Alastair Watt Macintyre Hay OBE (born April 1947)[1] is a British toxicologist, and a Professor of Environmental Toxicology; he works primarily in the fields of chemical warfare and biological warfare (CBW).

[3] Hay started his career at the chemical pathology department at the University of Leeds.

][4] He provided assistance to the forming of the Chemical Weapons Convention in 1993, becoming international law in 1997.

[5] Hay is an active advocate for promoting ethics to new generations of scientists,[6] and he has headed a group of the International Union of Pure and Applied Chemistry (IUPAC) for educational materials on chemical warfare,[7] which led to the creation of an online resource on "Multiple Uses of Chemicals".

[9][10] Hay was appointed Order of the British Empire (OBE) in the 2003 Birthday Honours for services to occupational health.