A systematic review of exposure to toxic metals as a risk factor for hematologic malignancies.

摘要

Background: Hematologic malignancies, also known as blood cancers, are some of the prevalent cancers in children, men and women in both developing and developed countries. Globally, the incidence and mortality rate of hematologic malignancies vary due to different exposure, etiology, and prognosis for individuals in different parts of the world. In an environmental context, various environmental health organizations have identified that human exposure to some toxic metals play a role in leading to negative health outcomes. Although there has been much research conducted on the association between toxic metals and hematologic malignancies, there is still a gap in knowledge about the degree of association between metals and hematologic malignancies. Researchers from different countries have done multiple studies and, published hundreds of articles demonstrating the link between toxic metals and hematologic malignancies. However, there has been no systematic review that comprehensively examines this literature. To further provide scientific evidence that supports the notion, this review summarized findings from different published scientific papers on the association between toxic metals and hematologic malignancies.;Objective: This review assessed all attainable and accessible published literature on the association between exposure to toxic metals and hematologic malignancies. These articles provided an up-to-date review of observations on the relationships between toxic metals and hematologic malignancies.;Methods: A literature search was conducted using the databases PubMed, Ovid MEDLINE, Ovid Embase and Google Scholar. Key words such as leukemia, lymphoma, myeloma, hematological malignancy, heavy metals, toxic metals etc. were used as part of our search strategy. There were no restrictions in terms of the country and language except the years and type of study for the analysis of the review. Abstracts reviewed and selected for the systematic review was based on an inclusion criteria which exempted articles before 1970, and hematological malignancies in children and pregnant women. Forty-nine full articles were retrieved with twenty two articles serving as the body for analysis of the review and twenty seven serving as articles for reference.;Results: Fifteen articles out of the twenty two articles were included in the analysis and seven articles were excluded. The reason for exclusion was mainly because of the poor definition of outcome and excluded type of studies which were ecologic studies and case report studies. The articles were broken down into two categories. The first category showed the relationship between toxic metals (lead, cadmium, mercury, nickel, cobalt, chromium, aluminum, and arsenic) and hematologic malignancies. The second category showed the relationship between exposure to unspecified metals, metals or metal-related occupation and specific types of hematologic malignancies. The results varied greatly depending on the type of metal and the hematologic malignancies, indicating either a significant or non-significant association or no association between the metals and hematologic malignancies.;Conclusion: This systematic review shows that there is a plausible relationship that exists between toxic metals and hematologic malignancies. However, based on the result from this review, it can be suggested that exposure to metals can be a potential risk factor for NHL and MM, exposure to lead and cadmium can be a potential risk factor for AML, exposure to lead and nickel can be a potential risk factor for LYM, and exposure to chromium can be a potential risk factor for NHL. In order to establish a causal relationship or association between toxic metals and hematologic malignancies, there is a need for a more advanced and concrete research that provides stronger evidence both in the United States and other international countries.