Low-dose Ionizing Radiation Exposure Research Articles

Effects of Low Dose Ionizing Radiation Exposure on Memory Performances is Rats During Adulthood

Effects of Low Dose Ionizing Radiation Exposure on Memory Performances is Rats During Adulthood

Occupational Radiation Exposure Among General Surgery Residents: Should We Be Concerned?

Low-dose ionizing radiation exposure is associated with development of solid organ tumors as well as increased risk of cataract formation in a linear-dose response. While occupational radiation exposure has been studied across subspecialties with regular fluoroscopy exposure such as interventional radiology and urology, the contribution of increasing endovascular case volume to occupational radiation exposure among general surgery residents remains largely unreported. In this study, we sought to determine typical occupational radiation exposure among a pool of general surgery residents as part of a formal radiation safety curriculum. A radiation safety program was introduced to a group of 28 general surgery residents who rotate on a vascular surgery service with a high endovascular volume in a hybrid room setting. All residents received training in proper use of a radiation dosimeter and minimizing exposure during fluoroscopy times in the operating room. Data was collected from radiation film dosimetry badges distributed to general surgery residents on a bimonthly basis throughout the year, and radiation exposure in mRem was compared between residents rotating on vascular and nonvascular surgical services during 4-week rotations. A total of 14 months of data were collected. Resident compliance was 84% with regular use and return of dosimeters at the end of each bimonthly cycle. The radiation exposure among residents rotating on vascular surgery was significantly higher compared to those on nonvascular rotations (mean = 71 mRem vs 3.13 mRem, p = 0.02). Exposure among senior residents was not statistically different than that of attending vascular surgeons (mean = 212 mRem vs 164 mRem, p = 0.20). All exposures were significantly lower than institutional ALARA dose limits for radiation exposure (5000 mRem/year). General surgery residents are routinely exposed to measurable occupational radiation levels, especially while participating in endovascular procedures during their training. However, data from our study suggests that these levels are below ALARA dose limits and senior surgical residents are not at greater risk than vascular surgery attending surgeons while on their vascular rotation. The results of this study will be used to help guide resident education on radiation safety and identify institution-specific practices which can minimize exposure and improve radiation safety adherence.

Thiol disulfide homeostasis in ionizing radiation and chemotherapeutic drug exposure.

This study aims to reveal the oxidant and antioxidant status in nurses with chemotheropathic drug exposure and radiology unit workers exposed to ionizing radiation (IR). Nineteen radiology unit workers, 14 nurses, and 15 controls were included the study. All of the participants using antioxidants, vitamin supplements, smokers, any therapeutic drugs, and exposed therapeutic or diagnostic X-ray or chemotherapeutic drugs in 12 months were excluded from the study. Total and native thiols, disulfide/native thiol percent ratios (SS/SH), disulfide/total thiol percent ratios, disulfide amounts, and native thiol/total thiol percent ratios, ischemia-modified albumin (IMA) were determined. Disulfide levels, disulfide/total thiol ratio, and disulfide/native thiol ratio of serum samples of both radiology unit workers and nurses were significantly higher and ratio of native thiol/total thiol was lower than the control group. The radiation dose in radiology unit workers was mean±SD: 0.02±0.009, median (min-max): 0.02 (0.001-0.04). Thiol-disulfide homeostasis was disturbed and the balance shifted in the direction of oxidant damage, even at low-dose IR exposure and normal range. As far as we know, the current findings first demonstrate an apparent chronic oxidative stress in the subjects who were occupationally exposed to antineoplastic drugs and radiation even if annual radiation exposure dose measurements are normal.

Modeling low-dose radiation-induced acute myeloid leukemia in male CBA/H mice

The effect of low-dose ionizing radiation exposure on leukemia incidence remains poorly understood. Possible dose-response curves for various forms of leukemia are largely based on cohorts of atomic bomb survivors. Animal studies can contribute to an improved understanding of radiation-induced acute myeloid leukemia (rAML) in humans. In male CBA/H mice, incidence of rAML can be described by a two-hit model involving a radiation-induced deletion with Sfpi1 gene copy loss and a point mutation in the remaining Sfpi1 allele. In the present study (historical) mouse data were used and these processes were translated into a mathematical model to study photon-induced low-dose AML incidence in male CBA/H mice following acute exposure. Numerical model solutions for low-dose rAML incidence and diagnosis times could respectively be approximated with a model linear-quadratic in radiation dose and a normal cumulative distribution function. Interestingly, the low-dose incidence was found to be proportional to the modeled number of cells carrying the Sfpi1 deletion present per mouse following exposure. After making only model-derived high-dose rAML estimates available to extrapolate from, the linear-quadratic model could be used to approximate low-dose rAML incidence calculated with our mouse model. The accuracy in estimating low-dose rAML incidence when extrapolating from a linear model using a low-dose effectiveness factor was found to depend on whether a data transformation was used in the curve fitting procedure.

