Unit V Literature Review

 PROFESSIONAL SAFETY PSJ 41

The Underestimated Impact of Carcinogens in the Workplace By Connie Muncy

WWORLDWIDE, WORKPLACE CANCER PREVENTION has a signifi-cantly lower profile than workplace injury prevention despite a real and present need to elevate the profile of workplace cancer prevention globally. Many organizations worldwide attest to the high number of annual work-related cancers and cancer deaths, but then say that workplace cancer statistics are underestimated, that the problem is worse than statistics bear out, and that the

profile of workplace cancer prevention must be elevated. This apparent consensus begs a few questions. Supported by rep- utable resources from around the globe, this article explores several questions:

•What is occupational cancer, how prevalent is it and what are its causes?

•Why does cancer prevention have a much lower profile than workplace injury prevention?

•Are current occupational exposure limits (OELs) for carcinogens adequate?

•What are the problems associated with cancer cluster investigations, how reliable are they and what must be done to im- prove them?

•What must be done to advance the cause of workplace cancer prevention?

•What are some valuable resourc- es available to those who want to help advance the cause of workplace cancer prevention?

What Is Cancer & How Prevalent Is It? According to the U.S. Department of

Health and Human Services’ 14th Report on Carcinogens, cancer affects almost everyone’s life, either directly or indirect- ly; approximately one out of two men and

one out of three women living in the U.S. will develop cancer at some point in his/her lifetime (NTP, 2016). According to Amer- ican Cancer Society (ACS, 2017a), cancer is the second most common cause of death in the U.S. and accounts for nearly one of every four deaths. World Health Organization (WHO, 2017) estimates that worldwide in 2012 (the most recent data), 14 million new cancer cases and 8.2 million cancer-related deaths occurred, and that the number of new cancer cases is expected to rise by about 70% over the next 20 years.

KEY TAKEAWAYS •Workplace can- cer statistics from around the world reflect the serious- ness of the global workplace cancer situation and reveal which worker groups are at greatest risk. •This article discusses why workplace cancer prevention has a lower profile than workplace injury and what actions must be taken to elevate the profile of workplace cancer prevention. •It also discusses important factors that influence work- place cancer cluster investigations.

OCCUPATIONAL HEALTH Peer-Reviewed

FIGURE 1 MOST COMMON CANCERS IN THE U.S.

Note. Adapted from Report on Carcinogens, 14th Edition, by National Toxicology Program, 2016.

REAL & PRESENT DANGER

VI TA

N O

VS KI

/I ST

O CK

/G ET

TY IM

AG ES

P LU

S

42 PSJ PROFESSIONAL SAFETY JULY 2018 assp.org

ACS (2017b) defines cancer as “a group of diseases which cause cells in the body to change and grow out of control.” This class of diseases is comprised of more than 200 different types of cancer; each is classified by the type of cell that is initially affect- ed. Figure 1 (p. 41) depicts the 10 most common cancers in the U.S. and their prevalence.

Canada’s Occupational Cancer Research Center provides simi- lar pie charts that illustrate the distribution of workplace cancers by type for manufacturing, construction and government ser- vices industry in Ontario:

•Manufacturing: mesothelioma, 44%; lung cancer, 42%; cancer of the large intestine, 3%; esophageal cancer, 2%; leukemia, 1%; bladder cancer, 1%; other cancers, 7%.

•Construction: mesothelioma, 61%; lung cancer, 30%; esoph- ageal cancer, 2%; cancer of the large intestine, 2%; leukemia, 1%; other cancers, 4%.

•Government services industry: cancer of the large intestine, 19%; mesothelioma, 18%; lung cancer, 11%; brain cancer, 11%; esophageal cancer, 9%; kidney(s) cancer, 8%; leukemia, 6%; blad- der cancer, 5%; lymphoma, 4%; other cancers, 9% (Del Bianco & Demers, 2013).

Medical News Today (MNT, 2016) clarifies the damaging na- ture of cancer:

Cancer is ultimately the result of cells that uncontrol- lably grow and do not die. Normal cells in the body follow an orderly path of growth, division and death. Programmed cell death is called apoptosis, and when this process breaks down, cancer begins to form. Unlike regular cells, cancer cells do not experience programmatic death and instead continue to grow and divide. This leads to a mass of abnormal cells that grows out of control.

Cancer harms the body when altered cells divide un- controllably to form lumps or masses of tissue called tumors (except in the case of leukemia where cancer prohibits normal blood function by abnormal cell division in the blood stream). Tumors can grow and interfere with the digestive, nervous and circulatory systems, and they can release hormones that alter body function.

