Blood serum levels of PCDFs and PCBs in Yu-Cheng children peri-natally exposed to a toxic rice oil

Risk for animal and human health related to the presence of dioxins and dioxin-like PCBs in feed and food

The European Commission asked EFSA for a scientific opinion on the risks for animal and human health related to the presence of dioxins (PCDD/Fs) and DL-PCBs in feed and food. The data from experimental animal and epidemiological studies were reviewed and it was decided to base the human risk assessment on effects observed in humans and to use animal data as supportive evidence. The critical effect was on semen quality, following pre- and postnatal exposure. The critical study showed a NOAEL of 7.0 pg WHO2005-TEQ/g fat in blood sampled at age 9 years based on PCDD/F-TEQs. No association was observed when including DL-PCB-TEQs. Using toxicokinetic modelling and taking into account the exposure from breastfeeding and a twofold higher intake during childhood, it was estimated that daily exposure in adolescents and adults should be below 0.25 pg TEQ/kg bw/day. The CONTAM Panel established a TWI of 2 pg TEQ/kg bw/week. With occurrence and consumption data from European countries, the mean and P95 intake of total TEQ by Adolescents, Adults, Elderly and Very Elderly varied between, respectively, 2.1 to 10.5, and 5.3 to 30.4 pg TEQ/kg bw/week, implying a considerable exceedance of the TWI. Toddlers and Other Children showed a higher exposure than older age groups, but this was accounted for when deriving the TWI. Exposure to PCDD/F-TEQ only was on average 2.4- and 2.7-fold lower for mean and P95 exposure than for total TEQ. PCDD/Fs and DL-PCBs are transferred to milk and eggs, and accumulate in fatty tissues and liver. Transfer rates and bioconcentration factors were identified for various species. The CONTAM Panel was not able to identify reference values in most farm and companion animals with the exception of NOAELs for mink, chicken and some fish species. The estimated exposure from feed for these species does not imply a risk.

Gestational exposure to polychlorinated biphenyls and dibenzofurans induced asymmetric hearing loss: Yucheng children study

INTRODUCTION

In 1979, approximately 2000 people in central Taiwan were exposed to polychlorinated biphenyls and dibenzofurans (PCBs/PCDFs) due to ingestion of contaminated rice oil. The children born to mothers exposed to PCBs/PCDFs were called Yucheng children. We conducted a follow-up study to examine the association between gestational PCBs/PCDFS exposure and auditory function in Yucheng children's early adulthood.

METHODS

In 1985 and early 1992, Yucheng children and their age, gender, socio-economic matched unexposed referent children were recruited for physical examination and long-term follow-ups. In 2007, Yucheng children and referent children were invited to participate in a health examination, including assessment of pure-tone air-conduction thresholds and distortion product otoacoustic emissions (DPOAEs) test. Gestational exposure to PCBs/PCDFs in Yucheng children were estimated by back-extrapolation of their mother's serum concentration to the time of childbirth.

RESULTS

A total of 86 Yucheng children (51.2% males) and 97 referent children (50.5% males) were included for analysis. No difference was found in demographic characteristics between two groups. Among the Yucheng children, 53 had estimated PCBs/PCDFs concentrations. We found that Yucheng children were at higher risk of having elevated hearing threshold at low frequencies in the right ear. Estimated maternal concentrations of 2,3,4,7,8-pnCDF at the time of birth were associated with increased hearing thresholds and decreased DPOAEs amplitudes at low frequencies in the right ear.

CONCLUSION

Gestational exposure to PCBs/PCDFs caused adverse asymmetrical hearing effects detectable even in early adulthood.

