Exposure to industrial chemicals and radiation has contributed more than previously thought to the rising incidence of breast cancer, according to a new report. State of the Evidence 2004: What is the connection between the environment and breast cancer, released by two US advocacy groups on breast cancer, says fewer than one in 10 cases of breast cancer occurs in women born with a genetic predisposition for the disease. The report amasses new evidence from 21 research studies published since February 2003, adding to existing evidence linking toxins in the environment to breast cancer.

Breast Cancer Fund State of the Evidence webpages. Risks 178.

The risk of ovarian cancer increases with increased exposure to diesel exhaust at work, according to a new study. Writing in the International Journal of Cancer, a research team from the Finnish Institute of Occupational Health describe how they assessed the risk a variety of cancers possibly linked to engine exhaust exposure. These included leukaemia and cancers of the throat, ovaries, testes, kidney and bladder. It found individuals with the highest cumulative exposure to diesel exhaust had more than 3.5 times the risk of ovarian cancer.

Johannes Guo, Timo Kauppinen and others. Risk of esophageal, ovarian, testicular, kidney and bladder cancers and leukemia among Finnish workers exposed to diesel or gasoline engine exhaust, International Journal of Cancer, volume 111, issue 2, pages 286-292, 2004.

In 2004, North American firefighters’ union IAFF published a list of ‘presumptive laws’ in Canadian provinces approving workers’ compensation for firefighters’ cancers. The report noted: “This document you are reading is designed to illustrate what a number of Canadian provinces have done or are doing in recognition of cancer as an occupational disease among fire fighters; to show the proliferation of presumptive cancer legislation across Canada and highlight some of the research that has led to these legislative advances. Ultimately, it’s only fair that fire fighters and their survivors are compensated for cancers that they suffer as a direct result of their occupation. And that’s why presumptive cancer legislation for fire fighters is… “an Act of fairness.”

Presumptive Cancer Legislation for Professional Fire Fighters: An Act of fairness, IAFF, September 2004.

Asbestos producer nations have blocked the addition of chrysotile (white) asbestos to the UN list of highly dangerous substances that cannot be exported to developing countries without their knowledge and agreement.

Hazards update, 18 September 2004.

A 2004 paper in the journal Environmental Health Perspectives reported that this included 28 definite, 27 probable and 113 possible human occupational carcinogens. By contrast, the influential 1981 Doll/Peto paper, which for over two decades was the most commonly cited estimate of the contribution of occupation to cancer incidence, only considered cancer risks posed by a list of 16 substances or industries. The report notes the (now widely cited) “tables should be useful for regulatory or preventive purposes and for scientific purposes in research priority setting and in understanding carcinogenesis.

Siemiatycki J, Richardson L, Straif K and others. Listing occupational carcinogens. Environmental Health Perspectives, volume 112, number 15, pages 1447-1459, 2004.

Children fathered by men who have been exposed to polycyclic aromatic hydrocarbons (PAH) at work have a greatly increased chance of developing brain tumours, researchers have found. The researchers used occupational data to estimate parental PAH exposure during the five years before the children’s birth. The data came from population-based studies carried out in seven countries, and compared 1,218 cases of childhood brain tumour and 2,223 matched ‘control’ children without cancer. Paternal occupational PAH exposure increased the odds a child developing any type of brain tumour by 30 per cent, the researchers report in the American Journal of Epidemiology.

S Cordier, C Monfort, G Filippini and others. Parental Exposure to Polycyclic Aromatic Hydrocarbons and the Risk of Childhood Brain Tumors: The SEARCH International Childhood Brain Tumor Study, American Journal of Epidemiology, volume 159, number 12, pages 1109-1116, 2004.

First IBM made sure an analysis of its own workforce cancer records was ruled inadmissible in court, after researchers claimed they showed a clear cancer excess (Risks 125). Now a major academic publisher is refusing to publish the analysis and is facing an embarrassing contributors boycott as a result. IBM says the paper is flawed but denies putting pressure on the publishing group Elsevier to stop the paper’s publication. Dr Joe LaDou of the University of California at San Francisco, the guest editor of a special issue of Clinics in Occupational and Environmental Medicine on microelectronic industry health and safety, has joined other contributors in the protest which has seen them all withdraw their papers until the contentious article is reinstated.

The Observer, 20 June 2004. Risks 162.

Secondhand smoke causes cancer – and the evidence is so compelling the International Agency for Research on Cancer (IARC) says it ‘puts a final stop to all controversies fuelled at various degrees by the tobacco industry.’ IARC’s Monograph on tobacco smoke and involuntary smoking was prepared by a scientific working group of 29 experts from 12 countries, which reviewed all published evidence related to tobacco smoking and cancer, and which concluded both smoking and exposure to secondhand smoke should be classified as ‘Group 1’ carcinogens, definitely causing cancer in humans.

IARC Monographs on the evaluation of carcinogenic risks to humans, volume 83, Tobacco smoke and involuntary smoking, 2004. Risks 161.

Formaldehyde, a chemical to which an estimated 1 million European Union workers are exposed at work, definitely causes cancer in humans, officials say. The International Agency for Research on Cancer (IARC) has upped its assessment of the chemical to ‘Group 1’. Previous evaluations, based on the smaller number of studies available at that time, had concluded that formaldehyde was probably carcinogenic to humans, but new information from studies of persons exposed to formaldehyde has increased the overall weight of the evidence. Based on this new information, an expert working group has determined that there is now sufficient evidence that formaldehyde causes nasopharyngeal cancer in humans, a rare cancer in developed countries. The move follows protracted arguments between the chemical industry – which played down the link – and health advocates, who argued the commonly used industrial chemical should be subject to stringent controls.

IARC working group, 2-9 June 2004. IARC news release, 15 June 2004.

A double ‘relative risk’ (RRx2) test used by courts and government agencies to determine if a cancer is occupational ‘is useless’, top US scientists have said. The RRx2 system  requiring a condition to be twice as common in the affected group than in the general population is used by lawyers and state compensation agencies to set a cut off below which compensation will not be paid. But Richard Clapp and David Ozonoff, writing in 2004 in the American Journal of Law and Medicine, note: “To an epidemiologist using generally accepted methods of epidemiological analysis, however, a RR of 2.0 or more is not necessary in order to show that a causal link is ‘more likely than not’ present in the study population. In our experience as epidemiologists who participate in the legal process as experts, some attorneys maintain and some courts believe that a RR of 2.0 is needed before one can conclude from an epidemiological study that the outcome was ‘more likely than not’ due to the exposure. The arithmetic basis of this proposition would seem quite transparent, but like many things in the subtle and complex science, there are sound and accepted reasons why this argument is not valid. The reasons are both technical and ethical.” They note that the relative risks across a “usually hetrogenous” study group could mask much higher and genuine occupational risks in someone without few or none of other risk factors present in the group, leading to “a serious under-estimate of the effects of his or her exposure.” They add: “Without a specification of the underlying causation model, which in almost all cases is insufficiently known to allow an accurate calculation, or even any calculation, of the fraction of cases due to exposure, the doubling of the RR… is useless as a criterion for evidentiary admissibility.”

Clapp RW, Ozonoff D (2004). Environment and health: vital intersection or contested territory?  American Journal of Law and Medicine, volume 30(2-3), pages 189-215.