ENVIRONMENTAL FACTORS IN THE EPIDEMIOLOGY OF CANCER

ENVIRONMENTAL FACTORS IN THE

EPIDEMIOLOGY OF CANCER

Martin Rusnak, MD, PhD

Assoc. Prof. of Public Health, Trnava University

Environmental Health Project

ASIH

CONTENTS

environmental risks assessment

case studies

risk reduction policies

REALISTIC GOALS FOR REDUCING CANCER MORTALITY
W.C. Willett, G.A. Colditz, N.E. Mueller: Causes and Prevention: Strategies for Minimizing Cancer Risk. Scientific American, 1998

Women's Probability of Acquiring Cancer by Age 75

Men's Probability of Acquiring Cancer by Age 75

RISK

RISK - the probability that an individual will suffer injury, disease, or death under a specific set of circumstances (possible effects on animals and plants as well as on environment itself included)

RISK ASSESSMENT - evaluation of the potential effects of toxic chemical releases known to be occurring, to evaluation of the potential effects of releases due to events whose probability of occurrence is uncertain

qualitative
quantitative

RISK MANAGEMENT - measures to prevent the occurrence of an event as well as appropriate remedial actions to protect the public and/or the environment in case the event does occur

RISK COMMUNICATION - to invite and encourage public participation, to communicate the nature and extent of the risk in understandable terms to both experts and layperson, to share background information fully with all affected groups to help make it possible to arrive at an informed estimate of the risk and wise approach to its management

Estimates of comparative risks to individuals by Moeller, D.W.: Environmental Health, revised edition. Harvard University Press, 1997, 480 pp.
Hazard	Probabilistic risk estimate	Degree of uncertainty
Death before age 85, all causes	0.7	Low
Death from cancer, lifetime risk	0.25	Low
Death from cigarette smoking, one pack per day for 40 years	0.13	Medium
Death from occupational exposure to benzene, 10 ppm concentration, for 30 years	0.05	Medium-High
Death from motor vehicle crash, lifetime risk	0.02	Low
Death from drinking water with EPA limit of chloroform, lifetime risk	<0.0005	High
Death from inhaling formaldehyde in urban air, 5 ppb concentration, lifetime risk	<0.000008	High

Estimates of comparative risks to populations by Moeller, D.W.: Environmental Health, revised edition. Harvard University Press, 1997, 480 pp.
Hazard	Annual total deaths in U.S.	Degree of uncertainty
Cigarette smoking	300,000	Low
Alcohol abuse	150,000	Low
Highway travel	45,000	Low
Homicide	20,000	Low
Indoor air toxins	6,000	Medium
Outdoor air toxins	3,000	High
Pesticide residues in foods	3,000	High
Airline travel	1,000	Low

Proportion of cancer deaths attributable to various factors, England and Wales, 1995
	% of all cancer deaths
Agent or class of agents	Best estimate	Range of estimates
Diet	35	20-60
Tobacco	31	29-33
Natural hormones	15	10-20
Infections	10	5-15
Electromagnetic radiation	8	5-10
Alcoholic beverages	5	3-7
Environmental pollution	2	<1-4
Medicines and medical procedures	1	0.5-2
Industrial products	<1	<1-4
Other	?	?

Dose - response curves for cancer and noncancer agents

Public concern about environmental carcinogens is out of proportion with the true risk according to: Harvard Report on Cancer Prevention. Volume 1:Causes of Human Cancer. In: Cancer Cause & Control, vol.7, suppl., 1996, pp.555-558

CASE STUDIES

Ionizing Radiation and Cancer

X rays discovery in 1895 followed shortly by reports of radiation injuries including development of cancers

several decades later observations of bone sarcomas in a number of young women who ingested radium in conduction with their work in applying luminous compounds to watch dials

follow up data on two bombed cities in Japan (1945 - 1970) revealed that dominant effects of ionizing radiation among the survivors were the solid tumors: cancers of the lungs, breast, thyroid, etc.

ionizing radiation emissions from nuclear power plants are closely controlled and involve negligible levels of exposure for communities near such plants. Although reports about cancer case clusters in such communities have raised public concern, studies show that clusters do not occur more often near nuclear plants than they do by chance elsewhere in the population.

CASE STUDY

Electric and Magnetic Fields and Leukemia

a case-control study of leukemia in children living in the Denver area (1979) suggested that the relative cancer risk for children living in homes located near high-current power lines was double that for children living elsewhere.

Subsequent reviews of several of the studies of the health effects of electric and magnetic fields revealed a number of methodological deficiencies: no quantitative assessment of power-frequency field exposures, the sample populations were small.
Oak Ridge review: "there is no convincing evidence in the published literature to support the contention that exposures to extremely low frequency electric and magnetic fields generated by sources such as household appliances, video display terminals, and local power lines are demonstrable health hazards."

CASE STUDY

Indoor Radon and Lung Cancer

Radon is an odorless, colorless, tasteless gas that is produced by the natural decay of uranium and radium in the soil

The EPA estimates that 14,000 people in the United States die each year from lung cancer due to radon exposure.

The EPA recommends that if your home has annual radon concentrations at or above their guideline of 4 picocuries per liter (pCi/l) steps should be taken to reduce the radon level to below 4 pCi/l.

Radon levels can be readily lowered for about $500 to $2500

Average annual effective dose of ionizing radiation to the US public (exclusive of contribution from cigarettes)
	Annual Dose
Source	mSv	mrem
Natural sources Radon Cosmic, terrestrial, internal	2.0 1.0	200 100
Medical X-ray diagnosis Nuclear medicine	0.39 0.14	39 14
Consumer products	0.10	-10
Occupational	-0.01	-1
Nuclear fuel cycle	<0.001	<0.1
TOTAL	3.6	360

Cancer is a preventable illness

Reduced exposure to tobacco smoke, including environmental tobacco smoke, represents the first priority;

Alcoholic beverages should be consumed only in moderation, especially by smokers and by women (because alcohol intake may be involved in the etiology of breast cancer)

With respect to diet, increased consumption of vegetables, fruits, legumes, grains, reduced of red meat, animal fat, refined carbohydrates, and salt, greater use of plant oils as added fats
Reduction of excess energy intake in early life, avoidance of obesity in adult life, and increased physical activity throughout life are also desirable;

Avoidance of exposure to ultraviolet radiation, prudent use of potentially carcinogenic medical products and procedures, strict control of occupational exposures, sound environmental policies with strict enforcement, and continuous scrutiny of food additives and contaminants can also contribute to cancer prevention, but only to a small degree compared to the previous factors