Nationwide Molecular Epidemiology of Measles Virus in Japan Between 2008 and 2017

Genotyping evidence that supports the interruption of endemic measles virus (MV) transmission is one of the essential criteria to be verified in achieving measles elimination. In Japan since 2014, MV genotype analyses have been performed for most of the measles cases in prefectural public health institutes nationwide. With this strong molecular epidemiological data, Japan was verified to have eliminated measles in March, 2015. However, even in the postelimination era, sporadic cases and small outbreaks of measles have been detected repeatedly in Japan. This study investigated the nationwide molecular epidemiology of MV between 2008 and 2017. The 891 strains in the total period between 2008 and 2017 belonged to seven genotypes (D5, D4, D9, H1, G3, B3, and D8) and 124 different MV sequence variants, based on the 450-nucleotide sequence region of the N gene (N450). The 311 MV strains in the postelimination era between 2015 and 2017 were classified into 1, 7, 8, and 32 different N450 sequence variants in D9, H1, B3, and D8 genotypes, respectively. Analysis of the detection period of the individual N450 sequence variants showed that the majority of MV strains were detected only for a short period. However, MV strains, MVs/Osaka.JPN/29.15/ [D8] and MVi/Hulu Langat.MYS/26.11/ [D8], which are named strains designated by World Health Organization (WHO), have been detected in many cases over 2 or 3 years between 2015 and 2017. The WHO-named strains have circulated worldwide, causing outbreaks in many countries. Epidemiological investigation revealed repeated importation of these WHO-named strains into Japan. To demonstrate the elimination status (interruption of endemic transmission) in situations with repeated importation of the same strains is challenging. Nevertheless, the detailed sequence analysis of individual MV strains and chronological analysis of these strains provided sufficient evidence to show that Japan has still maintained its measles elimination status in 2017.

Association of maternal serum concentration of hydroxylated polychlorinated biphenyls with maternal and neonatal thyroid hormones: The Hokkaido birth cohort study

BACKGROUND

Evidence on the toxicity of hydroxylated metabolites of polychlorinated biphenyls (OH-PCBs) for thyroid hormones (TH) is limited, and the underlying mechanism remains unknown.

OBJECTIVES

We aimed to investigate the effects of environmental prenatal exposure to OH-PCBs and maternal and neonatal TH levels, taking the maternal-fetal TH transfer into account.

METHODS

In this prospective birth cohort (the "Hokkaido study") we included 222 mother-neonate pairs. We measured five OH-PCB isomers in maternal serum samples either during pregnancy or within 5 days of delivery. Thyroid stimulating hormone (TSH) and free thyroxine (FT4) levels were obtained from maternal blood samples at an early gestational stage (median; 11.1 weeks) and from heel prick samples of neonates between 4 and 7 days after birth. Multiple linear regression analysis and structural equation modeling (SEM) were performed to investigate the associations between maternal OH-PCB and maternal and neonatal TH levels.

RESULTS

Median concentration of ∑OH-PCBs was 25.37 pg/g wet weight. The predominant isomer was 4-OH-CB187, followed by 4-OH-CB146+3-OH-CB153. In the fully adjusted linear regression analysis, maternal ∑OH-PCBs was positively associated with maternal FT4, and 4-OH-CB187 was positively associated with both maternal and neonatal FT4 levels. Maternal OH-PCBs showed no significant association with TSH among mothers and neonates. Path analysis indicated the indirect pathway from 4-OH-CB187 exposure to increased neonatal FT4, via maternal THs and neonatal TSH.

CONCLUSIONS

These findings suggest that maternal exposure to OH-PCBs during pregnancy may increase both maternal and neonatal FT4 levels. Neonatal FT4 is presumed to be increased by prenatal 4-OH-CB187 indirectly, and this process may be mediated by maternal THs and neonatal TSH.

Sex-related differences in the associations between maternal dioxin-like compounds and reproductive and steroid hormones in cord blood: The Hokkaido study

BACKGROUND

Prenatal exposure to dioxin-like compounds (DLCs) irreversibly affects fetal reproductive and steroid hormone synthesis.

OBJECTIVE

This study aimed to assess the relationships between maternal DLCs and cord blood reproductive and steroid hormones.

METHODS

Participants in this study were pregnant women who enrolled in the Sapporo Cohort of the Hokkaido Study between 2002 and 2005. We quantified 29 DLCs during the 2nd and 3rd trimesters in maternal blood. Additionally, we measured the concentrations of progesterone, estradiol (E2), testosterone (T), androstenedione, dehydroepiandrosterone (DHEA), cortisol, cortisone, sex hormone-binding globulin (SHBG), luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin, inhibin B, and insulin-like factor-3 (INSL3) in cord blood samples.

RESULTS

Data from 183 mother-child pairs were analyzed. We observed sex-dependent associations of DLCs on T/E2 ratios, DHEA, cortisol, cortisone, adrenal androgen/glucocorticoid (AA/GC: sum of DHEA and androstenedione)/(sum of cortisol and cortisone) ratios and SHBG. An increase in maternal DLCs related to decreased T/E2 ratios and SHBG and inhibin B levels, and increased AA/GC ratios and FSH and DHEA levels in male cord blood samples. However, an increase in maternal mono-ortho polychlorinated biphenyls related to increased cortisol, cortisone, and SHBG levels, and decreased DHEA levels and AA/GC ratios in female cord blood samples.

CONCLUSIONS

Prenatal exposure to DLCs alters steroidogenesis and suppresses the secretion of inhibin B in male cord blood. Relationships between maternal DLCs and cord blood hormones differ between boys and girls. Further studies are required to clarify whether the effects of in utero exposure to DLCs on adrenal hormones extend into infancy and puberty.

Accumulation properties of polychlorinated biphenyl congeners in Yusho patients and prediction of their cytochrome P450-dependent metabolism by in silico analysis

In what has become known as the Yusho incident, thousands of people in western Japan were poisoned by the accidental ingestion of rice bran oil contaminated with polychlorinated biphenyls (PCBs) and various dioxins and dioxin-like compounds. In this study, we investigated the accumulation patterns of 69 PCB congeners in the blood of Yusho patients in comparison with those of non-exposed controls. The blood samples were collected at medical check-ups in 2004 and 2005. To compare the patterns of PCB congeners, we calculated the concentration ratio of each congener relative to the 2,2',4,4',5,5'-hexaCB (CB153) concentration. The concentration ratios of tetra- and penta-chlorinated congeners in the blood of Yusho patients were significantly lower than those of controls. To examine the cytochrome P450 (CYP)-dependent metabolic potential of the 2,3',4,4'5-pentaCB (CB118), CB153, and 2,3,3',4,4'5-hexaCB (CB156) congeners, we conducted PCB-CYP (CYP1A1, CYP1A2, CYP2A6, and CYP2B6) docking simulation by in silico analysis. The docking models showed that human CYP1A1, CYP2A6, and CYP2B6 isozymes have the potential to metabolize CB118 and CB153. On the other hand, it was inferred that CB156 is difficult to be metabolized by these four CYP isozymes. These results indicate that CYP1 and CYP2 isozymes may be involved in the characteristic accumulation patterns of PCB congeners in the blood of Yusho patients.

Compound-specific isotopic and congener-specific analyses of polychlorinated biphenyl in the heat medium and rice oil of the Yusho incident

Compound-specific isotope analysis (CSIA) can be used to examine the source and transformation processes of organic pollutants in the environment. We performed a carbon stable isotope analysis of polychlorinated biphenyl (PCB) congeners in the PCB heat-transfer medium (heat medium) and the original Kanechlor-400 (KC-400, a commercial brand of PCBs) involved in the Yusho incident. The main purpose is to investigate whether isotope fractionation occurred in the rice oil deodorization process that caused the incident. The carbon isotope ratios (δ¹³C values) of the targeted PCB congeners ranged from - 29.39 to - 27.00‰ in the heat medium and from - 28.77 to - 27.05‰ in the original KC-400. No significant differences were found in the δ¹³C values, suggesting carbon isotope fractionation did not occur for the targeted PCB congeners in the heat medium when deodorization of rice oil occurred at temperatures above 200 °C. Furthermore, we also conducted a congener-specific analysis of 64 PCB congeners found in the heat medium and rice oil contaminated by it. The total PCB congener concentrations were 503 mg/g in the heat medium and 81 μg/g in the rice oil. The concentrations of the highly chlorinated congeners were significantly lower in the heat medium than in the original KC-400, and the compositional ratios of the lowly chlorinated congeners were relatively lower in the rice oil than in the heat medium. These results suggest that the PCB congener patterns gradually changed from that of the original KC-400 in the deodorization process and subsequent contamination into the rice oil. Thus, a combination of CSIA and congener-specific analysis is a new approach for investigating the changing PCB congener profiles in samples from the Yusho incident.

