Toxicology and Pollution

• To identify human-induced and natural sources of toxic elements and identify their implications and tendencies to bioaccumulate and bio-magnify affecting the agriculture sector is the goal of week 6-7 ULOe.

Metalanguage

• Essential terms relevant to study environmental science ULOe will be defined to establish a standard frame in natural sciences regarding global environmental toxicology and issues.
• Toxicology, pollution, global diseases affecting human health, and the implications of toxic substances to food and agriculture are essential to review.
• Terms are encountered throughout environmental science studies concerning the relationship between people, development, and ecological health/safety.
• This involves a broader understanding of toxic/hazardous substances and their disposal/treatment processes.
• Toxicology is a scientific discipline overlapping with biology, chemistry, pharmacology, and medicine, studying the adverse effects of chemical substances on living organisms, diagnosing, and treating toxin exposures.
• Allergens are antigens that produce an abnormally potent immune response, where the immune system targets and fights a threat or invader that could potentially harm the body, causing an allergic reaction.
• Neurotoxins are toxins destructive to nerve tissue, forming an extensive class of exogenous chemical/neurological insults that can adversely affect the function of developing and mature nervous tissue.
• Mutagens are physical or chemical agents that cause an increase in D.N.A. modifications by altering the organism's D.N.A.
• Teratogens are agents disrupting embryonic or fetal development, causing congenital disabilities or pregnancy cessation and include radiation, maternal infections, chemicals, or drugs.
• Carcinogens are substances/agents promoting cancer development (carcinogenesis) by causing genome damage or disrupting cells' metabolic processes.
• Persistent Organic Pollutants (P.O.P.s) are organic compounds resistant to biochemical, photolytic, and other environmental degradation processes that can bioaccumulate with potentially detrimental effects on ecological and human health, also known as "forever chemicals".
• Acute effects are physiological reactions causing severe symptoms that could rapidly develop through acute exposure to toxic substances but may lead to chronic health effects if the cause is not removed.
• Chronic effects: Adverse effects on animals/humans with symptoms developing slowly due to prolonged/continuous exposure to low concentrations of hazardous substances.
• Risk assessment is the combined effort of identifying and analyzing potential events that can negatively affect individuals, assets, and the environment, making mindful judgments on the tolerability of risk analysis while examining influential factors.
• Risk management evaluates, prioritizes, and identifies risks, followed by the coordinated/economical application of resources to control, monitor, minimize the probability/impact of unfortunate events, and maximize opportunities
• Pesticides are chemical compounds used to eliminate pests like insects, rodents, fungi, and weeds and are used in public health to kill disease vectors and pests that damage crops.
• Herbicides are pesticides used to kill unwanted plants (weeds), selectively targeting weeds by interfering with their growth without harming the desired crop.
• Insecticides are substances that formulate to eliminate or mitigate insects, including ovicides used against insects and larvicides used to kill insect larvae
• Fungicides are biocidal chemical compounds/biological organisms (plants/animals) used to kill parasitic fungi/spores, which can severely damage agriculture, decreasing yield, crop quality, and profit.

Environmental health and toxicology

• The W.H.O. (World Health Organization) defines health as a state of complete physical, mental, and social well-being.
• Health can be improved to live a happier, longer, more productive, and more satisfying life.
• Disease is influenced by environmental factors, such as the Earth's climate system, by impairing physical and psychological functions.
• Disease is the impairment of individual well-being and the capacity to function, attributed to inadequate behavioral and environmental change.
• Factors resulting in morbidity (illness) and mortality (death) are diet/nutrition, infectious agent, hereditary qualities, poisonous substance, injury, and stress.
• Environmental health focuses on disease-causing external factors, including elements of the natural, social, cultural, and technological worlds.

Global burden of disease

• The Global Burden of Disease (GBD) is a comprehensive regional/global research program assessing mortality and disability from major diseases/injuries/risk factors.
• The GBD considers health, social, political, environmental, and economic factors to determine the cost a particular disease/disability exerts on individuals/society.
• DALYs (Disability Adjusted Life Years) are a measure of disease burden.
• Smallpox was completely wiped out in 1977.
• Polio has been eliminated everywhere except for a few remote villages in northern Nigeria.
• Epidemics of typhoid fever, cholera, and yellow fever are now rarely encountered.
• AIDS has become a highly treatable disease.
• Chronic diseases now account for nearly 60% of the 56.5 million total deaths worldwide each year and about half of the global disease burden, according to the WHO.
• Infectious and emergent diseases still responsible for millions of deaths.
• Numerous pathogens afflict humankind, including viruses, bacteria, protozoans, parasitic worms, and flukes.
• Parasites rarely cause death, but can be extremely debilitating and cause poverty.
• Diarrhea, acute respiratory illnesses, malaria, measles, and tetanus kill about 11 million children under age 5 every year in the developing world.
• Improved nutrition, clean water, better sanitation, and inexpensive inoculations could eliminate most deaths.
• Emergent diseases are those not previously known or have been absent for at least 20 years
• Rapid international travel could potentially cause diseases to quickly spread.

