Concurrent urinary organophosphate metabolites and acetylcholinesterase activity in Ecuadorian adolescents
Graphical abstract
Introduction
Organophosphate pesticides are widely used in agriculture and inhibit the activity of acetylcholinesterase (AChE) (Taylor, 2011), an enzyme that regulates neurotransmission in the central and peripheral nervous systems (Soreq, 2001), and is a well-established biomarker of effect for organophosphate exposure (Lionetto et al., 2013). The inhibition of AChE leads to the buildup of acetylcholine, potentially leading to the acute signs and symptoms of clinical organophosphate toxicity with effects on various organs such as the brain, heart, skeletal muscle, and lungs (Sultatos, 1994).
Controlled experimental studies in animals and in-vitro have described positive associations between organophosphate biomarkers and inhibition of circulating red blood cells and brain AChE activities (Banerjee et al., 1991; Eskenazi et al., 1999; Maxwell et al., 2006; Pereira et al., 2014). However, there is a limited body of literature from population-based studies that have characterized the associations between urinary organophosphate metabolite concentrations and AChE activity. This void is especially noticeable in non-occupational and pediatric populations. Some studies of pregnant women (Naksen et al., 2015) and children (Grandjean et al., 2006) did not find significant associations between AChE activity and dialkyl phosphates (DAPs), which are non-specific urinary organophosphate metabolites (Sudakin and Stone, 2011). However, studies of agricultural workers in Egypt reported significant inverse associations between 3,5,6-trichloro-2-pyridinol (TCPy), a specific metabolite for chlorpyrifos, and AChE activity in adults (Crane et al., 2013), whereas in adolescents there was evidence of a threshold, in which negative associations were observed but only among those with concentrations above 3161 μg of TCPy/g creatinine (Farahat et al., 2011).
Organophosphate pesticides have relatively short half-lives of about 24 h (±a few hours depending on the compound) (Bouchard et al., 2003; Griffin et al., 1999; Nolan et al., 1984), which reduce the exposure window that urinary metabolite concentrations reflect (which is approximately 3–6 days, considering that 94–97% of substances are excreted within this time period which equates to about 4–5 half-lives (Hallare and Gerriets, 2020)), and contribute to the substantial variability of such measures (greater within individual variability than between individuals (Bradman et al., 2013; Griffith et al., 2011)). Conversely, AChE activity reflects a much wider exposure window (enzymatic inhibition can last for 82 days if inhibited irreversibly as occurs by exposures with many organophosphate pesticides (Mason, 2000)) and, albeit less sensitive and specific, is a more stable marker of exposure than urinary metabolites (i.e., relatively low intraindividual variation over time (Bradman et al., 2013; Lefkowitz et al., 2007)). Besides AChE inhibition due to organophosphate pesticides, AChE activity can be inhibited by carbamate insecticides, nerve agents such as tabun, sarin, and soman, the repellent N,N-diethyl-3-methylbenzamide (DEET) and cholinesterase-inhibitor medications such as neostigmine, physostigmine, pyridostigmine or rivastigmine. (Abd-Ella et al., 2015; Corbel et al., 2009; Taylor, 2011; Trang and Khandhar, 2021). Additionally, in pediatric populations, age is positively associated with AChE activity (Suarez-Lopez et al., 2012).
Because of the disparate characteristics of these two constructs of organophosphate pesticide exposures (AChE and organophosphate urinary metabolites), and the limited and conflicting data characterizing the association between such constructs, it is important to characterize their relationship within population-based studies and using more specific urinary biomarkers of organophosphate exposure.
In this study, we investigate the associations between erythrocytic AChE activity and specific urinary metabolite concentrations for various organophosphate pesticides (cholinesterase inhibitors), including malathion, chlorpyrifos, diazinon and parathion among adolescents living in agricultural settings in the Andes of Ecuador. We hypothesized that greater concentrations of organophosphate urinary metabolites were associated with A) lower AChE activity in a subset of participants that had both AChE activity and urinary organophosphate metabolite concentrations measured in biospecimens collected on the same day; and B) greater AChE inhibition (a more negative percent change) between 2 examinations in a subset of participant who, in addition to having concomitant AChE and urinary metabolite concentrations, had an additional AChE measurement a few months prior.