Current state of yusho and prospects for therapeutic strategies

The mass food poisoning incident yusho occurred in Japan in 1968. It was caused by the ingestion of rice bran oil contaminated with polychlorinated biphenyls and various dioxins and dioxin-like compounds including polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDFs). Notably, PCDFs were found to contribute to approximately 65% of the total toxicity equivalent in the blood of yusho patients. Lipophilic dioxins are retained in the body for a longer period than previously estimated. Victims suffered from characteristic skin manifestations associated with non-specific systemic symptoms, neurological symptoms, and respiratory symptoms. The severe symptoms seen in the initial phase subsequently faded, but recently, improvements have scarcely been observed. The Yusho Group has been researching treatments for this condition. Several clinical trials with chelating agents or dietary fibers aimed at accelerating the excretion of compounds. While some treatments increased dioxin excretion, none provided satisfactory symptom relief. Concurrently, various phytochemicals and herbal extracts have been found to possess biological activities that suppress dioxin-induced toxicity via aryl hydrocarbon receptor or activate the antioxidant nuclear factor-erythroid 2-related factor-2 (NRF2) signal pathway, making them promising therapeutic candidates. Here, we summarize the current status of yusho and findings of clinical trials for yusho patients and discuss the treatment prospects.

Association of prenatal exposure to PCDD/Fs and PCBs with maternal and infant thyroid hormones: The Hokkaido Study on Environment and Children's Health

Polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs) are persistent organic pollutants that are universally detected. Some congeners of PCDDs, PCDFs or PCBs have dioxin-like toxicity, whereas non-dioxin-like PCBs are considered to have different toxicity. Reports of the relationships between prenatal exposure to PCDDs, PCDFs or PCBs and thyroid homeostasis in pregnant women and infants have been inconsistent. The aim of this study was to investigate the effect of maternal serum PCDD/F or PCB levels on maternal and neonatal thyroid hormone (TH) levels in a prospective cohort. Of the 514 subjects in the prospective cohort, 386 mothers and 410 infants were included for analysis. Fifteen dioxins and seventy PCBs in maternal blood collected between 23 and 41weeks of gestation were measured using high-resolution gas chromatography and high-resolution mass spectrometry. Blood samples to measure thyroid stimulating hormone (TSH) and free thyroxine (FT4) levels were obtained from mothers at an early gestational stage (median ten weeks), and from infants between four and seven days of age, respectively. Multiple linear regression analysis was conducted. Median concentration of total PCBs, PCB 153 were 104,700, and 20,500pg/g lipid, respectively. Median total dioxin-TEQ was 13.8pg/g lipid. Total dioxin-TEQ, coplanar PCBs were positively associated with neonatal FT4 (beta=0.224, 0.206, respectively). The association was stronger in boys (beta=0.299, 0.282, respectively). Several PCDD/F and PCB isomers were also positively associated with neonatal FT4. Total PCBs or non-dioxin-like PCBs were not associated with any maternal or neonatal THs. No DLC grouping or congeners were associated with neonatal TSH. Non-ortho PCBs were positively associated with maternal FT4. Three PCB congeners had significant positive association(s) with maternal THs. In conclusion, the results of our study suggest that perinatal exposure to background-level DLCs increases neonatal FT4, especially in boys.

Prenatal exposure to dioxin-like compounds is associated with decreased cord blood IgE and increased risk of wheezing in children aged up to 7years: The Hokkaido study

INTRODUCTION

In utero exposure to dioxin-like compounds (DLCs) may cause imbalance of immune development in early infancy. However, there are few epidemiological studies into the effects of in utero exposure to DLCs on allergies and infections during childhood. This study evaluates associations between concentrations of maternal DLCs and cord blood immunoglobulin (Ig) E, as well as allergies and infections during childhood.

METHOD

We recruited 514 pregnant women in a maternity hospital in Sapporo, Japan, and measured concentrations of DLCs in 426 maternal blood samples using high-resolution gas chromatography/high-resolution mass spectrometry. We examined the relationship between concentrations of maternal DLCs and cord blood IgE at birth (n=239), as well as for allergies and infections in children at 3.5 (n=327) and 7 (n=264) years, using regression analysis adjusted for confounding variables.

RESULTS

We found a positive association between maternal DLC concentrations and frequency of wheezing in children aged up to 7years [odds ratio (OR); 7.81 (95% confidence interval (CI), 1.42 to 42.9)]. At 3.5years, boys showed inverse associations between maternal DLC concentrations and cord blood IgE [partial regression coefficient; -0.87 (95% CI), -1.68 to -0.06], and frequency of wheezing [OR; 0.03 (95% CI), 0.00 to 0.94] but girls did not.

DISCUSSION

As one reason for the significant association observed at 7 but absent at 3.5years, we suggest that allergic symptoms are more obvious in older children due to matured immune function.

CONCLUSION

The findings suggest that prenatal exposure to DLCs may modify offspring immune responses and result in increased risk of allergy among children of school age.

Gender-specific association of exposure to non-dioxin-like polychlorinated biphenyls during pregnancy with methylation levels of H19 and long interspersed nuclear element-1 in cord blood in the Hokkaido study

BACKGROUND

Associations between prenatal exposure to polychlorinated biphenyls (PCBs) and reduced birth-size, and between DNA methylation of insulin-like growth factor-2 (IGF-2), H19 locus, and long interspersed nuclear element-1 (LINE-1) and reduced birth-size are well established. To date, however, studies on the associations between prenatal exposure to PCBs and alterations in methylation of IGF-2, H19, and LINE-1 are lacking. Thus, in this study, we examined these associations with infant-gender stratification.

METHODS

We performed a prospective birth cohort study using the Sapporo cohort from the previously described Hokkaido Birth Cohort Study on Environment and Children's Health conducted between 2002 and 2005 in Japan. In the final 169 study participants included in this study, we measured the concentrations of various non-dioxin-like PCBs in maternal blood during pregnancy using high-resolution gas chromatography/high-resolution mass spectrometry. IGF-2, H19 and LINE-1 methylation levels in cord blood were measured using the bisulfite pyrosequencing methods Finally, we assessed the associations between prenatal exposure to various PCBs and the gene methylation levels using multiple regression models stratified by infant gender.

RESULTS

We observed a 0.017 (95% confidence interval [CI]: 0.003-0.031) increase in the log₁₀-transformed H19 methylation levels (%) in cord blood for each ten-fold increase in the levels of decachlorinated biphenyls (decaCBs) in maternal blood among all infants. Similarly, a 0.005 (95% CI: 0.000-0.010) increase in the log₁₀-transformed LINE-1 methylation levels (%) in cord blood was associated with each ten-fold increase in heptachlorinated biphenyls (heptaCBs) in maternal blood among all infants. In particular, we observed a dose-dependent association of the decaCB levels in maternal blood with the H19 methylation levels among female infants (P value for trend=0.040); likewise a dose-dependent association of heptaCB levels was observed with LINE-1 methylation levels among female infants (P value for trend=0.015). Moreover, these associations were only observed among infants of primiparous women.

CONCLUSION

Our results suggest that the dose-dependent association between prenatal exposure to specific non-dioxin-like PCBs and increases in the H19 and LINE-1 methylation levels in cord blood might be more predominant in females than in males.

Dioxin-metabolizing genes in relation to effects of prenatal dioxin levels and reduced birth size: The Hokkaido study

OBJECTIVES

We investigated the effects of maternal polymorphisms in 3 genes encoding dioxin-metabolizing enzymes in relation to prenatal dioxin levels on infant birth size in Japan.

METHODS

We examined the relationship between dioxin exposure and birth size in relation to the polymorphisms in the genes encoding aromatic hydrocarbon receptor (AHR [G>A, Arg554Lys]), cytochrome P450 (CYP) 1A1 (T6235C), and glutathione S-transferase mu 1 (GSTM1; Non-null/null) in 421 participants using multiple linear regression models.

RESULTS

In mothers carrying the GSTM1 null genotype, a ten-fold increase in total dioxin toxic equivalency was correlated with a decrease in birth weight of -345g (95% confidence interval: -584, -105).

CONCLUSIONS

We observed adverse effects of maternal GSTM1 null genotype on birth weight in the presence of dioxins exposure during pregnancy.

Change in decay rates of dioxin-like compounds in Yusho patients

BACKGROUND

Once ingested, dioxins and dioxin-like compounds are excreted extremely slowly. Excretion can be evaluated by its half-life. Half-lives estimated from observed concentrations are affected by excretion and ongoing exposure. We investigated the change in apparent half-life using a theoretical model based on exposure to dioxin and dioxin-like compounds.

METHODS

We carried out longitudinal measurements of the blood concentration of dioxins and dioxin-like compounds in a Yusho cohort during 2002 to 2010. We estimated the change in decay rates of 2,3,4,7,8-PeCDF and octachlorodibenzodioxin (OCDD) using a second-order equation.

RESULTS

We found that the decay rate of OCDD increased, whereas the decay rate of 2,3,4,7,8-PeCDF of patients with a relatively high concentration of 2,3,4,7,8-PeCDF decreased. OCDD results were in accordance with decreasing levels of dioxin and dioxin-like compounds in the environment. The decay rate of OCDD in the body was affected by the decay rate of OCDD in the environment by ingestion because it was near the steady-state. In contrast, the decay rate of 2,3,4,7,8-PeCDF in the body was affected less by ingestion from the environment because it was far higher than in the steady-state.

CONCLUSION

We demonstrated that the level of 2,3,4,7,8-PeCDF in the environment is decreasing. The excretion half-life is longer than the environmental half-life, thus the excretion half-life in a Yusho patient is increased.

