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Background: Residential use of pesticides has been associated with increased risk of childhood acute lymphoblastic leukemia (ALL). We evaluated determinants of glyphosate concentrations in house dust and estimated ALL risk in the California Childhood Leukemia Study (CCLS)., Methods: The CCLS is a population-based case-control study of childhood leukemia in California. Among those < 8-years (no move since diagnosis/reference date), we collected dust (2001-2007) from the room where the child spent the most time while awake and measured > 40 pesticides. Three-to-eight years later, we collected a second sample from non-movers. We used Ultra-Performance Liquid Chromatography Tandem Mass Spectrometry to measure glyphosate (µg/g dust) for 181 ALL cases and 225 controls and for 45 households with a second dust sample. We used multivariable Tobit regression to evaluate determinants of glyphosate concentrations. Odds ratios (ORs) and 95 % confidence intervals (CI) were calculated for ALL and quartiles of the concentration (first samples) using unconditional logistic regression. We computed the within- and between-home variance and intraclass correlation coefficient (ICC)., Results: Glyphosate was frequently detected (cases: 98 %; controls: 99 %). Higher concentrations were associated with occupational pesticide exposure, nearby agricultural use, treatment for lawn weeds and bees/wasps, and sampling season. Increasing concentrations were not associated with ALL risk (adjusted OR Q4vsQ1  = 0.8, CI: 0.4-1.4). We observed similar null associations for boys and girls, Hispanics and non-Hispanic whites, and among those who resided in their home since birth (76 cases/117 controls) or age two (130 cases/176 controls). The ICC was 0.32 indicating high within-home temporal variability during the years of our study., Conclusions: We observed higher concentrations in homes associated with expected predictors of exposure but no association with childhood ALL risk. Due to continuing use, potential exposure to young children is high. It will be important to evaluate risk in future studies with multiple dust measurements or biomarkers of exposure., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Controversy persists regarding the role of a low ratio of 2-hydroxyestone (2-OHE(1))/16alpha-hydroxyestrone (16alpha-OHE(1)) as a potential estrogen metabolism marker of increased risk for breast cancer. Most of the evidence has been provided by case-control studies, where tumor effects on hormone metabolism are not known. Studies in populations at various risk of breast cancer are not consistent, with some suggesting that levels of the ratio may be altered by changes in diet and exercise. We studied Asian American women participating as controls in a case-control study of breast cancer in which migration history--a composite of the subject's place of birth, type of residence in Asia (urban or rural), length of time living in the West, and grandparents' place of birth--was associated with a 6-fold risk gradient that paralleled the historical differences in incidence rates between the United States and Asian countries. This population offered the possibility to address whether the ratio of 2-OHE(1):16alpha-OHE(1) differs according to recognized breast cancer risk factors, including migration history. Overnight 12-hour urines were obtained from 368 premenopausal and 143 naturally postmenopausal women of Chinese, Japanese, or Filipino descent who donated urines between 1985 and 1988. The estrogen metabolites 2-OHE(1) and 16alpha-OHE(1) were measured with an ELISA kit and adjusted for creatinine levels. In each ethnic group, the ratio of 2-OHE(1):16alpha-OHE(1) was consistently lower in women born in the West than in those who had migrated from Asia. For premenopausal women, the ratio declined 20% due to lower levels of 2-OHE(1). Among postmenopausal women, the ratio was 23% lower in those born in the West, but no consistent patterns based on place of birth were observed for either 2-OHE(1) or 16alpha-OHE(1). The ratio did not vary with most recognized breast cancer risk factors, except for lower metabolite ratios in women with a younger age at first birth and more children, which runs contrary to the hypothesis, because both characteristics reduce breast cancer risk. Our study suggests that the ratio of 2-OHE(1):16alpha-OHE(1) may be a marker for lifestyle influences on estrogen metabolism associated with westernization.