More dangerous, or malignant, tumors form when two things occur:

1) a cancerous cell manages to move throughout the body using the blood or lymphatic systems, de- stroying healthy tissue in a process called invasion;

2) that cell manages to divide and grow, making new blood vessels to feed itself in a process called an- giogenesis. So, what causes cells to uncontrollably grow and become can-

cerous? According to MNT (2016), cells can experience uncon- trolled growth if mutations to DNA exist. Cancer occurs when a cell’s gene mutations make the cell unable to correct DNA damage and unable to “commit suicide.” Some causes of cancer include:

•Being born with certain genetic mutations. •An increase in the number of possible cancer-causing muta-

tions in our DNA that occurs with age (i.e., age is an important risk factor for cancer).

•Eight viruses, known as oncoviruses (e.g., Epstein-Barr virus, Hepatitis B and C, HIV, Kaposi sarcoma-associated herpesvirus) (AIHA, 2016; NTP, 2016).

•Certain bacteria (e.g., h pylori) and funguses (e.g., aflatoxins) (NTP, 2016).

•Carcinogens, a class of substances that are directly responsible for damaging DNA, promoting or aiding cancer. When a body is exposed to carcinogens, free radicals are formed that try to steal electrons from other molecules in the body. These free radicals damage cells and affect their ability to function normally.

•Ionizing radiation (e.g., gamma rays, X-rays). •Ultraviolet radiation (A, B, C). •Tobacco (smoke, smoking, smokeless). •Alcoholic beverage consumption increases cancer risk in

multiple ways: a) metabolizing ethanol in alcoholic drinks to acetaldehyde,

which is a toxic chemical and a probable human carcinogen; ac- etaldehyde can damage both DNA and proteins;

b) generating reactive oxygen species (chemically reactive molecules that contain oxygen), which can damage DNA, pro- teins and lipids (fats) through oxidation;

c) impairing the body’s ability to break down and absorb var- ious nutrients that may be associated with cancer risk, including vitamin A, nutrients in the vitamin B complex, vitamins C, D, E and carotenoids;

d) increasing blood levels of estrogen, a hormone linked to the risk of breast cancer;

e) alcoholic beverages may also contain various carcinogen- ic contaminants that are introduced during fermentation and production, such as nitrosamines, asbestos fibers, phenols and hydrocarbons (NCI, 2013).

•Shift work. In 2007, International Agency for Research on Cancer (IARC) concluded that shift work is “probably carcino-

Carcinogen Agriculture Mining Manufacturing Electrical Construction Trade Transportation Finance Services

TABLE 1 PROPORTION OF THE WORKFORCE EXPOSED TO CARCINOGENS

Note. Proportion of the workforce exposed to carcinogens, by industry sector. Adapted from Occupational Carcinogens: Assessing the Environ- mental Burden of Disease at National and Local Levels, Table 4, by T. Driscoll, K. Steenland, A. Prüss-Üstün, et al, 2004, Geneva, Switzerland: World Health Organization.

assp.org JULY 2018 PROFESSIONAL SAFETY PSJ 43

genic to humans” (Straif, Baan, Grosse, et al., 2007). The evi- dence is strongest for breast cancer, although the risk of prostate and colorectal cancer may also be increased by shift work. Re- cently, 38 women with breast cancer who had previously worked night shifts for at least 20 years were compensated by the Danish National Board of Industrial Injuries (Moukangoe, Jansen van Rensburg, 2015). Possible mechanisms by which shift work in- creases the risk of cancer under study include:

a) Light at night suppresses the production of melatonin, which has direct and indirect anticancer effects.

b) Sleep disruption stimulates the hypothalamic-pituitary axis to re- lease glucocorticoids, which results in depression of immune function.

c) Phase shift, in which the peripheral rhythms of functions such as digestion are out of phase with central sleep and wake rhythms. This may result in changes in the control of cell and tissue proliferation.

d) Shift work may result in changes in lifestyle factors such as smoking, diet, alcohol use or exercise.

e) Decreased production of vitamin D. •Anything else that suppresses or weakens the immune system

(i.e., inhibits the body’s ability to fight infections and increases the chance of developing cancer).

Principal Carcinogenic Occupational Exposures Occupational cancer is caused wholly or partly by exposure to

a cancer-causing agent (carcinogen) at work, or by a particular set of circumstances at work (IOSH, 2017a). These agents may be chemical, biological or physical in nature.

