8.14 Pollution and Human Health

Overview

Infectious diseases are still a significant cause of death worldwide, particularly in developing countries. 

Factors such as malnutrition, unclean water, poor sanitary conditions, and lack of proper medical care can all contribute to the spread of infectious diseases. 

Examples:

• Malnutrition and cholera: In many parts of sub-Saharan Africa, malnutrition is prevalent and can make individuals more susceptible to infectious diseases. In addition, poor sanitation and lack of access to clean water in these areas can lead to the spread of cholera, a waterborne disease that can cause severe diarrhea and dehydration.
• Malnutrition and measles: In areas where malnutrition is prevalent, children may be more vulnerable to measles. This is due to the fact that malnutrition weakens the immune system, making it more difficult for the body to fight off the measles virus.
• Poor sanitation and typhoid: In developing countries, poor sanitation and lack of access to clean water can lead to the spread of typhoid, a bacterial infection that can cause fever, abdominal pain, and diarrhea.
• Poor sanitation and dengue fever: Poor sanitation and lack of proper waste management can lead to the spread of dengue fever, a mosquito-borne disease that is spread by the Aedes mosquito. Dengue fever is common in tropical and subtropical areas, particularly in urban and semi-urban areas, where poor sanitation and lack of proper waste management can provide a breeding ground for mosquitoes.
• Lack of proper medical care and tuberculosis: In many low- and middle-income countries, lack of proper medical care can make it difficult to diagnose and treat tuberculosis (TB), an infectious disease that primarily affects the lungs. This can lead to the persistence of TB in a community and make it difficult to control the spread of the disease.

Antibiotics

Additionally, the overuse of antibiotics and other drugs has led to the development of drug-resistant pathogens, making it more difficult to treat these diseases. 

Here are some specific examples of how the overuse of antibiotics and other drugs has led to the development of drug-resistant pathogens:

• Methicillin-resistant Staphylococcus aureus (MRSA): This bacterial infection is resistant to many common antibiotics, including methicillin, and is a major cause of hospital-acquired infections. Overuse of antibiotics in hospitals and other healthcare settings has led to the development of MRSA, which can be difficult to treat and can lead to serious illness or death.
• Multi-drug-resistant tuberculosis (MDR-TB): Tuberculosis is a bacterial infection that primarily affects the lungs. Overuse of antibiotics and poor infection control practices have led to the development of drug-resistant strains of TB, such as MDR-TB, which is resistant to at least two of the most effective drugs used to treat TB.
• Vancomycin-resistant Enterococcus (VRE): This bacterial infection is resistant to the antibiotic vancomycin, which is often used as a last resort to treat infections caused by other drug-resistant bacteria. Overuse of antibiotics in hospitals and other healthcare settings has led to the development of VRE, which can cause serious infections in people with weakened immune systems.
• Carbapenem-resistant Enterobacteriaceae (CRE): This bacterial infection is resistant to carbapenems, a class of antibiotics often used to treat infections caused by other drug-resistant bacteria. Overuse of antibiotics in hospitals and other healthcare settings has led to the development of CRE, which can cause serious infections in people with weakened immune systems.
• Antimicrobial-resistant gonorrhea: Antimicrobial resistance in Neisseria gonorrhoeae, the bacteria that causes gonorrhea, has been observed globally. The overuse of antibiotics has led to the emergence of antibiotic-resistant strains of the bacteria, making it more difficult to treat the infection.

Climate Change

Climate change can also exacerbate the spread of infectious diseases by altering patterns of precipitation, temperature, and vegetation, which can affect the distribution and transmission of pathogens and their vectors. 

Here are some specific examples:

• Vector-borne diseases: Climate change can affect the distribution and population dynamics of disease vectors, such as mosquitoes and ticks. Warmer temperatures and changes in precipitation patterns can lead to an increase in the range and abundance of these vectors, which can increase the transmission of diseases such as malaria, dengue fever, and Lyme disease.
• Waterborne diseases: Climate change can also affect the transmission of waterborne diseases by influencing the quality and quantity of water resources. Changes in precipitation patterns, sea-level rise, and extreme weather events can lead to flooding, water pollution, and the displacement of communities. These factors can create ideal conditions for the spread of waterborne diseases such as cholera, typhoid, and hepatitis A.
• Food-borne diseases: Climate change can also affect the spread of food-borne diseases by altering the distribution and abundance of food-producing organisms. Extreme weather events such as droughts and floods can lead to crop failures and food shortages, which can in turn increase the risk of malnutrition and food-borne diseases.
• Heat-related illnesses: Climate change can also lead to an increase in extreme heat events, which can lead to heat-related illnesses such as heat stroke, dehydration, and heat exhaustion. These illnesses can be particularly dangerous for vulnerable populations such as the elderly, young children and people with chronic health conditions.
• Allergies and respiratory diseases: Climate change can exacerbate allergies and respiratory diseases by increasing the levels of allergens and pollutants in the air. Warmer temperatures can lead to increased growth of mold, higher levels of smog, and an increase in the amount of pollen in the air.

Urbanization and Population Growth

The spread of disease can also be driven by factors such as urbanization and population growth, which can lead to overcrowding and poor living conditions. 

