1. Pesticide and Heat Analysis
Rietta Wagoner and Nicolas Lopez-Galvez
Statistical Consulting Group
31 October 2017

2. Background
Migrant grape workers at commercial grape farm in Northern Mexico
Pruning, prepping plants in spring
Harvesting and packaging grapes during summer
Many different pesticides used throughout year to control pests that can threaten the grape crop. Workers may be exposed to pesticides.
Hot, arid climate creates potential for workers to become overheated.

3. Data Collected
Table 1. Participants and Data Collection by Sampling Event
Type of Data
March n
June n
August n
Total n
Questionnaire
Categorical (multiple choice), Binary, and Continuous (age)
N/A
11* 17 28
Environmental measurements and field observations (WBGT)
Continuous (unit-less measurement)
1 day
3 days
Urine-
Specific gravity analysis 10 7* 34
Urine- Pesticide metabolite Concentration
Continuous (mass per mass) 20
Pesticide on hands
Continuous (mass per surface area)
Core Body Temperature
Continuous (temperature) 8 8* 24
Temperature of Hands 11 38
* Five of the workers from March repeated an additional round of sampling in June 
 the best predictors of weighted-average daily metabolite concentration (kissel et al, 2004).

4. Heat Statistical Questions
Question 1 : Which is the best way to predict heat stress?
Question 2: Are heat measurements (core body temp, WBGT, hand temp.) correlated?
Question 3: Which heat measurement (core body temp., WBGT, hand temp.) best predicts urine specific gravity?

5. Pesticide Statistical Questions
Question 1: Are the levels of pesticides in the urine correlated with the concentration of pesticide on the hands
Done- Spearman’s correlation
Question 2: Do pesticide concentrations differ by seasons/months?
Done- Wilcoxon rank-sum comparison
Question 3 : What approach is best for understanding interaction between heat and pesticide

6. Upcoming Questions and Approach
Farm owner wants to know why certain pesticides are in the workers’ urine, especially those he does not apply on his organic grapes. The following questions came out of discussion with the owner:
Do workers arrive with pesticides already in their bodies (from food, working on other farms, etc.)?
Approach: measure workers’ urinary concentration of pesticides as soon as they arrive at farm and again after they have been working for 1 month
Are workers being exposed to pesticides sprayed in the dorms to control bedbugs?
Approach: Collect dust samples from dorms and analyze for presence of pesticides
Are workers’ urinary levels of pesticides higher than the general population?
Approach: Measure urinary levels of pesticides in general population and administer questionnaire (what foods do you eat, do you apply pesticides in your home, etc.). Compare to farm workers.
Are workers in organic section of farm being exposed to non-organic pesticides?
Approach: Compare urinary pesticide levels of organic workers to non-organic workers

7. Other things we should consider?

8. Thank you! Contacts: Rietta Wagoner rwagoner@email.arizona.edu
Nicolas Lopez-Galvez