Science Module 3 Exam Review

Chemicals of Major Public Health Concern

• The World Health Organization identifies 10 chemicals of major public health concern: air pollution, arsenic, asbestos, benzene, cadmium, dioxin and dioxin-like substances, inadequate or excess fluoride, lead, mercury, and highly hazardous pesticides.

Neurodevelopmental Toxicants Effects on Humans

• Widely used chemicals are known or suspected neurodevelopmental toxicants.
• Associated with serious learning disabilities, loss of intelligence, poor impulse control, developmental delays, hearing impairment, ADHD, and autism, potentially impacting a child's future mental and behavioral health in adulthood.

Mercury

• Mercury is the only metal that is liquid at standard temperature and pressure.
• A naturally occurring, but rare, element in the Earth's crust.
• It has a high surface tension, forming rounded liquid beads.
• The name derives from the Roman god Mercury.
• Mercury and its compounds are highly toxic, historically used as a therapeutic agent in some ways.

What Happens to Mercury in the Environment?

• Mercury is found in air, water, and soil; seldom appears as a silver liquid in the environment.
• It persists in the environment, cycling between air, water, sediments, soil and biota.
• It does not break down in the environment.
• Mercury can travel long distances in the air, evaporate from water, and adhere to soil and sediments.
• Methylmercury, a toxic organic mercury compound, bioaccumulates in plants and fish, concentrating up the food chain.
• Industrial releases contribute to environmental mercury, although industrial air releases have trended down over decades.
• Mercury's transboundary nature requires international cooperation to tackle it effectively.

How Is Mercury Used?

• Industrial processes, such as chlorine production (mercury chlor-alkali plants) for PVC and polyurethane production.
• Artisanal and small-scale gold mining.
• Products such as electrical switches, relays, measuring equipment, fluorescent light bulbs, batteries, dental fillings.
• Laboratories, cosmetics, pharmaceuticals (in some vaccines as preservatives), paints, and jewelry.

What Are the Mercury Human Exposure Sources?

• Industrial processes (coal-fired power stations, residential heating systems, cement production, incineration, metal mining, and non-ferrous metal production) release mercury into the environment.
• Consumption of contaminated fish, shellfish, and marine mammals is the main methylmercury exposure source, especially for those reliant on predatory fish as a protein source.

How Does the Mercury Human Exposure Happen?

• Food (ingestion of contaminated fish/marine life, methylmercury being the most toxic).
• Inhalation (mercury vapor from occupational activities or spills).
• Direct skin contact (from mercury use).
• Dental fillings and cosmetics are the primary sources of skin contact exposure to elemental mercury.
• Some cultures use mercury in traditional medicine or religious practices, while this is not recommended or permitted in the U.S.

Household Items Containing Mercury

• Thermometers (containing about ½ gram of mercury).
• Thermostats (in sealed glass "tilt switches").
• Gauges (barometers, manometers, blood pressure and vacuum gauges with silver liquid).
• Electrical switches and relays (some older appliances).
• Some athletic shoes (made before 1997 with flashing lights).
• Vintage toys and games (drawing screens and mercury maze games).
• Fluorescent, HID, metal halide, high-pressure sodium, and neon lights.
• Some tattoo inks, contact lens solutions, and cosmetics (containing the mercury compound thimerosal).

Cosmetics Containing Mercury Compounds

• Avoid skin creams, beauty and antiseptic soaps, and lotions containing mercury, often marketed as skin lighteners or anti-aging treatments.
• Check product labels for "mercurous chloride," "calomel," "mercuric," "mercurio," or "mercury" to be aware of mercury presence.

Mercury Toxicity

• Mercury is a highly toxic heavy metal impacting human health and the environment.
• Affects the central nervous system, thyroid, kidneys, lungs, immune system, eyes, gums, and skin.
• Symptoms can include memory loss, language impairment, and other complications in neurological development.
• There's no safe exposure level of elemental mercury.

Signs and Symptoms of Mercury Poisoning

• Irritability
• Shyness
• Tremors
• Vision or hearing changes
• Memory problems
• Depression
• Numbness/tingling in hands/feet

Mercury Intoxication

• Mercury intoxication (chronic or acute) is a global environmental health issue.
• Children, babies, and developing fetuses are highly vulnerable to mercury's adverse effects.
• Fetal exposure to high methylmercury levels can cause congenital malformations, cerebral palsy, and neurocognitive issues.
• Neurodevelopmental impacts include mental retardation, congenital malformations, vision/hearing loss, developmental delays, and language disorders.

First Reported Mercury Related Disease

• Minamata Disease: Chisso Corporation's industrial waste releases resulted in mercury contamination of Minamata Bay's fish and shellfish.
• Residents experienced health problems: neurological disorders in newborns, animals' strange behaviors, and an increase in developmental disorders.

Minamata Convention on Mercury

• First global environmental agreement of the 21st century.
• A comprehensive approach to mercury throughout its lifecycle, from mining to waste management.
• Aims to reduce and eliminate mercury use.

Mercury Poisoning - Grassy Narrows (Canada)

• Mercury contamination occurred in the Wabigoon River system from a pulp and paper mill.
• Significant historical mercury exposure continues to affect the Ojibway community's health and culture.
• Recent studies show ongoing health impacts on residents.

