In 1988, with the protracted Iran-Iraq War in its closing phase after eight years, then President Saddam Hussein launched an unprecedented chemical attack on the Kurdish town of Halabja. The attack was aimed at quashing a rebellion in the northeast of Iraq led by the Kurds in response to Hussein’s suppression of the population.

More than three decades on, rates of “terminal diseases, birth deformities, and still-born babies” are still on the rise among the surviving Kurdish community...