Arsenic

Arsenic's toxic history stretches back to ancient Rome, where it was called the "inheritance powder" — a favored tool of poisoners precisely because it mimicked natural illness [1]. Industrially, arsenic exploded into global use in the 19th century as an agricultural pesticide and wood preservative (CCA-treated lumber), contaminating soil at millions of sites across the US [2]. The bigger story today is geology: arsenic occurs naturally in bedrock, and as groundwater dissolves rock over millennia, it concentrates in wells across Bangladesh, India, and the American West and Midwest. The 2001 discovery that tens of millions of Bangladeshis were being slowly poisoned by their own government-drilled wells — meant to prevent waterborne disease — became one of the largest mass poisonings in history [3]. In the US, the EPA estimates 13 million people drink water with arsenic above the 10 ppb limit, mostly from private wells in states like Nevada, Maine, and Michigan [4].

Your biggest risk is drinking water from a private well, especially if you live in New England, the upper Midwest, or the Southwest — regions where arsenic-bearing bedrock is common [1]. But municipal water is not entirely safe: older systems sometimes exceed the 10 ppb federal limit. Food is the second major route — rice accumulates arsenic from paddy water, and apple and grape juice historically had elevated levels [2]. Pressure-treated lumber installed before 2004 used arsenic compounds; if your deck or playground equipment is from that era, handling and weathering can expose nearby soil [3]. Occupational exposure is highest in mining, smelting, glass manufacturing, and semiconductor production. Tobacco also contains arsenic — yet another reason to avoid smoke.

Arsenic doesn't kill quickly — it accumulates in your hair, nails, and skin over years while silently damaging multiple organ systems [1]. It works by interfering with how your cells produce energy, disrupting enzymes that your body relies on for basic metabolism. Long-term exposure at levels as low as 10 ppb in drinking water increases your lifetime risk of bladder, lung, and skin cancer. Beyond cancer, arsenic hardens arteries and raises the risk of heart attack, damages insulin-producing cells to cause Type 2 diabetes, and impairs brain development in children even at concentrations that don't trigger visible symptoms [2]. A telltale sign of chronic exposure is Mees' lines — white bands across the fingernails — and a distinctive patchy darkening of the skin [3]. Children absorb a higher percentage of what they ingest, making them especially vulnerable.

People on private well water in the Northeast, Midwest, and Mountain West face the highest drinking-water risk and should test their wells every 1–3 years [1]. Infants who drink formula mixed with well water, and young children who spend time on old CCA-treated decks, face elevated exposures. Frequent rice consumers — particularly those who eat rice-based infant cereals — should diversify grains [2]. Workers in mining, smelting, electronics manufacturing, and wood preservation face occupational exposure. Pregnant women are at heightened risk because arsenic crosses the placenta.

Test your well water annually for arsenic (less than 10 ppb is the federal limit, but below 5 ppb is safer for children) [1]. Install a certified reverse-osmosis or activated-alumina filter on your drinking and cooking water — simple carbon filters do not remove arsenic. Cook rice in a large volume of water (6:1 ratio) and drain the excess to reduce arsenic content by up to 50% [2]. Limit apple and grape juice for young children. If you have pre-2004 pressure-treated wood on a deck, seal it annually and wash hands after touching it; consider replacing sections near where children play. Eat a varied diet — selenium from seafood and Brazil nuts can help your body process arsenic [3]. If you work in smelting or mining, wear NIOSH-approved respiratory protection and change clothes before leaving the worksite.