Factors contributing to disease emergence

• Microbial Adaptation, such as genetic drift in Influenza A.
• Changing Human Susceptibility, such as mass immunocompromising with HIV/AIDS.
• Climate and Weather, such as diseases with zoonotic vectors moving further from the tropics due to climate warms.
• Changes in Human Demographics and Trade, such as the rapid travel enabling COVID to propagate globally.

Ecological epidemiology

• Ecological epidemiology studies the ecology of infectious diseases, focusing on population and community-level interactions between hosts, pathogens, parasites, and diseases affecting humans and wildlife.
• Ebola hemorrhagic fever kills up to 90% of its human victims, with a global outbreak killing ¼ of all gorillas.
• Chronic wasting disease (CWD) is caused by a prion and belongs to a family of irreversible, degenerative neurological diseases known as transmissible spongiform encephalopathies (TSE), including mad cow disease, scrapie, and Creutzfelt-Jacob disease.
• Tropical diseases, such as malaria, cholera, yellow fever, and dengue fever, are moving into new areas as mosquitoes, rodents, and other vectors expand into new habitats.
• Protozoan parasites that cause malaria are resistant to most drugs.
• Mosquitoes that transmit Malaria have developed resistance to many insecticides.
• Antibiotics are ineffective against certain diseases (e.g., viral infections).
• Antibiotics are given when a person could recover fully even without them and starting and not finishing a full prescription.
• Antibiotics are widespread in animal agriculture.

Ecotoxicology

• Ecotoxicology studies toxins (poisons) and their effects, particularly on living systems, drawing from biochemistry, histology, pathology, and pharmacology.
• Toxins damage/kill living organisms by reacting with cellular components to disrupt metabolic functions.
• They are harmful even in extremely dilute concentrations, with billionths or trillionths of a gram capable of causing irreversible damage.
• Allergens are immune-activating agents that act as antigens, so white blood cells recognize them as foreign and stimulate specific antibody production.
• Formaldehyde is a potent sensitizer and can trigger reactions to other substances, resulting in concentrations in indoor air that are thousands of times higher than in healthy outdoor air.
• Sick building syndrome causes headaches, allergies, and chronic fatigue from poorly ventilated indoor air contaminated with carbon monoxide, mold spores, nitrogen oxide, formaldehyde, and pollutants from various sources.
• Immune System Depressants suppress the immune system and contain high levels of pesticide residues, polychlorinated biphenyls (PCBs), and other contaminants that disrupt the immune system and make it susceptible to a variety of infections.
• Endocrine disruptors are chemicals that disrupt the natural activity of hormones, interfering with growth, development, and physiology in animals and humans.
• Hormone mimics share shapes with natural hormones and amplify their effects.
• BPA(Bisphenol A) is a hormone mimic used for plastic products that can cause abnormal chromosome numbers, leading to miscarriages/mental retardation/altered sexual development
• Hormone blockers prevent natural hormones from attaching to their target organ
• Endocrine disruption is linked to increased risk of increased risk of breast cancer, develop- mental and reproductive toxicity, allergies, and immuno-toxicity.

Neurotoxins

• Neurotoxins are metabolic poisons that attack neurons and affect the nervous system's control of body activities.
• Different types of neurotoxins act in different ways.
• Heavy metals destroy nerve cells/cause permanent brain damage.
• Organophosphates/carbamates inhibit acetylcholinesterase, altering the transfer of signals.
• Anesthetics/chlorinated hydrocarbons disrupt nerve cell membranes.
• Most are fast-acting and highly toxic.
• Mutagens are agents that damage/modify genetic material (D.N.A.) in cells, causing congenital disabilities or neoplastic (tumor) formation.
• Cells have repair mechanisms, but there is no "safe" threshold for mutagen exposure.
• Teratogens are chemical substances/factors causing abnormalities during embryonic growth/development.
• Alcohol is a popular teratogen, leading to fetal alcohol syndrome, including craniofacial abnormalities, developmental disorders, and mental defects.
• Carcinogens are substances that cause cancer, invasive, and out-of-control growth.
• Cancer is the second leading cause of death in the U.S.
• Bioaccumulation is a selective absorption and storage of molecules within cells, allowing nutrients/minerals to accumulate and absorb/store harmful substances.
• Biomagnification occurs when toxins are magnified through food webs, accumulating at the base and concentrating at the highest trophic level.
• Persistent Organic Pollutants (POPs) are resistant to degradation and persist for years, accumulating in long-living top predators.

