This volume of the IARC Monographs provides an evaluation of the carcinogenicity of opium consumption.

Opium is a highly addictive narcotic drug that has been used for centuries for medicinal and non-medicinal purposes. It has analgesic, hypnotic, antitussive, gastrointestinal, and cognitive effects.

Produced from the juice (latex) of the unripe seedpod of the poppy plant (Papaver somniferum), opium has a complex chemical composition consisting of at least 25 alkaloids (e.g. morphine, codeine, thebaine) and other substances. There are several forms of opium (raw or crude opium, dross, refined opium or opium sap), all of which can be smoked or ingested. Opium derivatives such as morphine, codeine, and heroin were not considered in the present monograph.

Although opium production and distribution are controlled internationally, opium is produced illicitly in some 50 countries worldwide, with more than 80% coming from Afghanistan. The world’s largest per capita consumers of raw or minimally processed opium are the Islamic Republic of Iran, Afghanistan, and Pakistan. In 2018, there were an estimated 5 million users of illicit opium worldwide.

After reviewing epidemiological evidence, animal bioassays, and mechanistic data to assess the carcinogenic hazard to humans of opium consumption, the IARC Monographs Working Group concluded that opium consumption is carcinogenic to humans (Group 1).

Contents

• Library Cataloguing Data
• Note to the Reader
• List of Participants
• Preamble
• General Remarks
• 1. Exposure Characterization
  • 1.1. Identification of the agent
  • 1.2. Methods of measurement, detection, and analysis
  • 1.3. Production
  • 1.4. Use and consumption
  • 1.5. Regulation and legislation
  • 1.6. Quality of exposure assessment in key epidemiological studies of cancer and mechanistic studies in humans
  • References
• 2. Cancer in Humans
  • 2.1. Cancer of the oesophagus
  • 2.2. Cancer of the urinary bladder
  • 2.3. Cancers of the respiratory tract
  • 2.4. Cancer and preneoplastic lesions of the stomach
  • 2.5. Other cancers
  • 2.6. Evidence synthesis for cancer in humans
  • References
• 3. Cancer in Experimental Animals
  • 3.1. Mouse
  • 3.2. Rat
  • 3.3. Hamster
  • 3.4. Evidence synthesis for cancer in experimental animals
  • References
• 4. Mechanistic Evidence
  • 4.1. Absorption, distribution, metabolism, and excretion
  • 4.2. Evidence relevant to key characteristics of carcinogens
  • References
• 5. Summary of Data Reported
  • 5.1. Exposure characterization
  • 5.2. Cancer in humans
  • 5.3. Cancer in experimental animals
  • 5.4. Mechanistic evidence
• 6. Evaluation and Rationale
  • 6.1. Cancer in humans
  • 6.2. Cancer in experimental animals
  • 6.3. Mechanistic evidence
  • 6.4. Overall evaluation
  • 6.5. Rationale
• List of Abbreviations
• Annex 1 Supplementary material for Section 1, Exposure characterization
• Annex 2. Methodological considerations for epidemiological studies on opium consumption and cancer

This publication represents the views and expert opinions of an IARC Working Group on the Identification of Carcinogenic Hazards to Humans, which met remotely, 11–20 September 2020

Lyon, France – 2021