Low dose ionizing radiation exposure and risk of thyroid functional alterations in healthcare workers

PurposeTo evaluate the possible role of occupational low dose ionizing radiation exposure in increasing the healthcare workers’ risk of thyroid functional alterations. Methods120 healthcare workers exposed to ionizing radiation (60 belonging to category A with a potential exposure to an annual dose between 6 and 20 mSv and 60 to category B potentially exposed to an annual dose between 1 and 6 mSv) were compared with a control group consisting of 60 unexposed healthcare subjects assessing serum levels of different thyroid function parameters as free triiodothyronine, free thyroxine, thyroid stimulating hormone and thyroid autoantibodies. Age, gender, history of thyroid diseases, job task, dosimetric values were analysed as possible influencing factors using linear and multiple logistic regression analysis. ResultsExposed workers showed significantly higher average levels of thyroid stimulating hormone, and lower average levels of free triiodothyronine and free thyroxine than non-exposed workers, although nonsignificant differences were observed between the two different exposure categories. According to the values of the thyroid hormones a condition of hypothyroidism has been considered in 11 exposed workers (9.2 %) and interestingly this clinical condition was significantly associated with ionizing radiation exposure. ConclusionsLow dose ionizing radiation exposure would seem to significantly influence levels of free triiodothyronine, free thyroxine, thyroid stimulating hormone, then suggesting a possible increased risk of hypothyroidism in healthcare workers although no relationship could be determined with exposure category. However, further studies are necessary to confirm such association on greater number of workers in order also to define a possible dose-response relationship.

Effects of Low Dose Radiation on Biological Processes in Peri-tumoral and Tumoral Areas n Squamous Cell Skin Cancer

Very low dose ionizing radiation (LDR) may have paradoxically beneficial effects via an adaptive response. This adaptive response can mitigate against the potential adverse effects of high-dose radiation therapy and chemotherapy. In this study we aimed to:1.identify the specific molecular details behind the adaptive response to LDR and2.integrate the LDR adaptive response into clinical practice. Our aim was to determine how low dose radiation modifies genetic expression in both healthy and tumor tissue. To determine this, a human clinical trial (n=8) was conducted in 2018 to ascertain the biological effects of integrating 0.1Gy of LDR into standard radiotherapy (2Gy fractions) over the first two weeks of radiation treatment for epidermoid skin cancers. RNA was obtained from skin biopsies and processed for genetic expression using Affymetrix Human gene chips Clarion-D (138K genes). 8 patients with squamous skin cancer, were studied according to the experimental design showed in Figure 1. Biopsy samples were collected and total RNA preparation (100 ng), labeled cRNA synthesis, hybridization, scanning, and image analysis were performed. Changes in biological response were measured using Affymetrix microarrays. Experiments 17F1 and 17F2 were performed in duplicate, and experiments 18F3 and 18F4 were performed in triplicate. Pathway analysis was performed using the Affymetrix Transcriptome Analysis Console software and the Wikipaths database. Comparisons were performed as noted in Table 1. The difference in gene expression in healthy tissues due to LDR exposure is quite low (only 325 genes, mostly downregulated) as noted in Figures 2A and 3A and Tables 2 and 3. The 20 most important biological processes enriched are shown in Figure 4 and include Senescence and Autophagy in malignant cells, and the Genotoxicity Pathway (both downregulated). The difference in gene expression in tumor tissue due to LDR exposure is significantly more pronounced (5,651 genes, mostly upregulated) as noted in Figures 2C and 3C. The 20 most important biological processes enriched are shown in Figures 5 and 6 and Tables 4-6, and include the Allograft rejection pathway in skin cancer (upregulated). Our results suggest that very low doses of radiation (0.1Gy) have a narrow effect on gene expression when applied in the healthy peritumoral area. Down regulated genes predominate, and DNA repair mechanisms are stimulated by the first low dose in healthy tissue.

Strengths and Weaknesses of Dosimetry Used in Studies of Low-Dose Radiation Exposure and Cancer.

