Methodological limitations (exposure assessment, possible confounders, limited sample size), affecting most reviewed studies, should be remedied in future studies.
Indeed, the existing epidemiological studies do not allow clearly demonstrating health effects of radionuclides at levels naturally encountered in drinking water due to methodological limitations (exposure assessment, possible confounders, and limited sample size).
Methodological limitations (exposure measurement methods, control for confounding, sample size) affect most studies.
Despite these limitations, exposure to inorganic lead, non-arsenical insecticides and work in petroleum refining have been identified as relevant occupational risk factors for brain cancer.
An instrument that could overcome these limitations (exposure to radiation and measurement of spinal curvature in a single plane) is an electromagnetic device [ 28].
A serious limitation was exposure misclassification, likely non-differential since exposure assignments should be unrelated to disease status.
Tertiary prevention involves treatment of established clinical disease to limit morbidity and mortality as well as limitation of exposure.
Still, this study provides little support for the lung cancer-DE hypothesis because: The large size may have contributed to a limitation of exposure assessment where a job matrix was used without consideration of time or place when ranking exposure.
But, it has limitation of exposure to the anterior maxillary anterior wall and lacrimal recess, and access to the anterior wall [8].
In particular, the provision of the two safety functions, confinement of radioactive material and limitation of exposure to radiation, is explained and some of the potential challenges to them are identified.
