Environmental Ethics and Policy

• There are multiple approaches to environmental ethics that guide resource management and conservation.

Environmental Ethics

• Frontier Ethic: Utilizes unlimited resources and relocates once resources become depleted.
• Sustainable Ethic: Focuses on using resources carefully for long-term availability.
• Conservation Ethic: Emphasizes responsible resource use and management.
• Preservation Ethic: Advocates for protecting landscapes in their natural, unaltered state.

Early Voices in Environmental Ethics

• John Muir: Founder of the Sierra Club, who championed the preservation ethic.
• Gifford Pinchot: Founder of the US Forest Service, supported the conservation ethic.
• Aldo Leopold: Promoted a land ethic that emphasized ecosystem protection.

Waves of U.S. Environmental Policy

• Wave 1: Characterized by expansion and settlement, leading to environmental degradation like the Dust Bowl.
• Wave 2: Focused on conservation and preservation efforts.
• Wave 3: Addressed pollution, resulting in the Clean Air Act and the formation of the EPA.

Species and Speciation

• r/K-selected Species: Reproductive strategies vary in speed of growth and reproduction.
• Speciation: Can occur via allopatric (geographic isolation) or sympatric (same area) processes.
• Resource Partitioning & Character Displacement: Reduces interspecies competition, encouraging species diversification.

Environmental Toxicology

• Toxicants: Synthetic materials that can harm people and ecosystems.
• Carcinogens: Toxic substances, such as asbestos and dioxins, that cause cancer.
• Mutagens: Toxic substances, such as UV light and radiation, that cause genetic mutations.
• Teratogens: Toxic substances, such as thalidomide, that cause developmental defects.
• Neurotoxins: Toxic substances that target nerve cells and affect the nervous system's development.
• Precautionary Principle: Recommends protective measures be implemented even without complete scientific certainty of potential harm.
• Biomagnification vs. Bioaccumulation: Refers to how toxins accumulate within organisms and ecosystems.

Thimerosal in Vaccines

• Contains ethylmercury, which is cleared faster from the body than methylmercury.
• Primarily used as a preservative, it is now mainly in children's influenza vaccines since 2001.
• Studies have found no link between thimerosal and autism, and autism rates are the same in vaccinated and unvaccinated groups.

Vaccines and Autism

• A controversial study that falsely linked the MMR vaccine to autism had ethical violations, undisclosed conflicts of interest, and was fraudulent.
• No convincing evidence connects vaccines to autism; current studies emphasize genetic and environmental factors.

Lead Exposure

• Poses a major environmental health risk, particularly where leaded gasoline, smelting processes, or old paint were common.
• Even low levels of exposure can affect behavior, especially in children; replacing lead pipes is an increasing concern.

Air Pollution

• Air pollutants affect climate, humans, and ecosystems via harmful primary and secondary pollutants.
• The Clean Air Act (1963) addresses air pollution, limits pollutants, and phases out harmful chemicals like CFCs.
• The act led to programs like "Cap and Trade" for sulfur dioxide and reducing greenhouse gas emissions.

Stratospheric Ozone Depletion

• The Montreal Protocol (1987) successfully cut CFC production, protecting the ozone layer, with a projected return to pre-1980 levels by 2060-2075.

Acid Deposition

• Acidic pollutants from the air can deplete soil nutrients, harm plant and aquatic systems, and damage infrastructure.

Indoor Air Pollution

• Common sources are VOCs, radon, cigarette smoke, mold, and formaldehyde, which can harm health over time.

Pesticide Exposure in Yaqui Children (Sonora, Mexico)

• Compared children in a high-pesticide exposure area (Valley) with those in a low-exposure area (Foothills).
• Valley children had poorer performance in memory, coordination, and motor skills tests compared to Foothills children.
• Valley parents reported more pregnancy issues, such as premature births and spontaneous abortions.

DDT (Dichlorodiphenyltrichloroethane)

• Toxic to insects by disrupting sodium ion channels in neurons, leading to spasms and death.
• Has low acute toxicity to humans, but long-term exposure can cause endocrine disruption, cancer, and reproductive issues.
• Caused thinning of bird eggshells, decreasing bird populations; some populations recovered after DDT was restricted.
• Was key in malaria control, but its ban in the U.S. and limited global use led to resurgences of malaria in some areas.
• Most uses of DDT were banned in the U.S. in 1972, but it is still permitted in certain situations for vector control and remains in use illegally for agriculture.

Chlorpyrifos

• Blocks an enzyme involved in nerve cell signaling, causing neurotoxicity.
• Found in human urine, blood, and other bodily fluids, prenatal exposure is linked to lower birth weights and developmental issues.
• Rat and zebrafish studies show impaired brain and behavioral development after chlorpyrifos exposure.
• Studies suggest a link between chlorpyrifos exposure and ADHD and lower mental development scores, but causality is not firmly established.

The Precautionary Principle

• If an activity or substance could harm humans or the environment, precautionary measures should be taken without full scientific certainty of harm.
• This principle underlies the regulation of chemicals like DDT and chlorpyrifos.

Endocrine Disruption

• Occurs when chemicals interfere with hormone systems, affecting reproduction, development, and other body functions.
• Growing evidence links endocrine-disrupting chemicals to problems such as reduced sperm count, fertility issues, and genital abnormalities.

Chlorpyrifos Regulation

• Household use was phased out in the early 2000s.
• In 2021, the EPA decided to ban chlorpyrifos in food production, but in 2023 this was overturned, leaving its future use uncertain.

Endocrine-Disrupting Pesticides and Other Environmental Chemicals

• DDT (Dichlorodiphenyltrichloroethane)
• Not acutely toxic to humans, it still disrupts the endocrine system, causing issues like eggshell thinning in birds.
• Accumulates in the food chain, with higher concentrations in top predators.
• Wildlife Evidence
• Found that DDE (a DDT metabolite) contributed to reduced alligator penis size at Lake Apopka.
• Tributyltin (TBT) and Snails
• An industrial chemical used in anti-fouling paints that caused female snails to develop male genitalia, a phenomenon termed "imposex."
• Persistence in Environment: Although banned globally in 2008, it remains in sediments, causing continued environmental issues.
• Atrazine
• A herbicide that interferes with photosynthesis in plants. It does not directly affect humans but can still have indirect effects on ecosystems.
• Use in Agriculture: Applied to corn fields as a pre-emergent herbicide, it is resistant to leaching and can be found in groundwater, rivers, and well water.
• Research on Effects: May act as an endocrine disruptor in amphibians, leading to abnormal sexual development and health issues.

Key Concepts for Exam Preparation

• Types of Toxicants: Mutagens (DNA mutations), Endocrine Disruptors (hormone systems), Carcinogens (cancer), Teratogens (birth defects), Neurotoxins (nervous system).

Mechanisms of Toxicants

• Endocrine Disruptors can interfere with hormone receptors, disrupt hormone production, or alter hormone synthesis.
• Mutagens can cause DNA damage potentially leading to cancer or genetic disorders.

Research and Causality Standards

• Temporality, Strength of Association, Consistency, Biological Plausibility, and Recovery.

Indoor Air Pollutants

• VOCs, Radon, Cigarette Smoke, Living Organisms like Mold, and Carbon Monoxide and Formaldehyde

Take-Home Messages

• Understand specific toxicants and their impacts on human health, wildlife, and ecosystems.
• Understand the broader categories of toxicants (e.g., endocrine disruptors, mutagens).
• Evidence shows certain pesticides and chemicals disrupt ecosystems, wildlife development, and human health, leading to regulation and policy shifts.