Determinants of polychlorinated aromatic hydrocarbons in serum in three age classes--Methodological implications for human biomonitoring

Human biomonitoring provides an integrated measure for individual exposure to environmental pollutants. Better insight in inter-individual variability of biomarkers of exposure may help in the interpretation of biomonitoring studies. The aim was to study the impact of outliers, determine the optimal unit for fat-soluble biomarkers in serum and quantify the major determinants for biomarkers of exposure to polychlorinated aromatic hydrocarbons (PCAHs) in three age groups. Data were obtained from the Flemish Environment and Health Study (2002-2006). Marker PCBs (sum of 138, 153, 180), hexachlorobenzene (HCB) and p,p'-DDE were measured in cord blood samples of 1196 newborns, in serum samples of 1679 adolescents (14-15 years) and 1583 adults (50-65 years). Exclusion of influential outliers in multiple linear regression models lead to models that are better applicable to the general population. In terms of adjusted R2, the regression model with the pollutant expressed in volume-based units and blood fat as a separate independent variable was superior compared to models with other units. We found highly consistent relationships between the serum concentration of PCAHs and blood fat, age, changes in body weight, animal fat in the diet, local vegetable consumption (HCB and p,p'-DDE only) and being breastfed as a baby (in adolescents only). The impact of sex and BMI differed by age. For biomarkers of persistent pollutants that reflect long-term exposure, the relation between the covariates and the biomarkers can be well quantified.

Exposure to a mixture of polychlorinated biphenyls and polychlorinated dibenzofurans resulted in a prolonged time to pregnancy in women

BACKGROUND

Polychlorinated biphenyls (PCBs), dibenzofurans (PCDFs), and dibenzodioxins (PCDDs) may affect the female reproductive system in animals and humans. In 1978-1979, a mass poisoning occurred in central Taiwan due to PCB/PCDF-contaminated cooking oil; this incident was called Yucheng ("oil disease" in Chinese).

OBJECTIVE

The purpose of our study was to determine whether PCB/PCDF exposure affected fertility in exposed women.

METHODS

After the event, we followed the exposed individuals and a reference group who were sex-, age-, and community-matched. In 2003, we obtained fertility histories from Yucheng and reference women by telephone interview. We used Kaplan-Meier survival curves and multivariable Cox regression to compare time to pregnancy (TTP) between Yucheng and reference women, and we performed multiple logistic regression to determine whether PCB/PCDF exposure caused infertility.

RESULTS

In total, 412 women responded, with a median TTP of 4 months in Yucheng women and 3 months in reference women (p = 0.019). After adjusting for confounders by Cox regression, we found a fecundability ratio of 0.90 [95% confidence interval (CI), 0.80-1.00] for Yucheng women. Among the 408 women who had non-contraceptive sexual activity for > 12 months, 19.7% of Yucheng women and 9.7% of reference women did not become pregnant (i.e., they were infertile). After we adjusted for confounders by logistic regression, the infertility odds ratio was 2.34 (95% CI, 1.23-4.59) for Yucheng women compared with the reference group.

CONCLUSIONS

We found prolonged TTP and reduced fertility among women previously exposed to PCBs/PCDFs. Because of the limited sample size and the relatively small decrease in the fertility rate, these effects require cautious interpretation and further investigation for confirmation.

Congener profiles of PCBs and PCDD/Fs in Yucheng victims fifteen years after exposure to toxic rice-bran oils and their implications for epidemiologic studies