A monograph systematically evaluating recent evidence on the dose-response relationship between low-dose ionizing radiation exposure and cancer risk required a critical appraisal of dosimetry methods in 26 potentially informative studies. The relevant literature included studies published in 2006-2017. Studies comprised case-control and cohort designs examining populations predominantly exposed to sparsely ionizing radiation, mostly from external sources, resulting in average doses of no more than 100 mGy. At least two dosimetrists reviewed each study and appraised the strengths and weaknesses of the dosimetry systems used, including assessment of sources and effects of dose estimation error. An overarching concern was whether dose error might cause the spurious appearance of a dose-response where none was present. The review included 8 environmental, 4 medical, and 14 occupational studies that varied in properties relative to evaluation criteria. Treatment of dose estimation error also varied among studies, although few conducted a comprehensive evaluation. Six studies appeared to have known or suspected biases in dose estimates. The potential for these biases to cause a spurious dose-response association was constrained to three case-control studies that relied extensively on information gathered in interviews conducted after case ascertainment. The potential for spurious dose-response associations from dose information appeared limited to case-control studies vulnerable to recall errors that may be differential by case status. Otherwise, risk estimates appeared reasonably free of a substantial bias from dose estimation error. Future studies would benefit from a comprehensive evaluation of dose estimation errors, including methods accounting for their potential effects on dose-response associations.

RIF1 controls replication initiation and homologous recombination repair in a radiation dose-dependent manner.

ABSTRACTRIF1 controls both DNA replication timing and the DNA double-strand break (DSB) repair pathway to maintain genome integrity. However, it remains unclear how RIF1 links these two processes following exposure to ionizing radiation (IR). Here, we show that inhibition of homologous recombination repair (HRR) by RIF1 occurs in a dose-dependent manner and is controlled via DNA replication. RIF1 inhibits both DNA end resection and RAD51 accumulation after exposure to high doses of IR. Contrastingly, HRR inhibition by RIF1 is antagonized by BRCA1 after a low-dose IR exposure. At high IR doses, RIF1 suppresses replication initiation by dephosphorylating MCM helicase. Notably, the dephosphorylation of MCM helicase inhibits both DNA end resection and HRR, even without RIF1. Thus, our data show the importance of active DNA replication for HRR and suggest a common suppression mechanism for DNA replication and HRR at high IR doses, both of which are controlled by RIF1.This article has an associated First Person interview with the first author of the paper.

Efeito da exposição à radiação ionizante de baixa dose na homeostase dinâmica de tiol‐dissulfeto e níveis de albumina modificada por isquemia: estudo observacional

BackgroundThe primary objective of this study was to investigate the effect of low dose ionizing radiation exposure on thiol/disulfide homeostasis and ischemia modified albumin levels. The secondary objective is to compare thiol/disulfide homeostasis and ischemia modified albumin levels among the personnel exposed to low dose ionizing radiation in anesthesia application areas, in and out of the Operation room. MethodsThe study included a total of 90 volunteers aged between 18 and 65 years old, with 45 personnel working in a setting with potential for radiation exposure (Exposed Group) and 45 personnel in a setting without radiation exposure (Control Group). Their native thiol, total thiol, disulphide, albumine and IMA levels were measured. Exposed group included personnel who were exposed to radiation outside the operating room – Operation room (‐) Group and inside the Operating room – Operation room (+) Group. ResultsAlbumin, native and total thiol levels were significantly lower in the participants exposed to radiation in the anesthesia application area, no statistically significant difference was found in terms of disulfide and ischemia modified albumin levels. In the Operation room (‐) group exposed to radiation, native thiol and total thiol values were significantly lower compared to the Operation room (+) groups. ConclusionAwareness of being in danger of oxidative stress should be established in personnel exposed to radiation in the anesthesia application area following low dose ionizing radiation exposure, and the necessary measures should be taken.

