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Residential/ Non- occupational Exposure Assessment Jeff Evans Biologist Health Effects Division Office of Pesticide Programs Purpose To present our use of a calendar based model (Calendex™), to address the temporal aspects of OP pesticide use

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Residential/ Non- occupational Exposure Assessment

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Non- occupational Exposure Assessment

Jeff Evans


Health Effects Division

Office of Pesticide Programs

  • To present our use of a calendar based model (Calendex™), to address the temporal aspects of OP pesticide use
    • Approach is similar to the OP case study presented to SAP (12/7-8/00)
  • To discuss the data used in our cumulative residential exposure assessment
  • To discuss with the Panel:
    • Use of distributions of the available data
    • Additional ways to incorporate survey data and other pesticide use in future assessments
residential op assessment uses
Residential OP Assessment: Uses
  • Indoor use: DDVP (crack and crevice, pest strips)
  • Pet use: DDVP and Tetrachlorvinphos (spray/dip, collars) – currently only qualitatively assessed
  • Home Lawns: Bensulide, Malathion, Trichlorfon
  • Golf Course: Acephate, Bensulide, Fenamiphos, Malathion, Trichlorfon
  • Home Garden: Acephate and Disulfoton (ornamental) , Malathion (ornamental and edible food)
  • Public Health: Fenthion, Malathion, Naled
expression of residential risk
Expression of Residential Risk

MOE = POD (mg/kg/day)

Exposure (mg/kg/day)

  • Routes considered, as appropriate
    • Oral, Dermal, Inhalation
age groups
Age Groups
  • Assessment performed for the following age groups:
    • Children 1-2 years old
    • Children 3-5 years old
    • Adults 20+
  • Assessments conducted for 12 distinct geographical regions, reflecting climate & pest pressure differences
    • One region split into two residential assessments
  • Includes remaining residential OPs that have significant exposure and appropriate exposure data
  • Pet products not quantified
    • Only screening level SOPs available at this time
regional framework
Regional Framework