In 1978-1979, a mass poisoning occurred in central Taiwan from rice-bran oil contaminated by heat-degraded PCBs was later called the Yucheng (oil disease in Chinese). Only a few studies have so far investigated the levels of specific polychlorinated biphenyl (PCB) or polychlorinated dibenzodioxin/furan (PCDD/F) congeners in the Yucheng victims. This study aimed to investigate the serum residual levels of thirty-three PCBs and seventeen 2,3,7,8-substituted PCDD/F congeners in the Yucheng victims 15 years after the exposure. Forty-one blood samples were collected from individual Yucheng victims in 1994-1995. The mean levels of total 33 PCBs and 17 PCDD/Fs were 2468 ng/g lipid (13.3 ng/g sample) and 6550 pg/g lipid (30.9 pg/g sample) respectively. The higher levels were found in PCBs #99, #138, #153, #156, #170, #179, and #180 among 33 PCB congeners, while 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, and OCDD had the higher concentrations among 17 PCDD/F congeners. The total TEQ was contributed in decreasing order by 10 PCDFs (44%), three non-ortho-PCBs (24%), six mono-ortho-PCBs (20%), and seven PCDDs (12%). The mean total PCB levels and TEQ value of the 17 PCDD/Fs in the Yucheng victims 15 years after the toxic exposure were still 9 and 46 times higher than those in the general population in Taiwan. Principle component analysis (PCA) indicated that seven PCB congeners, PCBs #99, #138, #153, #156, #170, #179, and #180, accounted for 73% of the total variances in PCBs. On the other hand, six PCDD/F congeners, 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, 1,2,3,6,7,8-HxCDF, 1,2,3,6,7,8-HxCDD, 1,2,3,4,6,7,8-HpCDF, and OCDD, accounted for 97% of the total variances in PCDD/Fs. In addition, PCA revealed that at least three characteristic patterns of congener profiles for PCBs were observed among the Yucheng victims. Similar trend was also observed for PCDD/Fs. These patterns may reflect distinctive exposure scenarios and/or different metabolizing capabilities among the Yucheng victims. We suggest that these patterns, in contrast to total PCB and PCDD/F levels, may be valuable for the future epidemiologic studies when linking exposure with specific health effect.

The endocrine and reproductive function of the female Yucheng adolescents prenatally exposed to PCBs/PCDFs

BACKGROUND

Polychlorinated biphenyls (PCBs) and related compounds such as polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-dioxins (PCDDs) alter sexual maturation and endocrine function in animals. In 1978-1979, a mass poisoning occurred in central Taiwan from cooking oil contaminated by heat-degraded PCBs and oxidated compounds PCDFs. We tested the hypothesis that in utero exposed to PCBs/PCDFs alter sexual maturation, endocrine, and reproductive function in the human pubescent females.

METHODS

In 1997-1999, girls aged 13-19 years, born to mothers exposed to PCBs/PCDFs, was invited to participate in the study. Menstruation characteristic was recorded daily for 84 days and serum levels of estradiol, LH, FSH, and testosterone were measured on the 3rd day of menstruation.

RESULTS

A total of 17 exposed girls and controls participated, the exposed girls reported shorter mean duration of bleeding per cycle than 16 unexposed (5.5 vs 6.5 days, P=0.0055). There was a higher rate of irregular menstrual cycle in the exposed girls (40% vs 0%, P=0.018). Serum levels of estradiol (P=0.016) and FSH (P=0.061) were higher in exposed girls as compared to controls.

CONCLUSIONS

We conclude that prenatal exposure to PCBs/PCDFs resulted in abnormal menstruation and higher estradiol and FSH levels in follicular phase of menstrual cycle in adolescent girls.

Serum concentrations and profiles of polychlorinated biphenyls in Taiwan Yu-cheng victims twenty years after the incident

In 1979, about 2000 people in central Taiwan were intoxicated via rice oil consumption that was contaminated with polychlorinated biphenyls (PCBs). This "Yu-cheng" incident was one of the two known major human PCB intoxication episodes. Twenty years after the intoxication, serum samples of 435 Yu-cheng victims, 414 adults and 21 children, were collected. Sixteen PCB congeners were analyzed with a gas chromatograph-electron capture detector. We found the median concentration of total PCBs in the adult serum was 1500 ng/g lipid, still substantially higher than that of the general population in Taiwan (3.7-fold) and most seafood consumers in the world. Most of analyzed PCB congeners in children were below or around the detection limits. Congener #138, however, had the highest concentrations, approximately accounting for 55% and 29% in the child and adult groups, respectively. Given that PCBs are persistent organic pollutants and endocrine disruptors, the concentrations and congener-specific profiles regarding the Yu-cheng victims provide valuable information for the investigation of such chemicals in humans.