The effect of low dose ionizing radiation exposure on dynamic thiol-disulfide homeostasis and ischemia modified albumin levels: an observational study

BackgroundThe primary objective of this study was to investigate the effect of low dose ionizing radiation exposure on thiol/disulfide homeostasis and ischemia modified albumin levels. The secondary objective is to compare thiol/disulfide homeostasis and ischemia modified albumin levels among the personnel exposed to low dose ionizing radiation in anesthesia application areas, in and out of the operation room. MethodsThe study included a total of 90 volunteers aged between 18 and 65 years old, with 45 personnel working in a setting with potential for radiation exposure (Exposed Group) and 45 personnel in a setting without radiation exposure (Control Group). Their native thiol, total thiol, disulphide, albumine and IMA levels were measured. Exposed group included personnel who were exposed to radiation outside the operating room – Operation room (−) Group and inside the operating room – Operation room (+) Group. ResultsAlbumin, native and total thiol levels were significantly lower in the participants exposed to radiation in the anesthesia application area; no statistically significant difference was found in terms of disulfide and ischemia modified albumin levels. In the Operation room (−) Group exposed to radiation, native thiol and total thiol values were significantly lower compared to the Operation room (+) Group. ConclusionAwareness of being in danger of oxidative stress should be established in personnel exposed to radiation in the anesthesia application area following low dose ionizing radiation exposure, and the necessary measures should be taken.

Neurodevelopmental effects of low dose ionizing radiation exposure: A systematic review of the epidemiological evidence

BackgroundThe neurodevelopmental effects of high doses of ionizing radiation (IR) in children are well established. To what extent such effects exist at low-to-moderate doses is unclear. Considering the increasing exposure of the general population to low-to-moderate levels of IR, predominantly from diagnostic procedures, the study of these effects has become a priority for radiation protection. ObjectivesWe conducted a systematic review of the current evidence for possible effects of low-to-moderate IR doses received during gestation, childhood and adolescence on different domains of neurodevelopment. Data sourcesSearches were performed in PubMed, Scopus, EMBASE and Psychinfo on the 6th of June 2017 and repeated in December 2018. Study eligibility criteriaWe included studies evaluating the association between low-to-moderate IR doses received during gestation, childhood and adolescence, and neurodevelopmental functions. Study appraisal and synthesis methodsStudies were evaluated using the Cochrane Collaboration′s risk of bias tool adapted to environmental sciences. A qualitative synthesis was performed. ResultsA total of 26 manuscripts were finally selected. Populations analyzed in these publications were exposed to the following sources of IR: atomic bomb (Hiroshima and Nagasaki), diagnostic/therapeutic radiation, and Chernobyl and nuclear weapon testing fallout.There was limited evidence for an association between low-to-moderate doses of IR and a decrease in general cognition and language abilities, that is, a causal interpretation is credible, but chance or confounding cannot not be ruled out with reasonable confidence. Evidence for a possible stronger effect when exposure occurred early in life, in particular, during the fetal period, was inadequate. Evidence for an association between IR and other specific domains, including attention, executive function, memory, processing speed, visual-spatial abilities, motor and socio-emotional development, was inadequate, due to the very limited number of studies found. Limitations, conclusions, and implications of key findingsOverall, depending on the domain, there was limited to inadequate evidence for an effect of low-to-moderate IR doses on neurodevelopment. Heterogeneity across studies in terms of outcome and exposure assessment hampered any quantitative synthesis and any stronger conclusion. Future research with adequate dosimetry and covering a range of specific neurodevelopmental outcomes would likely contribute to improve the body of evidence. Systematic review registration numberThe systematic review protocol was registered in PROSPERO (registration number CRD42018091902).

Assessment of Genomic Instability in Medical Workers Exposed to Chronic Low-Dose X-Rays in Northern China.

The increasing use of ionizing radiation (IR) in medical diagnosis and treatment has caused considerable concern regarding the effects of occupational exposure on human health. Despite this concern, little information is available regarding possible effects and the mechanism behind chronic low-dose irradiation. The present study assessed potential genomic damage in workers occupationally exposed to low-dose X-rays. A variety of analyses were conducted, including assessing the level of DNA damage and chromosomal aberrations (CA) as well as cytokinesis-block micronucleus (CBMN) assay, gene expression profiling, and antioxidant level determination. Here, we report that the level of DNA damage, CA, and CBMN were all significantly increased. Moreover, the gene expression and antioxidant activities were changed in the peripheral blood of men exposed to low-dose X-rays. Collectively, our findings indicated a strong correlation between genomic instability and duration of low-dose IR exposure. Our data also revealed the DNA damage repair and antioxidative mechanisms which could result in the observed genomic instability in health-care workers exposed to chronic low-dose IR.

