# Toxicity of pesticides to the developing foetus

> According to the EPA (2022), pesticides are substances, or a mixture of substances use for preventing, destroying, or repelling pests and or intended to be use as a plant regulator, defoliant, or desiccant.

## Introduction to Pesticide Exposure
According to the EPA (2022), pesticides are substances, or a mixture of substances used for preventing, destroying, or repelling pests and or intended to be used as a plant regulator, defoliant, or desiccant. A ‘pesticide’ is something that prevents, destroys, or controls a harmful organism or disease, or protects plants and plant products during production, storage, and transport.

Due to the increasing world population and high demand for food, there is an increase in the production and use of pesticides in food production, which has increased human exposure. A person can be exposed to pesticides at home, at school, at work, at sports complexes, or even on roads that have been treated with pesticides. Pesticides can enter the body through eating (fruits and vegetables), drinking (contaminated water), breathing them in, and skin contact. Skin contact is the most common form of exposure, followed by inhalation and then ingestion.

## Health Consequences
For pesticides to be effective against their targets, they must be biologically active, or toxic. Pesticide toxicity has health consequences on humans which could be immediate (eye irritation, rashes, blisters, blindness, nausea, dizziness, diarrhoea, and death) or long-term (cancers, birth defects, reproductive harm, immunotoxicity, neurological and developmental toxicity, diabetes, Parkinson’s disease, and disruption of the endocrine system). Reproductive harm includes birth defects, stillbirth, spontaneous abortion, sterility, and infertility.

## Foetal Exposure and the Placenta
Maternal exposure to pesticides during pregnancy increases the risk of foetal exposure. Pesticides can cross the placenta, an organ that connects the foetus and the mother and regulates the movement of substances between their bloodstreams.

The term "placenta barrier" is misleading; instead of providing a protective barrier, it acts as a route through which substances reach the foetus. Movement occurs via passive diffusion, driven by concentration gradients. Furthermore, the placenta is composed of lipids, making lipid-soluble pesticides easier to transfer. The umbilical cord also facilitates the movement of pesticides from the mother to the foetus.

## Vulnerability of the Developing Foetus
Foetuses are at the greatest risk of pesticide toxicity due to rapid cell division and the immaturity of formed organs. The foetus is most vulnerable during the first 12 weeks, as all major organs and body systems are forming.

Unlike adults, foetuses cannot protect themselves:
*   The liver is not yet fully matured to detoxify pesticides.
*   Kidneys are not yet able to excrete pesticides.
*   The nervous system is still developing.
*   The blood-brain barrier is not yet fully developed, allowing pesticides to reach the brain.

## Health Impacts on the Foetus
Immediate effects can include foetal death, spontaneous abortion, and premature birth. Exposure to teratogenic pesticides can result in disabilities such as cleft lips, missing fingers or toes, deformed ears and nostrils, and abnormal organ function (e.g., heart defects, neural tube defects). Carcinogenic pesticide exposure can result in childhood leukaemia.

Long-term effects manifesting in adulthood include:
*   Reproductive health problems (e.g., poor semen quality, reduced male fertility).
*   Neurological disorders (e.g., Parkinson’s disease, Alzheimer’s).
*   Hormonal imbalances.
*   Learning disabilities.
*   Cancers (e.g., breast and prostate cancer).
*   Endocrine disruption linked to ADHD, diabetes, cardiovascular disease, obesity, and early puberty.
*   Autism spectrum disorder.

## Measuring Toxicity
Methods used to measure pesticide toxicity include:
*   **In vivo:** Experiments carried out inside a living organism.
*   **Ex-vivo:** Experiments taking place outside the living organism.
*   **In vitro:** Experiments taking place in glass tubes or plates.
*   **Clinical laboratory studies:** Using cord blood or the first faeces of the baby.

## Recommendations for Healthcare Providers and Prevention
Nurses and healthcare providers should be knowledgeable about environmental health risk assessment, exposure reduction, and clinical counselling. It is beneficial to integrate toxicity and environmental health into nursing training.