Levels of PCDDs, PCDFs and Co-PCBs in human milk in Saitama, Japan, and epidemiological research

From 1998 to 2000, the dioxin levels were measured in the milk of 299 mothers who lived in Saitama prefecture, Japan. Factors that influenced the dioxin levels were investigated based on a questionnaire given to the milk donors at that time. It was found that the dioxin levels in the milk of the mothers who smoked were lower than those of non-smokers, and the dioxin levels were generally low in the mothers who were heavy smokers. The average dioxin levels in the milk of mothers who had been breast-fed were higher than those given formula, and there was a significant difference in the dioxin congeners. It was also found that the dioxin levels in milk of the women who regularly consumed fish and shellfish were generally higher. There was a strong correlation between summation operator TEQ and PCB126. The data suggested that PCB126 could be a useful indicator for the simplified analysis of dioxin in human milk.

Neonatal and childhood teeth in relation to perinatal exposure to polychlorinated biphenyls and dibenzofurans: observations of the Yucheng children in Taiwan

In order to determine the effect of perinatal polychlorinated biphenyls and dibenzofurans (PCBs/PCDFs) exposure on neonatal and childhood teeth in Yucheng children, we carried out complete dental examinations on 73 Yucheng children born to mothers who ingested high levels of PCBs/PCDFs and 75 matched controls, aged 7-11 years, in 1992. Ten of 73 (10%) exposed children were reported to have borne teeth during the neonatal period, while none of the controls did. The exposed group also had a significantly higher percentage of teeth with congenitally missing tooth germ compared to the controls (29 vs 2.7%) or rotation (19 vs 2.7%). The percentages of developmental defects increased significantly with increasing maternal serum PCB levels, childhood PCB and PCDF levels, and the duration of breast feeding. The maternal PCB level clearly played a more important role in an increased risk of neonatal teeth and developmental defects. The defects were apparent from the lowest tertile, with a total PCB level of <10 ppb in maternal serum measured nearest to childbirth. The number of permanent teeth tended to be less in exposed children than in the control group from the age of 11 years onwards. Our present study has demonstrated for the first time a dose-response relationship between perinatal PCBs/PCDFs exposure and dental defects.

Effect of prenatal exposure to polychlorinated biphenyls on cognitive development in children: a longitudinal study in Taiwan

BACKGROUND

From 1978 to 1979, a group of people in Taiwan were exposed to high levels of heat-degraded polychlorinated biphenyls (PCBs) owing to accidental ingestion of contaminated rice oil. Children born to mothers following the exposure ('Yucheng' children) were known to have hyperpigmented skin and other dysmorphology after birth.

AIMS

To determine the effect of prenatal exposure to PCBs on cognitive development in Yucheng children.

METHOD

One hundred and eighteen Yucheng children prenatally exposed to PCBs and degradation products, and community-matched control children who were exposed to background levels only, were followed from 1985 to 1998. The Bayley Scale for Infant Development, Chinese version of the Stanford-Binet IQ Test, Raven's Coloured Progressive Matrices and Raven's Standardised Progressive Matrices were used to assess the cognitive development of these children.

RESULTS

The Yucheng children scored lower than control children on each of these methods of measurement between the ages of 2 and 12 years.

CONCLUSIONS

Prenatal exposure to PCBs and their derivatives has long-term adverse effects on cognitive development in humans.

Dioxin-like PCBs in the environment-human exposure and the significance of sources

Dioxin-like PCBs represent an important component of the Sigma-TEQ in many environmental media. Specifically, in animal produce and in fish PCBs dominate the Sigma-TEQ ingested by humans. This in turn leads to high background body burdens in humans with PCB-TEQ greater than that associated with PCDD/Fs. High fish consumers are apparently subject to elevated TEQ exposure from dioxin-like PCBs. This has important implications for exposure assessment studies which have previously only been concerned with PCDDs and PCDFs. Unlike PCDD/Fs, dioxin-like PCBs are not controlled within the food chain. Sources and pathways of exposure are poorly defined. Aroclor formulations and their subsequent usage are considered to be the most important sources in terms of human exposure to some TEF-rated congeners, notably PCB-118, PCB-156 and part of PCB-126. Emissions from combustion sources contribute additional PCB-126. More research is needed to place these compounds in an integrated risk evaluation framework.

