Freisthler et al., 2022
Freisthler, Marlaina S., Robbins, C. Rebecca, Benbrook, Charles M., Young, Heather A., Haas, David M., Winchester, Paul D., & Perry, Melissa J.; “Association between increasing agricultural use of 2,4-D and population biomarkers of exposure: findings from the National Health and Nutrition Examination Survey, 2001–2014;” Environmental Health, 2022, 21(1); DOI: 10.1186/s12940-021-00815-x.
BACKGROUND: 2,4-Dichlorophenoxyacetic acid (2,4-D) is one of the most extensively used herbicides in the United States. In 2012, 2,4-D was the most widely used herbicide in non-agricultural settings and the fifth most heavily applied pesticide in the US agricultural sector. The objective of this study was to examine trends in 2,4-D urinary biomarker concentrations to determine whether increases in 2,4-D application in agriculture are associated with increases in biomonitoring levels of urine 2,4-D.
METHODS: Data from the National Health and Nutrition Examination Survey (NHANES) with available urine 2,4-D biomarker measurements from survey cycles between 2001 and 2014 were utilized. Urine 2,4-D values were dichotomized using the highest limit of detection (LOD) across all cycles (0.40 mug/L or 0.4 ppb). Agricultural use of 2,4-D was estimated by compiling publicly available federal and private pesticide application data. Logistic regression models adjusted for confounders were fitted to evaluate the association between agricultural use of 2,4-D and urine 2,4-D level above the dichotomization threshold.
RESULTS: Of the 14,395 participants included in the study, 4681 (32.5%) had urine 2,4-D levels above the dichotomization threshold. The frequency of participants with high 2,4-D levels increased significantly (p < .0001), from a low of 17.1% in 2001-2002 to a high of 39.6% in 2011-2012. The adjusted odds of high urinary 2,4-D concentrations associated with 2,4-D agricultural use (per ten million pounds applied) was 2.268 (95% CI: 1.709, 3.009). Children ages 6-11 years (n = 2288) had 2.1 times higher odds of having high 2,4-D urinary concentrations compared to participants aged 20-59 years. Women of childbearing age (age 20-44 years) (n = 2172) had 1.85 times higher odds than men of the same age.
CONCLUSIONS: Agricultural use of 2,4-D has increased substantially from a low point in 2002 and it is predicted to increase further in the coming decade. Because increasing use is likely to increase population level exposures, the associations seen here between 2,4-D crop application and biomonitoring levels require focused biomonitoring and epidemiological evaluation to determine the extent to which rising use and exposures cause adverse health outcomes among vulnerable populations (particularly children and women of childbearing age) and highly exposed individuals (farmers, other herbicide applicators, and their families).
Haas et al., 2015
Haas, D. M., Parker, C. B., Wing, D. A., Parry, S., Grobman, W. A., Mercer, B. M., Simhan, H. N., Hoffman, M. K., Silver, R. M., Wadhwa, P., Iams, J. D., Koch, M. A., Caritis, S. N., Wapner, R. J., Esplin, M. S., Elovitz, M. A., Foroud, T., Peaceman, A. M., Saade, G. R., Willinger, M., Reddy, U. M., & NuMo, M. b study; “A description of the methods of the Nulliparous Pregnancy Outcomes Study: monitoring mothers-to-be (nuMoM2b);” American Journal of Obstetrics & Gynecology, 2015, 212(4), 539 e531-539 e524; DOI: 10.1016/j.ajog.2015.01.019.
OBJECTIVE: The primary aim of the “Nulliparous Pregnancy Outcomes Study: monitoring mothers-to-be” is to determine maternal characteristics, which include genetic, physiologic response to pregnancy, and environmental factors that predict adverse pregnancy outcomes.
STUDY DESIGN: Nulliparous women in the first trimester of pregnancy were recruited into an observational cohort study. Participants were seen at 3 study visits during pregnancy and again at delivery. We collected data from in-clinic interviews, take-home surveys, clinical measurements, ultrasound studies, and chart abstractions. Maternal biospecimens (serum, plasma, urine, cervicovaginal fluid) at antepartum study visits and delivery specimens (placenta, umbilical cord, cord blood) were collected, processed, and stored. The primary outcome of the study was defined as pregnancy ending at <37+0 weeks’ gestation. Key study hypotheses involve adverse pregnancy outcomes of spontaneous preterm birth, preeclampsia, and fetal growth restriction.
RESULTS: We recruited 10,037 women to the study. Basic characteristics of the cohort at screening are reported.
CONCLUSION: The “Nulliparous Pregnancy Outcomes Study: monitoring mothers-to-be” cohort study methods and procedures can help investigators when they plan future projects.