The Bhut Jolokia, or more commonly known as the Ghost Pepper, used to be the hottest pepper. In 2000, India's Defence Research Laboratory reported a rating of 855,000 SHUs, and in 2004 a rating of 1,041,427 SHUs was made using HPL analysis. For comparison, Tabasco red pepper sauce rates at 5000–10,000, and pure capsaicin] (the chemical responsible for the pungency of pepper plants) rates at 16,000,000 SHUs.
In 2005, at New Mexico State University Chile Pepper Institute near Las Cruces, New Mexico, Regents Professor Paul Bosland found bhut jolokia grown from seed in southern New Mexico to have a Scoville rating of 1,001,304 SHUs by HPLC.
The effect of climate on the heat of these peppers is dramatic. A 2005 study comparing percentage availability of capsaicin and dihydrocapsaicin in bhut jolokia peppers grown in Tezpur (Assam), showed the heat of the pepper is decreased by over 50% in Gwalior's more arid climate. Elsewhere in India, scientists at Manipur University measured its average Scoville rating by HPLC at only 329,100 SHUs.