10 facts you should know about
occupational carcinogens
Carcinogens are the “time bombs” of hazardous substances in the workplace.
But many substances do not develop their deadly effect until years after exposure. It’s a risk for the worker that is often underestimated – and represents
an enormous challenge for industrial hygienists. The good news is that occupational cancer can be prevented through monitoring and protective measures.
© Drägerwerk AG & Co. KGaA
1
10 FACTS ABOUT OCCUPATIONAL CARCINOGENS
1. Cancer in the workplace is twice as common as occupational accidents.
Every year,
660,000 deaths occur
worldwide due to work-related cancer.*
* Nenonen N., Hämäläinen P., Takala J., et al. (2014) Global estimates of occupational accidents and fatal work-related diseases in 2014,
Singapore, Workplace Safety & Health Institute. http://goo.gl/UlZorD
2. Plastic is a deadly threat.
For many years, vinyl chloride was considered to be safe. This compound of carbon, hydrogen and chlorine is a raw material used in the
production of PVC. In 1974, seven cases of severe (and very rare)
liver cancer were found in individuals who worked at a PVC plant in
Louisville, Kentucky. Five of the afflicted workers, all of whom had
worked with vinyl chloride for 20 years, had already died.1
It is only because of the efforts of the National Institute for Occupational Safety and Health (NIOSH) and the energetic probing of a
few scientists that the connection between cancer and vinyl chloride
became known. The authorities reacted quickly: In 1974 OSHA established a threshold limit for vinyl chloride that was 500 times more
rigorous that before. As a result, liver tumors in workers as a result
of vinyl chloride exposure have not occurred since.
3. Carcinogens are toxic to cells.
Carcinogenic substances are a subgroup of toxic agents that have
the potential to cause cancer in living tissues. Carcinogen exposure
can occur from the inhalation, ingestion, or absorption of many different types of substances in our bodies.
Carcinogens may increase the risk of cancer by altering cellular
metabolism or damaging substances such as proteins, ribonucleic
acids, and especially DNA directly in cells – which interferes with
biological processes. This causes genetic abnormalities to develop
in the normal cell. With cancer, cells go out of control, multiply without order, and invade and destroy the surrounding tissue.
The changes in a cell’s DNA are called genetic “blueprint”. Some of
these changes may be inherited from our parents and grandparents.
If, and to what degree, a carcinogen actually causes cancer is highly
dependent on each individual organism.
© Drägerwerk AG & Co. KGaA
2
10 FACTS ABOUT OCCUPATIONAL CARCINOGENS
4. Substances are acutely toxic at first, then
carcinogenic.
Exposure time is a critical factor for carcinogenic substances in
the workplace. Most carcinogens do not develop their carcinogenic
effect in a brief exposure. However, they can cause toxic effects
in other ways. For instance, acute inhalation of chromium IV compounds starts by causing nausea, but can lead to caustic effects on
the skin and mucous membranes.
For the threat of cancer to exist, long-term exposure to a carcinogen
is often necessary. For example, many workers who were exposed
to asbestos for a prolonged period developed a particular form of
lung cancer called mesothelioma. It takes at least 20 years – and in
many cases 40 years – before the cancer appears. Since asbestos
is no longer used in the construction industry, no new cases of occupational mesothelioma are expected to occur in the United States
after 2042.2
5. Carcinogens pose a lifelong risk.
Carcinogens do not cause cancer in every case. Substances labeled
as carcinogens may have different levels of cancer-causing potential.
It is true that a large amount of a cancer-causing substance leads
to cancer much more frequently. But even very small doses can
develop a harmful effect – although the probability is clearly lower.
The risk of developing cancer due to contact with a carcinogen
remains throughout one‘s lifetime, since in many cases cell damage
does not develop until years after contact with the substance. And
for any particular person, the risk of developing cancer depends on
many factors – including how they are exposed to a carcinogen,
the length and intensity of the exposure, and the person’s genetic
makeup.