Effects of in utero exposure to polychlorinated biphenyls, methylmercury, and polyunsaturated fatty acids on birth size

The adverse effects of in utero exposure to polychlorinated biphenyls (PCBs) or methylmercury (MeHg), and the beneficial effects of nutrients from maternal fish intake might have opposing influences on fetal growth. In this study, we assessed the effects of in utero exposure to PCBs and MeHg on birth size in the Japanese population, which is known to have a high frequency of fish consumption. The concentrations of PCBs and polyunsaturated fatty acids in maternal blood, and the total mercury in hair (as a biomarker of MeHg exposure) were measured during pregnancy and at delivery. Maternal intakes of fish (subtypes: fatty and lean) and shellfishes were calculated from a food frequency questionnaire administered at delivery. Newborn anthropometric measurement data were obtained from birth records. The associations between chemical exposures and birth size were analyzed by using multiple regression analysis with adjustment for confounding factors among 367 mother-newborn pairs. The birth weight was 3073±37 g (mean±SD). The incidence of babies small for gestational age (SGA) by weight was 4.9%. The median concentrations of total PCBs and hair mercury were 108 ng/g lipid and 1.41 μg/g, respectively. There was no overall association between mercury concentrations and birth weight, birth length, chest circumference, and head circumference. We observed that the risk of SGA by weight decreased with increasing mercury concentration in regression analyses with adjustment for polyunsaturated fatty acids. Our results suggest that the beneficial effect of essential nutrition may mask the adverse effects of MeHg on birth size. The concentrations of PCBs had no association with birth size.

Unexpectedly long half-lives of blood 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) levels in Yusho patients

BACKGROUND

Dioxins and dioxin-like compounds have half-lives typically between 7.2 years and 15 years. Our previous study of patients poisoned by extremely high concentrations of 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) in the 'Yusho incident' in 1968 found that in some the half-life of blood 2,3,4,7,8-PeCDF tended towards infinity. This suggests that there are two groups of Yusho patients, those with 2,3,4,7,8-PeCDF half-lives around 10 years, and those with half-lives near infinity. We sought to establish the proportions of each in a cohort of 395 Yusho patients, and whether the proportions were changing over time.

METHODS

We undertook longitudinal measurement of the blood concentration of 2,3,4,7,8-PeCDF in our cohort between 2002 and 2010. We estimated the change in concentration for each patient using linear regression for measured 2,3,4,7,8-PeCDF concentration, then compared the distribution of changes in concentrations with our previous study.

RESULTS

In patients in whom the blood concentration of 2,3,4,7,8-PeCDF exceeded 50 pg/g lipid, the proportion 8.0% of patients exhibiting half-lives less than 13.3 years fell compared with our previous study (28.2%), while the proportion with near infinity half-lives increased.

CONCLUSION

The prolongation of the half-lives was likely a consequence of age-related factors.

Demographic, behavioral, dietary, and socioeconomic characteristics related to persistent organic pollutants and mercury levels in pregnant women in Japan

Persistent organic pollutants and mercury are known environmental chemicals that have been found to be ubiquitous in not only the environment but also in humans, including women of reproductive age. The purpose of this study was to evaluate the association between personal lifestyle characteristics and environmental chemical levels during the perinatal period in the general Japanese population. This study targeted 322 pregnant women enrolled in the Hokkaido Study on Environment and Children's Health. Each participant completed a self-administered questionnaire and a food-frequency questionnaire to obtain relevant information on parental demographic, behavioral, dietary, and socioeconomic characteristics. In total, 58 non-dioxin-like polychlorinated biphenyls, 17 dibenzo-p-dioxins and -dibenzofuran, and 12 dioxin-like polychlorinated biphenyls congeners, perfluorooctane sulfonate, perfluorooctanoic acid, and mercury were measured in maternal samples taken during the perinatal period. Linear regression models were constructed against potential related factors for each chemical concentration. Most concentrations of environmental chemicals were correlated with the presence of other environmental chemicals, especially in the case of non-dioxin-like polychlorinated biphenyls and, polychlorinated dibenzo-p-dioxins and -dibezofurans and dioxin-like polychlorinated biphenyls which had similar exposure sources and persistence in the body. Maternal smoking and alcohol habits, fish and beef intake and household income were significantly associated with concentrations of environmental chemicals. These results suggest that different lifestyle patterns relate to varying exposure to environmental chemicals.

[Blood PCB Concentrations and their Tendencies Examined in Fukuoka 2011-2014 Annual Inspections for Yusho]

We measured PCBs of blood of 154 people in the Yusho medical check-up from January 2011 through December 2014 and analyzed their PCB blood patterns. Eleven examinees were newly certified as Yusho patients during these 4 years. Of these 11, we identified three Yusho patients with the A pattern, five with the B pattern, and three with the BC pattern. We found no Yusho patients with the C pattern. The B pattern was found in 27 of the 154 examinees, such that the probability that an examinee with the B pattern would be certified as a Yusho patient was about 20%. Since 2012, any family members living with a Yusho patient have also been certified as Yusho patients. The number of such family cohabitants was 16, among whom the PCB pattern was uniformly the C pattern. There were 20 examinees born after 1989, and all those examinees were Yusho-suspected persons. The total PCB concentrations of this younger-age group was less than 0.5 ng/g on average and was low compared with the normal controls.

[The Distribution of Dioxin Concentrations in the Blood of Yusho Patients]

In 1968, the contamination of cooking oil by heat-degraded polychlorinated biphenyls (PCBs) caused a case of mass poisoning, the so-called Yusho incident. The cause of Yusho disease is thought to be ingested toxic substances, including not only PCBs but also polychlorinated dibenzofuran (PCDFs) in Kanemi rice oil. We previously measured dioxins concentrations in the blood of 854 Yusho patients by annual medical examination from 2001 to 2013. We determined the concentrations of 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, 1,2,3,6,7,8-HxCDF and 3,3',4,4',5,5'-HxCB (#169) in the blood of Yusho patients were more than double those of normal controls. In 2012, a new Yusho criteria was established. Family members living with a Yusho patient were also certified as Yusho patients and called Yusho family cohabitant patients. In this study, we compared the distribution of 2,3,4,7,8-PeCDF concentration in the blood of Yusho patients and Yusho family cohabitant patients. It was suspected that the distribution of 2,3,4,7,8-PeCDF concentration in Yusho family cohabitant patients would be lower than that of Yusho patients.

[Relationships between Half-Lives of Dioxins and SNPs in AhR among Yusho Patients]

Half-lives of blood levels of 2,3,4,7,8-Pentachlorodibenzofuran (PeCDF) are varied in Yusho patients. The objective was to evaluate a relationship between half-lives of PeCDF levels and types of SNP rs10249788 of aryl hydrocarbon receptor (AHR) gene in 93 Yusho patients. Based on physical symptoms, age, sex, body mass index and other factors, we set up suitable calculation formulas to fit the actual PeCDF levels thorough rates of change in PeCDF. We found that patients with C/T SNP had longer half lives than patients with C/C and T/T SNPs. Patients with T/T SNP are known to express higher amount of AHR mRNAs. However, detailed analysis could not be carried out in T/T group due to a limited number of patients (n = 11). Further research is warranted to determine the cause of the longer half-lives in C/T patients.

Individuals' half-lives for 2,3,4,7,8-penta-chlorodibenzofuran (PeCDF) in blood: correlation with clinical manifestations and laboratory results in subjects with Yusho

BACKGROUND

In 1968, many people developed dioxin poisoning (Yusho) in Japan. Ingestion of 2,3,4,7,8-pentachlorodibenzofuran (2,3,4,7,8-PeCDF) was considered to be the cause of this poisoning. Although some patients had high concentrations of 2,3,4,7,8-PeCDF in their blood, individuals' half-lives of 2,3,4,7,8-PeCDF were long.

OBJECTIVES

To evaluate the relationship between clinical and laboratory parameters and the individual half-life of 2,3,4,7,8-PeCDF in blood.

METHODS

Clinical and laboratory data were collected during annual check-ups from 2001 to 2008. We enrolled 71 patients, who were measured more than 3 times, and who had 2,3,4,7,8-PeCDF concentrations in blood >50pgg(-1) lipid. The half-life of 2,3,4,7,8-PeCDF for each patient was estimated using linear regression. Moreover, relationships between clinical and laboratory parameters and individual half-life were investigated by linear regression.

RESULTS

A shortened individual half-life for 2,3,4,7,8-PeCDF was significantly correlated with an increased red blood cell count, increased viscous secretions from the meibomian glands, existing black comedones, and severe cedar pollen allergy.

CONCLUSIONS

Symptoms that accelerate excretion of lipids from the body, such as viscous secretions from the meibomian glands, may lead to a shorter half-life of 2,3,4,7,8-PeCDF. Red blood cells are related to the half-life of 2,3,4,7,8-PeCDF. However, further studies are required to investigate the excretory mechanism of 2,3,4,7,8-PeCDF.

Concentration of hydroxylated polychlorinated biphenyls (OH-PCBs) in the blood of Yusho patients in 2010

Hydroxylated polychlorinated biphenyls (OH-PCBs) are formed as major metabolites of PCBs by cytochrome P450 enzyme-mediated oxidation. It has been reported that their total concentration in serum samples of Yusho patients ranged from 390 to 1300 pg/g. We measured the concentration of OH-PCBs in blood collected from 183 Yusho patients living in Japan in 2010. The major OH-PCB metabolites were 4-OH-CB187 (ND-1300 pg/g-wet), 4-OH-CB146 + 3-OH-CB153 (8.4-1200 pg/g-wet), 4-OH-CB109 (ND-530 pg/g-wet) and 4'-OH-CB172 (ND-380 pg/g-wet). The total OH-PCBs ranged from 36 to 3800 pg/g-wet. A positive relationship between the concentrations of OH-PCBs and PCBs was observed, but no significant relationship between the concentrations of OH-PCBs and PCDD/DFs was observed.

