Temporal patterns of activities potentially related to pesticide exposure

Abstract

Longitudinal information on human activity patterns is required to perform reliable assessments of chronic exposure to pesticides in nonoccupational settings. As part of a longitudinal, multimedia exposure survey in Maryland, USA, we collected 2521 person -days of information on the frequency of five activities that are potentially important to pesticide exposure in residential settings: preparation of pesticides; application of pesticides; contact with soil on the skin; contact with grass on the skin; and contact with carpet. Logistic regression was used to evaluate the data for variability by time of year, day of week, and several demographic factors. Eight percent of the population reported preparing pesticides on at least one occasion over the year, while 24% of the population applied pesticides at least once. The majority of the population reported contact with soil ( 68% ), grass ( 72% ), and carpet ( 64% ) over the course of a year. Skin contact with soil and grass was found to occur approximately twice as frequently ( p < 0.001 ) in spring and summer periods than in fall and winter periods. Similarly, contact with soil and grass was about 50% ( p < 0.05 ) more likely to occur on weekend days than on weekdays. These results indicate that short -term measurements ( e.g., 1 -day or 1 -week ) of these activities for an individual may not be equivalent to long -term average patterns. We also found that selected demographic characteristics were significant predictors of several of these activities. Thus, some demographic characteristics may be useful in categorizing exposure although it is unlikely that a single short -term measurement will suffice to describe annual average activity or multiple short -term activity periods.

Analysis of aggregate exposure to chlorpyrifos in the NHEXAS-Maryland investigation.

“…We found low temporal variability of chlorpyrifos concentration in carpet dust, indicating that the timing of dust sample collection may not be an important design consideration in the absence of a recent pesticide application event. But mean time spent inside the home and carpet contact rate varied significantly among cycles and among days for individuals (10,28). Dietary intake of chlorpyrifos exhibited low reliability, perhaps because of variation in shortterm food consumption and in the occurrence and exposure concentration of chlorpyrifos among servings of food commodities.…”

Video methods in the quantification of children's exposures

“…Care must be taken in the application of short-term activity patterns (i.e., videotaped data for 1 day) for the assessment of longitudinal exposure (e.g., exposure over various seasons) (Echols et al, 2001). We are making the effort through a longitudinal (Study 6, Table 1) to access how children activity pattern vary as they age and, therefore, possibly how to use these shortterm activity pattern to access longitudinal exposure for children (e.g., developing probabilistically relevant activity scenarios per age group).…”

Using human activity data in exposure models: Analysis of discriminating factors

“…Time spent at home varies among individuals (demographic characteristics), dayof-the-week, and seasons. Echols et al (1999) Results are focused on pesticide exposures; variables as above As above Echols et al (2001) Age, day-of-week NHEXAS format: 7 consecutive 24-h diaries for 249 people using 1-h blocks. Daily autocorrelation for some, but not all, activities (episodic vs. regular behaviors).…”