Source: USDA ERS

region 5 eastern uplands
Region 5 – Eastern Uplands
  • Lawn: DDVP, Malathion, Trichlorfon
  • Golf Course: Acephate, Bensulide, Fenamiphos, Malathion, Trichlorfon
  • Ornamental Gardens: Acephate, Disulfoton, Malathion
  • Home Garden: Malathion
  • Indoor: DDVP (pest strips and crack and crevice treatments)
road map
Road Map
  • Key Data Used (distributions selected)
    • Lawn
    • Golf Courses
    • Public Health
    • Home Garden
  • Characterization
  • Future Consideration of Survey Data
lawns use information
Lawns – Use Information
  • National Home & Garden Pesticide Use Survey (NHGPUS 1991)
    • percent of households using a given pesticide – regional distinctions
  • Treated lawns based on regions using the National Garden Survey 1996-1997
    • Percent of population hiring lawn care services
  • Lawn Size (Vinlove and Torla 1995 and ORETF Survey)
lawn size
Lawn Size
  • Uniform Distribution 500 – 15,000 ft2
  • Difficult to quantify
    • Only considers lot size minus footprint
    • Does not consider other structures/green space
lawns use information14
Lawns: Use Information
  • Label
    • site/pest relationships
    • application rates
  • State Cooperative Extension services
    • Timing of applications to control common pests
  • Comparative Insecticide Effectiveness for Major Pest Insects of Turf in the United States
lawn applicator exposure data
Lawn: Applicator Exposure Data
  • Data source: ORETF
  • Application Type:
    • Granular push-type rotary spreaders
    • Hose-end sprayer – ready to use and one requiring the user to add the concentrate
  • Clothing types:
    • Range of clothing
    • Short-sleeved shirt, short pants and long-sleeved shirt, long pants
lawn applicator exposure
Lawn: Applicator Exposure
  • Unit Exposure (UE)
    • mg of exposure/amount of active ingredient (a.i.) used
    • UE x ai/sq ft x area treated
      • Divided by body weight
lawn applicator exposure data17
Lawn: Applicator Exposure Data
  • Hose-end Sprayer
    • Uniform Distribution: 0.017 – 49 mg/lb ai
  • Granular Applicator
    • Uniform Distribution: 0.02 – 7.6 mg/lb ai
lawn applicator exposure data18
Lawn: Applicator Exposure Data
  • Well understood activity pattern
    • Easy to measure and develop distributions
  • However, selected a uniform distribution that:
      • Reflects range of clothing that can be worn
      • Survey data suggest that clothing worn while applying pesticides changes as growing season progresses
        • seasonal changes are only based on formulation type not equipment used
        • Hose-end includes both “mix you own” and “ready to use”
lawn post application exposure data
Lawn: Post- Application Exposure Data
  • Difficult activity pattern to determine what is representative
  • Residue transfer to skin(transfer coefficient)
    • Choreographed Activities of Adults Measured Using Biological Monitoring, (Vacarro 1996)
      • Crawling, football, Frisbee
    • Non-Scripted Activities of Children Measured Using Fluorescent Tracers, (Black 1993)
      • Mostly solitary play with toys and books. Also activities such as cartwheels
lawn post application exposure data20
Lawn: Post- Application Exposure Data
  • Duration: up to 2 and 3.5 hrs for adults and children respectively (Cumulative, EFH)
  • Adult TC: 1,930 – 13,200 cm2/hr
    • Uniform distribution (n – 16 Vacarro)
  • Child TC: 700 – 16,000 cm2/hr
    • Uniform distribution Vacarro (n – 16) and Black (n – 14)
lawn post application exposure data21
Lawn: Post- Application Exposure Data
  • Turf Transferable Residues (TTR)
    • Chemical specific dissipation data (mg/cm2)
      • Uniform distribution selected for each day’s residues
        • Each day includes a range of values instead of mean
          • First day values include “as soon as dry” up to 8 hours after application
          • Watering in and not watering in
          • Other days include potential for rainfall
lawn post application exposure data22
Lawn: Post- Application Exposure Data
  • Non-Dietary Ingestion (Hand-to-Mouth)
  • Most challenging activity pattern to assess
    • Hand-to-mouth frequency of events, (Reed 1999)
    • Adjust lawn residue data (TTR) to account for saliva wetted hands, (Clothier 2000)
    • Saliva extraction e.g., (Camann 1995)
lawn post application exposure data23
Lawn: Post- Application Exposure Data
  • Hand-to-mouth frequency of events (Reed 1999)
    • Children in day-care (n-20) at home (n-10)
    • Uniform distribution: 0.4 to 26 events/hr
    • Mean 9.5, median 8.5, 90th percentile 20
      • Issue: indoors vs. outdoors, active vs. quiet play
      • Freeman et al., 2001: outdoors (~2-3x less than indoors)
        • Small subset (4 out of 19)
lawn post application exposure data24
Lawn: Post- Application Exposure Data
  • Lawn residue data to account for saliva wetted hands(Clothier 2000)
    • Compared wet hand efficiency vs. dry hand efficiency (cyfluthrin, chlorthalonil and chlorpyrifos)
    • Dry hand transfer efficiency is similar to TTR measurements (0.9 to 3%) for 2 chemicals
      • Chlorpyrifos much lower overall (0.05 - 0.15%)
    • Wet palms: uniform distribution 1.4-3x higher than TTRs
lawn post application exposure data25
Lawn: Post- Application Exposure Data
  • Saliva extraction (uniform: 10 to 50%)
    • 50% removal by saliva wetted sponges – vigorous (Camann et al., 1995)
    • 20 – 40% hands rinsed with water/Ethanol and water/Isopropanol (Fenske and Lu, 1994)
    • ~10 – 22% soil removal from hands to account for possible residue/soil matrix (Kissel et al., 1998)
golf courses post application exposure data
Golf Courses: Post- Application Exposure Data
  • Percent of individuals participating in golf, 1992 Golf Course Operations by the Center for Golf Course Management
  • Number of hours playing golf
  • Percent of Golf Courses Applying Selected Pesticides (Doane GolfTrak, 1998-1999)
  • An activity pattern that is easy to understand and measure
golf courses post application exposure data27
Golf Courses: Post- Application Exposure Data
  • Residue transfer to skin (transfer coefficient)
    • Uniform distribution: 200 to 760 cm2/hr
    • Small data set (less than 10) includes walking and using a cart.
  • Chemical-specific turf residue data
public health post application
Public Health: Post- Application

