Humans have known about the dangers of lead for millennia, yet this heavy metal continues to plague us. In fact, what’s happening right now in Flint, Michigan, is just the latest example of humanity’s toxic relationship with lead (though also among the most preventable). Our knowledge of lead has evolved over time, but how much do you actually know about this natural neurotoxin?
Here are some basics at a glance, presented in a numerical index depicting how this element has been able to wreak havoc through the centuries—from the expansive Roman Empire to a midsize city in the midwestern United States.
The atomic number of lead (Pb): 82
Earliest recorded lead mine (in present-day Turkey): 6500 B.C.
Year Romans began piping their water through lead conduits: 312 B.C.
Year Greek physician and poet Nikander of Colophon first described lead’s damaging health effects: 200 B.C.
Number of years later Flint River water began corroding Flint’s lead water pipes: 2,214
Number of Flint children recently exposed to lead-contaminated drinking water: 12,000
Minimum number of years it takes lead to fully leave the body: 10
Amount of money Flint hoped to save by switching to Flint River water: $5,000,000
Estimated maximum cost to replace residential lead pipes in Flint: $1,500,000,000
Average monthly water bill per household in Flint: $140
Average monthly water bill for the rest of United States: $45
Percentage of Flint residents who live below the poverty line: 41
Percentage by which the median home price in Flint fell in December 2015: 8
Year Thomas Midgley Jr., a General Motors employee, developed tetraethyl lead as a gasoline additive: 1921
Year Thomas Midgley Jr. discovered he had lead poisoning: 1923
Number of years later the United States banned lead as a gasoline additive: 63
Estimated tons of lead burned in gasoline in the 20th century: 7,000,000
Year the first clinical account of childhood lead poisoning was published: 1892
Number of U.S. states that have submitted recent lead poisoning data to the Centers for Disease Control and Prevention (CDC): 26
Number of states that don’t report on lead poisoning at all: 13
Year the United States banned lead-based paints for use in housing: 1978
Number of American homes that still have deteriorating lead-painted walls: 38,000,000
Year the United States shuttered its largest and last lead smelter: 2013
Year the United States banned new lead water pipes: 1986
Number of American homes and buildings that still receive water from pipes containing lead: 10,000,000
Number of index cards on which the city of Flint recorded the locations of lead service lines: 45,000
Number of years it will take to replace all of Flint’s lead pipes: 15
Cost per day for anticorrosive additives that could have averted the Flint water crisis: $100
Number of cases of bottled water each Flint resident is allotted per day: 1
Blood lead level in micrograms per deciliter (µg/dL) of the average U.S. resident in 1976: 12.8
Average blood lead level in 1988 (after leaded gasoline was banned): 2.8
Highest blood lead level recorded in Flint during the water crisis: 38
Blood lead level limit for children under age 6 that the CDC deems elevated: 5
Age of Flint’s Gavin Walters when his blood levels tested at 6.5 µg/dL: 4
Blood lead level the CDC deems safe: 0
Decrease in IQ points for every microgram of lead in a child: 3/4
Total number of pencils made with lead: 0, actually
Action level for lead in water in parts per billion (ppb), per the U.S. Environmental Protection Agency: 15
Amount of lead in water the EPA deems safe: 0
Highest lead ppb level found in Flint water: 158
Percentage of Flint homes testing at 25 ppb or higher: 10
Number of months Flint River water flowed through the city’s lead pipes: 17
Percentage of Flint residents who are African-American: 65
Estimated number of children ages 1 to 5 in the United States with elevated blood lead levels: 500,000
Odds that black children will have elevated blood lead levels compared with white children: 2:1
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