Pesticide Exposure of Residents Living Close to Agricultural Fields in the Netherlands:Protocol for an Observational Study

Background: Application of pesticides in the vicinity of homes has caused concern regarding possible health effects in residents living nearby. However, the high spatiotemporal variation of pesticide levels and lack of knowledge regarding the contribution of exposure routes greatly complicates exposure assessment approaches. Objective: The objective of this paper was to describe the study protocol of a large exposure survey in the Netherlands assessing pesticide exposure of residents living close ( Methods: We performed an observational study involving residents living in the vicinity of agricultural fields and residents living more than 500 m away from any agricultural fields (control subjects). Residential exposures were measured both during a pesticide use period after a specific application and during the nonuse period for 7 and 2 days, respectively. We collected environmental samples (outdoor and indoor air, dust, and garden and field soils) and personal samples (urine and hand wipes). We also collected data on spraying applications as well as on home characteristics, participants' demographics, and food habits via questionnaires and diaries. Environmental samples were analyzed for 46 prioritized pesticides. Urine samples were analyzed for biomarkers of a subset of 5 pesticides. Alongside the field study, and by taking spray events and environmental data into account, we developed a modeling framework to estimate environmental exposure of residents to pesticides. Results: Our study was conducted between 2016 and 2019. We assessed 96 homes and 192 participants, including 7 growers and 28 control subjects. We followed 14 pesticide applications, applying 20 active ingredients. We collected 4416 samples: 1018 air, 445 dust (224 vacuumed floor, 221 doormat), 265 soil (238 garden, 27 fields), 2485 urine, 112 hand wipes, and 91 tank mixtures. Conclusions: To our knowledge, this is the first study on residents' exposure to pesticides addressing all major nondietary exposure sources and routes (air, soil, dust). Our protocol provides insights on used sampling techniques, the wealth of data collected, developed methods, modeling framework, and lessons learned. Resources and data are open for future collaborations on this important topic

Climate control of terrestrial carbon exchange across biomes and continents

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Water balance components.

<p>Water balance components (means, SE, n = 5) were calculated over the summers of 2008–2010 (period V, calendar weeks 19–32). Water balance components (P, I, R and ΔW are in mm summer⁻¹, S is in mm mm⁻¹ and ET in mm day⁻¹. Positive values of water storage refer to changes in water volume as a result of a net rise in the water table between the first and last date of period V, whereas negative values refer to changes in water volume as a result of a net decrease in the water table between the first and last date of period V. Different letters denote statistically significant differences between tree density treatments for the same year based on 2-way ANOVAs with treatment as factor and block as random factor. Ns = P<0.10, (*) = 0.10≥P<0.05, * = P≤0.05, ** = 0.05>P≤0.01, *** = P<0.01.</p

Relationship between plot-LAI and mesocosm evapotranspiration (ET) for the summers of 2008, 2009 and 2010.

<p>ET of the mesocosms with trees (LT and HT) were averaged over the summer (period V) for each year separately and standardized by dividing by the ET from mesocosms without trees (NT mesocosms). Symbols above the dashed line indicate a higher evapotranspiration than NT mesocosms, whereas symbols below this line indicate lower evapotranspiration than NT mesocosms. The solid line indicates a weak, but significant, (<i>P</i><0.05), linear relationship (linear regression, R² = 0.25, y = 0.1x+1.1).</p

Seasonal changes in tree density effects on mesocosm water table.

<p>Bars represent mean water tables ±1 SE (n = 5) in cm relative to a fixed point per week, from week 38 in 2007 (38) until week 37 in 2008 (37). Positive values indicate a water table closer to the surface. Water table level was measured relative to a fixed point (the overflow outlet), which was 10–15 cm below the moss surface. Birch density treatments are identified by differently shaded bullets. NT = control without trees, LT = low tree density, HT = high tree density. Arrows indicate onsets of leaf senescence in 2007 and leaf emergence in 2008. * = week during which storage coefficient has been determined, ** week in which demineralized water has been added to each mesocosm. ETp periods indicates periods (I-V) differing in solar radiation and potential evapotranspiration, over which evapotranspiration has been averaged for <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0091748#pone-0091748-g001" target="_blank">Figures 1</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0091748#pone-0091748-g003" target="_blank">3</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0091748#pone-0091748-g004" target="_blank">4</a>. Note: mesocosm trees were planted in December 2007.</p

Vegetation composition understory.

<p>Abundances (means, SE, n = 5) of vascular plants, litter and moss in the mesocosms over the experiment (2007–2010). Data on 2008 are missing, due to a malfunctioning voice recorder. 100% of frame = species hit in all 150 points of the point-quadrat frame (see methods). For plants with horizontal (planar) leaf orientation 100% frame roughly corresponds to LAI = 1. Values over 100 indicate multiple hits per point. Statistics give results of repeated measures ANOVAs with treatment as within subject factor and year as between subject factor. Ns = P<0.10, (*) = 0.10≥P<0.05, ** = 0.05>P≤0.01, *** = P<0.01.</p

Seasonal changes in tree density effects on mesocosm evapotranspiration.

<p>Bars represent means +1 SE (n = 5) per birch density treatment averaged over periods (I–V) in order of increasing atmospheric demand for water. Periods I and II cover late autumn -early spring, whereas periods III–V represent mid spring-mid autumn (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0091748#pone-0091748-t002" target="_blank">Table 2</a>). Measurements spanned 1 year from week 38 in 2007 until week 37 in 2008, the only year for which we had water table data for all seasons. NT = control without trees, LT = low tree density, HT = high tree density. Different letters above the bars denote statistically significant (<i>P</i><0.05) differences between tree density treatments within a period based on five separate 2-way ANOVAs with treatment as factor and block as random factor, one ANOVA for each period.</p

Effects of tree density on water table (panel A) and mesocosm evapotranspiration (panel B).

<p>Bars represent means +1 SE (n = 5) per birch density treatment. NT = control without trees, LT = low tree density, HT = high tree density. Mesocosm evapotranspiration was averaged over the first summer (period V, calendar week 19–32, 2008). Water table values refer to the situation at the end of period V, as measured at the beginning of week 33. Water table level was measured relative to a fixed point (the overflow outlet), which was 10–15 cm below the moss surface. Different letters above the bars denote statistically significant (<i>P</i><0.05) differences between tree density treatments based on 2-way ANOVAs with treatment as factor and block as random factor.</p