Risk of cancer/ illness from asphalt

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Science says cancers and illness are linked to asphalt and hot asphalt fumes:
A powerpoint presentation on health and asphalt is available as an attachment at the bottom on this page.
There is a growing list of scientific papers that conclude exposure to hot asphalt emissions can significantly increase the incidence of many types of cancers above background.
There are no studies on children near asphalt plants, although there are various reasons (age, metabolic rate, body proportions, activity levels, growth rates) why children can be more susceptible to carcinogens than adults.
Like many long term studies on cancer, it may take a generation or so before we are aware of the full consequences and dangers of exposure to certain chemicals from asphalt plants. We expect the evidence for asphalt to lag several decades behind that for cigarette smoking (only recently did "big tobacco" stop refuting the health risks from smoking). Many new scientific papers now find a connection between cancer and asphalt, but some of the early and some current studies do not detect associations or strong associations.
It is universally agreed that exposure to chemicals in asphalt causes cancer in animals. Components of asphalt fumes, including benzene are highly carinogenic (we even know how these chemicals biologically induce cancer). Overall, the fact that we are now seeing evidence of increased cancer risk in humans from a number of studies on asphalt is troubling and points to even stronger associations as populations age and we get more data. 
So if some papers say yes, and some no, about asphalt causing cancer in humans, which do we go with? Some studies say several fold increase, some say 10-50% increase in cancer rates. What do we do? Toss a coin, take a bet about our children's future? If we bet no effect, and find out that these negative papers were funded by asphalt industries, then we've failed to take a precautionary approach for our children. If we bet on low levels of cancer rates, then how many collateral deaths are worth it for the sake of having an asphalt plant close by?
Overall, all agree that asphalt fumes contain strongly carcinogenic material (Polycyclic aromatic hydrocarbons or PAHs). The disagreements seem to be over the level of exposure that causes a specific and public health risk. This is why the issue of still air over Kunda Park especially in winter is such an important issue, as the still air and temperature inversions will greatly magnify the concentration of carcinogens, and their risk. 
Not safe at any level?  

Agencies set "safe levels" such as 5 parts per billion in drinking water for benzene (benzene is a carcenogen produced by asphalt plants). However, biological researches are starting to understand there is no such thing as safe levels for some carcinogens like benzene because some carcinogens at any level can damage cells.  

Considering that the consequence could be very high (i.e. cancers and health), it is surprising that our government authorities have not undertaken a comprehensive health assessment of this proposal, including an up to date review of the literature, including epidemiological, biochemical, pharmacological, and molecular biology data, and have not sought expert advice from current leaders/scientists in the area (eg, the Boston Health Department and Boston Researchers like Prof. Mike McClean). This sort of review probably should be required under council's "duty of care".

Indeed, with this awareness of impact to health, some residents have asked Sunshine Coast Regional Council to exercise their duty of care to the residents and children and protect them from avoidable exposure to harmful carcinogens, in particular those emanating from the proposed Kunda Park Asphalt Plant. They have asked that council undertake a site specific health risk assessment for the community, for food shops, and commercial workers, and include the issue of temperature inversions in the study.

