The difference in Cd intake from food could also suggest the reason for the difference in urinary Cd levels between Japanese and U. A report on U. Thus, the urinary Cd level of Asahikawa children median: 0. Only one subject a girl has urinary Cd above this value in the present study 4. Further examination of dietary pattern is recommended in this subject and, if possible, followed by dietary modification to minimize long-term risk of environmental Cd exposure.
Children are most susceptible to the neurobehavioral effects of Pb exposure. Secondhand smoke exposure has been shown to associate with elevated blood Pb levels in a national representative of US children from NHANES — even after adjustment for lead in house dust [ 37 ]. Further study, which measures serum cotinine and house dust lead levels, would help elucidate the contribution of environmental tobacco smoke on blood Pb levels in Asahikawa children. Blood Pb level has been shown to be very low 1. This level is the lowest known amongst developed countries. Epidemiological evidence shows that there is no safety margin for childhood Pb exposure, but rather a continuum of toxicity.
The benchmark dose BMD , i. The strengths of this study include the fairly homogenous study population and the use of sensitive methods to determine of Hg, Cd, and Pb levels. Moreover, the validated DHQ used in this study covered extensive range of seafood and other food items and all participants completed the DHQ with no missing data points were noted.
The use of blood Cd and blood Hg as recent exposure metrics also adds the strength to this study. The limitations of this study include the cross-sectional nature of data collection, the limited number of subjects, and the necessarily subjective nature of responses to the DHQ. In conclusion, the exposure to MeHg in Japanese children is above the U. EPA RfD, which, in part, is explained by their consumption of large predatory fish.
Cd and Pb exposures are low in this population. However, Cd may bioaccumulate due to its extremely long biological half-life; no safety margin exists for Pb exposure; and exposure to MeHg is expected to continue as a function of Japanese dietary habits. Therefore, this study underscores the need to reinforce parental advisory measures regarding seafood choice.
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Moreover, periodic biomonitoring, together with potential health risk assessments, should be carried out in the future in high-risk populations. The funding sources had no involvement in the study design; in the collection, analysis, and interpretation of data; and in the writing and publication of the report.
The first author gratefully acknowledged the Postgraduate Education Scholarship — from the Ministry of National Education, Republic of Indonesia. All the authors have no financial relationship with other organization related to the study subject. Only the governmental grant-in-aids are source of the research budget.
The authors declare that they have no conflict of interest. National Center for Biotechnology Information , U. Environ Health Prev Med. Published online Oct 8. Author information Article notes Copyright and License information Disclaimer. Corresponding author. Received Aug 27; Accepted Sep This article has been cited by other articles in PMC. Abstract Objectives To measure current Hg, Cd, and Pb exposure in Japanese children, and to estimate dietary intakes of foods responsible for high body burden. Methods Blood, hair, and urine samples were collected from 9 to year-old children in Asahikawa and measured for Hg, Cd, and Pb in these matrices.
Conclusions Those with high blood Hg level may be explained by more frequent intake of big predatory fish. Introduction Health implications of low-level chronic exposure to toxic metals such as mercury Hg , cadmium Cd , and lead Pb are contemporary issues in environmental health. Open in a separate window.
Blood, urine, and hair sampling and analyses Biological samples collection On arrival of the study subjects at a local community hall, urine samples were collected in a plastic tube acidified with nitric acid to stabilize the metals. SD standard deviation, BMI body mass index. Blood Hg, Cd, and Pb levels were examined in blood samples. Hair Hair mercury HgH levels ranged from 0. Dietary intake of foods with relevance to toxic metals exposure Dietary intake in children with low and high blood mercury level The dose—effect relationships between dietary intake and blood mercury levels were assessed indirectly by dividing the children into quartiles of HgB.
All analyses included age month , sex, and BMI as confounders 0. Cd The urinary Cd concentration reflects the lifetime body burden and is proportional to the concentration in the kidney. Pb Children are most susceptible to the neurobehavioral effects of Pb exposure. Conflict of interest All the authors have no financial relationship with other organization related to the study subject. References 1. Cadmium and children: exposure and health effects. Acta Paediatr Suppl. Neurobehavioural effects of occupational exposure to cadmium: a cross sectional epidemiological study. Occup Environ Med.