Persistent Organic Pollutants (POPs)

• POPs are long-lasting, global pollutants.
• They persist in the environment, widely distributed, and bioaccumulate in organisms, especially at higher trophic levels.
• Three main categories: organochlorine pesticides, industrial chemicals (like PCBs), and unintentional byproducts from industrial processes (like PCDDs/PCDFs).

Why Are POPs Dangerous?

• Exceptionally long-lasting.
• Widespread environmental distribution (air, water, soil).
• Bioaccumulation/biomagnification in living organisms.
• Toxic to humans and wildlife.

Distribution of POPs in the Environment

• POPs circulate between different environmental compartments (soil, water, air).
• Absorb to fatty tissues and accumulate, persisting in biota.
• Long half-lives in various environmental mediums.
• Transferred through food webs (bioaccumulation and biomagnification).

Human Exposure to POPs

• Exposure through diet, occupation, fires, burning of waste, accidents, indoors/outdoors.
• Short-term (acute) or long-term (chronic) exposure.

Human Health Effects from POPs

• Exposure from contaminated fatty foods (milk, dairy, fish).
• Potential for placental transfer/breastfeeding transmission.
• Considered endocrine disruptors, negatively impacting the nervous system, and are potential carcinogens.
• Public health and environmental concerns due to POPs' worldwide distribution and persistence.

Dioxin and Dioxin-like Substances

• Dioxins and dioxin-like substances (including PCBs) are persistent organic pollutants.
• Bio-accumulate in food chains.
• Exposure primarily through contaminated food, sometimes in occupational settings.
• PCBs use is diminishing (phase out by 2025), but environmental releases still occur from disposal.

Dioxin and Dioxin-like Substances Toxicity

• Associated with various health issues: chloracne, reproductive/developmental/neurodevelopmental effects, immunotoxicity, carcinogenicity, and thyroid/liver/tooth impacts.
• Unwanted byproducts of combustion and various industrial processes.

Case Study: Chronic Dioxin Poisoning (Vietnam)

• Agent Orange, a herbicide containing dioxin, was sprayed extensively during the Vietnam War.
• Millions of acres were defoliated.
• Responsible chemical companies were unaware of dioxin's toxicity, long-term effects are debatable.
• Red Cross estimates three million affected Vietnamese, including 150,000 children with birth defects.

Case Study: Acute Dioxin Poisoning (Ukraine)

• Dioxin-related skin condition, chloracne.
• Caused by exposure to particular halogenated aromatic hydrocarbon chemicals commonly found in fungicides, insecticides, herbicides, and food preservatives.

Stockholm Convention on Persistent Organic Pollutants

• International treaty to eliminate or restrict POP production and use.
• Actions required to reduce POPs emissions/releases. Measures to reduce human exposure: disposal, burning, minimizing contaminants in food and feed, worker exposure management, and environmental monitoring.

E-waste

• Electronic waste (E-waste or WEEE) from discarded electrical/electronic equipment and parts.
• Six categories: temperature exchange equipment, screens, lamps, large equipment, small equipment, IT/telecommunication equipment.
• Each E-waste category has a unique lifetime profile potentially impacting environmental and economic value.

Environmental and Health Hazards of E-waste

• Rapidly increasing global E-waste generation.
• Significant potential health risks from improper handling.
• Hazardous substances (heavy metals and aromatic hydrocarbons) release problems.
• Limited recycling of E-waste (15% formally treated).
• Unprofitable recycling for certain types of E-waste.

The Basel Convention on the Control of Transboundary Movements of Hazardous Wastes

• International convention to protect human health and the environment from hazardous waste.
• Aims to reduce hazardous waste generation, restrict transboundary movements (unless environmentally sound), and regulate permitted transfers.

Rare Earth Elements (REEs)

• A group of 17 elements found in low concentrations in nature, often costly and environmentally challenging to extract, process, and refine.
• Key components in many electronic devices and industrial applications.
• China is a major producer with environmental consequences (water/soil contamination).

REEs Top Countries Producers

• China (major producer, significant environmental issues).
• California's Mountain Pass mine is a U.S. rare earth facility sending concentrates to China.
• Other producers include India, South Africa, Canada, Australia, Estonia, Malaysia, and Brazil.

REEs Applications

• Rechargeable batteries, advanced ceramics, computers, DVD players, wind turbines, catalysts, monitors, televisions, lighting, lasers, fiber optics, superconductors, and glass polishing.
• Critical for electric vehicle motors (neodymium, dysprosium).
• Used in military equipment (night vision devices, jet engines).

REEs in Your Smartphones

• Smartphone production depletes rare earth elements.
• Global smartphone numbers projected to reach 18 billion by 2025.
• Low recycling rates lead to large amounts of e-waste.
• A new smartphone generates significant CO2e emissions during manufacture/first year usage.

How Can You Make a Difference?

• Don't discard electronics in general waste.
• Use established e-waste collections, take-back programs, or recycling facilities.
• Support community electronic recyclers.
• Avoid unnecessary purchases, and extend the life of your electronics.
• Support manufacturers with sustainable technologies and take-back programs.