Occupational radiation exposure and excess additive risk of cataract incidence in a cohort of US radiologic technologists

Abstract

ObjectivesPrevious analyses of cataract in radiation-exposed populations have assessed relative risk; radiogenic excess additive risk (EAR), arguably of more public health importance, has not been estimated. Previous analysis of a large prospective cohort of US radiologic technologists (USRT) quantified excess relative risk of cataract in relation to occupational radiation dose. We aim to assess EARs of cataract.MethodsWe estimated EARs of cataract/cataract surgery in the USRT cohort using generalised additive models in relation to occupational radiation exposure, and assessed risk modification by a priori-selected cataract risk factors (diabetes, body mass index, smoking, race, sex, birth-year, ultraviolet B (UVB) radiation exposure).ResultsThere were 11 345 cataract diagnoses and 5440 of cataract surgery during 832 462 and 888 402 person-years of follow-up, respectively. Cumulative occupational radiation exposure was associated with self-reported cataract, but not with cataract surgery, with EAR/104 person-year Gy=94 (95% CI: 47 to 143, p<0.001) and EAR/104 person-year Gy=13 (95% CI: <0 to 57, p=0.551), respectively. There was marked (p<0.001) variation of EAR by age and by diabetes status, with risk higher among persons ≥75 years and diabetics. There were indications of elevated risk among those with higher UVB radiation (p=0.045), whites (p=0.056) and among those with higher levels of cigarette smoking (p=0.062). Elevated additive risk was observed for estimated occupational radiation eye-lens doses <100 mGy (p=0.004) with no dose–response curvature (p=0.903).ConclusionsThe elevated additive risks associated with low-dose radiation, if confirmed elsewhere, have important public health and clinical implications for radiation workers as well as regulatory measures.

Low- and moderate-dose non-cancer effects of ionizing radiation in directly exposed individuals, especially circulatory and ocular diseases: a review of the epidemiology

“…The ICRP has classified cataract disease as a tissue reaction effect (International Commission on Radiological Protection 2012), with a threshold dose of 0.5 Gy below which there would be minimal excess risk. This is bordering on inconsistency with the findings in a number of datasets, in particular the USRT, in which there is significant excess risk under 100 mGy, although no association was seen for cataract extractions (Little et al 2018a;Little, Cahoon, et al 2020).…”

“…Solar UVR exposure (S€ oderberg et al 2016), diabetes, high BMI, cigarette smoking, corticosteroid medicines and ocular trauma are well-established risk factors for cataracts (Christen et al 1992;Cruickshanks et al 1992;Hodge et al 1995;Floud et al 2016). These factors have not been suggested as likely confounders of the radiation dose-response in the studies considered here that collected relevant information (Worgul et al 2007;Neriishi et al 2012;Little et al 2018a;Little, Cahoon, et al 2020;Su et al 2021). There is epidemiological (Delcourt et al 2005;Zoric et al 2008) and experimental (Devi et al 1965) evidence that cataract is correlated with malnutrition.…”

“…Although there was no breakdown by cataract type in the US radiologic technologists (USRT) cohort, the risk is very similar to those in other cohorts, with an ERR Gy À1 of 0.69 (95% CI 0.27, 1.16) (Little et al 2018a) (Table 2). A notable feature of the USRT cohort is that there is a significant excess cataract risk under 100 mGy, in part as a consequence of the huge size of this dataset, comprising over 12,000 cases (Little et al 2018a;Little, Cahoon, et al 2020;Little, Patel, et al 2020). Similar cataract risks were also seen after high to very high dose RT, with mean doses of 2.8 Gy (maximum 66 Gy), yielding an EOR Gy À1 of 0.92 (95% CI 0.65, 1.20) (Chodick et al 2016).…”

Etiology of posterior subcapsular cataracts based on a review of risk factors including aging, diabetes, and ionizing radiation

“…All studies (15/15) reviewed by Jacob et al showed IR leads to a general excess of cataracts, while some studies showed excess PSCs (8/15 studies), cortical cataracts (4/15 studies), or nuclear cataracts (4/15 studies). The subjects of more recent low dose cataract studies include workers at the Mayak nuclear fuel reprocessing facility (low and moderate doses) (Azizova et al 2018) and US radiologic technologists (Little et al 2020). In addition, survivors of childhood and adolescent cancers had a linear dose-related, long-term risk of pre-senile cataracts with IR exposures as low as 0.5 Gy (Chodick et al 2016).…”

Intraoperative Fluoroscopic Radiation Exposure During Hip Fracture Fixation: A Study Combining Surgical Experience and Fracture Complexity

“…There is evidence suggesting that orthopaedic surgeons are at greater risk of the development of malignancy, a possible consequence of increased occupational exposure to ionising radiation [ 1 , 2 ]. An association has also been identified between occupational radiation exposure and male infertility, as well as the development of cataracts [ 3 , 4 ].…”