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Cadmium exposure and neurodevelopmental outcomes in U. Environ Health Perspect. Early-life cadmium exposure and child development in 5-years old girls and boys: a cohort study in rural Bangladesh. Renal and neurologic effects of cadmium, lead, mercury, and arsenic in children: evidence of early effects and multiple interactions at environmental exposure levels. Current status of cadmium as an environmental health problem. Toxicol Appl Pharmacol.
A critical review of biomarkers used for monitoring human exposure to lead: advantages, limitations, and future needs. World Health Organization Guidance for identifying popuations at risk from mercury exposure. Harada M. Congenital Minamata disease: intrauterine methylmercury poisoning. Toxicological profile for mercury. Atlanta, U. S Department of Health and Human Services, Toxicological profile for cadmium. Toxicological profile for lead. Age of greatest susceptibility to childhood lead exposure: a new statistical approach. Declining risk of methylmercury exposure to infants during lactation.
Environ Res. For this purpose, we conducted similar studies in Vietnam and Thailand, where the circumstances are significantly different. The forms of the available samples differed depending on the region. In Thailand, three strains of immortalized primary culture viruses were available for each of the four serotypes 12 samples in total instead of the primary viral samples Additional File 3. The results are mostly similar to those obtained from the Indonesian samples Fig.
We also compared the ability to identify the virus and distinguish it into different serotypes when the samples were prepared from RNAs or directly from serum. When the same samples were prepared from RNAs and serum, the results were mostly consistent with each other Supplementary Fig.
Upon closer inspection, using RNA as a starting material gave slightly better results than using serum Supplementary Fig. However, RNA may not be an ideal material, as the isolation of RNA requires more manipulation than serum and more purification steps, making it more difficult to prepare on site.
S8e and f , suggesting that the detection success rate depends on the initial viral titer. The compositions of the serotypes determined are similar between the Indonesian and Vietnamese samples, and the fewer DENV2 samples is typical of these two countries, as well. For the Thai samples, we could detect the expected serotypes for eleven out of the twelve samples that were primarily cultured.
Serotyping dengue virus with isothermal amplification and a portable sequencer
The success detection rates were far higher than for the Indonesian and Vietnamese samples, due to their superior purity and higher viral titers Additional File 3. Based on the collected sequence information, we similarly called the SNVs for these samples, as well. We compared the detected SNVs among the Indonesian, Vietnamese and Thai samples to conduct a phylogenetic analysis of the dengue viruses in Southeast Asian countries Fig. We found that each of the serotypes was roughly separated based on its originating regions, with a few exceptions where similar genetic variations were identified in geographically separated regions, which may reflect the recent endemic history of the viruses.
To directly identify the functionally relevant SNVs, focusing on a particular genomic region may be needed. It is also worth noting that short amplicons have limited power to generate phylogenetic trees.
Nevertheless, we included this analysis to demonstrate what MinION could achieve. Future extensive analyses will be required to reveal the correlation of the geography and annual changes to the viral genome using longer amplicons. Our presented method will provide a practical means to conduct an on-site sequencing diagnosis. In this study, we developed a convenient and precise method for the sequencing analysis of tropical disease pathogens.
We compared older and newer versions of the flow cell and showed that the newer version yielded more sequencing reads and better accuracy Supplementary Fig. However, depending on the portion of the genome amplified, this method could also separate very closely related viruses. With the increasing number of clinical cases in which the genotypes of infecting pathogens are identified, progress in the development of knowledge of the etiology of tropical diseases will be accelerated. In that sense, we expect that this study will have a significant impact on the clinical practices in developing countries.
The clinical samples and corresponding clinical information were collected at Sam Ratulangi University in Manado, Sulawesi, Indonesia. All blood collection was carried out in accordance with relevant guidelines and regulations. Informed consent was obtained from all patients.
Biomonitoring of mercury, cadmium, and lead exposure in Japanese children: a cross-sectional study
The LAMP method was used to amplify the viruses as previously described 22 , 33 with a slight modification. The primers for serotyping have been previously published 34 , and we modified the primers to accommodate barcoding for MinION sequencing. X 2D Basecalling version 1.