Many factors play a role in the development of cancer. The im- portance of these factors varies depending on the type of cancer. A person’s risk of developing a particular cancer is influenced by a combination of factors that interact in ways that are not fully understood. Some of the factors include:

•personal characteristics, such as age, sex, and race; •family history of cancer;

•an individual’s susceptibility to a substance;

•diet and personal habits, such as cigarette smoking and alcohol consumption;

•the presence of certain medical conditions or past medical treatments, including chemotherapy, radiation treat- ment or some immune-system suppressing drugs;

•exposure to cancer-causing agents in the environment (e.g., sunlight, radon gas, air pollu- tion, infectious agents);

•the amount and duration of an exposure to cancer-caus- ing agents in the workplace (NIOSH, 2015).

Although everyday exposures to chemicals are usually too low to cause harmful health prob- lems, exposure in the workplace can be more serious. Chemical exposures in the workplace can happen at high levels and over long periods. That is why some

jobs require that employees wear protective clothing, equipment or respirators. Companies are supposed to notify employees of a potential danger to their health (ASTDR, 2017).

OELs for carcinogens have been established by various agen- cies including OSHA, NIOSH and ACGIH; however, one prob- lem with setting OELs for carcinogens, unlike other hazardous chemicals that have an identified “virtually safe dose,” is that there is not always a threshold below which there is no adverse health effect. For example, carcinogens always cause a risk no matter how low the dose is. Thus, exposure to workplace car- cinogens below an established OEL is no guarantee that cancer will not result.

Various agencies around the world publish lists of occupation- al carcinogens. For example, NIOSH (2018a) has published a list of substances considered to be potential occupational carcino- gens and IARC lists more than 50 substances that are known or probable causes of workplace cancer, and more than 100 other possible substances (IOSH, 2017a).

WHO (Driscoll, Steenland, Prüss-Üstün, et al., 2004) pub- lished data indicating the proportion of the workforce exposed to carcinogens by industry sector (Table 1).

Victoria Trades Hall Council Australia (VTHCA, 2015a) com- piled a list of examples of principal carcinogenic occupational exposures together with associated conditions (Table 2).

Canadian Center of Occupational Health and Safety (CCOHS, 2018b) reports the most common types of occupational cancer are lung cancer, bladder cancer and mesothelioma. The group has published an extensive list of examples of occupations and occupational groups that are more likely to have been exposed to carcinogens (CCOHS, 2018c), excerpted in Table 3 (p. 44).

Great Britain reports that almost half (48%) of occupational cancer deaths are in construction workers with the main carcin- ogens associated with those industries being asbestos, respirable crystalline silica, solar radiation (sun exposure) and diesel ex- haust emissions (IOSH, 2018b).

TABLE 2 OCCUPATIONAL CAUSES OF CANCER

Note. Adapted from Cancer: What Causes It? by Victoria Trades Hall Council Australia, 2015.

44 PSJ PROFESSIONAL SAFETY JULY 2018 assp.org

Global Occupational Cancer Statistics There is no disputing that statistics from around the world

bear out the fact that occupational cancer is a prevalent and se- rious problem and, more importantly, that the total numbers are significantly underestimated.

NIOSH (2015) asserts that 3% to 6% of all cancers worldwide are caused by exposures to carcinogens in the workplace with es- timated annual medical costs associated with occupational can- cers to be $4.3 billion in the U.S. alone. Using cancer incidence numbers in the U.S., this means that in 2012 (the most recent year available), there may have been as many as 91,745 new cancer cases that were caused by past exposure in the workplace. NIOSH (2015) says “this is probably an underestimate.”

Takala (2015) cites a 2009 study that found the proportion of can- cer deaths attributable to occupational causes in Finland was 8.3% (13.2% among males) and in the U.K. it was 5.3% (8% among males).

In Australia, the scientific consensus is that on average, 8% of cancer deaths are work-related. For some cancers, such as bladder and lung cancer, the figure is well above 10% (VTHCA, 2015b). In fact, Fritschi and Driscoll (2006) found that one in 10 male workers and one in 50 female workers developed cancer every year due to workplace exposure to carcinogens.

International Labor Organization (ILO) estimates the human toll at over 600,000 deaths a year, one death every 52 seconds. ILO calculates that approximately 13% of all cancers in developed countries are the re- sult of preventable, predictable workplace exposure (VTHCA, 2015a).