[On distribution of heavy metals in rice field soil in the "Itai-itai" disease epidemic district]

A comprehensive review on environmental pollutants and osteoporosis: Insights into molecular pathways

A significant problem that has an impact on community wellbeing is environmental pollution. Environmental pollution due to air, water, or soil pollutants might pose a severe risk to global health, necessitating intense scientific effort. Osteoporosis is a common chronic condition with substantial clinical implications on mortality, morbidity, and quality of life. It is closely linked to bone fractures. Worldwide, osteoporosis affects around 200 million people, and every year, there are almost 9 million fractures. There is evidence that certain environmental factors may increase the risk of osteoporosis in addition to traditional risk factors. It is crucial to understand the molecular mechanisms at play because there is a connection between osteoporosis and exposure to environmental pollutants such as heavy metals, air pollutants, endocrine disruptors, metal ions and trace elements. Hence, in this scoping review, we explore potential explanations for the link between pollutants and bone deterioration through deep insights into molecular pathways. Understanding and recognizing these pollutants as modifiable risk factors for osteoporosis would possibly help to enhance environmental policy thereby aiding in the improvement of bone health and improving patient quality of life.

Comparative physiological and transcriptomic analyses illuminate common mechanisms by which silicon alleviates cadmium and arsenic toxicity in rice seedlings

The inessential heavy metal/loids cadmium (Cd) and arsenic (As), which often co-occur in polluted paddy soils, are toxic to rice. Silicon (Si) treatment is known to reduce Cd and As toxicity in rice plants. To better understand the shared mechanisms by which Si alleviates Cd and As stress, rice seedlings were hydroponically exposed to Cd or As, then treated with Si. The addition of Si significantly ameliorated the inhibitory effects of Cd and As on rice seedling growth. Si supplementation decreased Cd and As translocation from roots to shoots, and significantly reduced Cd- and As-induced reactive oxygen species generation in rice seedlings. Transcriptomics analyses were conducted to elucidate molecular mechanisms underlying the Si-mediated response to Cd or As stress in rice. The expression patterns of the differentially expressed genes in Cd- or As-stressed rice roots with and without Si application were compared. The transcriptomes of the Cd- and As-stressed rice roots were similarly and profoundly reshaped by Si application, suggesting that Si may play a fundamental, active role in plant defense against heavy metal/loid stresses by modulating whole genome expression. We also identified two novel genes, Os01g0524500 and Os06g0514800, encoding a myeloblastosis (MYB) transcription factor and a thionin, respectively, which may be candidate targets for Si to alleviate Cd and As stress in rice, as well as for the generation of Cd- and/or As-resistant plants. This study provides valuable resources for further clarification of the shared molecular mechanisms underlying the Si-mediated alleviation of Cd and As toxicity in rice.

A transcriptomic (RNA-seq) analysis of genes responsive to both cadmium and arsenic stress in rice root

Cadmium (Cd) and arsenic (As) are nonessential and toxic elements in rice that often occur together in contaminated paddy field soils. To understand whether rice has a common molecular response mechanism against Cd and As toxicity, 30-day seedlings (Oryza sativa L. indica) were exposed separately to Cd and As³⁺ in hydroponic cultures for up to 7 days. Root transcriptomic analysis of plants exposed to Cd and As for 3 days revealed that a total of 2224 genes in rice roots responded to Cd stress, while 1503 genes responded to As stress. Of these, 841 genes responded to both stressors. The genes in common to Cd and As stress were associated with redox control, stress response, transcriptional regulation, transmembrane transport, signal transduction, as well as biosynthesis and metabolism of macromolecules and sulfur compounds. In plants exposed to Cd and As separately or in combination for 3 and 7 days, qRT-PCR verification revealed that the glutathione metabolism associated gene Os09g0367700 was significantly up-regulated with respect to unexposed controls and had a positive synergistic effect under combined Cd and As stress. In addition, the redox control related genes Os06g0216000, Os07g0638300 and Os01g0294500, the glutathione metabolism related gene Os01g0530900, the cell wall biogenesis related genes Os05g0247800, Os11g0592000 and Os03g0416200, the expression regulation related genes Os07g0597200 and Os02g0168200, and the transmembrane transport related genes Os04g0524500, also varied significantly with respect to an unexposed control and displayed synergistic effects after 7 days of simultaneous exposure to Cd and As. Our identification of a novel set of genes in rice which responded to both Cd and As³⁺ stress may be of value in mitigating the toxicity of co-contaminated soils. These results also provide a deeper understanding of the molecular mechanisms involved in response to multi-metal/loids stress, and may be used in the genetic improvement of rice varieties.

Relationship between Heavy Metal Exposure and Bone Mineral Density in Korean Adult

Background

Exposure to heavy metals from environmental and industrial sources remains a concern of serious public health risk. This study was conducted to analysis the relationship between heavy metal concentrations and bone density.

