Lead Poisoning

Taken in sufficiently large doses (0.25 oz. or more for a typical human), lead is a digestive agent with a three-month delay and a HT-4 roll to resist.

It inflicts 1d toxic damage, repeating at six-week intervals for three cycles. Once the victim loses 1/2 of his basic HP, he begins to suffer more severe symptoms. At the GM’s option, he may gain Bad Temper (15) or Laziness, or suffer spells of the agony, daze, or retching afflictions. Loss of appetite is also common. Multiple failed resistance rolls lead to intensifying symptoms, eventually resulting in seizures and coma.

Source: GURPS 4th - High-Tech, page 34