To reduce exposure:
*   Wear Personal Protective Equipment (PPE).
*   Use low-toxicity pesticides when available.
*   Read labels and practice safe work habits.
*   Wash hands before eating.
*   Thoroughly wash and scrub fruits and vegetables.
*   Peel fruits and vegetables.
*   Avoid exposure to agricultural areas where pesticides are used.

In the case of exposure, consulting a medical doctor is vital.

## Author and Supervisor
*   **Author:** Ngwengeh Catherine Tanue (Bachelor Degree Programme in Nursing)
*   **Supervisor:** Leena Koponen, Senior Lecturer, Savonia UAS (Internationality Business Unit)

## References
*   BMJ (2019). Prenatal and infant exposure to ambient pesticides and autism spectrum disorder in children: a population-based case-control study. BMJ 2019; 365.
*   Botsivali, M., & Kyrtopoulos, S. A. (2019). Transplacental exposure to carcinogens and risks to children: evidence from biomarker studies and the utility of omic profiling. Archives of toxicology, 93(4), 833–857.
*   Costa M. A. (2016). The endocrine function of human placenta: an overview. Reproductive biomedicine online, 32(1), 14–43.
*   D’Amico, R., et al. (2022). Toxic Exposure to Endocrine Disruptors Worsens Parkinson’s Disease Progression through NRF2/HO-1 Alteration. Biomedicines, 10(5), 1073.
*   Darbre P. D. (2017). Endocrine Disruptors and Obesity. Current obesity reports, 6(1), 18–27.
*   Del Pup, L., et al. (2015). Endocrine disruptors and female cancer: Informing the patients (Review). Oncology reports, 34(1), 3–11.
*   EPA (2022). Pesticides and Food: Healthy, Sensible Food Practices.
*   Haas J, et al. (2012). In Vivo Assay Guidelines.
*   Halldorsson, et al. (2021). Exposure to pesticides and childhood leukaemia risk: A systematic review and meta-analysis, Environmental Pollution, Volume 285, 117376.
*   Hu, R., et al. (2015). Long- and short-term health effects of pesticide exposure: a cohort study from China. PloS one, 10(6).
*   Isaković, J., et al. (2022). Overview of Neural Tube Defects: Gene–Environment Interactions, Preventative Approaches and Future Perspectives. Biomedicines. 10. 965.
*   Karel A, John N. Van Den Anker, (2017) Physicochemical and Structural Properties Regulating Placental Drug Transfer, Fetal and Neonatal Physiology (Fifth Edition).
*   Kim, K. H., Kabir, E., & Jahan, S. A. (2017). Exposure to pesticides and the associated human health effects. The Science of the total environment, 575, 525–535.
*   Li, Z., et al. (2022). Paediatric lung injury due to accidental ingestion of meperfluthrin: a case report. BMC pediatrics, 22(1), 43.
*   Qiu, L., & Deng, Y. (2021). Paraquat Poisoning in Children: A 5-Year Review. Pediatric emergency care, 37(12), e846–e849.
*   Riss TL, et al. (2013). Cell Viability Assays.
*   Sarah G. Obican, Anthony R. Scialli (2020) Teratology, Fetal Medicine (Third Edition).
*   Schneider, H., et al. (2022). Ex vivo dual perfusion of an isolated human placenta cotyledon: Towards protocol standardization and improved inter-centre comparability. Placenta, 126, 83–89.
*   Silver, M. K., et al. (2015). Distribution and Predictors of Pesticides in the Umbilical Cord Blood of Chinese Newborns. International journal of environmental research and public health, 13(1), 94.
*   The First Trimester | Johns Hopkins Medicine.
*   Turale, S. and Kunaviktikul, W. (2019). The contribution of nurses to health policy and advocacy requires leaders to provide training and mentorship. Int Nurs Rev, 66: 302-304.
*   Weerakkody, Y., Jones, J. Placental thickness. Reference article, Radiopaedia.org.
*   WHOa. (2020) Chemical safety: Pesticides.
*   WHOb. (2020) Recommended Classification of Pesticides by Hazard and guidelines to classification, 2019 edition.