Jan S.M. Boleij

Blood lead levels of dutch city children and their relationship to lead in the environment

Environmental and social variables were studied in several populations of Dutch city children who participated in the second Blood Lead Survey of the European Communities in 1981. Blood lead levels were low in all populations, with striking differences between inner city and suburban children. Several environmental and social variables were correlated with blood lead levels. An R 2 value of 0.52 was obtained in the multiple regression analyses, indicating that a reasonable amount of variation in blood lead levels was explained by the independent variables in the analysis. The value of air lead as single indicator of environmental lead pollution is discussed.

Identification of determinants of pesticide exposure among Kenyan agricultural workers using empirical modelling

The influence of factors such as type of pesticides used, use of personal protective devices and hygienic behaviour on acetylcholinesterase inhibition and activity levels in red blood cells of agricultural workers was studied in four areas in Kenya. Empirical modelling techniques were used to identify and quantify factors affecting acetylcholinesterase inhibition and activity. Use of personal protective devices was almost non-existent in areas 3 and 4 where mainly subsistence farmers were studied. Differences in hygienic behaviour between areas were relative small. WHO Class I pesticides were mostly found in area 1 (mainly large farms growing flowers) which also had highest amounts of pesticide use and highest frequency of pesticide spraying. Despite widespread use of protective devices in this area significant inhibition occurred. It became unclear whether acetylcholinesterase inhibition occurred as a result of protective clothing soaked with pesticides, thereby increasing dermal exposure, or because of other (unmeasured) factors. Inhibition, however, could have been much worse without protective devices. In area 1, most workers wore boots, which were found to be protective only when combined with an overall; wearing boots alone led to increased inhibition. Access to a washing facility or bathing facility had a positive effect on acetylcholinesterase levels. However, washing of hands and bathing immediately after spraying seemed reactive behaviour rather than proactive behaviour. Spraying was found to lead to more profound acetylcholinesterase inhibition than mixing. Workers who sprayed WHO Class III pesticides had less acetylcholinesterase inhibition than workers spraying more toxic pesticides.

The assessment of personal exposure to nitrogen dioxide in epidemiological studies

Abstract Personal and indoor exposure to nitrogen dioxide (NO 2 were studied in a population of housewives and children. Personal exposure, indoor concentrations and peak exposures were measured using Palmes diffusion tubes during three measurement periods of 1 week within 1 year. Very high peak concentrations were found in the kitchens (up to 2000 μg m −3 ). Three different estimates of personal exposure were constructed using indoor concentrations and time budget data. All three were found to be closely associated with measured personal exposure. The variability over time of personal and indoor concentrations, and of the three exposure estimates was investigated in a one-way analysis of variance. The within-location or within-subject variances of indoor concentrations and estimated personal exposures were found to be smaller, relative to the between-location or between-subject variances, than the within-subject variance of measured personal concentrations. The close association between measured indoor concentrations (or exposure estimates based on indoor concentrations) and measured personal exposure suggests that measuring indoor concentrations of nitrogen dioxide in the home is sufficient to estimate personal exposure accurately. Short term peak concentrations were found to be only weakly associated with indoor NO 2 sources and weekly average indoor NO 2 concentrations. Repeated exposure to short term peak concentrations has been suggested that diffusion type measurements of personal and indoor exposure to NO 2 , which are widely used suggests that diffusion type measurements of personal and indoor exposure to NO 2 , which are widely used in epidemiologic studies, may not adequately reflect the most biologically relevant exposure.

Indoor nitrogen dioxide pollution and respiratory symptoms of schoolchildren.

SummaryThe influence of indoor nitrogen-dioxide exposure on respiratory symptoms of schoolchildren was investigated in a case-control study. The election method used was useful in obtaining symptomatic children, but insufficient in defining cases and controls without additional information. No relationship between indoor NO2 and respiratory symptoms was found. Bias may have been present, especially because of the high mobility of the study population. Attempts to estimate historical exposure were inaccurate. Therefore the results do not exclude that an association between indoor NO2 and respiratory symptoms exists.

