Occupational Radiation Exposure and Glioma Risk: A Study Review

Introduction to Radiation as a Workplace Hazard

Radiation is a recognized workplace hazard, and there are two types of particular concern to industrial hygienists. Ionizing radiation is radiation capable of ionizing an atom — examples include x-rays and gamma rays. Non-ionizing radiation is a separate category that encompasses ultraviolet (UV) radiation, infrared radiation, static fields, radio frequencies, and extremely low frequency (ELF) fields (AIHA, 2014).

Overview of the Karipidis et al. Study on Glioma

Karipidis et al. (2007) examine the relationship between ionizing and non-ionizing radiation and glioma, a malignant cancer of the glial tissue in the nervous system. Gliomas represent 80% of all malignant brain tumors, and their exact cause remains unknown. Researchers have long suspected that radiation is a key causal factor, a suspicion that carries significant implications for occupational health. The study was published in the journal Occupational Medicine, one of the leading publications in the industrial hygiene field. This is a valuable area of research because, as evidence accumulates, findings may eventually be sufficiently conclusive for OSHA to establish formal exposure guidelines. Beyond regulatory action, employers may also wish to minimize their own liability and reduce radiation-related risk for their employees even in the absence of formal rules.

One reason the authors undertook this study was the observed fact that males are more frequently diagnosed with glioma, and it was hypothesized that occupational factors might help explain that disparity. Several prior studies had established that increased radiation exposure is a causal factor for brain tumors in general, but that data was not specific to glioma and did not isolate occupational causes. This particular study aimed to increase the sample size, focus on a specifically serious tumor type, and examine different forms of occupational radiation exposure separately.

Study Methodology and Measurement Tools

The authors examined cases in Melbourne, reviewing the occupational histories of each subject and evaluating the level of radiation exposure likely to result from those jobs. A control group was included in the study design. To determine occupational radiation exposure across the various jobs represented in the sample, the researchers used the Finnish Job Exposure Matrix, a well-established tool for assessing workplace exposures based on occupation type.

Beyond this matrix, there are a number of devices available to measure radiation exposure of different types. The International Atomic Energy Agency recommends dosimeters as a means of measuring ionizing radiation exposure for workers at nuclear power plants. Other instruments are designed to measure electric and magnetic fields, which are sources of non-ionizing radiation.

Conclusion

The article provides background into how radiation effects are studied, specifically with respect to occupational exposure. Normally, a hypothesis is developed by examining generalized evidence and asking targeted questions — for example, whether occupational exposure is a causal factor for a given condition. Even though this particular study did not produce meaningful positive findings, it illustrates the process by which potential links are investigated. When those links are ultimately confirmed, that is the point at which regulators will intervene to set exposure limits and develop strategies to minimize worker risk.

References

AIHA.org (2014). Nonionizing radiation overview. American Industrial Hygiene Association. Retrieved November 28, 2015.

Karipidis, K., Benke, G., Sim, M., Kauppinen, T., & Giles, G. (2007). Occupational exposure to ionizing and non-ionizing radiation and the risk of glioma. Occupational Medicine, 57(7), 518–524.