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At least 1,351 records · Page 75Linked to original sources
PubMed1985

Mutagenicity of ambient aerosol collected in an urban and industrial area of The Netherlands.

To investigate the influence of the densely populated and heavily industrialized Rijnmond area of The Netherlands on the genotoxicity of the ambient aerosol, aerosol samples were collected at locations within the area, and at a coastal region located upwind. The mutagenicity of extracts of the samples was compared in the Salmonella/microsome test. The dependence of the effects on sampling time and on sampling location was investigated with the aid of a series of simple mathematical models. These models were also used to estimate the increase in mutagenicity above background levels at the sites in the Rijnmond area due to emissions within that area. Application of the models showed that the clear and significant increases are not merely a result of the additions of mutagens emitted, but that possibly interactions between sampling time- and location-dependent factors play a role. Comparison of the results obtained with the different Ames-test variants (different strains, with and without liver homogenate) indicate that the conclusions concerning the time and location dependence of the effect were not dependent on the variant used.

Air Pollutants↗
PubMed1985

Radiation doses to the population in The Netherlands, due to external natural sources.

An estimate has been made of gamma doses to the population in the Netherlands, caused by natural radiation sources encountered in the environment. Data are given, derived from two independent types of measurement: Exposure/dose rate measurements in the living environment (private houses as well as workplaces), using a high pressure ionization chamber and thermoluminescent dosemeters (TLD) respectively and Individual monitoring, using TLD. The study included some 750 individuals, 400 houses and 275 workplaces. The participants were selected and divided into two groups on the basis of their location in areas of relatively high and low terrestrial radiation level respectively. Distinction was made between three categories of individuals with respect to their patterns of life. An estimate was made of the influence of the terrestrial component of the natural background and of some typical building materials on the indoor radiation level. An average indoor exposure rate of 9.5 muR . h-1 and a dose rate of 95 nGy . h-1 for individuals were found, both with a standard deviation of 15-20%.

Environmental Exposure↗
PubMed1986

Wet deposition of polycyclic aromatic hydrocarbons in The Netherlands.

The concentrations of 11 polycyclic aromatic hydrocarbons (PAH) in rainwater at four locations in the Netherlands in 1983 are reported. From literature data for these PAH in air, scavenging ratios were calculated. For PAH predominantly adsorbed on aerosols these scavenging ratios are in the range 3-13 X 10(4). For phenanthrene the scavenging ratios are in the range 0.35-2.5 X 10(4). The data for the aerosol-associated PAH at the various locations are discussed in terms of aerosol in-cloud scavenging, and are compared with reported data from Belgium and Germany. The scavenging ratios for phenanthrene are compared with those predicted on the basis of Henry's law constant and were found to be less than one order of magnitude higher than expected, possibly because of enhanced aqueous solubility.

Air Pollutants↗
PubMed1987

Concentrations of polycyclic hydrocarbons in airborne particles in The Netherlands and their correlation with mutagenicity.

The concentrations of 15 polycyclic aromatic hydrocarbons (PAH) were determined in ambient air particles sampled at four sites in an urban and industrialized area in The Netherlands, and at one site near the coast (generally upwind). The contributions of sources in the area to the background concentrations as measured at the coastal site, were investigated. The temporal and spatial variation of the PAH profile, i.e. the relative concentrations of the 15 individual PAH, were also investigated. Variation of the PAH profile was predominantly determined by volatility. The variation of the profile of the less-volatile PAH was small compared with the variation these PAH had in common. Slight indications for the influence of differing sources and chemical conversion on the profile were found. The role of chemical conversion was suggested by a linkage of the variation of the profile with differences in reactivity between the PAH. The similarity of the profiles at the background coastal site and at the sites influenced by local sources was striking. The PAH concentrations showed weak-to-moderate correlations with mutagenicity. The correlations increased if the results of samples taken during periods with wind from one sector were considered.

Air Pollutants↗
PubMed1988

Mutagenic activity in drinking water prepared from groundwater: a survey of ten cities in The Netherlands.

A survey of the mutagenic activity (Ames Salmonella/microsome assay) in drinking water prepared from groundwater in 10 cities of The Netherlands is presented. Mutagenic activity with strain TA98 with S-9 mix was found in the drinking water of six cities. There are strong indications that this mutagenic activity is caused by organics of natural origin. In the drinking water of three cities, trichloroethane, trichloroethene and tetrachloroethene were detected, which indicates that in these water-catchment areas organic pollutants have reached groundwater.

Humans↗
PubMed1989

Mutagenic activity and presence of the strong mutagen 3-chloro-4-(dichloromethyl)-5-hydroxy-2-(5H)-furanone (MX) in chlorinated raw and drinking waters in The Netherlands.