Low-dose radiation research and radiation protection policy implementation at the Department of Energy

One of the Department of Energy’s (DOE) highest priorities is the protection of workers, the public and the environment from the conduct of DOE activities. As a self-regulating agency, DOE develops radiation protection policies and orders that integrate national and international consensus standards into requirements that enable it to complete its diverse missions safely and effectively. DOE leadership is unequivocally committed to the well-being of its workforce involved in carrying out its mission. This commitment helps the Department identify and implement viable, safe, and cost-effective methods to protect its workers who deal with radioactive materials and hazardous substances. This paper provides information on a number of significant ongoing initiatives examining health effects associated with low-dose ionizing radiation exposure (less than 100 mSv), and a list of DOE policies and standards for protection of its workers, the public, and the environment.

The Effects of Low-Dose Irradiation on Human Saliva: A Surface-Enhanced Raman Spectroscopy Study.

Biological effects of low-dose ionizing radiation (IR) have been unclear until now. Saliva, because of the ease of collection, could be valuable in studying low-dose IR effects by means of surface-enhanced Raman spectroscopy (SERS). The objective of our study was to compare the salivary SER spectra recorded before and after low-dose IR exposure in the case of pediatric patients (PP). Unstimulated saliva was collected from ten PP before and after irradiation with a cone beam computed tomography (CBCT) machine used for diagnostic purposes. The SERS measurements have been recorded on dried saliva samples using a solid nanosilver plasmonic substrate synthesized using an original method developed in our laboratory. The experimental results showed that salivary SER spectra are dominated by three vibrational bands (441,735 and 2107 cm−1) that can be assigned to bending and stretching vibrations of salivary thiocyanate (SCN-). After exposure, an immediate increase of vibrational bands assigned to SCN- has been recorded in the case of all samples, probably as a result of IR interaction with oral cavity. This finding suggests that SCN- could be used as a valuable biomarker for the detection and identification of low-dose radiation effects.

Flexible Modeling of the Association Between Cumulative Exposure to Low-Dose Ionizing Radiation From Cardiac Procedures and Risk of Cancer in Adults With Congenital Heart Disease.

Adults with congenital heart disease are increasingly being exposed to low-dose ionizing radiation (LDIR) from cardiac procedures. In a recent study, Cohen et al. (Circulation. 2018;137(13):1334-1345) reported an association between increased LDIR exposure and cancer incidence but did not explore temporal relationships. Yet, the impact of past exposures probably accumulates over years, and its strength may depend on the amount of time elapsed since exposure. Furthermore, LDIR procedures performed shortly before a cancer diagnosis may have been ordered because of early symptoms of cancer, raising concerns about reversal causality bias. To address these challenges, we combined flexible modeling of cumulative exposures with competing-risks methodology to estimate separate associations of time-varying LDIR exposure with cancer incidence and all-cause mortality. Among 24,833 patients from the Quebec Congenital Heart Disease Database, 602 had incident cancer and 500 died during a follow-up period of up to 15 years (1995-2010). Initial results suggested a strong association of cancer incidence with very recent LDIR exposures, likely reflecting reverse causality bias. When exposure was lagged by 2 years, an increased cumulative LDIR dose from the previous 2-6 years was associated with increased cancer incidence, with a stronger association for women. These results illustrate the importance of accurate modeling of temporal relationships between time-varying exposures and health outcomes.

Absence of mutations in the human interferon alpha-2b gene in workers chronically exposed to ionising radiation.

Individuals chronically exposed to low-level ionising radiation (IR) run the risk of harmful and long-term adverse health effects, including gene mutations and cancer development. The search for reliable biomarkers of IR exposure in human population is still of great interest, as they may have a great implementation potential for the surveillance of occupationally exposed individuals. In this context, and considering previous literature, this study aimed to identify mutations in the human interferon alpha-2b (hIFNα-2b) as a potential biomarker of occupational chronic low-dose IR exposure linking low-IR exposure to the effects on haematopoiesis and reduced immunity. The analysis was performed in the genomic DNA of 51 uranium miners and 38 controls from Kazakhstan, and in 21 medical radiology workers and 21 controls from Italy. hIFNα-2b gene mutations were analysed with the real-time polymerase chain reaction (PCR) or Sanger sequencing. However, none of the investigated workers had the hIFNα-2b mutation. This finding highlights the need for further research to identify biomarkers for early detection of health effects associated with chronic low-dose IR exposure.