Range of residues that deposit onto lawns is based on a percent of public health use application rate (3.8 to ~30%) using values presented in Tietze et al., 1994 and the Spray drift model, AgDrift

  • Once an estimate of deposition is made the post application is assessed in the same way that lawn chemicals are
  • Estimates of % population based on percent of homes having lawns
  • Timing and pesticide used based on personal communication and publications prepared by organizations such as the Florida Coordinating Council of Mosquito Control
garden applicator exposure data
Garden : Applicator Exposure Data
  • An activity pattern that is easy to understand and measure
    • Shaker Can (n-20): uniform, 0.0034-0.356 mg/lb ai
    • Garden Duster (n-20) uniform, 7.99-1375.4 mg/lb ai
    • Small Tank Sprayer (n-20), uniform, 7.99-354.4 mg/lb ai
  • Similar issues regarding clothing as in lawn applications
garden applicator exposure data30
Garden: Applicator Exposure Data
  • Area Treated
  • Ornamental Gardens: uniform, 500 to 2,000 ft2
    • No data. Defined in the assessment as the area consisting of the perimeter around a median home area 2,250 sq ft2., with a 2.5 to 8 ft border
  • Vegetable gardens: log-normal, 135 to 8,000 ft2
    • May be easier for people to estimate than lawns
garden post application exposure
Garden: Post- Application Exposure
  • Post-application dermal exposure
    • An easily defined activity in agriculture
    • Home gardens are more difficult due to wide variety of crops grown (fruits and vegetables) and a wide variety of activities
      • Uniform distribution of 100 to 5,000 cm2/hr
    • Duration of garden activities: uniform, 5 to 60 min.
    • Chemical/regional specific residue data
indoor inhalation exposure data
Indoor: Inhalation Exposure Data
  • Applicator – uniform range of inhalation exposure values for pressurized aerosol can (PHED)
      • 0.72 – 2.499 mg/lb ai
  • Post application inhalation exposure (adults and children)
    • Pest Strips: 0.005 – 0.11 mg/m3

(Collins et al., 1973)

    • Crack and Crevice – 0.075 – 0.548 mg/m3

(Gold et al., 1983)

  • Duration of time spent indoors, and breathing rates
    • Up to 24 hours, at rest to moderate
methods summary
Methods Summary
  • All available data considered
    • e.g.,Lawn residue data available for all compounds and made regional adjustments where feasible
  • Addressed a variety of activity patterns
    • Some more straight forward : Application
    • Some more difficult : Hand-to-Mouth
  • Tended to use uniform distributions when presented with scenarios that had confounding variables
survey data
Survey Data
  • Overview of our use of survey data to address use and co-occurrence
  • Future considerations:
    • Use of existing macro activity pattern data
      • SHEDS example
    • Upcoming pesticide use survey
survey data macro activity patterns
Survey Data: Macro Activity Patterns
  • Human Activity Patterns
    • Calendar based models present an opportunity to consider an individual’s macro activity patterns that can lead to exposure to one or more chemicals
    • Macro Activity Patterns are broadly defined as where individuals spend their time
      • In the garden
      • Driving to work
survey data macro activity patterns40
Survey Data: Macro Activity Patterns
  • Our Basic Approach (Independence/Dependence)
    • Identify households based on reported use of an OP for a given scenario (e.g., NHGPUS)
      • 6% of households in Region 5 use lawn chemical A
    • Identify the time individuals spend on lawns or other locations
      • In the Exposure Factors Handbook, there are recommended values taken from surveys such as the National Human Activity Pattern Survey (NHAPS)
survey data macro activity patterns41
Survey Data: Macro Activity Patterns
  • STEP 1: Calculate Exposure from Food for Individual #1 on a given day (Food Exposure(from DEEM™))
  • STEP 2: Select Residential Treatments for Individual #1 on a given day
    • Specific to region, time and demographics of individual
      • Were pesticides applied in/around home?
      • If so, which treatments?
        • And how much, how often, during what time frame, with what frequency, and by whom?
  • Repeat Step 2 until all relevant residential uses are addressed
survey data macro activity patterns42
Survey Data: Macro Activity Patterns
  • Co-occurrence is driven by random probabilities (% households being treated)
    • (6% lawn use) x (10% crack and crevice) = 0.6%
  • However, once a household is selected, the probability of being on the lawn is 1 because:
    • We used a distribution of time spent on the lawn based only on individuals who were actually on lawns
    • Does not account for individual responses indicating they did not spend time on lawns
survey data macro activity patterns43
Survey Data: Macro Activity Patterns
  • Consolidated Human Activity Database (CHAD) hhtp://
    • Compilation of pre-existing human activity surveys collected at the national, state and city level
      • Review questionnaires and individual responses
      • Develop daily activity patterns for an individual based on responses to the questionnaires
      • Most surveys are cross-sectional rather than longitudinal
survey data macro activity patterns44
Survey Data: Macro Activity Patterns
  • Stochastic Human Exposure and Dose Simulation model - SHEDS
    • Developed by:
      • Valerie Zartarian
      • Jianping Xue
      • Haluk Ozkaynak