Chlorinated surface and drinking waters in The Netherlands were analysed for mutagenic activity (Ames test) and the strong mutagen 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX). Mutagenic activity and MX were formed during chlorine treatment of raw surface waters and purified surface water. Mutagenicity was also present in finished drinking waters which had been subjected to post-chlorination, but no MX could be detected. It is proposed that the mutagens responsible for most of the activity are acidic compounds as they were mainly extractable under acidic conditions. The precursors to the mutagenic compounds formed during post-chlorination of drinking water were efficiently removed by use of ozonation/activated carbon filtration. On the other hand, coagulation (Fe(III] in the presence of activated carbon powder seemed to have hardly any effect on the mutagen precursors. The calculated mutagenicity contribution from MX to the observed TA100 activity in the waters studied was less than 20%.

Chlorine↗
PubMed1996

Trace metals in the marine bivalve Macoma balthica in the Westerschelde estuary, The Netherlands. Part 3: variability of the role of cytosol in metal uptake by the clams.

Tellinid clams Macoma balthica were sampled every 2 months for 2.5 years at two locations from the Westerschelde estuary (The Netherlands) and submitted to in vitro short-term exposure to Cd, Cu and Zn. Total and heat-stable cytosolic metal concentrations have been measured before and after exposure to study the effects of the sampling season on metal uptake by the bivalve. We observed much higher uptakes of Cd and, to a lesser extent, Cu in winter than in summer, while Zn appears to be constantly regulated. These phenomena are amplified in the cytosol, especially for Cd, a non-essential element, for which the concentrations after exposure can reach 3.5-4 microg x g-1 (dry wt.) in winter, but only a maximum of 0.5 microg x g-1 in summer, all natural values being between 0.01 and 0.1 microg x g-1 on average. The contents (microg) of the various elements, either at the total or at the cytosolic level, are not constant, hence showing that the seasonal body weight fluctuation of the clams (dilution or concentration effect) is not the only parameter responsible for the metal uptake variability. Furthermore, we have shown that the proportion of cytosolic metal is not constant, but increases with the absolute cytosolic concentration up to 35-40%. Therefore, the cytosolic phase of the cells plays a growing role in Cd, Cu and Zn storage as long as their total concentration increases.

Animals↗
PubMed1988

Population screening for cervical cancer in the region of Nijmegen, The Netherlands 1976-1985.

In this study the results of a 9-year cervical screening program in the region of Nijmegen, The Netherlands are presented. All women aged 35 through 54 were invited every 3 years for a cervical smear. Overall attendance rates were 74%, 67%, and 63% at first, second, and third screening, respectively. The number of histologically confirmed severe epithelial abnormalities discovered in women who were screened for the first time was 3.8 per thousand smears, 1.0 per thousand in women who were screened twice and 0.7 per thousand in women who were screened three times in the program. Three years after the start of the screening program the incidence of invasive squamous cell cancer started to decline in the women aged 35 through 54 years. On the basis of the results of this study we may conclude a screening policy with an interval of 3 years to be a safe procedure. Whether this interval is the most efficient cannot be concluded. We have the impression that an interval of 4 to 6 years may lead to comparable results.

Adult↗
PubMed1991

Improved prognosis of ovarian cancer in The Netherlands during the period 1975-1985: a registry-based study.

Survival of 568 patients with ovarian cancer, diagnosed in 1975-1985, was studied by means of a population-based registry in the Southeast Netherlands. Patients diagnosed in the period 1981-1985 had a significantly better prognosis than patients diagnosed in 1975-1980. This improvement of survival declined with advancing age of the patients. In women younger than 60 years, mortality from ovarian cancer decreased, while incidence remained stable. Apart from the effect of new treatment methods, consisting of more extensive tumor reduction and cisplatin-based combination chemotherapy, advances in supportive care as well as a trend toward earlier diagnosis, possibly in combination with an increasing proportion of less malignant tumors, may explain the improvement in prognosis. Survival was strongly related to stage at diagnosis and to age, the prognosis of younger patients being more favorable. Patients with tumors of either germ cell or stromal origin generally survived longer than patients with epithelial tumors, but this difference disappeared after adjustment for stage and age. Patients still alive after 6 years did not have a survival significantly different from that of the general female population.

Adolescent↗
PubMedDate not supplied

Models of midwifery care. Denmark, Sweden, and The Netherlands.

The organization of maternity services in Denmark, Sweden, and the Netherlands was studied under the sponsorship of the World Health Organization European Headquarters Office of Maternal and Child Health. Midwifery care is highly respected and is a central feature of obstetric care in each of these countries. In Denmark and Sweden, almost all births are in the hospital, and autonomous midwives are employed by national health services. About three-quarters of Dutch midwives are in independent practice, and 34% of Dutch women give birth at home. In each country midwives provide "the first line" of care for normal pregnant women and are viewed as essential to the excellent perinatal outcomes these three countries enjoy.

