Lab 9: Environmental Health — Lead Investigation
Week of Tue, Nov 10 · lab closes Mon, Nov 16 · 30 points
This lab's items
- Lab Write Up30 pts
Exact due times are in Canvas. Late assignments are not accepted without a valid, documented reason. Make-up assignments are not given without valid documentation.
Know these cold
- Lead (Pb) is a heavy metal that occurs naturally in Earth's crust but became a widespread environmental contaminant through industrial processes: leaded gasoline (1920–1996), lead paint (banned in the U.S. for residential use in 1978), lead solder in pipes, and industrial emissions.
- There is no safe level of lead exposure. Lead causes irreversible neurodevelopmental harm: in children, even low-level exposure reduces IQ, attention span, and impulse control; increases behavioral problems; and impairs hearing. Effects are permanent.
- Exposure pathways for lead: ingestion (eating lead paint chips, dust, or contaminated soil; drinking water from lead pipes or fittings), inhalation (lead dust from renovation, smelting, or contaminated soil), and dermal contact (less significant for inorganic lead).
- The 'dose makes the poison' principle: every toxic substance has a dose-response relationship. Below a threshold, many toxins cause no detectable harm; above it, harm increases with dose. Lead is unusual because there is no known safe threshold in children.
- Sources of lead exposure in the U.S. today: old housing with lead-based paint (pre-1978 homes — deteriorating or disturbed during renovation), lead solder in older plumbing, industrial contamination, some imported consumer goods, and occupational exposure (battery manufacturing, smelting, automotive work).
- Flint, Michigan water crisis (2014–2019): after switching water sources, the new water corroded lead pipes, leaching lead into drinking water. Blood lead levels in children spiked. The crisis highlighted how environmental justice intersects with environmental health — low-income communities of color faced the greatest risk.
- Remediation approaches: replacing lead pipes and plumbing (most effective), lead paint encapsulation or removal, soil remediation (replacing or covering contaminated soil), and public health interventions (nutrition — calcium, iron, and vitamin C compete with lead absorption).
- Environmental justice principle: lead exposure is disproportionately concentrated in low-income communities and communities of color, where older housing is more common and remediation investment is lower. This reflects a broader pattern of environmental health disparities.
Discussion and forum — how to show up
Netiquette from the syllabus: address ideas, not people. Complete sentences, correct spelling. Personal matters go to email, never the board.
Meerk's quiz — open the Lab 9 gate
10 questions, no time limit. 85% on your first attempt in a 24-hour window opens the gate. Retakes inside the window are practice — they help you learn, they don't count. Work alone; the point is to know it, not to have seen it.
Dinner Table Question
Ask at home: The Flint water crisis lasted years before the government acted. If you suspected your tap water was contaminated, what would you do first — and who would you trust to tell you the truth?
En español: La crisis del agua de Flint duró años antes de que el gobierno actuara. Si sospecharas que tu agua del grifo estaba contaminada, ¿qué harías primero — y en quién confiarías para que te dijera la verdad?