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A study published in the Journal of Global Health connects prenatal exposure to pyrethroid (PYR) pesticides and adverse impacts on neonatal immune function.
This study adds to a wide body of science that showcases the disproportionate risks to infants and children from pesticide exposure.
In exploring the association of maternal PYR exposure throughout different trimesters with neonatal health, the researchers find reduced neonatal lymphocyte counts and increased lymphocyte apoptosis (cell death).
Lymphocytes, a type of white blood cell, play a crucial role in the immune system, helping to fight off infections, viruses and cancer. When lymphocyte counts are decreased, increased vulnerability to additional health effects occurs.
The results also reveal that while these effects occur throughout all trimesters during gestation, the third trimester represents a particularly sensitive window for adverse effects on immune development.
Study background
Infants and children face much higher hazards than adults from pesticide exposure, as documented on Beyond Pesticides’ Hazards of Pesticides for Children’s Health page.
Their small size and developing organ systems, propensity to crawl and play near the ground, tendency for frequent hand-to-mouth motion and greater intake of air and food relative to body weight make them particularly susceptible.
The hazards borne by children in the “windows of vulnerability” at a young age have critical implications for long-term health. Exposure prior to birth adds to the body burden experienced by infants and children.
“Moreover, the developing immune system is more susceptible to immunotoxic damage induced by environmental exposures than the adult immune system, and such exposures may potentially lead to long-term health consequences for children,” the researchers say.
For additional information, see Children and Pesticides Don’t Mix and Daily News coverage related to infants and children here.
Previous studies show the detection of at least one PYR metabolite (breakdown product) in over 95% of pregnant women during pregnancy. (See here and here.)
“Due to their high lipophilicity, PYRs can cross the placental barrier, leading to fetal exposure in utero,” the authors note.
They continue: “The fetal period is characterised by rapid growth and functional maturation of tissues and organs, making it a highly sensitive window for environmental toxicants. Consequently, the impact of prenatal PYRs exposure on offspring health has garnered significant attention.” (See research here.)
The primary metabolites of PYRs include: 3-phenoxybenzoic acid (3PBA), 4-fluoro-3-phenoxybenzoic acid (4F3PBA) and cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylic acid (cis-DBCA) [6].
3PBA is the most common metabolite, correlating with many PYRs, while cis-DBCA is the specific metabolite of deltamethrin and 4F3PBA is the specific metabolite of cyfluthrin.
Methodology and results
This study analyzes a birth cohort (373 mother-neonate dyads) from the first trimester of pregnancy through birth to find the impacts of maternal PYR exposure on neonatal immune function.
During pregnancy, urine measurements are assessed for metabolites of PYRs. At the time of birth, cord blood is collected and analyzed for lymphocyte cell counts and lymphocyte apoptosis rates.
“Our findings indicate that maternal PYRs exposure during pregnancy may reduce neonatal cord blood lymphocyte counts and increase lymphocyte apoptosis rates, thereby adversely affecting neonatal immune development,” the researchers state.
The results highlight particular risks during the third trimester, as increased PYR metabolites correlate with decreased cord blood T cell and B cell counts in the newborns.
The authors explain:
“The third trimester represents a pivotal sensitive window for the maturation of lymphocyte cell lineages, as this period is characterised by rapid proliferation and functional differentiation of lymphoid progenitor cells in the fetal thymus, spleen, and bone marrow, equivalent exposure levels to environmental toxicants may exert more significant effects on the differentiation and maturation of lymphocytes.”
Previous research
In a study of birth outcomes in Arizona, published in the Journal of Exposure Science & Environmental Epidemiology, researchers find that preconception and prenatal exposure to certain carbamates, organophosphates, and pyrethroids increases the risk of lower Apgar scores, a metric used to assess neonatal health at one minute and five minutes after birth.
The results reveal that exposure to “several pesticide active ingredients at any point during preconception and/or pregnancy were associated with increased odds of low Apgar scores: the carbamates carbaryl and formetanate hydrochloride; the organophosphates diazinon and tribufos; and the pyrethroid cypermethrin.”
This multi-institutional study, led by the University of Arizona with researchers from Harvard Chan School of Public Health and UCLA Fielding School of Public Health, provides novel insights, as it incorporates pesticide exposure over a 15-year period both before conception and throughout pregnancy. (See more here.)
A study in Environmental Science & Technology shows that maternal exposure to organophosphate and pyrethroid insecticides adversely affects newborn health.
Through amino acid and acylcarnitine metabolomics (the study of small molecules known as metabolites) with over 400 mother-infant pairs, this research analyzes metabolic pathways linking pesticide exposure to negative birth outcomes.
Notably, the authors report that “Results indicated that third-trimester maternal urinary levels of 3- phenoxybenzoic acid (3-PBA) and diethyl dithiophosphate (DEDTP) were negatively associated with birth weight.”
“Specifically, a one-unit increase in their ln-transformed [natural logarithm form] concentrations was associated with a 1.508% decrease in birth weight for 3-PBA and a 1.366% decrease for DEDTP.” (See Prenatal Insecticide Exposure Linked to Negative Birth Outcomes in a Biomonitoring Study.)
Similar to the current study, a literature review published in Science of the Total Environment reports numerous peer-reviewed studies associating prenatal and childhood pesticide exposure with measurable alterations to children’s immune systems, including indicators of immunosuppression and increases in pro-inflammatory cytokines, among other adverse health effects.
These immune system alterations are linked to higher infection risk and potentially contribute to autoimmune diseases and allergies later in life. (See Childhood, Prenatal Pesticide Exposure Impacts Immune System, According to Study and additional Daily News coverage on pyrethroids and prenatal exposure here and here.)
The organic solution
Learn how organic agriculture and land management practices can mitigate the toxic effects of petrochemical pesticides and synthetic fertilizers.
The Pesticide-Induced Diseases Database facilitates access to epidemiologic and laboratory studies based on real-world exposure scenarios that link numerous categories of public health effects to pesticides, while the Gateway on Pesticide Hazards and Safe Pest Management provides information on specific pesticide active ingredients, as well as alternatives.
Originally published by Beyond Pesticides.
