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• Toxicology


  A scientific discipline that overlaps with biology, chemistry, pharmacology, and medicine involves studying the adverse effects of chemical substances on living organisms and diagnosing and treating exposures to toxins and toxins
• Allergens


  An antigen that produces an abnormally potent immune response where the immune system targets and fights a threat or an invader that could potentially harm the body
• Neurotoxins


  Toxins that are destructive to nerve tissue
• Mutagens


  A physical or chemical agent that causes an increase in D.N.A. modifications by altering the organism's D.N.A.
• Teratogens


  Any agent that can disrupt embryonic or fetal development causes a child's congenital disability or may completely cease the pregnancy
• Carcinogens


  Any substance or agents that promote cancer development (carcinogenesis), causing genome damage or disruption of cells' metabolic processes
• Persistent Organic Pollutants (P.O.P.s)


  Organic compounds that are resistant to biochemical, photolytic, and other environmental degradation processes
• Acute effects


  A physiological reaction in a human or animal body which cause severe symptoms that could rapidly develop through acute exposure to toxic substances
• Chronic effects


  An adverse effect on animals or the human body with symptoms that develop slowly, due to prolonged and continuous exposure to low concentrations of a hazardous substance
• Risk assessment


  The combined effort of identifying and analyzing potential events can negatively affect individuals, assets, and even the environment. It also makes mindful judgments on the tolerability of the risk analysis and examines factors influencing it
• Risk Management


  The evaluation, prioritization, and identification of risks followed by coordinated and economical application of resources to control, monitor, and minimize the probability or impact of unfortunate events or to maximize the realization of opportunities
• Pesticides


  Chemical compounds used to eliminate pests, such as insects, rodents, fungi, and weeds
• Herbicides


  Pesticides used to kill unwanted plants (weeds)
• Insecticides


  Substances that formulate to eliminate or mitigate insects, including ovicides, which are used against insects and larvicides to kill insect larvae
• Fungicides


  Biocidal chemical compounds or biological organisms (plants or animals) used to kill parasitic fungi, or their spores can cause severe damage in agriculture, resulting in decreased yield, crop quality, and profit
• The World Health Organization (W.H.O.) defines health as a state of complete physical,mental, and social well-being. A person can be ill to some extent; however, health can beimproved to live a happier, longer, and more productive and satisfying lives. The diseasecan also be influenced by environmental factors such as the Earth's climate system by impairing physical and psychological functions
• Disease is defined as the impairment of an individual's well-being and capacity to function and is mostly attributed to inadequate behavioral and environmental change
• The factors that result in morbidity (illness) and mortality (death) are diet and nutrition, infectious agent, hereditary qualities, a poisonous substance, injury, and stress
• Environmental health focuses on disease-causing external factors, including elements of the natural, social, cultural, and technological worlds in which we live
• Global Burden of Disease (GBD)


  A comprehensive regional and global research program of disease burden that assesses mortality and disability from major diseases, injuries, and risk factors. It considers the health, social, political, environmental, and economic factors to determine the cost that particular disease and disability exert upon the individual and society
• Mortality data is now based on Disability Adjusted Life Years (DALYs) as a measure of disease burden
• Smallpox was completely wiped out in 1977. Polio has been eliminated everywhere in the world 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
• According to the WHO, 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
• Infectious and emergent diseases still kill millions of people. A wide variety of pathogens afflict humans, including viruses, bacteria, protozoans, parasitic worms, and flukes
• Diarrhea, acute respiratory illnesses, malaria, measles, tetanus, kill about 11 million children under age 5 every year in the developing world. Better nutrition, clean water, improved sanitation, and inexpensive inoculations could eliminate most deaths
• Emergent diseases


  Those not previously known or that have been absent for at least 20 years
• Rapid international travel makes it possible for these new diseases to spread around the world at jet speed
• Emergent diseases in humans and ecological diseases in natural communities arise due to stresses in biological systems that upsets normal ecological relationships
• Many emergent diseases originated from a non-human animal species, such as HIV which originated in chimpanzees, and SARS which came from the Masked Palm Civet native to China
• Factors Contributing to Disease Emergence

  • Microbial adaption - genetic drift and genetic shift in Influenza A
  • Changing human susceptibility - mass immunocompromising with HIV/AIDS
  • Climate and weather - diseases with zoonotic vectors such as West Nile Disease (transmitted by mosquitoes) are moving further from the tropics as the climate warms
  • Change in human demographics and trade - rapid travel enabled COVID to rapidly propagate around the globe
  • Economic development , use of antibiotics to increase meat yield of farmed cows leads to antibiotic resistance
  • Breakdown of public health - the current situation in Zimbabwe
  • Poverty and social inequality - tuberculosis is primarily a problem in low- income areas
  • War and famine – Gulf war, Ukraine war
  • Bioterrorism 2001 Anthrax attacks
  • Dam and irrigation system construction -malaria and other mosquito borne diseases
• Ecological Epidemiology


  The study of the ecology of infectious diseases. It includes population and community level studies of the interactions between hosts and their pathogens and parasites and covers diseases of both humans and wildlife
• Ecological Epidemiology


  • Ebola hemorrhagic fever kills up to 90% of its human victims. A global outbreak killed ¼ of all the gorillas
  • Chronic wasting disease (CWD) is caused by a prion. CWD is one of a family of irreversible, degenerative neurological diseases known as transmissible spongiform encephalopathies (TSE) that include mad cow disease in cattle, scrapie in sheep, and Creutzfelt-Jacob disease in humans
  • Tropical diseases, such as malaria, cholera, yellow fever, and dengue fever, have been moving into areas from which they were formerly absent as mosquitoes, rodents, and other vectors expand into new habitat
• The protozoan parasite that causes malaria is now resistant to most drugs, while the mosquitoes that transmit it have developed resistance to many insecticides
• Antibiotics do not work against certain diseases, e.g., viral infections. They are given when the person could recover fully without them and starting and not finishing a full prescription. Hence, there is also a widespread use of antibiotics in animal agriculture
• Ecotoxicology


  The study of toxins (poisons) and their effects, particularly on living systems because many substances are known to be poisonous to life (whether plant, animal, or microbial)
• Toxin's damage or kill living organisms because they react with cellular components to disrupt metabolic functions. They are harmful even in extremely dilute concentrations. In some cases, billionths, or even trillionths of a gram can cause irreversible damage
• Allergens


  Some allergens act as antigens directly; that is, white blood cells recognize them as foreign and stimulate the production of specific antibodies. Certain allergens function indirectly by linking and modifying the composition of foreign materials and become antigenic and induce an immune system to the response
• Formaldehyde is an excellent example of a widely used chemical that is a potent sensitizer of the immune system. It is directly allergenic and can also trigger reactions to other substances
• Some people who suffer from sick building syndrome have headaches, allergies, and chronic fatigue. And other symptoms caused by improperly ventilated indoor air contaminate with carbon monoxide, mold spores, nitrogen oxide, formaldehyde, and other pollutants emitted from carpets, furniture, fabrics, and construction materials and other sources
• Immune System Depressants


  Suppress the immune system