Examples:

• Urbanization and the spread of vector-borne diseases: Urbanization can lead to the spread of vector-borne diseases by creating ideal breeding conditions for disease vectors such as mosquitoes and ticks. Urbanization can also increase human-vector contact through the construction of housing in areas previously occupied by wildlife.
• Population growth and the spread of waterborne diseases: Population growth can lead to the spread of waterborne diseases by increasing the demand for water and sanitation services, which can lead to the overuse and contamination of water resources. In addition, population growth can lead to overcrowding, which can make it more difficult to control the spread of waterborne diseases through proper hygiene and sanitation practices.
• Urbanization and the spread of air-borne diseases: Urbanization can lead to the spread of air-borne diseases by increasing the levels of air pollution and allergens in the air. Urbanization can also lead to overcrowding, which can make it more difficult to control the spread of air-borne diseases through proper ventilation and hygiene practices.
• Urbanization and the spread of food-borne diseases: Urbanization can lead to the spread of food-borne diseases by increasing the demand for food and the concentration of food production and distribution in urban areas. Urbanization can also lead to overcrowding, which can make it more difficult to control the spread of food-borne diseases through proper food handling and storage practices.
• Urbanization and the spread of diseases through transportation: Urbanization can lead to the spread of diseases through transportation by increasing the number of people moving in and out of urban areas, and by increasing the number of people traveling long distances. This can facilitate the spread of diseases through the movement of infected individuals and the transport of pathogens on vehicles and other means of transportation.

To address these issues, it is important to invest in public health infrastructure, improve access to clean water and sanitation, and promote education and awareness about how to prevent the spread of infectious diseases. Additionally, there must be an increased research and development of new drugs, vaccines, and other medical treatments to combat drug-resistant pathogens.

Dysentery

Dysentery is an inflammatory disease of the intestine, especially of the colon, that results in severe diarrhea with blood and mucus in the feces. It is caused by a variety of organisms such as bacteria (Shigella), viruses (rotavirus) or parasites (Entamoeba histolytica). Dysentery is most common in developing countries and areas with poor sanitation and limited access to clean water. It is most often spread through contaminated food and water, and can also be spread through close personal contact. The symptoms of dysentery include diarrhea, abdominal pain, fever, and blood and mucus in the stool. If left untreated, dysentery can lead to severe dehydration, malnutrition, and even death. Treatment for dysentery typically includes antibiotics or antiparasitic drugs, as well as fluid replacement to prevent dehydration. It is also important to improve sanitation and access to clean water to prevent the spread of dysentery.

Mesothelioma & Asbestos

Mesothelioma is a rare and aggressive form of cancer that is primarily caused by exposure to asbestos. Asbestos is a naturally occurring mineral that was widely used in building materials and other industrial products until the 1970s, when its link to mesothelioma and other serious health problems became known.

Exposure to asbestos can occur through inhalation of asbestos fibers, which can become lodged in the lining of the lungs and other organs, leading to the development of mesothelioma. The latency period for mesothelioma can be decades, meaning that symptoms may not appear until many years after the initial exposure to asbestos.

While asbestos is the primary cause of mesothelioma, there are also some cases where the disease can be caused by other forms of pollution. For example, exposure to certain types of silica dust has been linked to an increased risk of mesothelioma, as has exposure to other types of carcinogens, such as diesel exhaust.

Respiration

Respiration is the process by which an organism obtains energy from food, typically by converting glucose and oxygen into carbon dioxide and water. In mammals and other animals, this process takes place in the lungs, where oxygen is taken in and carbon dioxide is expelled.

There are two types of respiration: aerobic and anaerobic. Aerobic respiration is the process by which cells use oxygen to produce energy. This process occurs in the mitochondria, the powerhouses of the cell, and results in the production of carbon dioxide and water. Anaerobic respiration is the process by which cells produce energy without the use of oxygen. This process occurs in the absence of oxygen and results in the production of lactic acid or ethanol as a by-product.

Respiration is a vital process for all living organisms, as it allows them to produce the energy needed to carry out their various functions. In humans, respiration is controlled by the respiratory system which is composed of the nose, trachea, bronchi, and lungs. The diaphragm, a muscle located at the base of the lungs, plays an important role in respiration by contracting and relaxing to help draw air into the lungs.

Impairment or failure of respiration can lead to serious health problems, such as hypoxia, which is a deficiency of oxygen in the body, or hypercapnia, an excess of carbon dioxide in the blood. Respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), and lung cancer can also affect respiration.

Tropospheric Ozone

Tropospheric ozone is a form of air pollution that occurs in the lower atmosphere, or troposphere, which is the layer of the atmosphere closest to the Earth's surface. It is different from the stratospheric ozone, which is a layer of ozone that naturally occurs in the upper atmosphere and protects the Earth from harmful ultraviolet radiation.

Tropospheric ozone is created by chemical reactions between pollutants from human activities, such as emissions from vehicles, power plants, and industrial facilities, and volatile organic compounds (VOCs) from natural sources, such as trees and plants. These reactions occur in the presence of sunlight, and the highest concentrations of tropospheric ozone are typically found in urban and industrial areas.

Tropospheric ozone is a harmful air pollutant that can have serious health effects, particularly for people with respiratory conditions, such as asthma and emphysema. It can also damage crops, forests, and other natural resources.

Measures to reduce tropospheric ozone pollution include controlling emissions from industrial facilities, vehicles, and power plants, and increasing the use of alternative transportation options, such as public transit, biking and walking. In addition, promoting energy efficiency, renewable energy, and sustainable land-use practices can also help to reduce ozone formation.