Environmental Contaminants and Human Health PDF

 MED102 General Chemistry Environmental Contaminants and Human Health Dr Stella Loizou Learning Objectives (LOBs) Discuss the key contaminants that have an effect in human health  Environmental Contaminants Harmful chemicals present in soil, air and water Accum...

 MED102 General Chemistry Environmental Contaminants and Human Health Dr Stella Loizou Learning Objectives (LOBs) Discuss the key contaminants that have an effect in human health  Environmental Contaminants Harmful chemicals present in soil, air and water Accumulation over time might harm human health! These compounds may come directly from: a) Human sources such as: - industrial manufacturing - agricultural run-off - wastewater discharge or b) Natural sources such as: - taste and odour causing chemicals in water generated by algae and bacteria blooms Key Contaminants Nitrosamines Volatile Organic Compounds (VOCs) Endocrine disrupting chemicals (EDCs) Toxic metals and elements Pesticides Pharmaceuticals and personal care products (PPCPs) Fuels and fuel additives Nitrosamines Nitrosamines group consists of a large number of compounds formed by various combinations of amines and nitrogen compounds Each has the foundational structure N-N=O There are hundreds of individual nitrosamine compounds → nearly all are carcinogenic to animals in in vivo studies Volatile Organic Compounds (VOCs) in air Organic solvents that are widely used in industry → for the manufacture of rubber, plastics, cleansing agents E.g.: benzene, toluene, xylene Fuels Volatile Organic Compounds (VOCs) Volatile Organic Compounds (VOCs) Effects in human health: Neurodepressants Neurotoxic to foetus (intrauterine growth restriction, microcephaly) Carcinogenic Endocrine disrupting chemicals (EDCs) Chemicals that interfere with the endocrine system (for example by mimicking the natural hormones) https://youtu.be/ibfAF66JzFE Associated with: Endocrine problems Sperm count decline Cryptorchidism Cancer (breast and testes)  Endocrine disrupting chemicals (EDCs) Common EDCs Used In DDT, Chlorpyrifos, Atrazine, 2, 4-D, Glyphosate Pesticides Lead, Phthalates, Cadmium Children's Products Industrial Solvents or Lubricants and their by- Polychlorinated biphenyls (PCBs) and Dioxins products Bisphenol A (BPA), Phthalates, Phenol Plastics and Food Storage Materials Brominated Flame Retardants, PCBs Electronics and Building Materials Phthalates, Parabens, UV Filters Personal Care Products, Sunscreen Triclosan Anti-Bacterial Soaps, Toothpastes Textiles, Clothing, Microwave Popcorn Bags, Old Perfluorochemicals Teflon Cookware Environmental Contaminants in Foodstuffs Environmental contaminants of food-safety concern include: Toxic metals and elements Organometallic compounds Agricultural chemicals and persistent organic pollutants (POPs) such as: - Halogenated hydrocarbon pesticides - Polychlorinated biphenyls (PCBs) - Dioxins Polycyclic aromatic hydrocarbons (PAHs) Phthalates Nitrates and Nitrites Toxic Metals and Elements - Lead Sources of lead pollution: paints, industrial processes and products Nowadays lead is removed from gasoline → less amount released into the environment Affects: Nervous system Gene function Composition of blood Kidney function Endocrine system (synthesis of Vitamin D) Toxic Metals and Elements - Lead Toxic Metals and Elements - Cadmium Causes: Renal dysfunction Osteoporosis and bone pain Abdominal pain Vomiting and diarrhoea Anaemia Bone marrow involvement Cancer Presence of cadmium: shellfish, molluscs, leafy vegetables  Toxic Metals and Elements - Cadmium Mass cadmium poisoning of Toyama Prefecture, Japan, starting ~1912 Cadmium was released into rivers by mining companies in the mountains → this water was used in the rice fields → the rice absorbed heavy metals, especially the cadmium → cadmium accumulated in the people eating contaminated rice! → Itai-itai disease Cadmium poisoning signs and symptoms: weak and brittle bones → fractures severe pains in spine and joints kidney failure anaemia death  Toxic Metals and Elements - Mercury Sources of mercury: 50% originates from natural sources (volcanoes, weathering of rocks) The rest: From industrial processes (paper and pulp production) → release into water (fresh or salt water) → seafood (fish, shellfish) contaminated with mercury Toxic Metals and Elements - Mercury Affects: Nervous system Skin Kidneys Bone marrow → effect on blood cells, immune system and bone formation  Toxic Metals and Elements - Mercury Japanese Minamata Bay disaster Minamata Bay, 1950s-1960s: heavily polluted by wastewater, mixed with mercury dumped into Hyakken Harbour from the Chisso chemical factory Highly toxic chemical → bioaccumulated in shellfish and fish in Minamata Bay and the Shiranui Sea → people consumed the polluted fish and shellfish → mercury poisoning → the most horrific mercury poisoning disaster the world! By 2005, more than 2955 victims had been officially recognised as having Minamata disease (1784 of whom had died) Toxic Metals and Elements - Mercury Minamata disease → Methylmercury poisoning Symptoms include: Ataxia Numbness in the hands and feet General muscle weakness Loss of peripheral vision Damage to hearing and speech In extreme cases: insanity, paralysis, coma and death follow within weeks of the onset of symptoms A congenital form of the disease can also affect foetus in the womb Polycyclic Aromatic Hydrocarbons (PAHs) Environmental source of PAHs: combustion of organic matter Major carcinogenic constituents isolated from cigarette tar and products of air pollution Common sources of PAHs in non-processed foods are thermal treatments (grilling, roasting, baking, frying) and processing procedures The highest PAHs levels were found in: grilled food smoked fish mussels from polluted waters leafy vegetables grown in areas heavily exposed to air pollution Pesticides The use of pesticides is increased worldwide Major chemical classes of pesticides are: Organochlorines Organophosphates Carbamates Health Risks From: nausea, vomiting, headaches To: teratogenic, carcinogenic, immunotoxic, endocrine disruption Polychlorinated Compounds Polychlorinated Biphenyls (PCBs) They are persistent organic pollutants (POPs) → resistant to environmental degradation Accumulate in animal feeds, particularly those of animal and marine origin → introduced into food chain Milk is a useful indicator of environmental pollution with PCBs Dioxins They are POPs (t1/2~ 7-11 years) Introduced into the environment as by-products of industrial processes but can also result from natural processes (volcanic eruptions, forest fires) Accumulate in animal feeds → absorbed by fat tissue → accumulate in food chain Health Risks Highly toxic Can cause reproductive and developmental problems Damage the immune system Interfere with hormones Cause cancer Phthalates Used as plasticisers in wide range of household and consumer goods (their use in plastic food packaging materials is now limited) As a result of their extensive use and their moderate resistance to degradation, phthalates are widely distributed in the environment and are often found at low levels in food Linked to: Endocrine disruption Lower sperm count Nitrates and Nitrites Nitrates and Nitrites themselves are not carcinogenic But nitrates can be reduced to nitrites when reacting with dietary amines → form nitrosamines → potent liver carcinogens Nitrates and Nitrites are used to preserve meat products  Summary Long term exposure to environmental contaminants can have health effects like: Organ damage Endocrine problems Immunosuppression Reproductive problems and birth defects Effects on mental or physical development of children Cancer Children and especially the foetus are more vulnerable than adults to the adverse effects of environmental contamination… Question 1 One of the symptoms of Itai-itai disease is soft and brittle bones, leading to fractures. This disease is caused due to: a. Lead poisoning b. Cadmium poisoning c. Arsenic poisoning d. Mercury poisoning