Determination of Cadmium and Lead Accumulation in Leafy Vegetables and Biochemical Impacts on Consumers in Osun State

Determination of Cadmium and Lead Accumulation in Leafy Vegetables and Biochemical Impacts on Consumers in Osun State

Abstract

The increasing contamination of food crops with heavy metals poses a serious threat to public health, particularly in developing regions. This study evaluated the accumulation of cadmium (Cd) and lead (Pb) in common leafy vegetables consumed in Osun State, Nigeria, and investigated their biochemical impacts on consumers. Samples of Amaranthus hybridus, Telfairia occidentalis, and Celosia argentea were collected from major markets and farms across the region. Atomic Absorption Spectrophotometry (AAS) was used to determine metal concentrations, while serum samples from frequent consumers were analyzed for liver and kidney function markers such as AST, ALT, creatinine, and urea.

The findings revealed that cadmium and lead levels in vegetables from some locations exceeded the World Health Organization (WHO) permissible limits. Consumers exposed to these contaminated vegetables showed mild alterations in biochemical markers, indicating potential risks to hepatic and renal health. The results highlight the urgent need for environmental monitoring, public education, and strict regulation of farming practices in polluted areas. Promoting safe cultivation and awareness about heavy metal risks can significantly reduce exposure and improve community health outcomes.

CHAPTER ONE

1.0 Introduction

Heavy metal pollution is one of the most persistent environmental challenges affecting agricultural productivity and human health. Rapid urbanization, industrial activities, and the use of contaminated irrigation water have led to an increase in heavy metal deposits in soils and crops. Among these metals, cadmium (Cd) and lead (Pb) are of particular concern because of their toxicity, non-biodegradability, and tendency to bioaccumulate in the food chain.

Leafy vegetables, often consumed daily, serve as a major route through which these metals enter the human body. Because of their large surface area and high transpiration rate, these vegetables easily absorb heavy metals from contaminated soil, water, or air. Continuous consumption of contaminated vegetables may lead to chronic metal poisoning, causing damage to vital organs such as the liver, kidneys, and nervous system.

In Osun State, where vegetable farming supports many local livelihoods, several farms are located near industrial zones, waste dumps, or roadsides—areas that may have elevated heavy metal levels. Consequently, understanding how cadmium and lead accumulate in vegetables and their potential biochemical impacts on consumers is crucial for ensuring food safety and protecting public health.

1.1 Background of the Study

Heavy metals are natural components of the Earth’s crust, but human activities have significantly increased their environmental concentration. In Nigeria, improper waste disposal, mining, battery recycling, and the use of chemical fertilizers contribute heavily to soil contamination. Crops cultivated on such soils absorb these metals through their roots, which eventually accumulate in edible parts of the plant.

Cadmium is known to cause kidney dysfunction, bone demineralization, and liver injury, while lead affects the nervous and hematopoietic systems, particularly in children and pregnant women. Both metals interfere with enzymatic activity and metabolic processes, disrupting normal biochemical functions.

Research across Nigerian cities, including Lagos, Ibadan, and Kano, has shown alarming levels of heavy metals in vegetables sold in open markets. However, limited studies have examined this issue in Osun State, where vegetable consumption is common and agricultural practices vary widely. This study, therefore, aims to assess the extent of cadmium and lead contamination in selected vegetables and evaluate how their consumption may affect the biochemical health markers of residents.

1.2 Statement of the Problem

The growing rate of heavy metal pollution in agricultural produce has raised concerns about food safety and human health. In Osun State, many vegetable farms depend on water from streams and drainage channels, which often receive industrial effluents and domestic waste. This practice increases the likelihood of heavy metal accumulation in food crops.

Despite this risk, most consumers are unaware of the long-term health effects of ingesting contaminated vegetables. There is also inadequate monitoring of soil and water quality, as well as limited enforcement of environmental safety regulations. Without scientific data on the contamination levels and related biochemical impacts, communities remain vulnerable to metal toxicity and its complications.

1.3 Aim and Objectives of the Study

The main aim of this study is to determine the accumulation of cadmium and lead in leafy vegetables and evaluate their biochemical impacts on consumers in Osun State.

Specific objectives are to:

1. Quantify the concentrations of cadmium and lead in selected leafy vegetables from different markets and farms.

2. Compare the measured values with WHO and FAO safety limits.

3. Assess serum biochemical parameters (ALT, AST, urea, and creatinine) in frequent consumers of these vegetables.

4. Examine the relationship between vegetable metal concentration and changes in biochemical markers.

5. Suggest control measures to minimize heavy metal exposure from dietary sources.

1.4 Significance of the Study

This research provides valuable insights into environmental pollution and food safety in Osun State. The results can assist public health agencies, policymakers, and agricultural authorities in designing effective monitoring and control programs. By identifying contamination hotspots, the study will help guide safe farming practices and consumer awareness campaigns.

Furthermore, the findings contribute to scientific literature on biochemical responses to heavy metal exposure, providing data for future studies in toxicology, environmental biochemistry, and public health nutrition.

1.5 Scope of the Study

The study focuses on leafy vegetables commonly consumed in Osun State, such as Amaranthus hybridus, Telfairia occidentalis, and Celosia argentea. Sampling covers both urban and peri-urban farms, with biochemical assessments conducted on adult consumers. Parameters analyzed include cadmium and lead concentrations, and biochemical markers related to liver and kidney function.

1.6 Definition of Key Terms

• Heavy Metals: Metallic elements such as cadmium and lead that are toxic even at low concentrations.

• Bioaccumulation: The gradual buildup of substances like heavy metals in living organisms.

• Biochemical Markers: Indicators such as enzymes or metabolites used to assess organ function.

• Toxicity: The degree to which a substance can harm living organisms.

• Atomic Absorption Spectrophotometry (AAS): A laboratory technique for measuring metal concentration in samples.