Birth Rate↗
PubMed1986

Effect of population screening for cancer of the uterine cervix in Nijmegen, The Netherlands.

Since the introduction of a population screening program for cervical cancer in 1976, more than 85% of the female population between the ages of 35 and 54 years in the region of the city of Nijmegen, The Netherlands, has been screened. At first screening, severe epithelial abnormalities were diagnosed in 4.4 per 1,000 women, at second screening, in 1.5 per 1,000; and at third screening, in 1.0 per 1,000. The population screening program led to a marked increase in the detected number of carcinomata in situ. The number of cases of squamous cell cancer diagnosed in the first screening period did not increase. Once the population was screened, the detection rate of invasive squamous cell cancer in the group of women ages 35 through 54 decreased from 18.6 per 10(5) during the period prior to the screening to 9.0 per 10(5) after the first screening and 3.3 per 10(5) after the second screening. For the women above age 54, the incidence of invasive cancer was reduced by 58% after the second screening. The number of invasive cancers diagnosed in women under age 35 remained relatively small in spite of the large number of cases of carcinoma in situ.

Adult↗
PubMed1991

Impairments, disabilities, and handicaps of very preterm and very-low-birthweight infants at five years of age. The Collaborative Project on Preterm and Small for Gestational Age Infants (POPS) in The Netherlands.

The Project On Preterm and Small for gestational age infants (POPS) was started in the Netherlands in 1983 to investigate the relation between prenatal/perinatal factors and mortality/morbidity in very preterm and very-low-birthweight infants. Of the 1338 liveborn infants (less than 32 weeks and/or less than 1500 g) 966 were enrolled in the five-year (chronological age) follow-up programme; 96% of these children were assessed during a home visit. The overall outcome was expressed as impairments, disabilities, and handicaps according to World Health Organisation criteria. Of the assessed children, 13% had a disability and 14% were handicapped, which are much higher frequencies than those found in the general population. Handicaps were due mainly to abnormalities of neuromotor function, mental development, or language and speech development. Compared with the handicap frequency in the same cohort at two years of age, a more favourable outcome at five years of age was seen in 10%, and a less favourable outcome in 7% of the children. The findings show that most of those high-risk children survived without handicap or serious disability at preschool age.

Child, Preschool↗
PubMed1985

Epidemiological and immunological characteristics of childhood leukaemia in The Netherlands: population-based data from a nationwide co-operative group of paediatricians.

In this review results are presented from several population-based epidemiological and immunological studies of children with leukaemia in The Netherlands, who were diagnosed between 1973 and 1982 through a nationwide co-operative group of paediatricians. From 1973 till 1980 annual incidence rates appeared to be 3.1 per 10(5) person-yr. No significant trend was observed in this period. However a preliminary analysis of patients in the 1980-1982 period showed an increase. Mortality rates are decreasing since 1973, as expected. Incidence rates and proportions of different morphological and immunological subtypes reflect the pattern of occurrence in populations with a high standard of living. A relatively high incidence rate of acute lymphocytic leukaemia (ALL) is observed with a peak at the age of 3-5. The proportion of patients with T-cell phenotype among ALL-patients, immunologically typed between 1979 and 1982, appeared to increase with age, while the proportion of common ALL decreased. Statistical analysis of the data of patients with ALL in the Western part of the country including areas with nuclear plants, gave no indication for the presence of clustering. Subclassification of childhood leukaemia (CL), notably ALL, may be necessary for obtaining more specific etiologic clues. In view of the incidence of CL and ALL large scale, immunological and epidemiological investigations of CL, and the related non-Hodgkin's lymphomas, preferably population-based, are necessary.

Acute Disease↗
PubMed1992

Characteristics of the Edinburgh Post Natal Depression Scale in The Netherlands.

The Edinburgh Post Natal Depression Scale (EPDS), a 10-item self-rating depression scale, was translated into Dutch and compared in 293 postpartum women with other self-rating scales commonly in use in The Netherlands. In addition the structure of EPDS was analyzed by various factor analyses to reveal some of its dimensional aspects. The Dutch version of EPDS was found to be a self-rating scale with good psychometric characteristics which measures what it claims to measure: the strength of depressive symptoms. With LISREL a 2-factor model could be distinguished which contained subscales reflecting depressive symptoms and cognitive anxiety.

Adult↗
PubMed1995

Predicting the course of depression in the older population: results from a community-based study in The Netherlands.