Section snippets
Study description
The study of Secondary Exposures to Pesticides among Children and Adolescents (ESPINA) is a prospective cohort focused on understanding the effects of pesticide exposure on the development of children and adolescents residing in Pedro Moncayo County, Pichincha, Ecuador. Approximately one-fifth (Suarez-Lopez et al., 2012) of adults are employed in the floriculture industry in Pedro Moncayo, which is one of the main sites of flower production in Ecuador. A variety of insecticides are used during
Participant characteristics
The mean age was 14.5 years, 50.9% were female, 21.9% were indigenous (Table 1). We observed inverse associations of the percent indigenous participants with PNP urinary concentrations, whereas positive associations were observed with age and creatinine. There were no statistically significant differences in participants' sex, BMI-for-age z-score, height-for-age z-score, July/Oct AChE or hemoglobin by quartiles of PNP (Table 1: summer AChE). The subset of participants examined in both April and
Discussion
ESPINA is among the largest studies in adolescents investigating the effects of pesticide exposures on health. We obtained evidence in favor of our hypothesis considering that we observed an inverse association between all analyzed specific urinary organophosphate metabolites and AChE activity among a group of adolescents living in agricultural communities in the Ecuadorian Andes. The strongest associations were observed between PNP and both concurrent AChE activity and AChE% change between two
Conclusion
Our study provides novel toxicological data that quantifies the amount of AChE inhibition in relation to urinary organophosphate metabolite concentrations among adolescents living in agricultural settings. Greater urinary concentrations of PNP, TCPy and MDA were associated with lower AChE activity, particularly at concentrations above the 80th percentile. The strongest associations were observed between PNP and both concurrent AChE activity and AChE change between two time periods. These
Credit author statement
Ana Skomal: Conceptualization, Methodology, Writing - Original Draft. Jasen Zhang and Kun Yang: Statistical analysis, Software. Jessica Yen: Review & Editing. Jose Suarez-Torres: Review & Editing, Visualization, Project Administration, Data Collection. Dolores López-Paredes: Investigation, Supervision, Review & Editing, Data Collection. Antonia Calafat and Maria Ospina: Pesticide quantification, writing - Review & Editing. Danilo Martinez: Review & Editing, Data Collection. José R.
Disclaimer
The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention or the National Institutes of Health. Use of trade names is for identification only and does not imply endorsement by the CDC, the Public Health Service, or the US Department of Health and Human Services.
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.
Acknowledgments
Research reported in this publication was supported by the National Institute of Environmental Health Sciences of the National Institutes of Health under Award Numbers (R01ES025792, R01ES030378, R21ES026084, U2CES026560). We thank ESPINA study staff, Fundación Cimas del Ecuador, the Parish Governments of Pedro Moncayo County, community members of Pedro Moncayo and the Education District of Pichincha-Cayambe-Pedro Moncayo counties for their contributions and support on this project. We also
References (70)
- et al.
Residential agricultural pesticide exposures and risk of selected congenital heart defects among offspring in the San Joaquin Valley of California
Environ. Res.
(2014) - et al.
Semi-automated solid phase extraction method for the mass spectrometric quantification of 12 specific metabolites of organophosphorus pesticides, synthetic pyrethroids, and select herbicides in human urine
J. Chromatogr. B. Analyt. Technol. Biomed. Life Sci.
(2013) - et al.
Kinetic analysis of the protection afforded by reversible inhibitors against irreversible inhibition of acetylcholinesterase by highly toxic organophosphorus compounds
Biochem. Pharmacol.
(2006) - et al.
Reversible inhibition of acetylcholinesterase by carbamates or huperzine A increases residual activity of the enzyme upon soman challenge
Toxicology
(2007) - et al.