[Relationships between concentrations of dioxin isomers and symptoms, and among concentrations and half-lives of dioxin isomers, in patients with Yusho disease]

The relationships among dioxin isomers are not well understood. This study aimed to clarify the relationships among isomers using two methods. First, the relationships between isomers and symptoms were analyzed by analysis of variance. Second, concentrations and half-lives were determined for each isomer in each patient, and correlation coefficients for the concentrations and half-lives among isomers were calculated. Two isomers very similar to 2, 3, 4, 7, 8-pentachlorodibenzofuran (2, 3, 4, 7, 8-PeCDF) were correlated with symptoms of Yusho disease. The correlation coefficients among three isomers similar to 2, 3, 4, 7, 8-PeCDF were very high at 0.98, indicating that there may be a mechanism which maintains constant ratios among these isomers.

[Inter-laboratory crosscheck study of dioxins and PCBs in human blood samples]

We developed an analytical method for accurately determining the concentrations of dioxin and polychlorinated biphenyls(PCBs) in a blood volume of 5 g. Inter-laboratory crosscheck is available for maintaining the quality of dioxin and PCB analysis. We carried out the crosschecks of dioxin and PCB analysis in the blood with domestic analysis organizations. Two crosschecks each of dioxin and PCB analysis were carried out from 2007 through 2011. As a result, the findings of our analysis accorded well with the analyses of the other organizations. We believe that our analytical method is sufficiently reliable.

Improvement of measurement method for hydroxylated polychlorinated biphenyls (OH-PCBs) in blood samples using LC/MS/MS

Hydroxylated polychlorinated biphenyls (OH-PCBs) are well known as metabolites of PCBs in the human body. We improved a measurement method for OH-PCBs in blood samples using LC/MS/MS. A new 2 microm particle column was used, and the analytical conditions for the LC/MS/MS measurements were optimized. The improved method is more sensitive than the conventional method for 5g blood samples. And, this method is effective at determining the concentrations of OH-PCBs, PCBs and dioxins from the same sample without special treatment of the sample such as derivatization.

[Examination of alkali digestion temperature in isomer specific analysis of PCB in whole blood sample]

We compared concentrations of PCB congeners between conventional 80 degrees C alkali digestion method and 30 degrees C alkali digestion method using 22 individual blood samples collected during 2009 annual Yusho examinations. The mean concentration of tri-CB in 30 degrees C alkali digestion method was lower than that of conventional method. However, concentration of total PCBs, 2,3',4,4',5-pentaCB (PCB118), 2,2',4,4',5,5'-hexaCB (PCB153) and 2,3,3',4,4', 5-hexaCB (PCB156), which were used as index for Yusho diagnosis, were equivalent between the methods. It was considered that the 30 degrees C alkali digestion method was available for blood PCB congener specific analysis in Yusho diagnosis.

The changes in dioxin concentrations in the blood of Yusho patients from 2004 to 2010

We measured the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) in blood collected from Yusho patients during medical health examinations performed from 2004 to 2010. Out of the 242 and 200 Yusho patients who received medical health examinations in 2004 and 2010, respectively, the concentrations of PCDDs, PCDFs, and PCBs in the blood of 136 patients were measured in both of those years. The concentrations of individual congeners of PCDDs, PCDFs, and PCBs in the blood of these 136 Yusho patients measured in 2004 were compared with those measured in 2010. Among individual congeners of PCDDs, PCDFs, and PCBs, most congeners of these compounds did not significantly decrease from 2004 to 2010. However, the concentrations of 1, 2, 3, 4, 6, 7, 8-heptaCDD, octaCDD, 1, 2, 3, 4, 7, 8-hexaCDF, tetraCB 52/69, pentaCB 101, octaCB 198/201, and octaCB 196/203 in the blood of Yusho patients were significantly decreased from 2004 to 2010. In addition, the concentrations of 1, 2, 3, 6, 7, 8-hexaCDD, 2, 3, 4, 7, 8-pentaCDF, and 1, 2, 3, 6, 7, 8-hexaCDF tended to decrease slightly from 2004 to 2010. These findings suggest that the PCDDs, PCDFs, and PCBs have remained in the blood of Yusho patients for a very long time, with over 40 years having passed since the outbreak of Yusho.

Development of a newly large-volume injection system for dioxin determinations in blood of Yusho patients

We developed a more effective method to measure the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and non-ortho-coplanar polychlorinated biphenyls (non-ortho PCBs) in the blood of Yusho patients using high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS) equipped with a newly large-volume injection system. The new injection system linked a LaviStoma system with a unique stomach-shaped inlet liner (SSIL) and a solvent-cut large-volume (SCLV) injection system. This approach made it possible to introduce volumes up to 200 microl into the HRGC/HRMS in comparison with the 20microl volume of the previously reported conventional SCLV method. Based on experiments conducted using the same blood sample, the concentrations of PCDDs, PCDFs, and non-ortho PCBs obtained by the developed method showed a close correlation to that by the conventional SCLV method. By improving the injection method, the operation time and labor for the purification procedure from blood could be reduced. Furthermore, the developed method was more effective than the conventional SCLV method for recovery of PCDDs, PCDFs, and non-ortho PCBs.

Genetic association of aromatic hydrocarbon receptor (AHR) and cytochrome P450, family 1, subfamily A, polypeptide 1 (CYP1A1) polymorphisms with dioxin blood concentrations among pregnant Japanese women

Dioxins are metabolized by cytochrome P450, family 1 (CYP1) via the aromatic hydrocarbon receptor (AHR). We determined whether different blood dioxin concentrations are associated with polymorphisms in AHR (dbSNP ID: rs2066853), AHR repressor (AHRR; rs2292596), CYP1 subfamily A polypeptide 1 (CYP1A1; rs4646903 and rs1048963), CYP1 subfamily A polypeptide 2 (CYP1A2; rs762551), and CYP1 subfamily B polypeptide 1 (CYP1B1; rs1056836) in pregnant Japanese women. These six polymorphisms were detected in 421 healthy pregnant Japanese women. Differences in dioxin exposure concentrations in maternal blood among the genotypes were investigated. Comparisons among the GG, GA, and AA genotypes of AHR showed a significant difference (genotype model: P=0.016 for the mono-ortho polychlorinated biphenyl concentrations and toxicity equivalence quantities [TEQs]). Second, we found a significant association with the dominant genotype model ([TT+TC] vs. CC: P=0.048 for the polychlorinated dibenzo-p-dioxin TEQs; P=0.035 for polychlorinated dibenzofuran TEQs) of CYP1A1 (rs4646903). No significant differences were found among blood dioxin concentrations and polymorphisms in AHRR, CYP1A1 (rs1048963), CYP1A2, and CYP1B1. Thus, polymorphisms in AHR and CYP1A1 (rs4646903) were associated with maternal dioxin concentrations. However, differences in blood dioxin concentrations were relatively low.

Concentrations of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and polychlorinated biphenyls in blood and breast milk collected from pregnant women in Sapporo City, Japan

We measured the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dioxin-like polychlorinated biphenyls (PCBs), and non-dioxin-like PCBs in paired samples of blood and breast milk collected from 67 secundiparas in Sapporo City, Japan, and combined this data with those of the 30 secundiparas previously measured. The arithmetic mean total toxic equivalents (TEQ-WHO) concentrations of PCDDs, PCDFs, non-ortho PCBs, and mono-ortho PCBs in blood and breast milk of the 97 secundiparous subjects were 3.0-23 (mean: 13, median: 14) and 2.7-20 (mean: 8.6, median: 8.5) pg TEQ g(-1) lipid, respectively. The sums of the concentrations of 56 non-dioxin-like PCB congeners that were measured in the subjects' blood and breast milk were 16-326 (mean: 107, median: 100) and 12-252 (mean: 73, median: 67) ng g(-1) lipid, respectively. The partitioning ratios of individual congeners of PCDDs, PCDFs, dioxin-like PCBs, and non-dioxin-like PCBs from blood to breast milk in secundiparas were almost the same as those of primiparas that have been recently reported, suggesting that the partitioning ratios of these compounds from maternal blood to breast milk in women is little affected by delivery. Furthermore, the partition of PCB congeners with chlorine at the 2-, 3-, 4'-, and 5-positions or the 2-, 4-, 4'-, and 5-positions of the biphenyl ring from the blood to the breast milk tended to occur at a higher level than that of other congeners. In particular, the levels of tetraCB-74 and hexaCB-146 in the breast milk for both primiparous and secundiparous mothers were slightly higher than those in the blood.