Significant POPs

• Polybrominated diphenyl ethers (PBDE) are flame retardants in textiles/plastics that are now found globally in humans and animals, harming children's reproductive/nervous systems.
• Perfluorooctane sulfonate (PFOS)/Perfluorooctanoic acid (PFOA, also known as C8) are nonstick, waterproof substances used in various products known to cause liver damage/reproductive problems; exposure is especially dangerous to women/girls.
• Phthalates are present in deodorants, plastics, and cosmetics, posing a toxic threat to animals, damaging the kidney/liver, and disrupting hormone function.
• Perchlorate is a waterborne contaminant that can interfere with iodine uptake in the thyroid gland.
• Bisphenol A (B.P.A.) is used in various products and has been linked to abnormal chromosome numbers.
• Atrazine is a herbicide used in the United States that damages hormonal functions.

Chemical interactions that increases toxicity

• Interactions occur when substances have antagonistic reactions or which materials will interfere with the effects or will somehow stimulate.
• Additive, is which materials occur together in exposures.
• Synergistic effect occurs when one substance intensifies the impact of another material, increasing the rate of lung cancer and cancer rates.
• There are several origins of poisonous and dangerous chemicals and factors related to each compound.
• Factors related to Toxic agent includes:
• Chemical composition and reactivity
• Physical Characteristics
• Presence of impurities or contaminants
• Factors Related to Exposure includes:
• Dose
• Route
• Duration
• Time
• Factors Related to Organisms:
• Storage
• Ability to metabolize
• Concurrent infections or physical/chemical stress
• Species and genetic characteristics
• Nutritional status
• Sex, Body weight, age
• Solubility determines how, where, and when a material will move through the body, classifying chemical substances into those that dissolve more easily in oil and water.
• Water-soluble compounds are transported easily, while oil-soluble toxins pass into tissues and cells, accumulating in lipid deposits and protected from metabolic breakdown.

Exposure and toxicity

• Exposure occurs through various routes, with airborne toxins causing more ill-health.
• Measuring Toxicity is done by exposing laboratory animals to specific substances
• LD50 is determine the dose to which fifty percent (50%) of the test population is sensitive.
• Acute effects are immediate health crises caused by a single dose, like reversible toxins and chronic toxins are long-lasting.
• Risk is possibility of harm or loss and severe damage.
• Risk assessment evaluates the threat to human health, including hazard identification, risk analysis/evaluation, data collection, exposure/risk calculations, and human health/ecological impact reports.
• Steps in estimating the four factors of exposing toxins include:
• Magnitude
• Frequency
• Duration
• Route
• Identification of the hazard is the process to determine whether exposure is likely to cause harm.
• Dose-response involves health effects and the relationship between people and the dose of a chemical and administer reasonably high doses of animals.
• Exposure appraisal happens with human exposure, nature of agents, discussions of the population size for agents.
• Risk to an individual is significant to the source of the exposure.
• Risk characterization delineates health risk in magnitude of the health issues which exposure.

Tolerance

• Tolerance is resisting exposure from exposure to a pollutant.
• Behavioral and physiological tolerance can result in adapting for higher level of pollutant.

Sustainable agriculture

• Agriculture is growing and the raising of animals, managing to help preserve critical habitats and improve soil health when practiced without care, it can present more threat to ecosystems.

Negative impacts to the environment:

• Land transformation is creating drainage of wetlands
• Land degradation declines in productivity such as soil erosion due to pesticides.
• Pesticides are general term for chemical control compounds called Biocides
• One way to classify pesticides is by chemical structure of carbon.
• Some toxic metals like arsenic
• Halogens like bromine
• Organophosphates are herbicides like a 90% of U.S. Soya Beans.
• Chlorinated hydrocarbons is used for herbicides that are highly toxic like the U.S. corn crops
• Natural organic pesticides and botanicals are extracts from plants.
• Microbial agents and biological controls which bacteria eliminate a digestive tract.
• Limits to global warming, flooding, acid rain and landslides.
• Agriculture is sustainable by using non-renewable resources and the operation enhances the quality of the life to society.

Advantages and Drawbacks to Sustainable Agriculture

• Advantages:
• Contributed to environmental
• Prevents pollution reduces costs
• Keeps Bio-diveristy
• Respects the environment
• Profits farming economically and saves social equity
• Drawbacks:
• Limited and difficult to produce masses of food
• Takes more time/ work
• Shorter shelf life
• Less fertile less income and limited farming

Food And Nutrition

• Despite predictions that runaway population growth would soon lead to terrible famines, world food supplies have more than kept up with increasing human numbers over the past two centuries.
• 850 million are chronically hungry due to poverty as a threat of food.
• Food Security occurs at multiple scales