Investigation of Biochemical Effects of Chronic Pesticide Exposure among Vegetable Farmers in Kaduna State

Investigation of Biochemical Effects of Chronic Pesticide Exposure among Vegetable Farmers in Kaduna State

ABSTRACT

Pesticides are widely used in agriculture to control pests and improve crop yields. However, chronic exposure to these chemicals can disrupt human biochemical functions and lead to long-term health problems. This study investigates the biochemical effects of chronic pesticide exposure among vegetable farmers in Kaduna State, Nigeria. Blood samples were analyzed for liver and kidney function markers, including alanine aminotransferase (ALT), aspartate aminotransferase (AST), urea, and creatinine. Oxidative stress markers such as malondialdehyde (MDA) and antioxidant enzymes—superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx)—were also evaluated. Structured questionnaires were used to collect demographic and occupational data. The results showed significantly higher serum levels of ALT, AST, urea, and creatinine in farmers compared to non-exposed controls. Furthermore, MDA increased while antioxidant enzyme activities declined, indicating oxidative stress. The findings suggest that continuous exposure to pesticides can impair hepatic and renal function while reducing the body’s antioxidant defense. Therefore, promoting protective equipment use and health monitoring among farmers is essential to reduce biochemical risks associated with pesticide exposure.

Keywords: Pesticide exposure, oxidative stress, antioxidant enzymes, liver function, kidney function, Kaduna State.

CHAPTER ONE

1.0 Introduction

Agriculture remains a vital sector of Nigeria’s economy, providing food, employment, and income for millions of people. Vegetable farming, in particular, supports rural livelihoods and contributes significantly to food security. To enhance productivity, farmers frequently apply pesticides to control pests and diseases. However, excessive and unsafe use of these chemicals has raised serious health concerns, especially in developing regions such as Kaduna State.

Pesticides contain various active ingredients, including organophosphates, organochlorines, carbamates, and pyrethroids. These compounds may persist in the environment and accumulate in the human body through inhalation, dermal absorption, or ingestion. Continuous exposure has been linked to liver, kidney, and nervous system dysfunctions. According to the World Health Organization (2021), about three million cases of pesticide poisoning occur annually, mostly among agricultural workers in developing countries.

In Nigeria, several studies have reported unsafe pesticide handling practices among farmers, such as mixing chemicals with bare hands, failure to wear gloves, and improper storage. These actions increase the risk of chronic exposure and accumulation of toxic compounds in body tissues. Over time, pesticides may alter biochemical processes by affecting liver enzymes, impairing kidney function, and reducing antioxidant defense systems that protect cells from oxidative damage.

Monitoring biochemical markers in farmers exposed to pesticides is vital for early detection of health risks. Parameters such as serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), urea, and creatinine can indicate liver and kidney impairment. Similarly, oxidative stress biomarkers like malondialdehyde (MDA) and antioxidant enzymes (SOD, CAT, and GPx) reflect cellular responses to toxic exposure.

1.1 Statement of the Problem

Despite widespread pesticide use among vegetable farmers in Kaduna State, limited biochemical studies have assessed the health consequences of chronic exposure. Many farmers handle these chemicals daily without adequate protective gear or awareness of long-term health implications. The absence of routine medical monitoring makes it difficult to identify early biochemical changes, leading to cumulative organ damage over time. Hence, there is an urgent need for scientific evaluation of biochemical effects associated with pesticide exposure in this region.

1.2 Aim and Objectives of the Study

The main aim of this study is to investigate the biochemical effects of chronic pesticide exposure among vegetable farmers in Kaduna State.

The specific objectives are to:

1. Determine serum levels of liver function markers (ALT, AST, ALP) in exposed farmers and control subjects.

2. Evaluate kidney function indicators (urea and creatinine) in both groups.

3. Assess oxidative stress markers, including malondialdehyde (MDA) and antioxidant enzyme activities (SOD, CAT, GPx).

4. Compare the biochemical results of exposed and non-exposed individuals to identify possible health risks.

1.3 Research Questions

1. Does chronic pesticide exposure alter liver and kidney function among farmers?

2. How does pesticide exposure affect oxidative stress and antioxidant enzyme activity?

3. Are there significant biochemical differences between exposed farmers and unexposed controls?

1.4 Research Hypotheses

• H₀₁: Pesticide exposure does not significantly affect liver and kidney biochemical parameters among farmers.

• H₀₂: There is no significant change in oxidative stress markers and antioxidant enzyme activities between exposed and control groups.

1.5 Significance of the Study

This study provides biochemical evidence of chronic pesticide exposure among vegetable farmers in Kaduna State. The findings will help raise awareness about pesticide toxicity, promote the use of personal protective equipment, and guide policymakers in designing health surveillance programs for agricultural workers. Moreover, it contributes to scientific literature on occupational health and environmental biochemistry in Nigeria.