Changes in the hearing threshold using high frequency audiometry in medical personnel exposed to ionizing radiation

<p class="abstract"><strong>Background:</strong> Effect on sensorineural hearing loss by low dose ionizing radiation exposure in radiation workers has been rarely evaluated. A case control study was done among the radiation associated workers and normal subjects.</p><p class="abstract"><strong>Methods:</strong> The study was designed in low dose of radiation exposing healthy medical personnel. Age and sex matched healthy control group of subjects were selected. Groups were evaluated by normal otoscopic evaluation; normal tuning fork test and normal standard pure tone audiogram at frequencies from 250 to 8000 Hz. They underwent impedance audiometry, transient evoked otoacoustic emissions, and high frequency audiometry (from frequencies 10000 to 20000 Hz) was done. </p><p class="abstract"><strong>Results:</strong> No statistically significant difference was found in the results of impedance audiometry, transient evoked otoacoustic emissions and standard pure tone audiogram from 250 to 8000 Hz between cases and controls. In the high frequency range, statistically significant difference was observed (p=0.0001). Mean thresholds were higher at all frequencies in cases compared to controls, except at 4000 Hz. A statistically significant correlation was found between duration of exposure and thresholds at 500 Hz (p=0.014) and 10000 Hz (p=0.048). Tinnitus, vertigo, ear block, hard of hearing and loss of appetite were seen more in cases, but was not significant.</p><p class="abstract"><strong>Conclusions:</strong> Taking account of the very low incidence of nerve and parathyroid injury in this series, the authors suggest that meticulous capsular dissection is superior to dissection of the entire nerve in avoiding transcient nerve damage as well as temporary hypocalcemia. However it is stated that a deliberate search for the nerve is definitely indicated in cases where there is likely to be distorted anatomy, as in infiltrating malignancies and recurrent thyroidectomies.</p>

Correction: Low-dose ionizing radiation exposure represses the cell cycle and protein synthesis pathways in in vitro human primary keratinocytes and U937 cell lines.

[This corrects the article DOI: 10.1371/journal.pone.0199117.].

Raman Micro-Spectroscopy of Dental Pulp Stem Cells: An Approach to Monitor the Effects of Cone Beam Computed Tomography Low-Dose Ionizing Radiation

The objective of this study was to determine the molecular and biochemical changes in dental pulp stem cells (DPSCs) due to consecutive low-dose ionizing radiation exposures using label-free Raman micro-spectroscopy (RMS). Ionizing radiation produces biological damage leading to health effects of varying severity. The effects and subsequent health implications caused by exposure to low-dose radiation, such as diagnostic exposure, remain ambiguous. We identified Raman biomarkers characteristic to low-dose cone beam computed tomography (CBCT) irradiation of the DPSCs. The biomarkers were monitored inside the cells using the relative intensity distribution of the 785 and 1734 cm−1 bands. The control cells presented a higher relative intensity of the nucleic acid specific Raman bands, whereas the irradiated cells revealed an increased intensity of the lipid-induced bands. The results obtained in this study demonstrate the capability of RMS for the detection of cell response to diagnostic radiation dose levels. This may indicate the potential of the technique for future applications such as monitoring the radiation responses in pediatric patients suffering repeated radiological exposures.

Low-dose ionizing radiation exposure represses the cell cycle and protein synthesis pathways in in vitro human primary keratinocytes and U937 cell lines.

The effects of the high-dose ionizing radiation used in radiotherapy have been thoroughly demonstrated in vitro and in vivo. However, the effects of low-dose ionizing radiation (LDIR) such as computed tomography-guided biopsies and X-ray fluoroscopy on skin cells remain controversial. This study investigated the molecular effects of LDIR on the human primary keratinocytes (HPKs) and U937 cells, monocytes-like cell lines. These cells were exposed to 0.1 Gray (Gy) X-ray as LDIR. The modulation of transcription was assessed using a cDNA array, and the protein expression after LDIR exposure was investigated using isobaric tags for relative and absolute quantification (iTRAQ) proteomic analysis at 24 hours. These effects were confirmed by immunoblotting analysis. The direct effects of LDIR on the U937 cells and HPKs and the bystander effects of irradiated HPKs on U937 cells were also investigated. LDIR downregulated c-Myc in both U937 cells and HPKs, and upregulated the p21WAF1/CIP1 protein expression in U937 cells along with the activation of TGFβ and protein phosphatase 2A (PP2A). In HPKs, LDIR downregulated the mTOR signaling with repression of S6 and 4EBP1 activation. Similar changes were observed as bystander effects of LDIR. Our findings suggest that LDIR inhibits protein synthesis and induces the cytokines activation associated with inflammation via direct and bystander effects, which might recapitulate the effects of LDIR in inflammated skin structures.