Plasma polychlorinated biphenyl levels in Dutch preschool children either breast-fed or formula-fed during infancy

OBJECTIVES

This study examined the influence of lactational and in utero exposure to polychlorinated biphenyls (PCBs) on plasma PCB levels in children.

METHODS

Plasma PCB levels were measured in 173 children at 3.5 years, of whom 91 were breast-fed and 82 were formula-fed in infancy.

RESULTS

Median plasma PCB levels were 3.6 times higher in breast-fed children (0.75 microgram/L) than in their formula-fed peers (0.21 microgram/L). Breast-feeding period and breast-milk PCB levels were important predictors for PCB levels in the breast-fed group. For children in the formula-fed group, PCB levels were significantly related to their material plasma PCB levels.

CONCLUSIONS

PCB levels in Dutch preschool children are related to transfer of maternal PCBs; therefore, strategies should be aimed at reducing maternal PCB body burden.

Middle-ear disease in children exposed prenatally to polychlorinated biphenyls and polychlorinated dibenzofurans

During 1978 and 1979, an episode of poisoning from ingestion of rice oil contaminated with polychlorinated biphenyls and polychlorinated dibenzofurans occurred in central Taiwan. We followed-up children who had been born between June 1978 and March 1985, as well as matched unexposed children. The mothers of exposed children had consumed contaminated oils before the children were born. In 1993, otolaryngologists examined the middle ear of each child with a pneumatic otoscope, and they measured the middle-ear pressure by tympanometry with a Rion RS20 impedance audiometer. The exposed children had a significantly higher prevalence of middle-ear diseases than their matched controls. The exposed children who had ear diseases had higher serum levels of 2,3,4,7,8-pentachloro- and 1,2,3,4,7,8-hexachloro-dibenzofurans than the children who did not have similar diseases. Therefore, in this study, children exposed to polychlorinated biphenyls and polychlorinated dibenzofurans had a higher incidence of middle-ear diseases than their controls.

Reassessment of PCDD/DFs and Co-PCBs toxicity in contaminated rice-bran oil responsible for the disease "Yu-Cheng"

Reassessment of dibenzo-p-dioxins and dibenzofurans (PCDD/DFs) and coplanar polychlorinated biphenyls (Co-PCBs) in toxic Yu-Cheng rice-bran oil was carried out. The contaminating source appears to be a mixture of KC-400 and KC-500. The oil contains 176 micrograms/g PCBs and 37.194 ng/g 2,3,7,8,-TCDD toxicity equivalency (TEQ). The TEQ contributions from the PCDDs (4.472 ng/g), PCDFs (19.568 ng/g), and Co-PCBs (13.154 ng/g) are 12% 53% and 35%, respectively. Complete identification and quantitation suggests that 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, 2,3,7,8,-TCDF. 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD and PCB# 77 are candidates for the primary causal agents of Yu-Cheng disease.

Polychlorinated dibenzo-p-dioxins and dibenzofurans via mother's milk may cause developmental defects in the child's teeth

Previous studies have shown developmental dental defects in rhesus macaques and rats experimentally exposed to dioxin. Now it was investigated if dioxin exposure from mother's milk in a normal breast-fed child population correlated with enamel hypomineralization of teeth that mineralize during the first 2 years of life. We studied 102 6-7-year-old Finnish children breast-fed for an average of 10.5 months. Milk samples were collected when the child was 4 weeks old. The concentrations of 17 most toxic polychlorinated dibenzo-p-dioxin and furan congeners were determined. The total exposure to dioxins was calculated from the concentrations in milk and the duration of breast feeding. Hypomineralization of the target teeth was found in 17 children. Both the frequency and severity of the lesions correlated with the total exposure. The results suggest that at the prevailing levels in human milk, dioxin may be an important cause of hypomineralization in the developing teeth of children.