Regulatory implementation of the occupational equivalent dose limit for the lens of the eye and underlying relevant efforts in Japan

Yokoyama, Sumi; Hamada, Nobuyuki; Tsujimura, Norio; Kunugita, Naoki; Nishida, Kazutaka; Ezaki, Iwao; Kato, Masahiro; Okubo, Hideki

doi:10.1080/09553002.2022.2115160

Cited by 2 publications

(1 citation statement)

References 39 publications

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“…The new occupational lens dose limit has thus far been implemented in many countries with publication of dedicated guidelines, and there are extensive discussions toward its regulatory implementation in other countries. In Japan, for example, the Japan Health Physics Society (JHPS) established an ad hoc expert committee in April 2013 to discuss relevant issues, the Radiation Council established a subcommittee in July 2017 to discuss the feasibility of implementing the new occupational lens dose limit, government ministries revised the laws in April 2020 to replace the then current occupational lens dose limit (150 mSv/year, effective since 1989) with the new one, and the revised laws came into effect (i.e., the new occupational lens dose limit was implemented into regulation) in April 2021, with flexibility given to some medical workers (e.g., interventionists) during a transition period: 50 mSv/year in the first two years (from April 2021 to March 2023), followed by 50 mSv/year but 60 mSv in the next three years (from April 2023 to March 2026) (33)(34)(35). In the United States, the National Council on Radiation Protection and Measurements (NCRP) published Commentary No.…”

Section: The Lensmentioning

confidence: 99%

Noncancer Effects of Ionizing Radiation Exposure on the Eye, the Circulatory System and beyond: Developments made since the 2011 ICRP Statement on Tissue Reactions

Hamada

2023

Radiation Research

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For radiation protection purposes, noncancer effects with a threshold-type dose-response relationship have been classified as tissue reactions (formerly called nonstochastic or deterministic effects), and equivalent dose limits aim to prevent occurrence of such tissue reactions. Accumulating evidence demonstrates increased risks for several late occurring noncancer effects at doses and dose rates much lower than previously considered. In 2011, the International Commission on Radiological Protection (ICRP) issued a statement on tissue reactions to recommend a threshold of 0.5 Gy to the lens of the eye for cataracts and to the heart and brain for diseases of the circulatory system (DCS), independent of dose rate. Literature published thereafter continues to provide updated knowledge. Increased risks for cataracts below 0.5 Gy have been reported in several cohorts (e.g., including in those receiving protracted or chronic exposures). A dose threshold for cataracts is less evident with longer follow-up, with limited evidence available for risk of cataract removal surgery. There is emerging evidence for risk of normal-tension glaucoma and diabetic retinopathy, but the long-held tenet that the lens represents among the most radiosensitive tissues in the eye and in the body seems to remain unchanged. For DCS, increased risks have been reported in various cohorts, but the existence or otherwise of a dose threshold is unclear. The level of risk is less uncertain at lower dose and lower dose rate, with the possibility that risk per unit dose is greater at lower doses and dose rates. Target organs and tissues for DCS are also unknown, but may include heart, large blood vessels and kidneys. Identification of potential factors (e.g., sex, age, lifestyle factors, coexposures, comorbidities, genetics and epigenetics) that may modify radiation risk of cataracts and DCS would be important. Other noncancer effects on the radar include neurological effects (e.g., Parkinsonŉs disease and dementia) of which elevated risk has increasingly been reported. These late occurring noncancer effects tend to deviate from the definition of tissue reactions, necessitating more scientific developments to reconsider the radiation effect classification system and risk management. This paper gives an overview of historical developments made in ICRP prior to the 2011 statement and an update on relevant developments made since the 2011 ICRP statement.

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Section: The Lensmentioning

confidence: 99%

Noncancer Effects of Ionizing Radiation Exposure on the Eye, the Circulatory System and beyond: Developments made since the 2011 ICRP Statement on Tissue Reactions

Hamada

2023

Radiation Research

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AOP report: Development of an adverse outcome pathway for deposition of energy leading to cataracts

Carrothers,

Appleby,

Lai

et al. 2024

Environ and Mol Mutagen

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Cataracts are one of the leading causes of blindness, with an estimated 95 million people affected worldwide. A hallmark of cataract development is lens opacification, typically associated not only with aging but also radiation exposure as encountered by interventional radiologists and astronauts during the long‐term space mission. To better understand radiation‐induced cataracts, the adverse outcome pathway (AOP) framework was used to structure and evaluate knowledge across biological levels of organization (e.g., macromolecular, cell, tissue, organ, organism and population). AOPs identify a sequence of key events (KEs) causally connected by key event relationships (KERs) beginning with a molecular initiating event to an adverse outcome (AO) of relevance to regulatory decision‐making. To construct the cataract AO and retrieve evidence to support it, a scoping review methodology was used to filter, screen, and review studies based on the modified Bradford Hill criteria. Eight KEs were identified that were moderately supported by empirical evidence (e.g., dose‐, time‐, incidence‐concordance) across the adjacent (directly linked) relationships using well‐established endpoints. Over half of the evidence to justify the KER linkages was derived from the evidence stream of biological plausibility. Early KEs of oxidative stress and protein modifications had strong linkages to downstream KEs and could be the focus of countermeasure development. Several identified knowledge gaps and inconsistencies related to the quantitative understanding of KERs which could be the basis of future research, most notably directed to experiments in the range of low or moderate doses and dose‐rates, relevant to radiation workers and other occupational exposures.

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Regulatory implementation of the occupational equivalent dose limit for the lens of the eye and underlying relevant efforts in Japan

Cited by 2 publications

References 39 publications

Noncancer Effects of Ionizing Radiation Exposure on the Eye, the Circulatory System and beyond: Developments made since the 2011 ICRP Statement on Tissue Reactions

Noncancer Effects of Ionizing Radiation Exposure on the Eye, the Circulatory System and beyond: Developments made since the 2011 ICRP Statement on Tissue Reactions

AOP report: Development of an adverse outcome pathway for deposition of energy leading to cataracts

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