A task-based assessment of parental occupational exposure to pesticides and childhood acute lymphoblastic leukemia.
Associations between parental occupational pesticide exposure and childhood acute lymphoblastic leukemia (ALL) vary across studies, likely due to different exposure assessment methodologies.



We assessed parental occupational pesticide exposure from the year before pregnancy to the child's third year of life for 669 children diagnosed with ALL and 1021 controls. We conducted expert rating using task-based job modules (JM) to estimate exposure to pesticides among farmer workers, gardeners, agricultural packers, and pesticide applicators. We compared this method to (1) partial JM using job titles and a brief description, but without completing the task-based questionnaire, and (2) job exposure matrix (JEM) linking job titles to the International Standard Classifications of Occupation Codes. We used unconditional logistic regression to calculate odds ratios (OR) and 95% confidence intervals (95% CI) for ALL cancer risk and pesticide exposure adjusting for child's sex, age, race/ethnicity and household income.



Compared to complete JMs, partial JMs and JEM led to 3.1% and 9.4% of parents with pesticide exposure misclassified, respectively. Misclassification was similar in cases and controls. Using complete JMs, we observed an increased risk of ALL for paternal occupational exposure to any pesticides (OR=1.7; 95% CI=1.2, 2.5), with higher risks reported for pesticides to treat nut crops (OR=4.5; 95% CI=0.9, 23.0), and for children diagnosed before five years of age (OR=2.3; 95% CI: 1.3, 4.1). Exposure misclassification from JEM attenuated these associations by about 57%. Maternal occupational pesticide exposure before and after birth was not associated with ALL.



The risk of ALL was elevated in young children with paternal occupational pesticide exposure during the perinatal period, using more detailed occupational information for exposure classification.
School of Public Health, University of California, Berkeley, Berkeley, CA, USA. Electronic address: gunier@berkeley.edu.
Robert B
RB
Gunier
School of Public Health, University of California, Berkeley, Berkeley, CA, USA.
Alice
A
Kang
School of Public Health, University of California, Berkeley, Berkeley, CA, USA.
S Katharine
SK
Hammond
Cedars-Sinai Medical Center, Heart Institute, Los Angeles, CA, USA.
Kyndaron
K
Reinier
East Carolina University, Brody School of Medicine, Department of Public Health, Greenville, NC, USA.
C Suzanne
CS
Lea
National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan.
Jeffrey S
JS
Chang
Division of Research, Kaiser Permanente Medical Group, Oakland, California, USA.
Monique
M
Does
International Agency for Research on Cancer, Lyon, France.
Ghislaine
G
Scelo
Medical Oncologist and Hematologist, Berkeley, CA, USA.
Janice
J
Kirsch
Valley Children's Hospital, Madera, CA, USA.
Vonda
V
Crouse
Department of Pediatric Hematology/Oncology, Kaiser Permanente Los Angeles Medical Center, Los Angeles, CA, USA.
Robert
R
Cooper
University of California, San Francisco, Department of Medicine, San Francisco, CA, USA.
Patricia
P
Quinlan
School of Public Health, University of California, Berkeley, Berkeley, CA, USA.
Catherine
C
Metayer
D000293:Adolescent; D002140:California / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016015:Logistic Models; D008297:Male; D018811:Maternal Exposure; D016273:Occupational Exposure; D018812:Paternal Exposure; D010575:Pesticides / Q000633:toxicity*; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000139:chemically induced / Q000453:epidemiology*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000139:chemically induced / Q000453:epidemiology*
D010575:Pesticides
Childhood leukemia; Job-specific modules; Occupational exposure; Pesticides