Effects of prenatal exposure to dioxin-like compounds on allergies and infections during infancy

Dioxin-like compounds are endocrine disruptors. The effects of prenatal exposure to environmental levels of dioxins on immune function during infancy have not been clarified, although dioxins induce immunosuppression in offspring of animals. Moreover, human studies have not assessed the effects of gender- or congener-specific differences. The purpose of this study was to investigate the association between dioxin levels in maternal blood and the risk of infection and allergies in infancy. We examined 364 mothers and their infants enrolled in a Hokkaido Study on Environment and Children's Health between 2002 and 2005 in Sapporo, Japan. Relevant information was collected from a baseline questionnaire during pregnancy, medical records at delivery, and a follow-up questionnaire when the child was 18 months of age that assessed development of allergies and infections in infancy. Dioxin-like compound levels in maternal blood were measured with high-resolution gas chromatography/high-resolution mass spectrometry. Relatively higher levels of polychlorinated dibenzofuran were associated with a significantly increased risk of otitis media, especially among male infants (odds ratio=2.5, 95% confidence interval=1.1-5.9). Relatively higher levels of 2,3,4,7,8-pentachlorodibenzofuran were also associated with a significantly increased risk of otitis media (odds ratio=5.3, 95% confidence interval=1.5-19). However, we observed a weak association between dioxin-like compound levels and allergic symptoms in infancy. At environmental levels, prenatal exposure to dioxin-like compounds may alter immune function and increase the risk of infections in infancy, especially among males. The compound 2,3,4,7,8-pentachlorodibenzofuran may be responsible for this.

[Promotive excretion of causative agents of Yusho by fermented brown rice with Aspergillus oryze in Yusho patients]

Forty two years have passed since the outbreak of Kanemi rice oil poisoning, namely, Yusho in the western Japan. However, even now the Yusho patients have been still suffering from several objective and subjective symptoms. In order to improve or, if possible, to cure such symptoms, the most important therapeutic treatment is considered to actively excrete the causative agents, that is, polychlorinated dibenzofurans (PCDFs) from the bodies of the patients and to reduce their body burdens. In rats, chlorophyll and dietary fiber have been shown to promote the fecal excretion of PCDFs and polychlorinated dibenzo-p-dioxins (PCDDs) and to reduce their levels in rats. In this study, we have examined whether such kinds of effect are also observed by fermented brown rice with Aspergillus oryzae (FBRA) containing 5% spirulina, which is so-called spirulina HI * GENKI, the health food and relatively rich with chlorophyll and dietary fiber, in eighteen Yusho patients. They were divided into two groups, namely group A, ten patients (3 males and 7 females) with the mean age of 67.7 years old and group B, eight patients (4 males and 4 females) with the mean age of 64.1 years old. Among the patients of group A, three patients were especially highly contaminated with PCDFs and we classified them into group A (High). Respective mean concentrations of PCDFs in the blood just before initiating this study were as follows; group A : 145 pg/g lipid, group A (High) : 371 pg/g lipid and group B : 52.1 pg/g lipid. Contamination levels of PCDFs, PCDDs and dioxin-like polychlorinated biphenyls (PCBs) in group A (High) were 1.7 to 2.6 times higher than those in group A and 2.4 to 7.1 times higher than those in group B. Accordingly, concentrations of dioxins (PCDFs + PCDDs + dioxin-like PCBs) in the blood of groups A, A (High) and B were, respectively, 194, 458 and 85 pg-TEQ/g lipid. Concentrations of PCBs were also the highest in group A (High) : 1399 ng/g lipid, in group A : 748 ng/g lipid and the lowest in group B : 456 ng/g lipid. Groups A and A (High) took around 7.0 g of spirulina HI * GENKI after each meal and three times a day for the first one year and for the second one year, they did not take spirulina HI * GENKI anymore. Group B took spirulina HI * GENKI with the same manner as the group A only for the second one year. The concentrations of PCDFs, PCDDs, dioxin-like PCBs and PCBs in the blood were also measured at the end of the first and second year, respectively. Assuming the body fat is also contaminated with these compounds at their concentrations on lipid weight basis in the blood and the content of body fat is 20% of 60 kg body weight, we computed the average amounts in their net excretion from the body of the patients due to spirulina HI * GENKI in the three groups. As a result, in group A (High), 341 ng-TEQ/patient of dioxins was excreted from the body, which was 3.4 times greater than that in group A and 12 times higher than that in group B. Therefore, promotive excretions of causative agents of Yusho were the most effective in group A (High) and we consider spirulina HI * GENKI is more effective from the therapeutic point of view in more highly contaminated Yusho patients.

[The rapid analysis of polychlorinated quaterphenyls in blood using different diameter capillary column with the high-resolution gas chromatograph high-resolution mass spectrometer]

The polychlorinated quaterphenyl (PCQ) concentrations in blood are important discriminative parameters in yusho patient. In this study, a rapid analytical method for PCQ using different diameter capillary column (rapid-Rtx65TG) with high-resolution gas chromatograph high-resolution mass spectrometer (HRGC/HRMS) instead of the gas chromatograph electron capture detector (ECD/GC) was developed. Using different diameter capillary columns, the analysis time of the HRGC/HRMS was drastically shortened, and the detection sensitivity was improved. In the rapid-Rtx65TG column, a small-bore capillary column (length 1m, I.D. 0.1mm) was connected with the inlet side of the GC, and behind that column, a large-bore capillary column (length 15mm, I.D. 0.53mm) for octadecachloroquaterphenyl (ODCQ) analysis was connected. In the HRGC/HRMS measurement of ODCQ by the rapid-Rtx65TG column, the minimum limit of detection for the apparatus was 0.4 pg, and the minimum limit of determination for the blood was 0.008 ppb. On ECD/GC in the conventional method and HRGC/HRMS in this study, the PCQ concentration in blood including yusho patients and yusho suspected persons was almost equivalent.

[Time serial changes in the concentrations of the etiological agents of fetal Yusho--PCDDs and PCDFs]

We determined polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) in 6 preserved umbilical cords of fetal Yusho patients and in 11 preserved umbilical cords of Yusho suspected persons who were born to mothers with Yusho from 1970 to 2002, which were Yusho group. As a control, we also analyzed PCDFs and PCDDs in 15 preserved umbilical cords of babies who were born to healthy mothers, which was healthy group, in the same period of time. As a result, 2,3,4,7,8-pentachlorodibenzofuran and 1,2,3,4,7,8-hexachlorodibenzofuran, true causal agents of fetal Yusho, were only determined in the umbilical cords of fetal Yusho patients, except for one umbilical cords of Yusho suspected persons. Decreasing rate in concentrations of PCDFs and PCDDs seemed to greater in Yusho group than in healthy group during this period of time. Therefore, we considered due to high exposure to PCDFs some drug metabolizing enzymes such as aryl hydrocarbon hydroxylase were induced and the excretion of PCDFs and PCDDs were enhanced from the bodies of Yusho group. In order to clarify this hypothesis, further more detail researches are required.

[The difference between male and female dioxin concentrations in the blood of Yusho patients]

In 1968, the contamination of cooking oil by heat-degraded polychlorinated biphenyls (PCBs) caused a case of mass poisoning, the so-called Yusho incident. The cause of Yusho disease is thought to be ingested toxic substances, including not only PCBs but polychlorinated dibenzofuran (PCDFs) in Kanemi rice oil. Extensive studies have been performed since 1995 by the Yusho study group involving follow-up surveys of human blood concentrations of the casual compounds in Yusho patients as well as clinical trials of the acceleration of the excretion of these compounds in Yusho patients. We have previously measured dioxin concentrations in the blood of 649 Yusho patients in annual medical examinations from 2001 to 2009. We determined that the concentrations of 2,3,4,7,8-PeCDF 1,2,3,4,7,8-HxCDF 1,2,3,6,7,8-HxCDF, and 3,3',4,4',5,5'-HxCB (#169) in the blood of Yusho patients were more than twice as high levels to as those of normal controls. In this study, we compared the concentrations of 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, 1,2,3,6,7,8-HxCDF, and 3,3',4,4',5,5'-HxCB (#169) in the blood of male Yusho patients with those of female Yusho patients. As a result, it was found that the mean concentrations of 2,3,4,7,8-PeCDF 1,2,3,4, 7,8-HxCDF 1,2,3,6,7,8-HxCDF, and 3,3',4,4',5,5'-HxCB (#169) in female Yusho patients were 2.9, 3.7, 2.4, and 1.3 times higher, respectively, than those of male Yusho patients.

Measurement method for hydroxylated polychlorinated biphenyls in the blood of Yusho patients by liquid chromatography-electrospray tandem mass spectrometry

Hydroxylated polychlorinated biphenyls (OH-PCBs) are formed as major metabolites of PCBs by cytochrome P450 enzyme-mediated oxidation. It has been reported that their total concentration in serum samples of Yusho patients ranged from 390 to 1300 pg/g. We developed a measurement method for OH-PCBs in blood samples by LC/MS/MS. This method is effective at determining the concentrations of PCDDs, PCDFs, Co-PCBs and OH-PCBs from the same sample without special treatment of the sample. The concentration of OH-PCBs in the blood of Yusho patients was examined using this method. The major OH-PCB metabolites were 4-OH-CB187 (54-906 pg/g-wet), 4-OH-CB146 + 3-OH-CB153 (32-527 pg/g-wet), 4-OH-CB109 (ND-229 pg/g-wet) and 4'-OH-CB172 (ND-143 pg/g-wet). The total OH-PCBs ranged from 95 to 1740 pg/g-wet.

