Semen abnormalities, sperm DNA damage and global hypermethylation in health workers occupationally exposed to ionizing radiation.

Dayanidhi Kumar,Hanumanthappa Krishnamurthy,Pratap Kumar,Guruprasad Kalthur,Satish Kumar Adiga,Navya Jain,Sandhya Kumari,Sujith Raj Salian,Shubhashree Uppangala,Srinivas Challapalli,Srinidhi Gururajarao Chandraguthi,Joël R Drevet

doi:10.1371/journal.pone.0069927

Abstract

BackgroundCytogenetic studies have demonstrated that low levels of chronic radiation exposure can potentially increase the frequency of chromosomal aberrations and aneuploidy in somatic cells. Epidemiological studies have shown that health workers occupationally exposed to ionizing radiation bear an increased risk of hematological malignancies.ObjectivesTo find the influence of occupational radiation exposure on semen characteristics, including genetic and epigenetic integrity of spermatozoa in a chronically exposed population.MethodsThis cross sectional study included 134 male volunteers of which 83 were occupationally exposed to ionizing radiation and 51 were non-exposed control subjects. Semen characteristics, sperm DNA fragmentation, aneuploidy and incidence of global hypermethylation in the spermatozoa were determined and compared between the non-exposed and the exposed group.ResultsDirect comparison of the semen characteristics between the non-exposed and the exposed population revealed significant differences in motility characteristics, viability, and morphological abnormalities (P<0.05–0.0001). Although, the level of sperm DNA fragmentation was significantly higher in the exposed group as compared to the non-exposed group (P<0.05–0.0001), the incidence of sperm aneuploidy was not statistically different between the two groups. However, a significant number of hypermethylated spermatozoa were observed in the exposed group in comparison to non-exposed group (P<0.05).ConclusionsWe provide the first evidence on the detrimental effects of occupational radiation exposure on functional, genetic and epigenetic integrity of sperm in health workers. However, further studies are required to confirm the potential detrimental effects of ionizing radiation in these subjects.

Highlights

The effect of exposure to low levels of diagnostic and therapeutic radiation sources at the workplace is a concern to a large number of health care workers [1]
We provide the first evidence on the detrimental effects of occupational radiation exposure on functional, genetic and epigenetic integrity of sperm in health workers
Evidence from laboratory studies indicate that testicular irradiation in mice can lead to sperm DNA fragmentation [11], which may result in a variety of checkpoint responses in early embryos [12],[13] and transgenerational genomic instability in the offspring [11]

Summary

Introduction

The effect of exposure to low levels of diagnostic and therapeutic radiation sources at the workplace is a concern to a large number of health care workers [1]. Ionizing radiation at chronic low doses has been considered as mutagenic and carcinogenic to humans. Cytogenetic studies have demonstrated that even low levels of chronic radiation exposure can potentially increase the frequency of chromosomal aberrations [2],[3] and aneuploidy [4]. Epidemiological studies have shown that health workers, who are occupationally exposed to ionizing radiation are predisposed to increased risk of hematological malignancies [5],[6]. Cytogenetic studies have demonstrated that low levels of chronic radiation exposure can potentially increase the frequency of chromosomal aberrations and aneuploidy in somatic cells. Epidemiological studies have shown that health workers occupationally exposed to ionizing radiation bear an increased risk of hematological malignancies

Objectives

Methods

Results

Conclusion