Environmental Health and Toxicology PDF

ENVIRONMENTAL HEALTH AND TOXICOLOGY https://redaway.com/blog/keeping-our-environment-healthy/ OBJECTIVES: Identify human-induced and natural sources of toxic elements Identify their implications and tendencies to bioaccumulate and bio- magnify affecting the agriculture se...

ENVIRONMENTAL HEALTH AND TOXICOLOGY https://redaway.com/blog/keeping-our-environment-healthy/ OBJECTIVES: Identify human-induced and natural sources of toxic elements Identify their implications and tendencies to bioaccumulate and bio- magnify affecting the agriculture sector. METALANGUAGE METALANGUAGE METALANGUAGE METALANGUAGE METALANGUAGE HEALTH – state of complete physical, mental, and social well-being, not merely the absence of disease or infirmity (W.H.O). DISEASE – abnormal change in the body’s condition – impairment of the important psychological & physical body functions ENVIRONMENTAL HEALTH AND TOXICOLOGY Factors of Morbidity (illness) and mortality (death) -diet and nutrition -infectious agent -hereditary qualities -poisonous substance -injury -stress. ENVIRONMENTAL HEALTH AND TOXICOLOGY Environmental health focuses on disease-causing external factors -natural -social -cultural -technological GLOBAL BURDEN OF DISEASE Global Burden of Disease (GBD) is a comprehensive regional and global research program of disease burden that assesses mortality and disability from major diseases, injuries, and risk factors.  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. 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 (WHO)  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 DISEASE Emergent diseases - not previously known or that have been absent for at least 20 years. Rapid international travel makes it possible for new diseases to spread around the world at jet speed. Factors Contributing to Disease Emergence: 1. Microbial adaption - e.g., genetic drift and genetic shift in Influenza A 2. Changing human susceptibility - e.g., mass immunocompromising with HIV/AIDS 3. Climate and weather - e.g., diseases with zoonotic vectors such as West Nile Disease (transmitted by mosquitoes) are moving further from the tropics as the climate warms. Factors Contributing to Disease Emergence: 4. Change in human demographics and trade - e.g., rapid travel enabled COVID to rapidly propagate around the globe 5. Economic development - e.g., use of antibiotics to increase meat yield of farmed cows leads to antibiotic resistance 6. Breakdown of public health - e.g., the current situation in Zimbabwe Factors Contributing to Disease Emergence: 7. Poverty and social inequality - e.g., tuberculosis is primarily a problem in low- income areas 8. War and famine – e.g., Gulf war, Ukraine war 9. Bioterrorism - e.g., 2001 Anthrax attacks 10.Dam and irrigation system construction - e.g., malaria and other mosquito borne disease ECOLOGICAL EPIDEMIOLOGY Study of the ecology of infectious diseases 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. Chronic wasting disease CWD (caused by prions) is 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 are moving into areas from which they were formerly absent as mosquitoes, rodents, and other vectors expand into new habitat ECOLOGICAL EPIDEMIOLOGY Resistance to Drugs, Antibiotics, and Pesticides The protozoan parasite that causes malaria is now resistant to most drugs, while the mosquitoes that transmit it have developed resistance to many insecticides. The following are the reasons for antibiotic resistance to develop - Antibiotics do not work against certain diseases, e.g., viral infections. ECOTOXICOLOGY -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. EFFECTS OF TOXINS Allergens - immune- activating agents Allergens act as antigens directly; that is, white blood cells recognize them as foreign and stimulate the production of specific antibodies. Example of Chemical that is potent sensitizer and allergenic Formaldehyde - can also trigger reactions to other substances Commonly used in plastics, wood products, insulation, glue, and fabrics. Formaldehyde concentrations in indoor air can be thousands of times higher than in healthy outdoor air. Sick building syndrome – people experience headaches, allergies, and chronic fatigue. Other symptoms caused by improperly ventilated indoor air contaminated with carbon monoxide, mold spores, nitrogen oxide, formaldehyde, and other pollutants emitted from carpets, furniture, fabrics, and construction materials  TOXICOLOGY – study of toxins (poisons) and its effects to both biotic and abiotic entities in the environment