[Blood PCB concentrations and their tendencies examined in Fukuoka 2007-2010 annual inspections for Yusho]

We performed PCB congener specific analysis using HRGC/HRMS and determined their concentrations and blood chromatogram classifications in 275 individual blood samples collected during annual Yusho examinations between 2007 and 2010. When both blood total PCB concentrations and blood chromatogram classifications were compared among eleven Yusho patients undergoing examinations between 2007 and 2010, the longitudinal concentrations and classifications in the respective individuals hardly changed over these years. In a subset of persons suspected of Yusho, it was found that the mean total blood concentrations of three index congeners, that is, 2, 3', 4, 4', 5-pentaCB (PCB118), 2, 2', 4, 4', 5, 5'-hexaCB (PCB153), 2, 3, 3', 4, 4', 5-hexaCB (PCB156) and mean blood total PCB concentrations gradually decreased between 2007 and 2010. Mean concentration of PCB118 in blood from persons suspected of Yusho was calculated as 0.035 ng/g in the 2010 examination, which was 36% lower than the mean value of 0.054 ng/g in the 2007 examination: the concentration of PCB118 showed the highest degree of decrease among the three index congeners. Among persons suspected of Yusho, occupational rates of persons with blood PCB concentrations below one ppb in the entire population increased from approx. 50% in 2007 to approx. 70% in 2010. The lowest concentration of PCB156 in blood of persons suspected of Yusho in 2010 was 0.43 pg/g, which was almost equivalent to the limit of the determination value on HRGC/HRMS, S/N = 10.

[Time serial changes in the concentrations of the related agents to fetal Yusho--dioxin-like PCBs and PCBs]

We determined dioxin-like polychlorinated biphenyls (PCBs) and PCBs in 6 preserved umbilical cords of fetal Yusho patients and in 11 preserved umbilical cords of Yusho suspected persons who were born to mothers with Yusho from 1970 to 2002, which were Yusho group. As a control, we also analyzed dioxin-like PCBs and PCBs in 15 preserved umbilical cords of babies who were born to healthy mothers, which was healthy group, in the same period of time. As a result, concentrations of three dioxin-like PCBs, that is, #156, #157 and #189 which were 6 to 20 times higher in fetal Yusho patients than in healthy babies were still 4 to 6 times greater in Yusho group than in healthy group about 20 years after the outbreak of Yusho, but could not recognize this characteristic anymore about 30 years after the outbreak. Decreasing rate in concentrations of dioxin-like PCBs and PCBs seemed to higher in Yusho group than in healthy group during this period of time. Therefore, we considered due to heavy exposure to PCDFs some drug metabolizing enzymes such as aryl hydrocarbon hydroxylase were induced and excretion of the related agents to fetal Yusho were enhanced from the bodies of Yusho group. In order to clarify this hypothesis, further more detail studies are needed.

Polychlorinated dibenzofurans as a causal agent of fetal Yusho

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dioxin-like PCBs) are highly-toxic environmental pollutants that are still ubiquitous. About 40 years ago, a mass food poisoning, termed "Yusho", occurred in western Japan, and the causal agent of Yusho was thought to be PCDFs. The preserved umbilical cords of babies who were born to mothers with Yusho 2-5 years after the outbreak of Yusho and diagnosed with fetal Yusho were recently obtained, and the concentrations of PCDDs, PCDFs, dioxin-like PCBs and polychlorinated biphenyls (PCBs) in these preserved umbilical cords were determined. Among babies with fetal Yusho, the pollutant concentrations in umbilical cords were compared between "black babies", a term that describes the dermatologic abnormality that is classically seen in fetal Yusho, and "non-black babies". There was almost no difference in the concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) toxic equivalents (TEQ) concentrations of PCDDs, PCDFs and dioxin-like PCBs found in these two groups of babies. Therefore, the Yusho infants with the dark brown skin pigmentation seemed to have a hypersensitive genetic predisposition to the production of melanin pigment in the skin after the exposure to these toxic compounds. The concentrations of PCDDs, PCDFs, dioxin-like PCBs and PCBs in the preserved umbilical cords of infants diagnosed with fetal Yusho and of healthy babies were also determined and compared. PCDDs, dioxin-like PCBs and PCBs were detected in both groups. PCDFs, however, were found at high concentration only in the babies with fetal Yusho. In 2,3,7,8-TCDD TEQ concentrations, 90% of the total TEQ concentrations were attributable to PCDFs after taking into account the baseline concentrations found in healthy babies. This evidence shows that fetal Yusho is caused by PCDF intoxication.

Relationship between the concentrations of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and polychlorinated biphenyls in maternal blood and those in breast milk

We measured the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dioxin-like polychlorinated biphenyls (PCBs), and non-dioxin-like PCBs in paired samples of blood and breast milk collected from 89 primiparous mothers in Sapporo City, Japan, and studied the relationships of these compounds between blood and breast milk for these women plus 30 primiparous mothers in whom these data had been previously reported. The present study is one of the few studies in which the concentration distributions of PCDDs, PCDFs, dioxin-like PCBs, and non-dioxin-like PCBs have been investigated in blood and breast milk collected from the same mothers. The arithmetic mean TEQ concentrations of PCDDs, PCDFs, non-ortho PCBs, and mono-ortho PCBs in blood and breast milk of these 119 subjects were 8.2, 2.9, 5.1, and 0.4 pg TEQ g(-1)lipid, respectively, and 4.8, 2.0, 4.0, and 0.4 pg TEQ g(-1)lipid, respectively, with the total TEQ concentrations of these dioxin-like compounds being 7.0-36 (mean: 17, median: 14) and 5.7-41 (mean: 11, median: 10) pg TEQ g(-1)lipid, respectively. The sums of the concentrations of 56 non-dioxin-like PCB congeners that were measured in the subjects' blood and breast milk were 43-445 (mean: 120, median: 106) and 34-366 (mean: 90, median: 81) ng g(-1)lipid, respectively, indicating that the total TEQ concentration and the total concentration of 56 non-dioxin-like PCB congeners in the maternal blood were notably higher than those in the breast milk. Statistically significant correlations were observed between maternal age and the total TEQ concentration of PCDDs, PCDFs, and dioxin-like PCBs or the total concentration of 56 non-dioxin-like PCB congeners in maternal blood, and significant correlations were also observed between maternal age and the total TEQ concentration of these dioxin-like compounds or the total concentration of 56 PCB congeners in breast milk. The total TEQ concentration of PCDDs, PCDFs, and dioxin-like PCBs in maternal blood showed a close correlation to that in subjects' breast milk, and there was also good correlation between the total concentration of 56 non-dioxin-like PCB congeners in maternal blood and that in subjects' breast milk. Pearson and Spearman correlation analyses showed a relationship between the total TEQ concentration of PCDDs, PCDFs, and dioxin-like PCBs and the total concentration of 56 non-dioxin-like PCB congeners in maternal blood, and also showed an association between the total TEQ concentration of these dioxin-like compounds and the total concentration of 56 PCB congeners in breast milk. The concentration of hexaCB-153 in maternal blood showed significant correlations to the total TEQ concentration of PCDDs, PCDFs, and dioxin-like PCBs or the total concentration of 56 non-dioxin-like PCBs in that sample. Moreover, the concentration of hexaCB-153 in breast milk also showed significant correlations to the total TEQ concentration of these dioxin-like compounds or the total concentration of 56 PCB congeners in that sample. These findings suggested that hexaCB-153 may be an indicator of total TEQ concentrations of PCDDs, PCDFs, and dioxin-like PCBs and total concentrations of 56 non-dioxin-like PCB congeners in blood and breast milk of primiparous mothers.

Prenatal exposure to PCDDs/PCDFs and dioxin-like PCBs in relation to birth weight

Several human studies have shown that low-level exposure to environmental contaminants, such as polychlorinated biphenyls (PCBs) and organochlorine pesticides, negatively influences birth outcomes. However, the effects of low-level exposure to polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like PCBs (DL-PCBs) on birth outcomes have not been clarified in human studies. A prospective cohort study was established to investigate the possible adverse effects of PCDDs/PCDFs and DL-PCBs on fetal growth and neurodevelopment. We recruited 514 pregnant women between July 2002 and October 2005 in Sapporo, Japan. We measured 29 congener levels of PCDDs/PCDFs and DL-PCBs in maternal blood. Using multiple liner regression analysis of the association between birth weight and the levels of PCDDs/PCDFs and DL-PCBs with full adjustments for potential confounders, a significant adverse effect was observed regarding total PCDDs toxic equivalents (TEQ) levels (adjusted beta=-231.5g, 95% CI: -417.4 to -45.6) and total PCDFs TEQ levels (adjusted beta=-258.8g, 95% CI: -445.7 to -71.8). Among male infants, significant adverse associations with birth weight were found for total PCDDs TEQ level, total PCDDs/PCDFs TEQ level, and total TEQ level. However, among female infants, these significant adverse associations were not found. With regard to individual congeners of PCDDs/PCDFs and DL-PCBs, we found significantly negative association with the levels of 2,3,4,7,8-PeCDF (adjusted beta=-24.5g, 95% CI: -387.4 to -61.5). Our findings suggest that prenatal low-level exposure to PCDDs and PCDFs, especially 2,3,4,7,8-PeCDF, may accumulate in the placenta and retard important placental functions, which result in lower birth weight.

