalatie binnenlucht, substantieel voor blootstelling via gewasconsumptie en beperkt voor blootstelling via grondingestie. De variatie in berekende blootstelling wordt met name be6nvloed door de keuze van het blootstellingsmodel, in mindere mate door de selectie van de contaminant en type input parameter (gestandaardiseerd of default). De variatie in berekende bloostelling in nauwelijks afhankelijk van bodemgebruik en nog minder van bodem type. Mis-communicate is een (moeilijk te vermijden) bron voor variatie in berekende blootstelling. Bovendien werd een overzicht gegeven van de karakteristieken van de humane blootstellingsmodellen en van de waarden voor de default input parameters, zoals in de verschillende landen gebruikt. Een aanbeveling is op de langere termijn een toolbox te ontwikkelen voor gebruik op Europees niveau, met een gestandaardiseerde methode ter bepaling van de humane blootstelling, maar met ruimte voor flexibele (land-specifieke) elementen

A novel concept in ground water quality management: Towards function specific screening values.

This paper is meant to initiate and feed the discussion on a more sophisticated procedure for the derivation and use of groundwater screening values (GSVs). To this purpose, the possibilities and tools for the derivation of function specific GSVs, i.e., GSVs that depend on the actual contact of humans and ecosystems with groundwater and groundwater-related mediums, are elaborated in this study. Application of GSVs geared to the specific use and function of specific groundwater volumes could result in a more effective and cost-efficient groundwater quality management, without compromising the protection of human health and the ecosystem. Therefore, a procedure to derive function specific GSVs was developed. For illustrative purposes, risk limits have been derived for human health and ecological protection targets, for arsenic, benzene, methyl tert-butyl ether (MTBE) and vinylchloride. Agriculture and Nature reserves (combined), Residential and Industrial land uses have been considered and two different groundwater management purposes, i.e., curative and sustainable groundwater management. For each of the four contaminants, this results in a series of risks limits for each function and land use combination. It is shown that for all four contaminants higher groundwater screening values are considered appropriate for less sensitive combinations of function and land use. In the process towards (policy) implementation of these function specific GSV, it is recommended to evaluate the selection of protection targets, the scientific basis of the risk assessment procedures applied and the methodology to assess the time factor for groundwater quality assessment, given the fact that groundwater is a dynamic medium. Moreover, protection levels must be harmonized with national or regional groundwater quality standards and correspond with the requirements of the Groundwater Daughter Directive of the European Union Water Framework Directive. Groundwater plumes that are judged as 'no need for remediation' are not compatible with the Water Framework Directive requirement to take actions to prevent or limit inputs of contaminants, even when no receptor is present. However, the European Commission formulated a series of exemptions, to avoid that the "prevent" requirement would imply an onerous and sometimes unfeasible task. The function specific GSVs derived in this study could be used to identify the groundwater volumes that do not result in an unacceptable risk

Guidance on the risk assessment of arsenic in soil for private vegetable gardening

Arseen kan van nature in de grond en het grondwater zitten of daar door activiteiten van de mens in het verleden in terecht gekomen zijn. Wanneer mensen zelf groenten telen, kunnen zij tijdens het tuinieren ongemerkt bodemdeeltjes inslikken. Hierdoor kunnen zij arseen binnenkrijgen. Dat kan ook door de groenten te eten die zijn geteeld op met arseen verontreinigde bodem. Op verzoek van de GGD'en heeft het RIVM een handreiking opgesteld over de beoordeling van de gezondheidsrisico's bij het eten en zelf telen van groenten op bodems die met arseen zijn verontreinigd. Die beoordeling is lastig, omdat onzeker is hoeveel arseen vanuit de bodem in de groenten terechtkomt. Daarnaast is er voor arseen geen actuele waarde voor de 'toelaatbare blootstelling' beschikbaar. De handreiking geeft een indicatie van de waarde die op dit moment het beste als 'toelaatbare blootstelling' voor arseen kan worden gebruikt. De blootstelling aan arseen via het zelf telen en eten van groenten is hierbij hoog ingeschat omdat de opname van arseen door de groenten uit de bodem onvoorspelbaar is. De blootstelling is vervolgens vergeleken met de zogenoemde achtergrondblootstelling aan arseen. Dit is de hoeveelheid arseen waar iedereen aan wordt blootgesteld (namelijk via in de winkel gekochte levensmiddelen als rijst, granen en melk, via drinkwater en mogelijk via andere bronnen), onafhankelijk van lokale bodemverontreiniging. De blootstelling via groenten die men zelf zou kunnen telen, draagt ongeveer 10 procent bij aan de achtergrond-blootstelling; de achtergrondblootstelling via andere levensmiddelen vormt het grootste deel. Ten slotte worden handelingsperspectieven geboden om de blootstelling aan arseen te verminderen bij het moestuinieren. Dat kan bijvoorbeeld voorlichting zijn om de hoeveelheid ingeslikte gronddeeltjes te verminderen.Arsenic is a naturally occurring substance in soil and groundwater, but it can also be present in soil and groundwater through past human activities. When people grow their own vegetables on plots contaminated with arsenic, they may unintentionally ingest soil particles whilst tending their crops and in doing so, they may ingest arsenic. This is also possible when eating vegetables that have been grown on soil contaminated with arsenic. RIVM was requested by the municipal health services (GGDs) to advise on the assessment of the human health risks of growing vegetables in soil contaminated with arsenic. This assessment is difficult because it is uncertain how much of the arsenic in the soil accumulates in vegetables. In addition, a current guideline value for 'tolerable exposure' to arsenic is lacking. This guidance provides an indication of a state-of-art guideline value for 'tolerable exposure' to arsenic. A conservative estimate (based on high exposure) of exposure to arsenic through vegetable consumption was made, because the assessment of the accumulation of arsenic in vegetables is unpredictable cumbersome. Subsequently, the exposure to arsenic through growing vegetables was compared to the so-called background exposure. This is the intake of arsenic by the general public through purchased foods such as rice, cereals and milk, drinking water and possibly other exposure routes, independent of local soil contamination. It was calculated that exposure through the vegetables which people are more likely to grow themselves contributes about 10% to background exposure; the remaining background exposure is predominantly from other food products. Finally, this report offers advice on how to reduce exposure to arsenic for people who grow their own vegetables. This can be done, for example, through information on how to reduce the amount of ingested soil.Programmacollege Gezondheid en Milie