Soil Pollution: Human Health Hazards And Risks

Soil pollution is a growing threat to human health, with an estimated 500,000 premature deaths globally each year. Polluted soils can affect human health in several ways, including:

- Direct exposure: Humans can be exposed to polluted soils through direct skin contact or by breathing in dust. Children playing on the ground may consume or inhale polluted soil.

- Indirect exposure: People may also be exposed to soil pollutants through contaminated drinking or bathing water, or by consuming food grown in polluted soils.

- Food security: Soil pollution can reduce crop yields and make foods unsuitable for human consumption, threatening food security.

- Soil fertility: Soil pollution affects soil fertility, which can jeopardise food security and harm human health.

- Water contamination: Polluted soils can contaminate water bodies, leading to water pollution and further threatening human health.

- Air pollution: Polluted soils can release pollutants into the air, contributing to air pollution and its associated health risks.

- Ecosystem health: Soil pollution can harm ecosystems, including plants and animals, which can have knock-on effects on human health.

- Antimicrobial resistance: Soil pollution can lead to the spread of antimicrobial resistance, reducing the effectiveness of antibiotics and other antimicrobial drugs.

- Climate change: Soil pollution can affect the carbon cycle and contribute to climate change, which has wide-ranging impacts on human health.

- Social inequalities: Soil pollution disproportionately affects vulnerable groups, such as children and the elderly, and poorer communities.

Soil pollution can cause food insecurity and malnutrition

Soil pollution can also affect the quality of the soil over time, making it harder to grow crops. This can be due to the presence of toxic levels of contaminants in the soil, which can be caused by the use of pesticides and fertilisers, or the disposal of industrial and household waste. Soil pollution can also be caused by natural conditions, such as the weathering of rocks, which release heavy metals into the soil.

The impact of soil pollution on food security is particularly significant in developing countries, where measures to assess and control or remedy polluted soils are often lacking. However, even in developed countries, soil pollution can pose a risk to human health due to the legacy of previous activities, such as the use of leaded petrol or lead-based paint.

The ingestion of contaminated food is the main route of exposure to soil pollutants. This can occur through the consumption of crops grown in polluted soils, or through the consumption of meat and dairy products from animals that have fed on contaminated fodder or prey. Soil pollutants can also be transferred to humans through contaminated drinking water, or by inhalation of polluted dust and vapours.

The health effects of soil pollution are wide-ranging and can affect multiple organs, including the lungs, skin, gut, liver and kidneys. Soil pollution has also been linked to various diseases, including cancer, asthma, allergies, and developmental impairments. Vulnerable groups, such as children and the elderly, are particularly at risk of the long-term effects of soil pollution.

Soil pollution can cause diseases and disorders of the respiratory, digestive, reproductive, nervous, cardiovascular, and immune systems

Soil pollution can cause a variety of diseases and disorders of the respiratory, digestive, reproductive, nervous, cardiovascular, and immune systems. Soil pollution can also cause acute toxicity, mutagenesis, carcinogenesis, and teratogenesis.

Respiratory System

Soil pollution can cause respiratory diseases such as inflammatory bowel disease, appendicitis, irritable bowel syndrome, and enteric infections in infants. Soil pollution can also cause acute inflammation of the bronchial passages, chronic bronchitis, emphysema, and fibrotic changes from breathing in soil-derived dust.

Digestive System

Soil pollution can cause gut microbiota changes, which can lead to gastrointestinal disorders such as diabetes, obesity, metabolic disorders, and inflammatory bowel disease. Soil pollution can also cause intestinal permeability, which can lead to an increased risk of gastrointestinal disorders.

Reproductive System

Soil pollution can cause adverse effects on female fertility, including early puberty, polycystic ovarian syndrome, and endometriosis. Soil pollution can also cause adverse reproductive outcomes, including structural and functional abnormalities.