Exposure Rate [ug/min]


living room










Time (min)


8 CHAD diaries simulate a person’s year in specified age-gender cohort

1 person from each of 4 seasons

1 person from each of 2 day categories (weekend and weekday)

Fix 5 weekday diaries and 2 weekend diaries

Repeat 7 day activity patterns within each season






















Day of Year

survey data macro activity patterns47
Survey Data: Macro Activity Patterns
  • Residential Exposure Joint Venture (REJV)
    • Longitudinal survey data addressing the application pesticides in and around households
      • When and where applications are made
      • Multiple applications made in one day
      • What they wore while making those applications
      • Demographic information (children)
question 1
Question 1

Historically, the Agency has relied on means (primarily arithmetic or geometric) from residue and exposure studies for key input variables in exposure assessments. The recent development of calendar based models and others having features to incorporate distributions of exposure values has presented the Agency an opportunity to consider using all available data points from existing exposure and residue studies. In the Cumulative Risk Assessment Case study presented to the FIFRA Scientific Advisory Panel in September, 2000, most of the exposure variables were presented as uniform distributions. The exceptions were for variables that are reasonably well established , such as exposure durations taken from the Agency’s Exposure Factors Handbook. The data used in the Case Study and in the preliminary CRA, are believed to be from well conducted studies of generally high quality. However, these data sets tend to be small (e.g., n = 10 - 30) and are being used to address wide variety of exposure situations. The uniform distribution appears to be most appropriate for these relatively small data sets because it relies on easily established values such as the minimum and maximum and provides the most conservative estimate of the standard deviation (

question 2
Question 2

The use of calendar based models also allows exposure assessors to consider exposure from a variety of sources from the same or from different chemicals. Longitudinal survey data such as the National Human Activity Pattern Survey (NHAPS) are available for consideration by HED for use in future assessments. In addition, from a practical standpoint, the use of such survey data ensures combinations of exposure do not come from unrealistic random combinations that current models may produce (e.g., activities adding up more than 24 hours in a day).

question 2 continued
Question 2 (continued)

The use of calendar based models provides an opportunity to explore the potential for the co-occurrence of multiple sources of exposures from residential pathways. In the cumulative assessment, OPP used summary statistics from sources such as the Exposure Factors Handbook (EFH) regarding the time spent indoors, time spent on lawns and time spent at other outdoor locations. In the preliminary assessment, we assumed these activities were stochastically independent. OPP is currently evaluating data in the EFH such as data from the National Human Activity Pattern Survey (NHAPS) to determine if it can directly incorporate (i.e., empirically) information on an individual’s activity patterns over a full day from this database to account for the likelihood and duration that an individual might be exposed to a pesticide through various activities over the course of a day.