Concentrations of polychlorinated biphenyls in blood collected from Yusho patients during medical check-ups performed from 2004 to 2007

To elucidate the exposure levels of polychlorinated biphenyls (PCBs) for Yusho patients, we conducted a congener-specific analysis of polychlorinated biphenyls (PCBs) in blood collected from 242, 237, 300, and 96 Yusho patients during medical check-ups performed from 2004 to 2007, respectively, and in samples from 74, 113, 125, and 148 Yusho-suspected persons during those same years, respectively, and compared the individual congener concentrations of PCBs among the groups of Yusho patients, Yusho-suspected persons, and normal controls with the concentrations previously reported. Among the 209 PCB congeners, 8 congeners of mono-ortho PCBs and 56 congeners of non-dioxin-like PCBs were identified in the blood of Yusho patients and Yusho-suspected persons. Among the PCB congeners measured in the present study, hexaCB-153, hexaCB-138, heptaCB-180, and heptaCB-182/heptaCB-187 showed high ratios to total concentrations of 64 PCB congeners detected in the blood of Yusho patients and Yusho-suspected persons from 2004 to 2007, and the profiles of the major congeners were the same as those obtained in normal controls. With respect to the minor congeners of PCBs, several differences were observed among the three groups. The sums of the concentrations of 64 PCB congeners in the blood of Yusho patients from 2004 to 2007 were 645, 760, 667, and 510 ng g(-1) lipid for each year, respectively, and the concentrations were 1.5, 1.8, 1.5, and 1.2 times higher than those of normal controls for each year, respectively. Those of the Yusho-suspected persons were approximately 0.8, 1.1, 0.9, and 1.0 times higher than those of normal controls for each year, respectively. The ratios of heptachlorinated biphenyls (heptaCBs) to the total concentrations of 64 PCB congeners in the blood of Yusho patients and Yusho-suspected persons from 2004 to 2007 tended to be slightly higher than those in the normal controls. From the results comparing the concentrations of 64 PCB congeners in the blood between Yusho patients and normal controls, the concentrations of hexaCB-156, hexaCB-157, heptaCB-181, and heptaCB-189 for Yusho patients were 3.4, 3.8, 3.9, and 3.8 times, respectively, 3.9, 4.1, 3.9, and 4.4 times, respectively, 3.6, 3.9, 5.0, and 4.1 times, respectively, and 2.3, 2.5, 2.7, and 2.9 times higher than those of the normal controls for each year from 2004 to 2007, respectively. These results indicated that Yusho patients still have higher concentrations of hexaCB-156, hexaCB-157, heptaCB-181, and heptaCB-189 in their blood than do unaffected people, even though over 35 years have passed since the outbreak of Yusho. These four congeners can therefore be considered to be the most important congeners for evaluating the PCBs exposure of Yusho patients.

[Promotive excretion of causative agents of Yusho by intake of fermented brown rice with Aspergillus oryze in patients with Yusho --with regard to PCDFs and PCDDs]

Forty years have passed since the outbreak of Kanemi rice oil poisoning, namely, Yusho in the western Japan. However, even now the patients with Yusho have been still suffering from several objective and subjective symptoms. In order to improve or, if possible, to cure such symptoms, the most important therapeutic treatment is considered to actively excrete the causative agents, that is, polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) from the bodies of the patients and to reduce their body burdens. In rats, chlorophyll and dietary fiber have been shown to promote the fecal excretion of PCDFs and PCDDs and to reduce their levels in rats. In this study, we have examined whether such kinds of effect are also observed by fermented brown rice with Aspergillus oryzae (FBRA) containing 5% spirulina, which is so-called spirulina HI*GENKI, the health food and relatively rich with chlorophyll and dietary fiber, in eighteen patients with Yusho. They were divided into two groups, namely group A, ten patients (3 males and 7 females) with the mean age of 67.7 years old and group B, eight patients (4 males and 4 females) with the mean age of 64.1 years old. Respective mean concentrations of the three PCDF congeners, that is, 2,3,4,7,8-PenCDF, 1, 2,3,4,7,8-HxCDF and 1,2,3,6,7,8-HxCDF in the blood on lipid weight basis just before initiating this study were as follows; group A: 413, 152 and 45.7 pg/g lipid, and group B: 151, 42.7 and 17.3 pg/g lipid. Contamination levels of these PCDF congeners in group A were 2.6 to 3.6 times higher than those in group B. In respective mean concentrations of PCDFs, PCDDs and PCDFs/DDs in both groups were as follows; group A: 228, 30.9 and 258 pg-TEQ/g lipid, and group B: 82.4, 19.7 and 102 pg-TEQ/g lipid. Contamination levels of PCDFs and PCDDs were around 2 times higher in group A than in group B. Group A took around 7.0 g of spirulina HI*GENKI after each meal and tree times a day for the first one year and for the second one year, they did not take spirulina HI*GENKI any more. Group B took spirulina HI*GENKI with the same manner as the group A only for the second one year. The concentrations of PCDFs and PCDDs in the blood of groups A and B were also measured at the end of the first and second year, respectively. Assuming the body fat is also contaminated with PCDFs and PCDDs at their concentrations on lipid weight basis in the blood and the content of body fat is 20% of 60 kg body weight, we computed the average amounts in the net excretion of PCDFs and PCDFs/DDs from the body of the patients due to the intake of spirulina HI*GENKI in groups A and B. As a result, in group A, 85.0 and 99.6 ng-TEQ/patient, respectively were excreted from the body of the patients. In group B, only 38.1 nd 40.0 ng-TEQ/patient were excreted. Accordingly, promotive excretion of PCDFs and PCDDs from the patients with Yusho seemed much effective in group A, of which their concentrations in the blood were much higher than those of group B.

[Estimated half-life of penta-chlorodibenzofuran (PeCDF) and simulation of PeCDF excretion]

The half-life of 2,3,4,7,8-penta-chlorodibenzofuran (PeCDF) in the Yusho patients has been reported to be approximately seven years. In the present study, we estimated the half-life of PeCDF using data from the medical check-ups of more than 300 Yusho patients. We performed linear regression analysis with a binary logarithm of PeCDF blood level in Yusho patients as the dependent variable, and the measurement year as the independent variable. Our results showed that there were many patients who had shown no reduction of their blood PeCDF level for several years. This result contradicts the previously reported half-life period. Therefore, we believe that a more complicated excretion model needs to be established to explain the discrepancy we found. We hypothesized that there might be two mechanisms of PeCDF assimilation in human digestive tract. In the present study, we also used our hypothesis to simulate PeCDF excretion in Yusho patients.

[Dioxin concentration in the preserved umbilical cord from Yusho patients]

Dioxins are known as endocrine disrupters and widespread environmental contaminants. They are bioaccumulated in the human body. In this study, we determined concentrations of dioxins (PCDD, PCDF, Non-ortho PCB and Mono-ortho PCB) in eighteen umbilical cords provided by twelve mothers of Yusho patients and twelve umbilical cords provided by ten mothers of normal controls. The average concentrations of PCDD, PCDF, Non-ortho PCB, Mono-ortho PCB and total dioxins (PCDD/ F + Dioxin-like PCB) in the umbilical cords of Yusho patients and normal controls were 0.55, 4.55, 0.08, 0.08 and 5.26 pg-TEQ/g, respectively, and 0.50, 0.11, 0.03, 0.02 and 0.66 pg-TEQ/g, respectively. Total dioxins and PCDF concentrations in the umbilical cords of Yusho patient were about 8 and 40 times higher than those in the umbilical cords of normal controls, respectively. The average concentration of 2,3,4,7,8-PeCDF in the umbilical cords of Yusho patients was 10 pg/g. We couldn't detect 2,3,4,7, 8-PeCDF in the umbilical cords of normal controls. We suspected the 2,3,4,7,8-PeCDF concentrations in the mothers' blood were related to the 2,3,4,7,8-PeCDF concentrations in umbilical cords.

Concentrations of polychlorinated biphenyls in blood of Yusho patients over 35 years after the incident

We conducted a congener-specific analysis of polychlorinated biphenyls (PCBs) in blood collected from 242 Yusho patients (mean: 65.5 years, median: 67.0 years) and 74 Yusho-suspected persons (mean: 54.7 years, median: 55.0 years) in 2004, and compared each congener concentrations of PCBs among the groups of Yusho patients, Yusho-suspected persons, and normal controls (mean: 68.1 years, median: 67.0 years) with the concentrations previously reported. Among the 209 PCB congeners, 8 congeners of mono-ortho PCBs and 56 congeners of non-dioxin-like PCBs were identified in the blood of Yusho patients and Yusho-suspected persons. Among the PCB congeners measured in the present study, hexaCB-153, hexaCB-138, heptaCB-180, and heptaCB-182/heptaCB-187 showed high ratios to total concentrations of 64 PCB congeners detected in the blood of Yusho patients and Yusho-suspected persons, and the congener profiles were the same as those obtained in normal controls. The sums of the concentrations of 64 PCB congeners in the blood of Yusho patients and Yusho-suspected persons were 40-3032 (mean: 645, median: 536) and 20-1418 (mean: 355, median: 317) ng g(-1) lipid, respectively, and the concentrations were 50% higher and 20% lower than those of normal controls, respectively. The relative contribution ratios of the concentrations of the triCBs, tetraCBs, and pentaCBs to the total concentrations of 64 PCB congeners in the blood of Yusho patients were slightly lower than those of Yusho-suspected persons and normal controls, and the ratios of nonaCBs and decaCB-209 concentrations were nearly the same among the Yusho patients, Yusho-suspected persons, and normal controls. However, the ratios of the concentrations of hexaCBs, heptaCBs, and octaCBs to the total concentrations of 64 PCB congeners in the blood of Yusho patients tended to be slightly higher compared to those of the Yusho-suspected persons and normal controls. From the results comparing the concentrations of 64 PCB congeners in the blood between Yusho patients and normal controls, the concentrations of hexaCB-156, hexaCB-157, heptaCB-181, and heptaCB-189 of the Yusho patients were 3.4, 3.8, 3.9, and 3.8 times higher than those of the normal controls, respectively, indicating that even now, 35 years after exposure, Yusho patients still have a higher concentration of hexaCB-156, hexaCB-157, heptaCB-181, and heptaCB-189 in their blood than do unaffected people. These four congeners may be considered the most important congeners for evaluating the PCBs toxicity of Yusho patients.