6. O
ccupational cancer is more common than previously thought.
Approximately 3 to 6%
of all cancer cases are
due to substances in the
workplace 3,4
Europe: More than
100,000 deaths every
year are due to job-related cancer 5
7. A
mouse is not a human, and vice versa.
Detecting the cancer-generating property of a chemical agent is
often very difficult. It is not ethical to test a substance by exposing
people to it and seeing if they get cancer. That’s why scientists must
use other types of tests – which may not always give clear answers.
For example, it is not easy to deduce whether or not a substance is
carcinogenic from animal testing.
Rodents and humans often react to chemical substances in entirely
different ways. 19 out of 20 test substances that are considered
safe for humans cause cancer in rodents.7 However, of 19 sub-
USA: Each year, there
are as many as 90,000
new cases of cancer
and 30,000 work-related
deaths globally 6
stances known to cause cancer in humans, only seven prove to
be carcinogenic in rodents.8 Here’s another example: The artificial
sweetener saccharine gives rise to bladder cancer in male rats, but
not in female rats – or humans.9
This is why multiple sources should be used and combined, such as:
– Lab studies in animals and examinations
– Tests and lab studies of human cell cultures
– Human case and epidemiologic studies and observations from
practice
© Drägerwerk AG & Co. KGaA
3
10 FACTS ABOUT OCCUPATIONAL CARCINOGENS
8. T he chemical industry is subject to a
particularly high risk.
In the United States, most occupations don’t present a major
risk for developing cancer. However, there are some industries –
such as certain types of chemical manufacturing, mining, coal
production, and iron and steel founding – in which cancer risk is
higher for certain workers.
WHEN IS A SUBSTANCE CALLED
CARCINOGENIC?
When the evidence is conclusive, the substance is
labeled as a carcinogen. When the available evidence
is compelling but not felt to be conclusive, the substance may be considered to be a probable carcinogen. But in some cases, there simply isn‘t enough
information to be certain one way or the other.
Nasopharynx
Lung
Formaldehyde
Asbestos, crystalline silica,
diesel engine exhaust,
arsenic, chromium, nickel
Larynx
Acid mists, asbestos
Liver and biliary tract
Trichloroethylene, vinyl chloride
Mesothelioma
Asbestos
Bladder
Aromatic amines
Ovary
Asbestos
Leukemia
Benzene, formaldehyde
Skin
mineral oils, polycyclic
aromatic hydrocarbons
Non-hodgkin lymphoma
trichloroethylene
Graphic modified according to Siemiatycki, J, et al. Listing occupational carcinogens. Environmental Health Perspectives, Vol. 112, no. 15 (2004). p. 1447-1459
© Drägerwerk AG & Co. KGaA
4
10 FACTS ABOUT OCCUPATIONAL CARCINOGENS
9. Carcinogens are classified according to potential harm.
Various organizations test chemicals for their cancer-causing potential. Chemicals, mixtures, substance groups, and other carcinogens are
divided into different groups, as follows:
IARC*
Group 1: ACGIH*
Carcinogenic to humans
Group A1: Carcinogenic to humans
Group 2A:
Probably carcinogenic to humans
Group A2:
Probably carcinogenic to humans
Group 2B: Possibly carcinogenic to humans
Group A3: Confirmed carcinogenic to animals,
unconfirmed relevance to humans
Group A4:
Not classifiable as human carcinogen
Group A5:
Not carcinogenic to humans
Group 3:
Group 4:
Not classifiable with regard to
carcinogenicity to humans
Probably not carcinogenic
to humans
* International Agency for Research on Cancer (IARC)/Division of the World
Health Organization
occupational exposure limits bring
10. Binding
greater safety.
Most people know that asbestos is a potential cancer threat in
the workplace. But what about trichloroethylene, benzene, or the
various chromium compounds? The European Trade Institute has
listed 71 cancer-causing substances that constitute 80% of the
carcinogens to which people may be exposed in the workplace.
