ReviewCould pesticide exposure be implicated in the high incidence rates of depression, anxiety and suicide in farmers? A systematic review☆
Graphical abstract
Introduction
Mental health conditions are risk factors for a range of illnesses and contribute to poor health outcomes and national economic loss, according to World Health Organization (WHO), which implemented the Special Initiative for Mental Health 2019–2023 aiming to provide universal and quality access to interventions and special care for individuals with mental disorders (WHO, 2019a).
Worldwide, depressive disorders represent the third-leading cause of the burden of disease, affecting around 322 million people around the globe. (WHO, 2017). Considering that depression is associated with poor health outcomes, understanding what factors may give rise to depression and anxiety is important to have an effective health policy, planning, and evaluation, as well as scale-up quality interventions and services for people with depression.
The connection between pesticide exposure and mental health conditions has been investigated by several studies, such as those included in this systematic review. Studies have shown that farmers, which are occupationally exposed to pesticides, are more susceptible to anxiety and depression (Sanne et al., 2003; Meyer et al., 2010; Beard et al., 2014). Moreover, the study by Ringgenberg et al. (2018) showed increased suicide rate among farmers as compared with general. The mechanisms underlying such epidemiological associations are unknown; however, some studies addressed the involvement of genetic factors, oxidative damage, and alterations in neurotransmitter systems in pesticide effects (Savy et al., 2018; Martínez et al., 2018; Cattani et al., 2017; Cattani et al., 2021). In addition to occupational exposure to pesticides, social isolation, less educational attainment, and financial stress are suggested as causes of depression in agricultural areas (Beseler and Stallones, 2008; Hong et al., 2009).
The impacts of the pesticide exposure to farmer's mental health outcomes, especially in affective disorders, were not fully understood. Our research group is committed to understanding the harmful impacts of pesticides and other toxic compounds on human and environmental health. Using a pre-clinical animal model, we demonstrated that the poisonous effects of perinatal exposure to glyphosate on the central nervous system account for depressive-like behavior in male adult offspring (Cattani et al., 2014; Cattani et al., 2017), suggesting that neurodevelopmental exposure to the pesticide may impact mental health later in life. These results reinforce that the neurodevelopmental impacts of glyphosate, the major pesticide used in Brazil and around the globe, may account for long-term brain damage.
The knowledge about the harmful impacts of pesticide exposure on mental health is particularly relevant. Previously, in 2013, Freire and Koifman conducted a systematic review including 25 studies providing evidence of a probable connection between pesticide exposure and depressive disorders or suicide-related outcomes (Freire and Koifman, 2013). Nevertheless, their results were inconclusive in establishing a relationship between pesticide exposure and depression or suicide. However, later updated reviews seeking to attest a connection between occupational pesticide exposure and depression or suicide in agricultural workers are not available, as far as we know. Despite several studies showing the impacts of pesticides on human and environmental health, they are widely used around the globe, and hazardous pesticides are commonly used as a suicide method. Therefore, understanding the relationship between pesticides, mental health, and suicide could provide scientific evidence about the need for protective measures targeting agricultural population leading to a reduction of depression and suicide indices. It is also important to consider that the impacts of depression on human health can be long-lived, persistent or recurrent and can dramatically compromise the person's ability to live a pleasant and productive life at home and at work (WHO, 2017).
The WHO's Mental health action plan 2013–2030 and WHO's Mental Health Gap Action Program (mhGAP) include the management of depression and prevention of self-harm/suicide among the priority conditions covered by interventions for people with mental disorders (WHO, 2016;WHOWorld Health Organizationand Food and Agriculture Organization of the United Nations FAO, 2016, WHOWorld Health Organizationand Food and Agriculture Organization of the United Nations FAO, 2019). Moreover, according to WHO, self-poisoning with pesticides contributes to an important cause of the world's suicides. Although self-poisoning by pesticide ingestion has variable toxicity, depending on the dose and type of pesticide used, data demonstrate that the herbicide paraquat is the most hazardous one, killing about half of all people who ingest it, since there is no treatment available to reverse the effects of its acute toxicity (WHO and FAO 2019a, b).
Considering that the risk factors for depressive disorders and suicide are not completely understood, the present work is focusing to systematically review previous studies investigating if farmer's occupational exposure to pesticides is a risk factor for depressive disorders, anxiety, and suicide-related outcomes, including suicidal ideation, suicide attempts or suicide death/mortality.