Tupper is a medical doctor with a divinity degree. He speaks about the medical and ethical threats an asphalt plant, quarry, and cement plant pose to the community.
Tupper Morehead
 Reference 1
  Hansen ES.
"Among persons aged 40 to 89 years, significant increases were seen for lung cancer (SMR 290, 95% CI 188-429), nonpulmonary cancer (SMR 200, 95% CI 141-276), and liver cirrhosis (SMR 467, 95% CI 188-962). Bronchitis, emphysema, and asthma also occurred in excess (SMR 207, 95% CI 95-393). In conclusion, the inhalation of bitumen fumes may have contributed to the elevated mortality from cancer and respiratory diseases among mastic asphalt workers."
ed: SMR is a mortality ratio, so a SMR of 290 is a 2.9 increase in the incidence of lung cancer, click here for more details 
  Reference 2
Randem BG et al 2004
"Lung cancer incidence was increased in all four countries"
Reference 3
Am. J. Ind. Med. 37:478-492, 2000. Published 2000 Wiley-Liss, Inc
Stern FB, Ruder AM, Chen G. 2000
"Statistically significant increased PMRs were found for cancers of the lung, bladder, esophagus, larynx, and cancers of other and unspecified sites (PMR = 130, CI = 112-149). CONCLUSIONS: The present study underscores the need to control airborne exposures to hazardous substances and especially to examine fall prevention efforts within the roofing industry."
 Reference 4
 Grethe et al. 2003
Am. J. Ind. Med.
"Results Lung cancer was found elevated. Lung cancer was found more elevated in workers first exposed in the 1950s and 1960s and in mastic asphalt workers (SIR = 4.2, 95% CI = 1.2, 10, based on four cases) and pavers (SIR = 1.4, 95% CI = 1.0, 1.9). Conclusions Risk of lung cancer was found enhanced among the asphalt workers."   
 Reference 5 

First draft prepared by Ms Joann A. Wess, Dr Larry D. Olsen, and Dr Marie Haring Sweeney, National Institute for Occupational Safety and Health, Cincinnati, Ohio, USA

World Health Organization, Geneva, 2004

symptoms of eye, nose, or throat irritation are reported by workers during open-air paving
These fumes have been shown to be mutagenic
asphalt fume condensates caused tumours
Acute effects of exposure to asphalt among workers in the various sectors of the asphalt industry include symptoms of irritation of the serous membranes of the conjunctivae (eye irritation) and the mucous membranes of the upper respiratory tract (nasal and throat irritation) and coughing.
Additional symptoms include skin irritation, pruritus, rashes, nausea, stomach pain, decreased appetite, headaches, and fatigue
Results from recent studies indicated that some workers involved in paving operations experienced lower respiratory tract symptoms (e.g., coughing, wheezing, and shortness of breath) and pulmonary function changes; bronchitis has also been reported.
mortality from lung cancer was increased among bitumen workers when compared with ground and building construction workers
showed a positive dose–response with lung cancer risk
investigators concluded that the exposure–response analyses suggest an association between lung cancer mortality and indices of average level of exposure to bitumen fumes
the analysis demonstrated an overall statistically significant excess of lung cancer among roofers
reported increases in risk of bladder cancer, stomach cancer, and leukaemia in workers generally classified as asphalt workers
Under various performance specifications, it is likely that asphalt fumes and paints contain carcinogenic substances.
Reference 6
Elizabeth Gehrman

"there are approximately 500,000 asphalt workers in the United States today who have significantly increased risk of lung, stomach, bladder, and nonmelanoma skin cancer "

Reference 7 
"The cancer mortality was significantly increased in asphalt workers"
Reference 8
Mariëtte Hooiveld
Toxicology and Industrial Health, Vol. 18, No. 9-10, 417-424 (2002)
"excess lifetime risk for lung cancer in this Dutch cohort of asphalt workers is above benchmark risks as applied by the Dutch Health Council"
 Reference 9
Molecular Carcinogenesis and the Molecular Biology of Human Cancer - Google Books Result
by David Warshawsky, Joseph R. Landolph, Joseph R ... - 2005
Reference 10 (other diseases than cancer)
Burstyn, Igor  et al
Epidemiology. 16(6):744-750, November 2005.
"We studied a relation between exposure to polycyclic aromatic hydrocarbons (PAH) and mortality from IHD (418 cases) in a cohort of 12,367 male asphalt workers from Denmark, Finland, France, Germany, Israel, The Netherlands and Norway.
exposure indices for benzo(a)pyrene were positively associated with mortality
occupational PAH exposure causes fatal IHD and demonstrate a consistent exposure-response relation for this association"
International Occupational Safety and Health Information Centre (CIS)

advises (regarding exposure to asphalt and asphalt fumes)"

"Fumes of this substance are possibly carcinogenic to humans"
"Do NOT take working clothes home"