http://www.nzdl.org/gsdlmod?e=d-00000-00---off-0envl--00-0- ---0-10-0---0---0direct-10---4-------0-1l--11-en-50---20-about--- 00-0-1-00-0--4----0-0-11-10-0utfZz-8- 00&cl=CL1.1&d=HASH0192c760fbf07f7d6fa34cb8.6.3&gt=1  Classification of Toxic Agents Allergens – activates the immune system – used in plastics, fabrics, glue, insulation and wood products Sick building syndrome: headaches, allergies, chronic fatigue, and other symptoms caused by poorly vented indoor air contaminated by allergens https://sites.google.com/site/asthmainchildrenreckoner/list-of-common-environmental-allergens  Classification of Toxic Agents Immune System Depressants – depresses the immune system – pesticide residues, PCBs (polychlorinated biphenyls) – makes the immune system susceptible to opportunistic infections https://www.spokaneaquifer.org/what-are-pcbs/ Classification of Toxic Agents Endocrine System Disruptors – interfere with the function of normal chemical messengers – hormone mimics: have similar shape to natural hormones and amply their effects – hormone blockers: prevent natural hormones from attaching to target organ – Dioxins and PCBs  ESD is linked to increased risk of: o breast cancer o developmental & reproductive toxicity o Allergies o immunotoxicity. Example of Hormone Mimicker BPA (Bisphenol A) - used for plastic products ranging from water bottles to tooth-protecting sealants - abnormal chromosome numbers which is the leading cause of miscarriages and several forms of mental retardation - environmental estrogen and may alter sexual development in both males and females Classification of Toxic Agents Neurotoxins – attack nerve cells –inhibit the enzyme that regulates signal transmission between nerve cells and the tissues or organs – responsible for widespread behavioral and cognitive problems – lead, mercury, ether, chloroform, organophosphates, carbamates, chlorinated https://www.theatlantic.com/health/archive/2014/03/the-toxins-that-threaten-our-brains/284466/ Classification of Toxic Agents Mutagens –damage DNA leading to birth defects or tumor growth –damage or modify the genetic material (D.N.A.) in cells – can be passed on to future generations (damage in reproductive cells) https://www.ck12.org/book/ck-12-biology/section/7.3/ Classification of Toxic Agents Teratogens – chemicals that cause birth defects (in fetus) – chemicals substance or other factors which cause different abnormalities during embryonic growth and development –can cause sensory impairment, lacks coordination, and disruption of nervous system functions – lead, mercury, alcohol – Affects craniofacial abnormalities, developmental order, behavioral problems, and mental defects. https://secure.thehubedu.com/shelves/7582-motor-development-kines-199?item_id=41592 Classification of Toxic Agents Carcinogens –substances that promotes cancer development –substances that cause cancer, invasive, and out-of-control cell https://www.shutterstock.com/search/carcinogen growth resulting in malignant tumors –may cause cancer by altering cellular metabolism or damaging DNA directly in cells – interferes with normal biological processes * Cancer rates rose over the 20th century in most developed nations, and cancer is now the second leading cause of death in the U.S., killing more than half a million people in 2002. Bioaccumulation and biomagnification increase concentrations of toxins. Bioaccumulation - absorption of cells of nutrients and essential minerals, but at the same time, harmful substances through these same mechanisms. Bioaccumulation and biomagnification increase concentrations of toxins. Biomagnification - effects of toxins also are magnified in the environment through food webs. Organisms ingest other organisms making toxins accumulated from the base and concentrated in the highest trophic level. M O BI LI T Y , D I S T R I B U T I O N , A N D F AT E Exposure and susceptibility to toxins determine how we respond tothem Persistent Organic Pollutants (POPs) – often accumulate in food webs and reach toxic levels in long-living predators (humans, sharks, bears) Polybrominated diphenyl ethers (PBDE) –used as flame-retardants in textiles, foam in upholstery, and plastic in appliances and computers –low exposures in the womb or after birth can irreparably harm children’s reproductive and nervous systems http://www.nuigalway.ie/elevate/pops/whattomeasure/ Persistent Organic Pollutants (POPs) – often accumulate in food webs and reach toxic levels in long-living predators (humans, sharks, bears) Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA –used as to make non-stick waterproof and stain-resistant products –has been shown to cause liver damage as well as various cancers and reproductive and developmental problems inrats –exposure may be especially dangerous to women and girls, (100x more sensitive than men to these chemicals) http://nourishnutritionboise.com/cookware/teflon-and-perfluorooctanoic-acid-pfoa/ Persistent Organic Pollutants (POPs) – often accumulate in food webs and reach toxic levels in long-living predators (humans, sharks, bears) Phthalates –found in cosmetics, deodorants, and plastics (PVC) – used food packaging, children’s toys, and medical devices –some cause kidney and liver damage and possibly some cancers – act as endocrine hormone disrupters, and have been linked to reproductive abnormalities and decreased fertility https://www.health.harvard.edu/blog/something-else-to-avoid-in-pregnancy-phthalates-2019031516224 Persistent Organic Pollutants (POPs) – often accumulate in food webs and reach toxic levels in long-living predators (humans, sharks, bears) Perchlorate –waterborne contaminant left over from propellants and rocket fuels – can interfere with iodine uptake in the thyroi d gland, disrupting adult metabolism and childhood development https://www.nrdc.org/experts/erik-d-olson/epa-refuses-protect-children-perchlorate-contaminated-tap-water Chemical Interactions can Increase Toxicity  Antagonistic reactions  some materials interfere with the effects or stimulate the breakdown of other chemicals (Vitamins E and A can reduce the response to some carcinogens)  others are additive when they occur together in exposures (rats exposed to both lead and arsenic show twice the toxicity of only one of these elements)  Chemical Interactions can Increase Toxicity  Synergism  an interaction in which one substance exacerbates the effects of another (occupational asbestos exposure or smoking increases lung cancer rates 20x; asbestos workers who smoke has 400x increase in cancer rates) https://www.babyboomers.com/article/asbestos-exposure-during-your-working-years-can-come-back-to-haunt- your-retirement/5e9e0a7ee4b007bf6ef1fa60 Solubility is one of the essential characteristics in determining how, where, and when a toxic material will move through the environment. It also includes the body at its place of action. The classification of chemical substances divides into two main groups: 1. Dissolve more easily in oil. 2. Dissolve more easily in water  MEASURING TOXICITY – a convenient way to describe the toxicity of a chemical is to determine the dose to which fifty percent (50%) of the test population is sensitive (LD50) https://v10plus.co.jp/10-toxic-beauty-ingredients-to-avoid/ https://life.bio.sunysb.edu/marinebio/fc.6.toxicity.measures.html RISK ASSESSMENT AND ACCEPTANCE  Risk – possibility of suffering harm or loss  Risk assessment: scientific process of estimating the threat that particular hazards pose to human health; includes risk identification, dose response assessment, exposure appraisal, and risk characterization  Exposure assessment: estimation or determination of the magnitude, frequency, duration, and route of exposure to a possible toxin Risk management: combines principles of environmental health and toxicology together with regulatory decisions based on socioeconomic, technical, and politicalconsiderations  Considerations in setting standards for environmental toxins:  combined effects of exposure to many different sources of damage  different sensitivities of members of the population  effects of chronic as well as acute exposures Exposure assessment is the process of estimating, measuring, characterizing, and modeling the following: 1. magnitude 2. frequency 3. duration, and 4. route of exposure to a possible toxin. https://images.app.goo.gl/zskX5jcF9wZmJKFo7 https://thoughtscapism.com/2018/05/07/measures-of-toxicity/ TOLERANCE - resist or withstand stress from exposure to a pollutant or Harmful condition. Behavioral tolerance results from changes in the behavior; for example, mice learn to avoid traps. Physiological tolerance as a result when the body of an individual adjusts to tolerate a higher level of pollutant.  What risks are generally considered acceptable?  high probability of exposure with low severity (mercury in sea foods)  low probability of exposure with high severity (nuclear power plants) Public policy decisions are made based on risk assessment and promotingthe best health possible in the population.  Examples of labels that have been required or proposed as a result of public health concerns.