This document discusses occupational and environmental causes of lung cancer. It states that smoking causes 80% of lung cancers worldwide, while 2-8% are caused by occupational exposures. Several specific occupational exposures are classified as known (Group 1) human lung carcinogens by IARC, including arsenic, asbestos, beryllium, cadmium, chloromethyl ethers, chromium, coal-related products, mustard gas, nickel, radon, and vinyl chloride. The document provides details on the lung cancer risks and evidence for each of these exposures. It also discusses some Group 2 lung carcinogens and notes several occupations and industries associated with increased lung cancer risks.

1. Occupational and Environmental
Causes of Lung Cancer

2. Overview
• Lung cancer is one of the leading causes of mortality
accounting for 1.3 million deaths annually worldwide
especially in developed countries rising at alarming
rates.
• Smoking is responsible for 80% of all lung cancers
worldwide.
• 2 to 8 % of all cancers are thought to be due to
occupational exposures .
• Prevention is key.
• Environmental as well as occupational cancers

3. Smoking Status and Tobacco
• In the 20th century, emergence of the Lung cancer, mostly
caused by Cigarette smoking.
• The risk of cancer increases with the amount of smoke per
day and duration of use; heavy smokers have maximum of 20
times the risk of developing lung cancer compared to non-
smokers.
• A cigar smoker has 5 times the fatal risk of lung cancer
compared to non-smokers.
• Second–hand smoke is what smokers exhale and what rises
from a burning cigarette, pipe or cigar.
• It is called environmental tobacco smoke (ETS), or involuntary
or passive smoking. It contains the same chemicals as smoke
that is actively inhaled. People exposed to second-hand
smoke have an increased risk of lung cancer.

4. The IARC classifies agents as follows:
• Group 1 – carcinogenic to humans
• Group 2
• 2A – probably carcinogenic to humans
• 2B – possibly carcinogenic to humans
• Group 3 – not classifiable
• Group 4 – probably not carcinogenic to humans

5. • Agents classified as known Group 1 lung carcinogens
include the categories of ionizing radiation, chemicals
and mixtures, occupational exposures, metals, dust and
fibers, personal habits, and other exposures.
• Indoor emissions from household combustion is
predominantly an environmental lung carcinogen; 16
agents are primarily occupational lung carcinogens and
8 agents are both potential environmental and
occupational lung carcinogens.

6. Known Human Occupational Lung
Cancers
• Arsenic
• Asbestos
• Beryllium
• Cadmium
• Chloromethyl ethers
• Chromium
• Coal-related products
• Mustard gas
• Nickel
• Radon
• Vinyl chlorine

7. IARC Group 1 Lung Carcinogens:
Ionizing Radiation
• All types of ionizing radiation have been documented to
be carcinogenic to humans (ie, Group 1). The types of
radiation primarily identified as lung carcinogens are α-
particles, γ-rays, and x-rays.
• Ionizing radiation: α-particles- Radon-222 decay
products and plutonium-239
• Cells that have been hit by an α-particle, as well as
nearby cells may undergo genetic changes that lead to
cancer.
• Alpha-particles can also produce reactive oxygen
intermediates that can produce oxidative damage to the
DNA

8. IARC GROUP 1 LUNG CARCINOGENS: DUST AND FIBERS
• Asbestos (All Forms)
• Asbestos is a naturally occurring fibrous silicate
mineral that exists in 2 forms: serpentine and
amphibole
• Asbestos affects parenchyma and pleura of lungs.
• The 3 lung-specific adverse health outcomes
associated with exposure to asbestos are asbestosis,
lung cancer, and mesothelioma

9. Chemicals and Mixtures
• Chloromethyl methyl ether (CMME) and Bis (chloromethyl)
ether (BCME)
• BCME arose from the use of mosquito coils that contain
octachlorodipropyl ether, also referred to as “S-2.”
• BCME and CMME are both alkylating agents provides
support that their mode of action is genotoxic.
• Intermediate product used in ion-exchange resins,
bactericides, pesticides and solvents

10. OCCUPATIONS AND MANUFACTURING PROCESSES
• The 2009 IARC work group determined that there was
sufficient evidence in humans for the carcinogenicity of
occupational exposures occurring during work activities
in the following 6 discrete occupational categories :
1. Coal gasification
2. Coke production
3. Iron and steel founding
4. Aluminium production
5. Painting
6. Rubber production industry

11. • The occupational groupings of coal gasification, coke
production, iron and steel founding, and aluminium
production, all have potential for high exposure to
PAHs, as well as to other chemicals.
• Benzo[a]pyrene (BaP), one of the high molecular weight
PAHs, has been classified into the group of most
carcinogenic agents by the IARC.
• One of the most important pathways by which humans
are exposed to PAHs is inhalation, and the majority of
PAHs present in the atmosphere come from incomplete
combustion or from pyrolysis

12. IARC GROUP 1 LUNG CARCINOGENS: METALS
Arsenic
• Arsenic, a chemical element classified as a metalloid, is
both an environmental and occupational lung
carcinogen.
• The most common forms of arsenic in the environment
are arsenite and arsenate.
• Occupational exposures occur primarily among workers
who breathe dust from lead, gold, and copper ore
mines and smelters.Synergistic with smoking.
• Most often seen in upper lobes

13. • Cadmium and Cadmium Compounds
• Cadmium is a soft, bluish-white metal recovered as a by-
product of zinc mining and refining.
• Environmental exposures to cadmium are primarily the
result of volcano emissions, fossil fuel , phosphate
fertilizers, iron and steel production emissions, cement
production.
• Chromium VI compounds are classified as Group 1 lung
carcinogens and are produced primarily from industrial
processes.

14. Lung Cancer - Coal-related
products
• PAH – Polyaromatic Hydrocarbon
• Known carcinogens are benz(a)anthracene and
7,12 dimethylbenzanthracene
• Lung cancer is seen in coke-oven workers chimney
sweeps
• PAH’s are formed through incomplete combustion
of coal, tar, coke and oil
• PAH’s found in coal gasification facilities, gas and
coke works, iron and steel foundries, petroleum
distillates and diesel exhaust.

15. Lung Cancer - Mustard Gas
• Bis (beta-chloroethyl) sulfide
• Poisonous gas used in WWI
• Causes squamous cell lung cancer.
• Excess lung cancers seen in Japanese and German
workers manufacturing mustard gas

16. IARC GROUP 2 LUNG CARCINOGENS
• Group 2–listed human lung carcinogens include the following:
• Acid mists, strong inorganic
• Art glass, glass containers, and pressed ware (manufacture of)
• Biomass fuel (primarily wood) indoor emissions from
household combustion of
• Carbon electrode manufacture
• Cobalt metal with tungsten carbide
• Frying, emissions from high temperature
• Insecticides, (occupational exposures in spraying and
application)
• Printing processes (occupational exposures in)
• Welding fumes