This article is a report on the course of depressive syndromes in a community-based sample of older subjects in The Netherlands (n = 238). After baseline, the course of depression was assessed in five waves of follow-up measurements, covering 1 year. 52% of the subjects were never depressed; 16% suffered an incident depression, half of which remitted during the study; 8% had a depression at the start which remitted during the study; 14% were chronically depressed and in 10% the course was variable. Of those depressed at the start of the study, 32% remitted without relapse, 25% remitted but relapsed later and 43% were chronically depressed. While demographic variables were not predictive, health-related variables were predictive of both the onset and the course of depressive syndromes. Chronicity was associated with recent visits to general practitioners, indicating that treatment could have been provided relatively easily in many cases.

Aged↗
PubMed1988

Mutagenicity of food pellets from human diets in The Netherlands.

Food pellets from human diets, prepared according to mean consumption figures in The Netherlands, were assessed on mutagenicity and mutagens were identified. Three types of human meals were compared: raw (C), heated (D) and heated with vegetables and fruit (E, a complete meal). In addition 2 animal diets were tested: commercial control diet (A), and a control diet to which vegetables and fruit had been added (B). All human diets contained: 40.6 energy (E)% fat, 13.2 E% protein, 46.2 E% carbohydrate and 5.2% (w/w) fibre. For animal diets these figures were 21.6, 26.0, 52.4 and 10.7% respectively. After extraction samples were tested in the Salmonella-microsome test, tester strains TA1538, TA98 and TA100. Human diets with heated products (D, E) were both clearly mutagenic with approximately 300-500 revertants per gram. Food pellets from animal diets (A, B) displayed no mutagenic activity. HPLC-derived chromatographic fractions of diets D and E showed 3 large mutagenic areas identified as IQ (2-amino-3 methyl-imidazo-[4,5-f]quinoline) and MeIQx (2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, DiMeIQx (2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline and PhIP (2-amino-6-phenylimidazo[4,5-b]pyridine) and other mutagens not completely defined. This mutagen profile was similar to that found previously for fried beef. Mass estimates for these potent mutagens amounted to 15-20 micrograms/kg. Health implications of these findings are discussed. As IQ, MeIOx and DiMeIQx have been found to be weakly carcinogenic in rodents and many other initiating and modulating factors may be present in a complex human diet, a chronic toxicity study is indicated.

Animal Feed↗
PubMed1988

Dose intercomparison at the radiotherapy centers in The Netherlands. 2. Accuracy of locally applied computer planning systems for external photon beams.

As part of a quality assurance program in The Netherlands, the performance of computer planning systems was tested. Relative dose values, determined with an ionization chamber, were compared with dose values obtained from locally applied computer planning systems. Several clinically relevant situations were investigated: perpendicular incident beams, wedged beams, oblique incident beams, variable source-surface distances (SSD) and off-axis planes. The mean value of the ratios of calculated to measured dose values is 0.994, with an uncertainty of 2.4% (1 S.D.) and a maximum deviation of 9%, for all combinations of energies, planning systems and geometries investigated. The uncertainty for each situation separately was less than 2% (1 S.D.), except for the wedged beams and off-axis plane, which showed uncertainties of 2.6% (1 S.D.). Part of the additional uncertainty for the wedged beams originates from the value chosen for the wedge factor. Systematic deviations between calculated and measured dose values were investigated for three commercially available planning systems, separately. The mean deviation was smaller than 1% (1 S.D.), for most situations. Only for the wedged beams, larger deviations, up to a mean deviation of 2.6%, were observed.

Humans↗
PubMed1993

Dose intercomparison at the radiotherapy centers in The Netherlands. 3. Characteristics of electron beams.

Dosimetric characteristics of a number of clinically applied electron beams were analyzed as part of a dosimetry intercomparison program performed at the radiotherapy centers in The Netherlands. Absorbed dose values, determined under reference conditions, were compared during site visits with stated dose values. The mean deviation was 0.2% with a standard deviation (SD) of 2.5%. The maximum deviation was 5.7%. The largest differences were due to differences in the calibration procedures and differences in the numerical values of conversion factors adopted from different dosimetry protocols. In addition, a number of clinically relevant parameters of the dose distribution on the central beam axis were analyzed including the depth of the 85% and 50% relative dose, the dose reduction at the depth of the 50% relative dose and the surface dose. The average difference between the stated and measured therapeutic depth (85% dose level) was -0.4 mm with an SD = 1.2 mm. Due to this dosimetric uncertainty observed a safety margin of about 3 mm at the therapeutic depth is recommended. The maximum difference between stated and observed mean energy of the electron beams had only a small influence, < 1%, on the absorbed dose determination. The normalized dose gradient is not an adequate parameter to describe the dose reduction beyond the therapeutic depth. The depth of a low dose level is a better parameter. The relative dose at the surface showed differences up to 10% between scanning electron beams and beams from accelerators with a single scattering foil and closed wall collimating system.

Electrons↗