Section snippets
Methodology
The present study was developed under PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) (Page et al., 2021) and Joanna Briggs Institute Critical Appraisals (JBI) guidelines (Munn et al., 2015; Aromataris and Munn, 2020). The methods of analysis and inclusion criteria were specified, the systematic review protocol was deposited and it is available in PROSPERO registration number CRD42022316285 (Zanchi, Marins, and Zamoner, 2022). We systematically reviewed cohort,
Study selection
A total of 298 individual study records published until November 2020 were identified in our searches in electronic databases. A flowchart showing a brief overview of the identification, screening and selection of the studies included in this systematic review is demonstrated in Fig. 1. Following the eligibility criteria described previously, 255 studies were excluded (n = 66 for duplicates, n = 175 excluded after reading the abstract, without occupational exposure or not targeting farmers).
Discussion
Mood or affective disorders are the most prevalent mental illnesses. The extensive use of pesticides leads to serious concerns about the impacts of these compounds to health and particularly to mental health (Conti et al., 2018).
The results presented herein suggest that previous pesticide poisoning might cause mental disorders, as well as dementia, Parkinson, and Alzheimer diseases. The severity of intoxication and farmers who experienced more than a single pesticide poisoning presented high
Funding
This work was supported by grants from Fundação de Amparo à Pesquisa e Inovação do Estado de Santa Catarina (FAPESC) chamada pública FAPESC/MS-DECIT/CNPq/SES-SC - apoio a programa de pesquisa para o Sistema Único de Saúde (SUS) – PPSUS [grant number FAPESC/PPSUS/TO#2017TR1365 and grant number FAPESC/PPSUS/TO#2021TR000533]; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq-Brazil) [grant number 433245/2018–2/CNPq-Brazil and grant number 313311/2021–8/CNPq-Brazil]; and Brazilian
Credit author statement
Ariane Zamoner: conceptualization, supervision, project administration, funding acquisition, Resources, Formal analysis, Writing- Reviewing and Editing; Mariane Magalhães Zanchi: Methodology; Study search and selection; Data extraction; Formal analysis and Writing; Katiuska Marins: Methodology; Study search and selection; Data extraction and Writing. All authors read and approved the final manuscript.
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
Acknowledgements
We acknowledge FAPESC, DECIT/CNPq/SES-SC, PPSUS, CAPES-PrInt, CNPq-Brazil, CAPES and PGFAR for grants and research scholarships. Mariane Magalhães Zanchi and Katiuska Marins are registered on Pharmacy Graduate Course/UFSC-Brazil (PGFAR/UFSC).
References (106)
- et al.
Behavioral effects and ChE measures after acute and repeated administration of malathion in rats
Environ. Toxicol. Pharmacol.
(2005) - et al.
In vitro and in vivo generation of reactive oxygen species, DNA damage and lactate dehydrogenase leakage by selected pesticides
Toxicology
(1995) - et al.
Pesticide exposure and self-reported incident depression among wives in the Agricultural Health Study
Environ. Res.
(2013) - et al.
A cohort study of pesticide poisoning and depression in Colorado farm residents
Ann. Epidemiol.
(2008) - et al.
Exposure to pesticides and mental disorders in a rural population of Southern Brazil
Neurotoxicology
(2016) - et al.
Mechanisms underlying the neurotoxicity induced by glyphosate-based herbicide in immature rat hippocampus: involvement of glutamate excitotoxicity
Toxicology
(2014) - et al.
Developmental exposure to glyphosate-based herbicide and depressive-like behavior in adult offspring: implication of glutamate excitotoxicity and oxidative stress
Toxicology
(2017) - et al.
Perinatal exposure to a glyphosate-based herbicide causes dysregulation of dynorphins and an increase of neural precursor cells in the brain of adult male rats
Toxicology
(2021) - et al.
Pesticide exposure, tobacco use, poor self-perceived health and presence of chronic disease are determinants of depressive symptoms among coffee growers from Southeast Brazil
Psychiatr. Res.
(2018) - et al.
Hippocampal neurogenesis: regulation by stress and antidepressants
Biol. Psychiatr.
(2006)
A neurotrophic model for stress-related mood disorders
Biol. Psychiatr.
Lipid peroxidation, oxidative stress and acetylcholinesterase in rat brain exposed to organophosphate and pyrethroid insecticides
Food Chem. Toxicol.
Association between pesticide exposure and suicide rates in Brazil
Neurotoxicology
Occupational exposure to pesticides, nicotine and minor psychiatric disorders among tobacco farmers in southern Brazil
Neurotoxicology
Pesticides, depression and suicide: a systematic review of the epidemiological evidence
Int. J. Hyg Environ. Health
Anxiety and depression following cumulative low-level exposure to organophosphate pesticides
Environ. Res.
