The Giant Mine is an abandoned gold mine in Yellowknife, Northwest Territories, Canada. Throughout its operation from 1948 to 2004, the Giant Mine released heavy amounts of arsenic trioxide into the environment, thus contaminating the soil and surface water within and around the vicinity of the mine site. Chronic arsenic (As) poisoning negatively impacts wildlife health and can induce multi-organ damages including neurodegeneration and visual dysfunction depending on concentration and duration of exposure. The aim of the current study was to comparatively assess retina layer changes and prevalence of ocular lesions in wild rodent populations (i.e. muskrats and red squirrels) breeding in arsenic endemic areas of Yellowknife, near the vicinity of the abandoned Giant mine site (∼2 km radius), at an intermediate location (approximately 20 km from the mine area) as well as a reference location (spanning 52-105 km from the city of Yellowknife, Canada). Eye globes were removed from euthanized muskrats and squirrels from the three sampling locations with increasing distance from the Giant mine area. Optical Coherence Tomography (OCT) was used to attempt a pan-retinal layer assessment, and histologic examination was utilized for assessment and confirmation of ocular lesions. The retinal layers were measured and statistically compared between the groups based on sampling locations to enhance the scope of histologic evaluations. The preliminary results revealed that thicknesses of ganglion cell layer (GCL), retina nerve fibre layer (NFL), and inner retina layer (IR) were statistically reduced in the muskrats from arsenic endemic area, particularly near the vicinity of the Giant mine compared to the control group. Generalized ocular pathology was histologically confirmed in all the muskrats from the arsenic endemic areas with the manifestation of moderate to severe lymphocytic plasmacytic uveitis (LPU), keratitis and subcapsular cataracts. Inner retinal degeneration was also observed in all the muskrats from the arsenic endemic areas, while muskrats from the control group were predominantly normal. Three muskrats from the control group were noted to have a mild LPU and keratitis. Significant histopathologic changes were not detected in the squirrel eyes from the three groups except for incidental mild cornea scars from all the locations. In general, these preliminary findings confirm the presence of ocular lesions and retina abnormalities in wild muskrats in the Yellowknife area and provide the first evidence of visual dysfunction and impairment in wildlife inhabiting arsenic endemic areas of Canada.

中文翻译：

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在加拿大西北地区耶洛奈夫的砷污染地区繁殖的野生麝香（Ondatra zibethicus）和红松鼠（Tamiasciurus hudsonicus）砷中毒和眼部病理学的比较研究。

巨型矿山是加拿大西北地区耶洛奈夫的一座废弃金矿。从1948年到2004年的整个运营过程中，巨人矿山向环境中释放了大量的三氧化二砷，从而污染了矿场内外的土壤和地表水。慢性砷（As）中毒会对野生动植物的健康造成负面影响，并可能根据暴露的浓度和持续时间而引起多器官损伤，包括神经变性和视觉功能障碍。本研究的目的是比较评估在废弃的巨型矿场附近（约2公里）的耶洛奈夫砷病流行地区繁殖的野生啮齿动物种群（即麝鼠和红松鼠）的视网膜层变化和眼部病变的发生率半径），位于中间位置（距矿区约20公里）以及参考位置（距加拿大耶洛奈夫市52-105公里）。随着距离巨型矿区的距离的增加，从三个采样地点的安乐死的麝香鼠和松鼠中摘除了眼球。使用光学相干断层扫描（OCT）进行全视网膜层评估，并使用组织学检查评估和确认眼部病变。测量视网膜层并根据采样位置在各组之间进行统计学比较，以扩大组织学评估的范围。初步结果表明，砷流行区的麝香中神经节细胞层（GCL），视网膜神经纤维层（NFL）和视网膜内层（IR）的厚度有统计学意义的降低，与对照组相比，尤其是在巨人矿山附近。在组织学上证实了砷流行区所有麝鼠的普遍眼病理学表现，表现为中度至重度淋巴细胞性浆细胞性葡萄膜炎（LPU），角膜炎和囊下白内障。在砷流行地区的所有麝香中也观察到了视网膜内变性，而对照组的麝香主要是正常的。对照组中的三只麝香被发现患有轻度LPU和角膜炎。除所有部位偶有轻度角膜瘢痕外，三组松鼠眼均未发现明显的组织病理学改变。一般来说，