Other related information on asphalt, benzene and cancer:
The Queensland State Environmental Protection Agency, in reviewing Allen’s application, stated “Emissions of odour, VOC, toxic air pollutants and particulates are the major issues from an asphalt plan”. Web ed: VOC are volatile organic compounds, and include aromatic hydrodcarbons like benzene.
The (US) Department of Health and Human Services (DHHS) has determined that benzene causes cancer in humans. Long-term exposure to high levels of benzene in the air can cause leukemia, cancer of the blood-forming organs. http://www.bt.cdc.gov/agent/benzene/basics/facts.asp


Not safe at any level
While agencies set "safe levels" such as 5 parts of benzene per billion (5 in 1,000,000,000) in drinking water, biological researches are starting to understand there is no such thing as safe levels for some carcinogens because some carcinogens at any level can damage cells.


It is well documented through numerous epidemiological studies that the principal human health hazards are bone marrow depression and leukaemia.
Some community groups suggest it is better to be safe than sorry regarding asphalt plants which may be a reasonable precautionary principle.
Is there enough evidence to say an asphalt plant is safe for children now and for the rest of their lives?

Another important study was conducted by the National Cancer Institute (NCI) in collaboration with the Chinese Academy of Preventive Medicine. Investigators followed almost 30,000 workers exposed to benzene in 233 factories in China, and a similar group of unexposed control workers. The large sample size permitted elevated risks to be detected at low levels of exposure. This study suggested an increased risk of leukemia in workers exposed to less than 10 ppm (parts per million).

These and other epidemiologic studies of benzene show a fairly consistent excess risk to exposed workers of leukemia, and suggestions of excesses in other blood and bone marrow cancers as well.

What Does the Animal and Laboratory Evidence Say?

The human data are supported by animal studies. There is sufficient evidence for the carcinogenicity of benzene in experimental animals. Key animal studies support the finding of an excess risk of leukemia in humans from exposure to benzene by inhalation and ingestion. The details of these studies have been reviewed and found to support the association between benzene and cancer.

Benzene has been shown to induce chromosomal aberrations, or changes, in mammalian cells in vitro (outside a living organism). In vivo (within a living organism) studies have shown that benzene exposure leads to chromosome changes in bone-marrow cells. Such changes are commonly found in human leukemia cells.




How benzene works

Benzene, or benzolis an organic chemical compound and a known carcinogen with the molecular formula C6H6. Benzene is an aromatic hydrocarbon. The term 'aromatic' was derived from the fact that many of the compounds have a sweet scent. The configuration of six carbon atoms in aromatic compounds is known as a benzene ring, after the simplest possible such hydrocarbon, benzene.

Benzene works by causing cells not to work correctly. For example, it can cause bone marrow not to produce enough red blood cells, which can lead to anemia. Also, it can damage the immune system by changing blood levels of antibodies and causing the loss of white blood cells.

  • The seriousness of poisoning caused by benzene depends on the amount, route, and length of time of exposure, as well as the age and preexisting medical condition of the exposed person.

Long-term health effects of exposure to benzene

  • The major effect of benzene from long-term exposure is on the blood. (Long-term exposure means exposure of a year or more.) Benzene causes harmful effects on the bone marrow and can cause a decrease in red blood cells, leading to anemia. It can also cause excessive bleeding and can affect the immune system, increasing the chance for infection.
  • Some women who breathed high levels of benzene for many months had irregular menstrual periods and a decrease in the size of their ovaries. It is not known whether benzene exposure affects the developing fetus in pregnant women or fertility in men.
  • Animal studies have shown low birth weights, delayed bone formation, and bone marrow damage when pregnant animals breathed benzene.
  • The Department of Health and Human Services (DHHS) has determined that benzene causes cancer in humans. Long-term exposure to high levels of benzene in the air can cause leukemia, cancer of the blood-forming organs.
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Wayne Knibb,
Oct 19, 2008, 4:23 PM