Methods

This study used data from a nation-based sample of Koreans (n=2,429) from 2008 to 2011 Korea National Health and Nutrition Examination Survey. We were obtained heavy metals (lead, mercury and cadmium), socioeconomic and demographic factors and bone mineral density (BMD) measured by T-score.

Results

Menopausal women, current smoker or the frequent alcohol drinking, low educational level and low family income were greater in the osteopenia or osteoporosis groups than normal group, and were associated with an increased blood heavy metal concentration levels. The highest quartile group in blood lead had a 1.47 times (95% confidence interval [CI] 1.16-1.87) risk of osteopenia or osteoporosis. In case of blood cadmium, the risk for osteopenia or osteoporosis increased 2.1 times (95% CI 1.64-2.68).

Conclusions

We observed a significant association between blood heavy metals (lead and cadmium) levels and low BMD. Our findings suggest that heavy metal exposure may be a risk factor for osteoporosis.

Investigation of renal damage among residents in the cadmium-polluted Jinzu River basin, based on health examinations in 1967 and 1968

The purpose of this study was to investigate the prevalence of renal disorders in the Jinzu River basin in Toyama Prefecture, Japan where Itai-itai disease was endemic, based on the results of epidemiological studies performed in 1967 and 1968. Furthermore, was there a regional accumulation of the prevalence of abnormal urinary findings in that area? Early morning urine samples were collected from 13 183 subjects (6155 men, 7028 women) who then responded to questionnaires about lifestyle and health. The subject participation rate was 90%. Our findings showed that subjects living in the area of the Jinzu River basin have significantly higher prevalence of abnormal urinary findings compared to subjects living in neighboring river basins and these geographical distributions demonstrated a definite regional accumulation in those areas. The findings of this study verified the regional accumulation of renal disorders in the Jinzu River basin and indicate an association of the occurrence of renal disorders with the water from the Jinzu River.

Relationship between cadmium concentration in rice and renal dysfunction in individual subjects of the Jinzu River basin determined using a logistic regression analysis

We investigated the association between the Cd concentration in rice and renal dysfunction in individuals living in the Cd-polluted Jinzu River basin, using a logistic regression analysis. In the cases of logistic regression analysis for people (1) who had either resided in the present hamlet since birth or who had moved there from a non-polluted area and for those (2) who had resided in the present hamlet since birth, except for glucosuria in males, all partial correlation coefficients between the Cd concentration in rice and occurrence of abnormal urinary findings were statistically significant in both sexes. The allowable level of Cd concentration in rice was calculated by substituting the abnormality rates of urinary findings of the controls in the 40-49, 50-59 and 60-69 year age groups into the logistic regression formula for people (3). The value for subjects aged 50 years was 0.13 and 0.17 ppm for males and females, respectively, with regard to proteinuria and 0.15 and 0.10 ppm for males and females, respectively, with regard to proteinuria+glucosuria.

Biological monitoring of cadmium exposure in itai-itai disease epidemiology

Cadmium (Cd) concentrations in blood and urine were significantly higher in itai-itai disease patients, suspected patients and inhabitants in Cd-polluted areas in Japan. Urinary Cd concentrations were mainly related to the body burden of Cd and did not decrease for several years following cessation of Cd exposure. There was a close association between urinary Cd excretion and the occurrence of beta 2-microglobulinuria (beta 2-mg-uria). Probit regression analysis between urinary Cd excretion and, beta 2-mg-uria indicated that the threshold value may be set around 4 micrograms/g creatinine (cr.). Studies on inhabitants in Cd-polluted areas showed that urinary, beta 2-mg levels of more than 1000 micrograms/l or 1000 micrograms/g cr. were irreversible, while increased urinary excretion of beta 2-mg was associated with increased mortality. At present, beta 2-mg in urine is not a suitable indicator for monitoring renal tubular dysfunction in the general population since the significance of slightly increased excretion of urinary beta 2-mg has yet to be clarified.

Elevated urinary excretion of metallothionein due to environmental cadmium exposure

Metallothionein, a low molecular weight cadmium-binding protein, has been determined for the first time in urine of "itai-itai" disease patients and other Japanese women environmentally exposed to cadmium. On a group basis, the urinary metallothionein levels of "itai-itai" disease patients and suspected patients were significantly higher than that of women living in a cadmium-polluted area. Women living in a non-polluted area excreted significantly less metallothionein than women living in a cadmium-polluted area. A similar trend was observed for urinary beta 2-microglobulin, a nonspecific index of renal tubular dysfunction. However, mean levels of urinary cadmium in the "itai-itai" disease patients, suspected patients and women living in the cadmium-polluted area were similar. It is suggested that if, in addition to beta 2-microglobulin and cadmium, metallothionein is used as another index of cadmium exposure, monitoring of renal tubular dysfunction caused by cadmium may be more effectively carried out.