1.6 Scope and Limitation of the Study

The study focuses on vegetable farmers in selected local government areas of Kaduna State. It evaluates liver, kidney, and oxidative stress biomarkers. Limitations may include sample size, seasonal variations in pesticide use, and lack of advanced laboratory facilities for molecular analysis.

1.7 Operational Definition of Terms

• Pesticide: A chemical substance used to destroy or control pests.

• Oxidative Stress: A condition resulting from an imbalance between reactive oxygen species and antioxidants.

• Antioxidant Enzymes: Biological molecules that protect cells from oxidative damage.

• Biochemical Markers: Measurable indicators of physiological and metabolic processes.

CHAPTER TWO

2.0 Literature Review

This chapter reviews relevant studies on pesticide exposure, its biochemical mechanisms, and health implications. It highlights research findings within Nigeria and globally while identifying existing gaps addressed by this study.

2.1 Overview of Pesticides and Their Classification

Pesticides are grouped based on their target pests or chemical composition. Major classes include organophosphates, carbamates, organochlorines, and pyrethroids. Each group acts differently but shares the common goal of pest control. For example, organophosphates inhibit acetylcholinesterase, causing overstimulation of the nervous system. Although effective for pest control, their persistence and bioaccumulation make them hazardous to humans.

Farmers in developing countries often overuse these chemicals to maximize yields. According to WHO (2020), misuse and overexposure to pesticides are responsible for numerous occupational illnesses in agricultural communities.

2.2 Routes and Mechanisms of Exposure

Farmers are primarily exposed through dermal contact, inhalation, and ingestion of contaminated food or water. In Kaduna’s warm climate, high temperatures increase volatilization, thereby raising the risk of inhalation. Poor hygiene, lack of gloves, and reusing pesticide containers also contribute to exposure. Once absorbed, pesticides undergo metabolism in the liver, generating reactive metabolites that can damage tissues and enzymes.

2.3 Biochemical and Health Effects of Pesticide Exposure

Pesticides interfere with metabolic reactions by inducing oxidative stress and modifying enzyme systems. They can increase the production of reactive oxygen species (ROS), leading to lipid peroxidation and DNA damage. Research by Singh et al. (2021) found that exposed individuals exhibited elevated malondialdehyde (MDA) levels and decreased antioxidant enzyme activities (SOD, CAT). These biochemical alterations indicate oxidative damage.

Furthermore, pesticides affect hepatic and renal function. Elevated levels of ALT, AST, and ALP are biomarkers of liver injury, while increased urea and creatinine indicate impaired kidney function. Adeoye et al. (2020) reported that chronic pesticide exposure among Nigerian farmers caused significant changes in these parameters, confirming biochemical stress on vital organs.

2.4 Oxidative Stress and Antioxidant Defense

Oxidative stress results when the production of free radicals exceeds the body’s antioxidant capacity. Antioxidant enzymes, including SOD, CAT, and GPx, form the first line of defense against oxidative injury. Pesticide exposure reduces their activity, leading to the accumulation of peroxidized lipids and cellular damage. Studies by Owolabi et al. (2022) demonstrated that antioxidant enzyme levels were significantly lower in exposed farmers compared to unexposed individuals.

2.5 Health Implications of Chronic Exposure

Long-term exposure to pesticides has been associated with numerous disorders, such as endocrine disruption, respiratory problems, and neurotoxicity. The World Health Organization (2021) estimates that millions of farmers worldwide suffer chronic health effects due to pesticide use. In Nigeria, limited protective practices and weak regulation worsen the situation, leading to higher occupational risks.

2.6 Pesticide Use Practices in Nigeria

Several studies confirm unsafe pesticide handling in Nigeria. Abdullahi et al. (2019) observed that most vegetable farmers in Kaduna State mix chemicals with bare hands and fail to use protective clothing. They also often ignore safety intervals before harvesting. Such behavior promotes chronic exposure and health deterioration. Awareness campaigns and sustainable pest management strategies are urgently needed to mitigate these risks.

2.7 Research Gaps

Although several studies have addressed pesticide toxicity in Nigeria, limited biochemical data exist for Kaduna State farmers. Most research focused on acute poisoning rather than long-term biochemical effects. This study fills that gap by assessing both organ function and oxidative stress biomarkers in chronically exposed individuals.

2.8 Summary of Literature Review

Previous findings confirm that chronic pesticide exposure alters biochemical markers related to liver, kidney, and oxidative stress. However, localized studies are essential to evaluate the specific health risks among Kaduna vegetable farmers. Understanding these biochemical patterns will guide interventions to protect farmers’ health and promote safer agricultural practices.