Twin frequency and industrial pollution in different regions of Hesse, Germany.

AIMS: To investigate whether twinning occurs more frequently in residents in the vicinity of a toxic waste incinerator (TWI). METHODS: Within a longitudinal environmental study that addressed child health second grade school children and their parents were recruited. The proportion of twinning in the TWI region was compared with two comparison areas. In a second confirmatory investigation, birth records for the years 1994-97 from the Hessian Perinatal Survey (HEPS) were accessed to determine whether the incidence of twinning was higher in regions around the TWI compared to adjacent reference areas. RESULTS: In the environmental study, 61.5% of the children and 95% of their mothers participated. In mothers, twinning was 5.3% in the TWI region compared to 1.6% and 2.3% in the comparison regions. The proportion of mothers with fertility assessment/treatment was 5.7%, 8.3%, and 0% respectively. The prevalence of twinning was not significantly higher (4.5%) in mothers with treatment compared to mothers without (3.7%). From the HEPS, data of 20 603 births was analysed. The incidence of twins was significantly higher in areas which surround the TWI and other industries (1.4-1.6 per 100 births) compared to births in reference areas (0.8 per 100). CONCLUSIONS: Twinning rates may be associated with exposure to industrial pollution. Future environmental health studies that consider multiple births as an outcome are warranted. These should also investigate whether the incidence of monozygotic or dizygotic twinning may be associated with industrial pollution.

Early childhood determinants of organochlorine concentrations in school-aged children.

We investigated whether early childhood factors such as breast-feeding, parity, and smoking contribute to the variation of organochlorine compounds (OC: dichlorodiphenyldichloroethene, hexachlorobenzene, beta-hexachlorocyclohexane, and the sum of polychlorinated biphenyls including the congeners 101, 118, 138, 153, 170, 180, 183, and 187) at approximately 7 y of age. OC were measured in whole blood of 350 children. Pregnancy characteristics and the child's living conditions were gathered by questionnaires administered to the parents and interviews with the mother. Height and weight were determined during the medical examination. Exclusion of incomplete data and nonbiologic children of the mothers yielded a sample of 337 children. We applied regression analysis with indicator variables, controlling for confounders. No systematic association was detected for birth order or maternal smoking during pregnancy. The OC concentrations are diluted in children with a higher body mass index (>18 kg/m(2)). We found a strong, dose-dependent relationship between the duration of breast-feeding (none, 1-4 wk, 5-8 wk, 9-12 wk, >12 wk) and the concentration of all five OCs. Of the potential determinants analyzed, more of the variance of the OC concentration is accounted for by breast-feeding than by any other variable. Exclusive breast-feeding beyond 12 wk was associated with a doubling of OC whole blood concentration compared with bottle-fed children (dichlorodiphenyldichloroethene, 0.28 microg/L versus 0.55 microg/L; beta-hexachlorocyclohexane, 0.05 microg/L versus 0.14 microg/L; hexachlorobenzene, 0.14 microg/L versus 0.25 microg/L; sum of polychlorinated biphenyls, 0.25 microg/L versus 0.55 microg/L). These findings indicate that breast-feeding can lead to an extended duration of increased OC exposure in childhood.

Exposure to polychlorinated biphenyls and levels of thyroid hormones in children.

As part of an epidemiologic study on exposure to a toxic waste incineration plant we investigated whether blood concentrations of polychlorinated biphenyls (PCBs), lead, and cadmium, as well as concentration of mercury in 24-hr urine samples were associated with thyroid hormone status. As an indication of status, we determined levels of thyroid-stimulating hormone (TSH), free thyroxine (FT(4)), and free triiodothyronine (FT(3)) in children living in households where [less than/equal to] 10 cigarettes were smoked per day. Eight PCB congeners (PCBs 101, 118, 138, 153, 170, 180, 183, and 187) were measured in whole blood samples. Of these, seven congeners (PCB 101 was not detected in any sample) and the sum of all PCB congeners were analyzed as predictors for thyroid hormone status in separate linear regression models adjusted for potential confounders. In addition, the possible effects of cadmium, lead, and mercury on levels of thyroid hormones were examined. Blood concentrations and information on questionnaire data were available for 320 children 7-10 years of age. We found a statistically significant positive association between the mono-ortho congener PCB 118 and TSH as well as statistically significant negative relationships of PCBs 138, 153, 180, 183, and 187 to FT(3). There was no association for the PCB congeners and FT(4). Blood cadmium concentration was associated with increasing TSH and diminishing FT(4). Blood lead and urine concentration of mercury were of no importance to thyroid hormone levels. The results stress the need for future studies on the possible influences of PCB and cadmium exposure on thyroid hormones, particularly in children. These studies should also take neurologic development into account.

