There are many differences between China and the UK. Including other aspects of water quality/analysis, diet, etc. For example, distribution of selenium in China is very complicated with adjacent areas sometimes have very different selenium intake.Therefore, we simply cannot pick up this paper and apply it to the UK.
However, the issues raised do need further consideration for China and for higher levels of iodine supplementation everywhere.
They mention 200-300 micrograms of iodine per litre. If we are generous, perhaps some could consume as much as 10 litres a day? (Keeps the arithmetic simple!) That means, 2000-3000 micrograms (2-3 milligrams) a day.
Interestingly, that is close to the 3000 micrograms a day claimed as typical Japanese iodine intake. (Though that is quite variable both between individuals and for each individual.)
This paper does NOT mean that ordinary/typical UK iodine intake is a concern. Indeed, it is still a concern that inadequate iodine intake seems to be increasing here in the UK.
Chemosphere. 2023 Nov 2:140581.
doi: 10.1016/j.chemosphere.2023.140581. Online ahead of print.
Association between different water iodine exposures and thyroid cancer: A retrospective study of high water iodine areas in China from 2009 to 2020
Yi Chen 1 , Chunpeng Lv 1 , Xiaodan Zhang 1 , Kunying Yang 1 , Jiahui Li 1 , Zheng Shen 2 , Li Ai 2 , Dianjun Sun 3 , Wei Zhang 4
PMID: 37925030 DOI: 10.1016/j.chemosphere.2023.140581
Abstract
In recent years, the incidence of thyroid cancer has been on a significant rise worldwide, and a number of environmental factors have been suspected to be risk factors for thyroid cancer, especially the relationship between iodine intake and thyroid cancer has attracted attention. In this study, we want to assess the relationship between different water iodine exposures and thyroid cancer incidence before and after water alteration in areas with high water iodine in China. Thyroid cancer patients (2009-2020) were enrolled at two hospitals, both in Heze City, Shandong Province, an area with high water iodine levels. According to the criteria of the study, 5826 cases out of 8785 cases were selected for inclusion in the study. Before and after water alteration, the incidence of thyroid cancer was highest in areas with water iodine concentrations of 200-300 μg/L in high iodine areas. In areas where water iodine decreased to adequate iodine levels, there was a strong negative correlation between the decreased level of water iodine and the incidence of thyroid cancer. In addition, in cases with pathology reports, we found that the greater the decrease in water iodine values, the markedly smaller the maximum diameter of the thyroid cancer lesions. Taken together, these findings suggest that we should continue to monitor the incidence of thyroid cancer in areas with high water iodine and continue to optimize population iodine intake to reduce the incidence of thyroid cancer.
Keywords: Retrospective study; Thyroid cancer; Water iodine alteration.
As so often, the full paper is behind a paywall:
Lugois iodine ( graves) 
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