Leukemia

Leukemia is a cancer of the bone marrow and blood. The two primary types of leukemia are lymphocytic leukemia, which involves an increase of white blood cells called lymphocytes; and myelogenous leukemia (also known as myeloid or myelocytic leukemia), which involves an increase in white blood cells called granulocytes. Leukemia can be acute or chronic. Acute forms of leukemia progress rapidly, whereas chronic forms of leukemia progress slowly, leading to different approaches to diagnosis and treatment.

Lung Cancer, the Number One Cancer Killer

Each year, about 200,000 people in the United States are told they have lung cancer and more than 150,000 people die from this disease. Deaths from lung cancer represent about one out of every six deaths from cancer in the U.S.

Risk Factors
Research has found several causes and risk factors for lung cancer. A risk factor is anything that changes the chance of getting a disease. Lung cancer risk factors include :

1. Smoking.

Estimation of exposure

To estimate the proportion of workers exposed to carcinogens for lung cancer and leukaemia, we use the exposed proportions  of workers in the industrial sectors or occupations who were exposed to the carcinogens (from CAREX, a European survey described below in Section 5.2).  This was  the approach recently used in a global estimate of the disease burden (Ezzati et al., 2002; WHO, 2002; Concha-Barrientos et al., 2004).  However, should exposure data be available for the national or local level, they should be used instead of the CAREX data.  For the CRA project (Concha-Barrientos et al., 2004), routine employment data were used to determine the proportion of people in each industrial sector.  The exposed populations were then divided into high and low exposure groups.  This information was then combined with the CAREX data to estimate the proportion of workers exposed at high or low levels to the carcinogens.

Ideally, the above information should come from data assessed in the country or study area, particularly the first three requirements, but since this is not always possible values based on the global analysis can be used (Concha-Barrientos et al., 2004).

Choice of health outcomes

Work-related malignant conditions can arise from a variety of exposures, but we consider only the three  main documented occupational cancers: lung cancer, leukaemia and malignant mesothelioma.  Although other cancers are known to have occupational causes, there are not enough data on exposure and risk, and the number of cases are too few, for the data to be  included in this guide.  These other cancers
(and their causative agents) include:

1. bladder cancer (aromatic amines, benzidine dyes and methylene-bis-ortho-chloroaniline);
2. liver cancer (vinyl chloride);
3. nasal cavity and middle ear cancer (hardwood dust, chromium VI compounds, nickel compounds);
4. bone and articular cartilage cancer (ionizing radiation);
5. skin cancer (arsenic, by-products of distillation, ionizing radiation);
6. lung cancer (from passive smoke in the workplace).

In the comparative risk assessment (CRA) study of Concha-Barrientos et al. (2004), the criteria used to assess causal connections between exposures and outcomes of interest were a consistent relationship between the risk factor and the outcome across different studies and settings; and the strength of the evidence of the relationship.
Data sources were evaluated to assess the strength of the evidence linking specific cancers with exposure to chemical or physical agents.