The use of palmes diffusion tubes for measuring NO2 in homes

Abstract The results of exposure chamber and field validation tests of NO2 diffusion tubes are reported. In an exposure chamber about 50 test runs at various relative humidities were performed. The field validation consisted of comparisons between tubes and a chemiluminescence monitor in nine homes during several days in kitchen, living room, bedroom and outdoors. The results indicate a dependency on relative humidity, while the often quoted accuracy of 10% for the diffusion tubes might be too optimistic for the use of the tubes in homes.

Estimating human exposure to nitrogen dioxide: results from a personal monitoring study among housewives.

Abstract Weekly average personal exposure to nitrogen dioxide (NO 2 ) was measured in a population of housewives living in Wageningen, The Netherlands, together with weekly average indoor NO 2 concentrations and indoor NO 2 peak concentrations. In part of the population the personal exposure measurements were repeated. The personal exposure and the indoor concentrations were in line with those in other studies in Holland. In general they were higher than the levels found in studies in the United States and Canada, but lower than those reported for Great Britain and Japan. The NO 2 peak concentrations were high, especially in the kitchen. Relationships between personal exposure and indoor concentrations were investigated using bivariate and multiple regression techniques. Indoor concentrations were found to be highly related to personal exposure. The contribution of peak concentrations to the explanation of personal exposure was small. An analysis of variance of the repeated personal exposure measurements showed that due to variation of personal exposure in space and/or time the “error” variance (within persons) was almost as large as the “true” variance (due to differences between persons). Therefore, it will be necessary to repeat personal exposure measurements in order to obtain reliable exposure estimates in health effect studies.

Indoor carbon monoxide pollution in The Netherlands

Abstract Most houses in the Netherlands are equipped with gas-fired heaters and cooking appliances,since large amounts of natural gas are available within the country since the mid-1960s. Carbon monoxide poisoning due to coal fires has virtually ceased to exist when coal-fired heaters were replaced by gas heaters. However, such poisonings still occur, although to a lesser extent, due to the use of instantaneous water heaters (geisers) that are gas fired. An investigation was carried out to establish the CO production potential of geisers under normal conditions of use. The study involved 254 houses; the results indicated that 17% of the geisers produced a CO level of more than 50 μL/L in the kitchens where they were located, after 15 min of operation. Presence of a flue, burner type, and maintenance system proved to be the main controlling factors.

Indoor NO2 pollution and personal exposure to NO2 in two areas with different outdoor NO2 pollution

Indoor NO2 concentrations were measured in the kitchen, the living room and bedroom of 612 houses in two different areas in the Netherlands. In a group of housewives living in these homes, personal exposure to NO2 was measured. NO2 concentrations indoors were dependent on the presence or absence of (un)vented gas appliances. Personal NO2 exposure was only different between the two areas in the group with the lowest indoor concentrations. In this study, it was determined that gas appliances inside the house are the most important factor with respect to NO2 exposure and that outside NO2 concentration played a secondary role, except in situations where gas appliances were absent.

Effects of indoor exposure to nitrogen dioxide on pulmonary function of women living in urban and rural areas

The health effects of indoor NO{sub 2} pollution were studied among two populations of adult women. One population was living in a rural area, one in an urban area. Exposure to NO{sub 2} was measured in the homes of the complete study population. Over 500 women were studied. Data on pulmonary function and respiratory symptoms were used to assess the respiratory health of the women. Significant associations were found between exposure to NO{sub 2} and pulmonary function among the non-smoking women living in the rural area, but not among the smoking women in that area, or among the non-smoking and smoking women living in the urban area.

Variation of indoor nitrogen dioxide concentrations over a one-year period

Abstract In 15 homes, the indoor NO 2 concentration was measured repeatedly during 1 yr, to obtain estimates of within-home and between-home variability. Diffusion tubes were used to measure weekly average concentrations in the kitchen, living room and bedroom of each home, once every two weeks. The results indicate that in all seasons except summer, the NO 2 concentrations within locations within homes were stable and that between homes, indoor concentrations were systematically different. This information is important for the evaluation of health effect studies in which indoor NO 2 concentrations are used as a measure of exposure.