Residential proximity to greenhouse agriculture and neurobehavioral performance in Ecuadorian children
Int. J. Hyg. Environ. Health
(2020) - et al.
Organophosphate pesticide metabolite levels in pre-school children in an agricultural community: within- and between-child variability in a longitudinal study
Environ. Res.
(2011) - et al.
Organophosphate pesticide levels in blood and urine of women and newborns living in an agricultural community
Environ. Res.
(2012) - et al.
Plasma and red blood cell cholinesterase activity as indications of the threshold of incipient toxicity of ethyl-p-nitrophenyl thionobenzenephosphonate (EPN) and malathion in human beings
Toxicol. Appl. Pharmacol.
(1962) - et al.
An educational intervention on the risk perception of pesticides exposure and organophosphate metabolites urinary concentrations in rural school children in Maule Region, Chile
Environ. Res.
(2019) - et al.
Associations of maternal organophosphate pesticide exposure and PON1 activity with birth outcomes in SAWASDEE birth cohort, Thailand
Environ. Res.
(2015)
Summary data of home proximity to the nearest greenhouse (floricultural) crops and areas of greenhouse crops around various distances from homes in agricultural settings in Ecuador
Data Br
Chlorpyrifos: pharmacokinetics in human volunteers
Toxicol. Appl. Pharmacol.
Acetylcholinesterase inhibition dose-response modeling for chlorpyrifos and chlorpyrifos-oxon
Regul. Toxicol. Pharmacol.
Effect of methyl parathion and chlorpyrifos on certain biomarkers in various tissues of guppy fish, Poecilia reticulata
Pestic. Biochem. Physiol.
Home proximity to flower plantations and higher systolic blood pressure among children
Int. J. Hyg. Environ. Health
Associations of acetylcholinesterase activity with depression and anxiety symptoms among adolescents growing up near pesticide spray sites
Int. J. Hyg. Environ. Health
Lower acetylcholinesterase activity among children living with flower plantation workers
Environ. Res.
Residential proximity to greenhouse crops and pesticide exposure (via acetylcholinesterase activity) assessed from childhood through adolescence
Environ. Res.
Diagnostic aspects of organophosphate poisoning
Toxicology
Differential acetylcholinesterase inhibition of chlorpyrifos, diazinon and parathion in larval zebrafish
Neurotoxicol. Teratol.
The repellent DEET potentiates carbamate effects via insect muscarinic receptor interactions: an alternative strategy to control insect vector-borne diseases
PLoS One
Toxicological Profile for Malathion
Exposure to parathion
Arch. Environ. Health
Inhibition of human fetal brain acetylcholinesterase: marker effect of neurotoxicity
J. Toxicol. Environ. Health
A toxicokinetic model of malathion and its metabolites as a tool to assess human exposure and risk through measurements of urinary biomarkers
Toxicol. Sci.
Attention-deficit/hyperactivity disorder and urinary metabolites of organophosphate pesticides
Pediatrics
Variability of organophosphorous pesticide metabolite levels in spot and 24-hr urine samples collected from young children during 1 week
Environ. Health Perspect.
Evidence for inhibition of cholinesterases in insect and mammalian nervous systems by the insect repellent deet 7
Longitudinal assessment of chlorpyrifos exposure and effect biomarkers in adolescent Egyptian agricultural workers
J. Expo. Sci. Environ. Epidemiol.
Exposures of Children to Organophosphate Pesticides and Their Potential Adverse Health Effects
Biomarkers of chlorpyrifos exposure and effect in Egyptian cotton field workers
Environ. Health Perspect.
Log-transformation and its implications for data analysis
Shanghai Arch. Psychiatry
Lipid peroxidative damage on malathion exposure in rats
Neurotox. Res.
Cholinesterase inhibition in chlorpyrifos workers: characterization of biomarkers of exposure and response in relation to urinary TCPy
J. Expo. Sci. Environ. Epidemiol.
Acute pesticide poisoning in Ecuador: a short epidemiological report
J. Public Health
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