Early postnatal parathion exposure in rats causes sex-selective cognitive impairment and neurotransmitter defects which emerge in aging
Behav. Brain Res.
Use of human neuroblastoma SH-SY5Y cells to evaluate glyphosate-induced effects on oxidative stress, neuronal development and cell death signaling pathways
Environ. Int.
Paraquat induces redox imbalance and disrupts glutamate and energy metabolism in the hippocampus of prepubertal rats
Neurotoxicology
Biochemical evidence on positive effects of rolipram a phosphodiesterase-4 inhibitor in malathion-induced toxic stress in rat blood and brain mitochondria
Pestic. Biochem. Physiol.
Serotonergic systems targeted by developmental exposure to chlorpyrifos: effects during different critical periods
Environ. Health Perspect.
JBI Manual for Evidence Synthesis
Erythrocyte acetylcholinesterase as biomarker of pesticide exposure: new and forgotten insights
Environ. Sci. Pollut. Res. Int.
Suicide and pesticide use among pesticide applicators and their spouses in the agricultural health study
Environ. Health Perspect.
Pesticide exposure and depression among male private pesticide applicators in the agricultural health study
Environ. Health Perspect.
Structural equation modeling of the relationships between pesticide poisoning, depressive symptoms and safety behaviors among Colorado farm residents
J. Agromed.
Structural equation modeling of pesticide poisoning, depression, safety, and injury
J. Agromed.
Depression and pesticide exposures in female spouses of licensed pesticide applicators in the agricultural health study cohort
J. Occup. Environ. Med.
Depression and pesticide exposures among private pesticide applicators enrolled in the Agricultural Health Study
Environ. Health Perspect.
Social and economic variables related with Paraquat self-poisoning: an ecological study
BMC Publ. Health
Pesticide exposure and health conditions of terrestrial pesticide applicators in Córdoba Province, Argentina
Cad. Saúde Pública
Mortality from and incidence of pesticide poisoning in South Korea: findings from national death and health utilization data between 2006 and 2010
PLoS One
Pesticide practices and suicide among farmers of the Sundarban region in India
"Self-directed violence surveillance; uniform definitions and recommended data elements."
Does farming have an effect on health status? A comparison study in west Greece
Int. J. Environ. Res. Publ. Health
Health symptoms associated with pesticides exposure among flower and onion pesticide applicators in arusha region
Annals of global health
[A cross-sectional study about mental health of farm-workers from Serra Gaucha (Brazil)]
Rev. Saude Publica
Occupational risk assessment of organophosphates with an emphasis on psychological and oxidative stress factors
Toxicol. Ind. Health
Cholinesterase inhibition in chlorpyrifos workers: characterization of biomarkers of exposure and response in relation to urinary TCPy
J. Expo. Sci. Environ. Epidemiol.
Depressive symptoms and sleepiness among Latino farmworkers in eastern North Carolina
J. Agromed.
Self-poisoning in Sri Lanka: factors determining the choice of the poisoning agents
Int. J. Soc. Psychiatr.
The estimation of pesticide exposure in depression scores: in case of Korean orchard farmers
J. Pest. Sci.
International Standard
Interrelation of glycemic status and neuropsychiatric disturbances in farmers with organophosphorus pesticide toxicity
Open Biochem. J.
Risk factors associated with depression and suicidal ideation in a rural population
Environ Health Toxicol
Neurologic symptoms in licensed private pesticide applicators in the agricultural health study
Environ. Health Perspect.
Toxic influence of organophosphate, carbamate, and organochlorine pesticides on cellular metabolism of lipids, proteins, and carbohydrates: a systematic review
Hum. Exp. Toxicol.
Epidemiology of women and depression
J. Affect. Disord.
Neurological and mental health outcomes among conventional and organic farmers in Indiana, USA
Ann. Agric. Environ. Med. : AAEM
Depressive symptoms and severity of acute occupational pesticide poisoning among male farmers
Occup. Environ. Med.
Cited by (11)
Association of pesticide exposure with neurobehavioral outcomes among avocado farmworkers in Mexico
2024, International Journal of Hygiene and Environmental HealthIndicators of occupational pesticide exposure are associated with psychiatric symptoms
2024, Environmental Toxicology and Pharmacology
- ☆
This paper has been recommended for acceptance by Da Chen.