PCDD/PCDF indoor exposure in day-care centers and PCDD/PCDF blood concentrations of female employees.

We determined blood concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in 41 female employees with previous exposure to pentachlorophenol-based wood preservatives from 10 day-care centers in the Hamburg, Germany, area. We compared the blood concentrations with estimated age-dependent reference values and analyzed the correlation between PCDD/PCDF indoor air exposure and blood concentrations. The analyses based on the PCDD congeners 1,2,3,4,7,8-, 1,2,3,6,7,8-, and 1,2,3,7,8,9-hexaCDD (hexaCDD), 1,2,3,4,6,7,8-heptaCDD (heptaCDD), octaCDD, and the 2,3,7,8-tetrachlorodibenzo-p-dioxin toxicity equivalents calculated according to the international NATO-CCMS model (I-TEQ). In comparison to the estimated reference values, the blood concentrations of hexaCDD and I-TEQ spread around the mean estimate. Data for octaCDD scattered in some cases distinctly above the upper confidence limit. Reference values for heptaCDD could not be estimated. The correlation between PCDD/PCDF indoor air exposure and PCDD/PCDF blood concentrations was examined by linear multiple regression analysis considering different exposure variables and taking confounders into account. Analyses were carried out with the total study group and with a restricted subgroup. Associations were shown between the PCDD/PCDF indoor air concentrations and blood concentrations for heptaCDD and for the I-TEQ, whereas hexaCDD showed no association. OctaCDD showed a negative association in the total study group and no association in the subgroup analysis. In summary, the analyses showed no clear association between PCDD/PCDF indoor air exposure in day-care centers and PCDD/PCDF blood levels of female employees previously exposed to wood preservatives. By contrast, the results consistently indicated a positive association between PCDD/PCDF blood concentrations and exposure to wood preservatives in private homes.

[Thyroid hormone level in children in the area of a toxic waste incinerator in South Essen]. / Schilddrüsenhormonspiegel bei Kindern in der Umgebung einer Sonderabfallverbrennungsanlage (SVA) in Südhessen.

As part of an environmental epidemiological study on potential exposure to a toxic waste incineration we investigated whether children in an area with a toxic waste incinerator (TWI) have different levels of thyroid hormones than children in two comparative regions. The TWI region is situated in the Rhine valley (about 30 km across) with low mountains on both sides. Other industries such as a chemical plant are nearby, and several municipalities are located in the environment of these. One comparative area 20 km north is also industrially and agriculturally used, but has no incinerator (Rhine Valley comparison group, RVC group). South-East of the incinerator region in an area of low mountains (about 400 m high) we investigated the second comparison group (Odenwald comparison group, OWC group). Altogether 671 children from 18 municipalities participated in 1994/95 (participation 61.5%). Blood samples were taken from 341 children, aged 7 to 10 years, living in non-smoking households or in households with only light smokers. Serum levels of thyrotropin stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3) were analysed. In a self-administered questionnaire for the parents, which was checked during the medical examination, we gathered information on age, gender, passive smoking, consumption of fish, as well as use of wood preservatives and pesticides at home. By means of adjusted regression analysis the first step was to check whether the TWI group had means of TSH, FT4 and FT3 that differed from the OWC group and the RVC group. If differences were at least marginally significant, the second step was to analyse whether children from different municipalities had statistically different mean values and if the pattern of these municipalities fitted into the three regions. For the latter, children from a town in the Odenwald served as comparison group. The TWI group had statistically significantly (p < or = 0.05) reduced FT3 and FT4 values with a higher prevalence of FT3 values below clinical references (TWI group: 7.7%, RVC group: 3.2%, OWC group: 1.2%). Children from four out of nine TWI municipalities showed statistically significantly lower FT3 means than children from the reference town, and one of the seven municipalities from the comparative areas. The mean FT4 was significantly lower in four municipalities of the TWI area and in one of the two other areas. The mean TSH was only marginally different, mainly influenced by gender differences with boys having higher TSH levels. Comparison of the municipalities did not reveal a consistent pattern. Industrial pollution might influence the regulatory system of the pituitary thyroid axis. Reduced peripheral thyroid hormones associated with exposure to polychlorinated biphenyls (PCB) and dioxins/furans (PCDD/F) were found in previous studies. Our results suggest that children exposed to toxic waste incineration in their environment have lower thyroxine and triiodothyronine levels.