Mind the Dent: When Your Can Leaks Metal

Aluminium migration refers to the slow seepage of aluminium from a can’s wall into the drink it holds. On pristine cans, an invisible polymer lining keeps your beverage and the metal apart. Dent that wall, and you break the shield.

Why It Matters:

• Tea stored in dented aluminium cans reached 9.6 mg/L of aluminium after seven months — about 15 times more than smooth cans.
• Your kidneys can’t flush aluminium quickly; repeated exposure builds up over time.
• Acidic or plant‑rich drinks like tea are especially aggressive at dissolving metal once the coating is compromised.

How It Works:

1. The can’s protective lining is designed to block liquid from touching aluminium.
2. A dent cracks or stretches that lining, exposing raw metal to your drink.
3. Over weeks or months, aluminium dissolves into the liquid — faster if the drink is acidic — and you swallow it unknowingly.

Quick Facts:

• Beer in intact cans showed a minor aluminium increase, around 0.14 mg/L.
• Tea in intact cans rose to about 0.6 mg/L by the end of its shelf life.
• Tea in dented cans skyrocketed to 9.6 mg/L — a 15× leap.
• Aluminium isn’t acutely toxic, but chronic buildup has been linked to neurological and bone issues.
• The solution is simple: choose smooth cans and don’t store dented ones for months.

Your body never lies. If the package is damaged, assume the contents are, too.

That tiny dent you shrugged off could be a doorway for metal exposure. Next time you’re tempted by a discounted can with a blemish, ask yourself if a few cents saved is worth months of slow aluminium seepage.

Study reference: Aluminium migration into beverages: are dented cans safe? (Rahman HA et al., 2008).