Nervous System

Soil pollution can cause neuroinflammation, oxidative stress, microglial activation, cerebrovascular dysfunction, and alterations in the blood-brain barrier. Soil pollution can also cause neurobehavioural changes, such as cognitive decline, impaired learning, and memory.

Cardiovascular System

Soil pollution can cause oxidative stress, inflammation, and activation of innate immune responses, which can lead to cardiovascular disease. Soil pollution can also cause acute myocardial infarction, arrhythmia, and heart failure.

Immune System

Soil pollution can cause systemic inflammation, which can lead to an increased risk of chronic diseases such as asthma, type 1 and 2 diabetes, and atherosclerosis.

Soil pollution can cause cancer

Soil can become polluted in various ways, such as through the application of pesticides and fertilisers, industrial emissions, and waste disposal. These pollutants can accumulate in soil above critical thresholds, affecting soil fertility and food security. Human exposure to soil pollution is estimated to contribute to more than 500,000 premature deaths globally each year.

Certain pollutants in soil, such as heavy metals and toxic organic chemicals, are particularly harmful to human health. Heavy metals, such as cadmium and lead, are classified as human carcinogens and can cause various health issues, including renal toxicity, osteoporosis, and nervous system disturbances. Exposure to these metals can occur through contaminated food and water, inhalation of dust, or direct skin contact with polluted soil.

Studies have found positive associations between soil pollution and increased cancer risks, specifically for lung, stomach, and gastrointestinal cancers. For example, a study in China found a direct relation between long-term environmental exposure to cadmium and lead and an increased risk of mortality from all cancers, as well as from stomach, oesophageal, and lung cancers.

Additionally, certain regions with high levels of soil pollution have been identified as hotspots for human exposure, including contaminated sites, agricultural and urban soils, and previously flooded areas.

Further research and policy interventions are needed to address soil pollution and its impact on human health, particularly cancer risks.

Soil pollution can cause developmental disorders

• Ingestion of contaminated food -- Soil pollution can contaminate crops, which can then be ingested by humans. Soil pollution can also contaminate drinking water, which can also be ingested by humans.
• Inhalation of contaminated soil -- Soil pollution can contaminate the air, which can then be inhaled by humans.
• Dermal contact with contaminated soil -- Humans can come into direct contact with contaminated soil, which can lead to developmental disorders.

Soil pollution can cause a variety of developmental disorders in humans, including:

• Neurological disorders -- Soil pollution can cause neurological disorders such as autism, attention deficit disorder, intellectual disability, and reduced IQ.
• Respiratory diseases -- Soil pollution can cause respiratory diseases such as asthma, acute respiratory infections, and lung cancer.
• Cardiovascular diseases -- Soil pollution can contribute to cardiovascular diseases such as ischaemic heart disease, acute myocardial infarction, arrhythmia, and heart failure.
• Cancer -- Soil pollution has been linked to various types of cancer, including breast cancer, ovarian cancer, and lung cancer.
• Other disorders -- Soil pollution has also been associated with other disorders such as diabetes, obesity, and metabolic diseases.

Soil pollution can cause neurodevelopmental disorders

Secondly, soil pollution can disrupt the endocrine system, which plays a critical role in brain development and function. Endocrine disruption can occur through changes in steroid metabolism and biosynthesis, receptor degradation, DNA methylation, and direct and indirect effects on steroid receptor activity.

Thirdly, soil pollution can disrupt the immune system, which plays a critical role in brain development and function. Exposure to environmental contaminants can provoke an innate immune response and/or alter its trajectory. For example, exposure to infectious agents and subsequent activation of either the maternal or fetal immune system has been associated with alterations in fetal brain development and increased risk of neurodevelopmental disorders including autism spectrum disorder.

Finally, soil pollution can impact the placenta, which plays a unique and critical role in neurodevelopment. The placenta is the site of nutrient exchange between mother and fetus, but it also provides critical support of fetal growth through hormone and neurotransmitter production. Disruption of the placenta can impact neurodevelopment.

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