Congener-specific analysis of non-dioxin-like polychlorinated biphenyls in blood collected from 195 pregnant women in Sapporo City, Japan

We conducted a congener-specific analysis of non-dioxin-like polychlorinated biphenyls (non-dioxin-like PCBs) in blood collected between July 2002 and July 2004 from 195 pregnant women living in Sapporo City of Hokkaido Prefecture, Japan. The present study is one of the few studies in which full congener concentrations of non-dioxin-like PCBs have been measured in the blood of pregnant women. Of the 195 pregnant women, 101 were primipara (mean: 28.8 years, median: 28.0 years) and 94 were multipara (mean: 32.3 years, median: 33.0 years). Among the 197 non-dioxin-like PCB congeners, 58 congeners were identified in the blood of pregnant women. The arithmetic mean total concentrations of 58 non-dioxin-like PCB congeners in the blood of primiparous and multiparous mothers in Sapporo City were 42.2-329.3 (mean: 114.5, median: 98.6) and 31.5-258.0 (mean: 100.3, median: 91.4)ngg(-1)lipid, respectively. The results show that the contamination of non-dioxin-like PCBs in the blood of women has decreased compared to past levels in other domestic areas, in which the subject age was similar to that in this study. The results of the present study indicate that current levels of non-dioxin-like PCBs in the blood of Japanese women and can be used as baseline data for future temporal trends. The sums of the ratios of the concentrations of hexaCBs and heptaCBs to the total concentrations of 58 non-dioxin-like PCB congeners in the blood of primiparous and multiparous mothers were 78.5% and 77.7%, respectively. The hexaCBs ratios in the blood of primiparous and multiparous mothers were 45.4% and 44.7%, respectively. HexaCB-153 among hexaCBs congeners, the most abundant congener in the blood of primiparous and multiparous mothers, contributed approximately 22.0% and 21.8% to the total concentrations of 58 non-dioxin-like PCBs congeners that were measured in the blood, respectively. Among the non-dioxin-like PCB congeners measured in the present study, hexaCB-138, heptaCB-170, heptaCB-180, and heptaCB-182/heptaCB-187 also showed high ratios to total concentrations of 58 non-dioxin-like PCB congeners detected in the blood of primiparous and multiparous mothers. With regard to the relationship between the total concentrations of 58 non-dioxin-like PCB congeners in maternal blood and the number of deliveries or the age of primiparous and multifarious mothers, the total levels of these PCB congeners tended to decreases with increases in the number of deliveries and significantly increased with increasing maternal age in both groups. Furthermore, significant correlations were observed between the total concentrations of these PCB congeners in blood and the age of primiparae and multiparae. The concentrations of hexaCB-153 in the blood of primiparous and multiparous mothers showed a close correlation to the total concentrations of these PCBs, suggesting that hexaCB-153 could be an indicator of total concentrations of non-dioxin-like PCB congeners in the blood of pregnant women.

Congener-specific analysis of non-dioxin-like polychlorinated biphenyls in blood collected from 127 elderly residents in Nakagawa Town, Fukuoka Prefecture, Japan

We conducted congener-specific analysis of non-dioxin-like polychlorinated biphenyls (non-dioxin-like PCBs) in blood collected in February 2004 from 127 elderly residents living in Nakagawa Town, Fukuoka Prefecture, Japan. The present study is one of the few studies in which 56 non-dioxin-like PCBs congeners were measured in human blood. Of the 127 elderly residents, 51 were men (mean: 68.1 years) and 76 were women (mean: 68.1 years). Among 197 non-dioxin-like PCB congeners, 56 were identified in the blood of elderly residents. The arithmetic mean total concentrations of 56 non-dioxin-like PCBs congeners in the blood of elderly men and women in Nakagawa Town were 419 (median: 378) and 363 (median: 323)ngg(-1)lipid, respectively, and the concentrations were in the range of 172-1102 and 119-1226ngg(-1)lipid, respectively, indicating that the total concentrations in elderly men are significantly higher than those in elderly women. The contamination of non-dioxin-like PCBs in the blood of elderly men and women in Fukuoka Prefecture was found to have decreased compared to past levels. The ratios of hexachlorinated biphenyls (hexaCBs) to the total concentrations of 56 non-dioxin-like PCBs congeners in the blood of elderly men and women were 44.6% and 45.6%, respectively, which was particularly high compared with those of other congeners. 2,2',4,4',5,5'-HexaCB (#153) among hexaCBs congeners, the most abundant congener in the blood of elderly men and women, contributed approximately 23.0% and 23.5% to the total concentrations of 56 non-dioxin-like PCBs congeners, respectively. Furthermore, 2,2',3,4,4',5'-hexaCB (#138), 2,3,3',4',5,6-hexaCB (#163)/2,3,3',4',5',6-hexaCB (#164), 2,2',3,4,4',5,5'-heptaCB (#180), and 2,2',3,4,4',5,6'-heptaCB (#182)/2,2',3,4',5,5',6-heptaCB (#187) also showed high ratios to the total concentrations of 56 non-dioxin-like PCBs congeners detected in the blood of elderly men and women. A statistical examination of the relationship between the total concentrations of 56 non-dioxin-like PCBs congeners in blood and the age of elderly residents who were over 60 years indicated statistically significant correlations between the total concentrations of these PCBs congeners and the age of elderly women. However, similar correlations were not observed in elderly men. The results of the present study have indicated the current levels of non-dioxin-like PCBs in the blood of elderly men and women in Fukuoka Prefecture, Japan and can be used as baseline data for those over age 60.

Concentrations of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and dioxin-like polychlorinated biphenyls in blood and breast milk collected from 60 mothers in Sapporo City, Japan

We measured the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), non-ortho polychlorinated biphenyls (non-ortho PCBs), and mono-ortho polychlorinated biphenyls (mono-ortho PCBs) in paired samples of blood and breast milk collected from 60 mothers in Sapporo City, Hokkaido Prefecture, Japan. The present study is one of the few studies in which PCDDs, PCDFs, and dioxin-like PCBs have been measured in blood and breast milk collected from 60 same mothers. Of these 60 mothers, 30 were primipara (mean: 30.1 years, median: 28.0 years) and 30 were multipara (mean: 32.2 years, median: 32.5 years). The arithmetic mean TEQ concentrations of PCDDs, PCDFs, non-ortho PCBs, and mono-ortho PCBs in blood and breast milk of the primiparous mothers were 9.0, 3.3, 5.7, and 0.4 pg TEQ g(-1) lipid, respectively, and 5.2, 2.2, 4.5, and 0.4 pg TEQ g(-1) lipid, respectively, with the total TEQ concentrations of these dioxin-like compounds being 9.3-42.9 (mean: 18.4, median: 17.3) and 7.0-41.1 (mean: 12.3, median: 11.4) pg TEQ g(-1) lipid, respectively. In the case of multiparous mothers, the arithmetic mean TEQ concentrations of these dioxin-like compounds in blood and breast milk were 7.1, 2.7, 5.3, and 0.4 pg TEQ g(-1) lipid, respectively, and 3.9, 1.7, 3.8, and 0.4 pg TEQ g(-1) lipid, respectively, with the total TEQ concentrations being 3.4-28.1 (mean: 15.5, median: 13.9) and 2.7-20.0 (mean: 9.8, median: 9.2)pg TEQ g(-1) lipid, respectively. The total TEQ concentrations of PCDDs, PCDFs, non-ortho PCBs, and mono-ortho PCBs in blood and breast milk of primiparous mothers in Sapporo City appeared to be generally lower than those recently surveyed throughout the greater area of Japan. Significant correlations were observed between age and the total TEQ concentrations of PCDDs, PCDFs, non-ortho PCBs, and mono-ortho PCBs in the blood of primiparae and multiparae, and significant correlations were also observed between age and the total TEQ concentrations of these dioxin-like compounds in the breast milk of primiparae and multiparae. The total TEQ concentrations of PCDDs, PCDFs, and dioxin-like PCBs in the blood of primiparous mothers showed a close correlation to those in their breast milk and also showed good correlations between the total TEQ concentrations of these dioxin-like compounds in the blood of multiparous mothers and those in their breast milk. The result of a comparison of the arithmetic mean concentrations of each congener of PCDDs, PCDFs, non-ortho PCBs, and mono-ortho PCBs in blood and breast milk indicated that the transfer of octachlorodibenzo-p-dioxin (OCDD) from the blood to the breast milk was lower than those of other congeners. In contrast, among mono-ortho PCBs congeners, the arithmetic mean concentrations of 2,3',4,4',5-pentachlorobiphenyl (PentaCB) (#118) and 2,3,3',4,4'-PentaCB (#105) in the breast milk were slightly higher than those in the blood, which suggested that breast-fed infants may be at higher risk from mono-ortho PCBs.