Binding occupational exposure limits are being mandated for at
least 50 substances that cause work-related cancer.10
Conclusion:
Occupational cancers can be prevented.
All types of occupational cancer are preventable. To minimize
the risk of cancer caused by on-the-job exposure, substances
considered to be carcinogenic should not be used at all. But that
* American Conference of Governmental Industrial Hygienists (ACGIH)
is not always possible. However, taking appropriate measures can
significantly reduce the health danger to workers. Strong regulatory
control – including occupational exposure limits, worker education,
and constant attention to safe practices – are needed to minimize
workplace exposure to carcinogens.
However, occupational exposure limits are only one component of
better work and health safety because these substances can still
represent a threat to health. Besides minimizing exposure to potentially carcinogenic substances, appropriate protective and safety
gear is important. In addition, all employees who handle carcinogenic substances should have occupational training and medical
supervision.
© Drägerwerk AG & Co. KGaA
5
10 FACTS ABOUT OCCUPATIONAL CARCINOGENS
Occupational cancer was known about as far back as 1755
1895:
2011:
Identification of 2-naphthylamine
as cause of bladder cancer in
dye plant workers
1755:
Recognition of testicular
cancer in chimney sweeps
as an occupational cancer
Classification of formaldehyde as carcinogenic
1974:
Recognition of vinyl chloride as
the cause of liver tumors in the
plastics industry
IMPRINT
USA
Dräger Safety AG & Co. KGaA
Revalstraße 1
23560 Lübeck
www.draeger.com
© Drägerwerk AG & Co. KGaA
6
10 FACTS ABOUT OCCUPATIONAL CARCINOGENS
SOURCES :
1Mundt, KA, Dell, LD, Austin, RP et al. Historical cohort study of 10,109 men in the North American vinyl chloride
industry, 1942–72: update of cancer mortality to 31 December 1995. Occup Environ Med. 2000; 57: 774–781
2Price B, Ware A. Time trend of mesothelioma incidence in the United States and projection of future cases: an update
based on SEER data for 1973 through 2005. Crit Rev Toxicol. 2009;39(7):576-88
3 Straif K. The burden of occupational cancer. Occupational and Environmental Medicine. 2008;65(12):787-788
4Driscoll T, Takala J, Steenland K, et al. 2005. Review of estimates of the global burden of injury and illness due to occupational exposures. Am J Ind Med 48:491-502
5Figures of the European Trade Institute (ETUI) at https://www.etui.org/Topics/Health-Safety/Occupational-cancers
(Accessed: October 31, 2016)
6Centers for Disease Control and Prevention. U.S. Cancer Incidence Statistics: an Interactive Atlas. https://nccd.cdc.
gov/DCPC_INCA/. (Accessed October 29, 2015)
7Ennever FK, Noonan TJ, Rosenkranz HS. The predictivity of animal bioassays and short-term genotoxicity tests for
carcinogenicity and non-carcinogenicity to humans. Mutagenesis. 1987 Mar;2(2):73-78
8Salsburg, D. The Lifetime Feeding Study in Mice and Rats - An Examination of Its Validity as a Bioassay for Human
Carcinogens. Fundamental & Applied Toxicology 1983;3:63-67
9National Cancer Institute: What have studies shown about a possible association between specific artificial sweeteners and cancer? At https://www.cancer.gov/about-cancer/causes-prevention/risk/diet/artificial-sweeteners-factsheet#q2 (Accessed: October 31, 2016)
10Wriedt H. Carcinogens that should be subject to binding limits on workers’ exposure. 2016. At http://www.etui.org/
Publications2/Reports/Carcinogens-that-should-be-subject-to-binding-limits-on-workers-exposure (Accessed: October
31, 2016)
For an extensive list of potentially carcinogenic substances that includes IARC, ACGIH and OSHA classifications, go to:
https://www.ehs.uci.edu/programs/sop_library/CARCIN.pdf
© Drägerwerk AG & Co. KGaA
7