**7. Conclusions and future directions**

*Oncogenes and Carcinogenesis*

**84**

**Name** Cancer

Carcinogens, American Cancer Society

Cancer-Causing Substances in the Environment,

National Cancer Institute

Chemicals of Public Health Concern, World Health Organization

(WHO)

Radon and Health, WHO

Arsenic Fact Sheet, WHO

Elimination of asbestos-related diseases, WHO

Science and Technology: Health, Environmental Protection

Work-Related Lung Disease (WoRLD) Surveillance System,

National Institute for Occupational Safety and Health (NIOSH)

U.S. Geological Survey (USGS)

CARcinogen EXposure Canadian Surveillance Project (CAREX)

Lung Cancer and the Environment, Centers for Disease Control

and Prevention (CDC)

**Table 1.**

*Sources of information on environmental carcinogens associated with lung cancer.*

http://www.carexcanada.ca/

https://ephtracking.cdc.gov/showCancerLcEnv.

action

Agency (EPA)

The IARC Monographs, International Agency for Research on

**Website** http://monographs.iarc.fr/

http://www.cancer.org/Cancer/CancerCauses/

OtherCarcinogens/index

https://www.cancer.gov/about-cancer/

causes-prevention/risk/substances

http://www.who.int/ipcs/assessment/public\_

health/chemicals\_phc/en/index.html

http://www.who.int/mediacentre/factsheets/

http://www.who.int/mediacentre/factsheets/

http://www.who.int/mediacentre/factsheets/

fs343/en/

http://www.epa.gov/gateway/science/

humanhealth.html

http://www2.cdc.gov/drds/WorldReportData/

http://www.usgs.gov/

data.

fs372/en/

fs291/en/

**Description**

Compilation of factors that increase the risk of human cancer:

occupational exposures, physical agents, biological agents, and lifestyle

Environmental carcinogens from different sources (e.g., indoor,

Information of environmental carcinogens to affect human health.

Information on the 10 chemicals or groups of chemicals of major public

health concern

Health effects and guide line of Radon.

Contents include health effects, prevention, and control on Arsenic.

Information about asbestos related diseases.

Information on human health impacts associated with environmental

Contents on occupationally-related respiratory disease surveillance

Organization that provides impartial information on the health of U.S.

Project that combines academic expertise and government resources to

generate an evidence-based carcinogen surveillance program

Information about exposure to environmental carcinogen and the risk

for lung cancer.

environment and the natural hazards

exposures

pollution, medical tests)

The geographical conditions facilitating human exposure to environmental lung carcinogens such as arsenic, asbestos and radon occur commonly across the globe. While millions of individuals are known to be exposed to potentially damaging doses of these carcinogens, another significant part of the population is unaware of its exposure. Despite the worldwide impact of the public health risk posed by these compounds, the genomic and epigenetic consequences of these exposures are drastically understudied. Barriers such as: (i) availability of individual-level exposure data; (ii) collection of genomic, epigenomic, and transcriptomic readouts following acute and chronic exposure to carcinogens; and (iii) obtaining enough samples to reach statistical power; impose even further challenges to determining the true extent of environmentally-induced health effects.

Understanding these mechanisms could have a significant impact on the establishment of safe exposure limits for each of these agents. For instance, most of the current frameworks used to regulate arsenic exposure in drinking water have been derived from studies performed in specific populations exposed to high levels of arsenic, such as Bangladesh, Chile, and China [9, 133, 134]. However, an increased risk of arsenic-related health effects (including cancer) has been documented at levels below current safety thresholds that are commonly found in water sources throughout North America and Europe [7]. Thus, characterizing the effects of these agents at the genomic/epigenomic level will not only aid in determining the oncogenes that are perturbed in environmentally-induced lung cancers, but may also uncover early molecular events that can be used as diagnostic and prognostic markers.

The fraction of lung cancer patients who have never smoked or have ceased smoking is likely to increase in the coming years. Exposure to environmental carcinogens, such as arsenic, asbestos, and radon will play a key role in their etiology. Further elucidation of the detailed mechanisms driving environmentally-induced lung tumors will provide the much-needed insight to define specific detection methods and intervention strategies. Collectively, uncovering these carcinogen-specific mechanisms, as well as the affected genes driving malignant transformation, will greatly contribute to the development of personalized approaches to provide better support to lung cancer patients.
