An assessment of dioxin exposure across gestation and lactation using a PBPK model and new data from Seveso.

On July 10, 1976, an explosion at a chemical plant in Seveso, Italy, released up to 30kg of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-the most potent dioxin congener. Twenty years later, the Seveso Women's Health Study (SWHS) initiated a follow-up assessment of a cohort of female Seveso residents. Researchers collected serial blood, measured for TCDD levels, and recorded information about the women's medical history after the explosion. The study's aims were to: 1) modify the human PBPK model for TCDD (Emond et al. 2004; Emond et al. 2005; NCEA-USEPA, 2010) to include repetitive gestation and lactation; 2) simulate TCDD blood concentrations during different life stages including pregnancy and lactation, under different exposure scenarios; and 3) use this PBPK model to compare the influence of gestation and lactation on elimination of TCDD. After optimization of the model, it was assessed using data from the SWHS cohort. The 23 women in Subcohort A, were 4-39years old and in Subcohort B, the 18 women were 3-17years old when the explosion occurred. The model accurately predicted the blood concentrations during the 20years post-exposure, including periods of pregnancy and lactation. The model was also used to analyze the contribution of gestation and lactation to the mother's elimination of TCDD. The results suggest that gestation and lactation do not significantly impact TCDD blood elimination. Future efforts will focus on using additional data to evaluate the PBPK model and improving the mathematical descriptions of lactation and multiple gestations.

Addition of either pioglitazone or a sulfonylurea in type 2 diabetic patients inadequately controlled with metformin alone: impact on cardiovascular events. A randomized controlled trial.

BACKGROUND AND AIMS: Metformin is the first-line therapy in type 2 diabetes. In patients inadequately controlled with metformin, the addition of a sulfonylurea or pioglitazone are equally plausible options to improve glycemic control. However, these drugs have profound differences in their mechanism of action, side effects, and impact on cardiovascular risk factors. A formal comparison of these two therapies in terms of cardiovascular morbidity and mortality is lacking. The TOSCA.IT study was designed to explore the effects of adding pioglitazone or a sulfonylurea on cardiovascular events in type 2 diabetic patients inadequately controlled with metformin. METHODS: Multicentre, randomized, open label, parallel group trial of 48 month duration. Type 2 diabetic subjects, 50-75 years, BMI 20-45 Kg/m(2), on secondary failure to metformin monotherapy will be randomized to add-on a sulfonylurea or pioglitazone. The primary efficacy outcome is a composite endpoint of all-cause mortality, nonfatal myocardial infarction, nonfatal stroke, and unplanned coronary revascularization. Principal secondary outcome is a composite ischemic endpoint of sudden death, fatal and non-fatal myocardial infarction and stroke, endovascular or surgical intervention on the coronary, leg or carotid arteries, major amputations. Side effects, quality of life and economic costs will also be evaluated. Efficacy, safety, tolerability, and study conduct will be monitored by an independent Data Safety Monitoring Board. End points will be adjudicated by an independent external committee. CONCLUSIONS: TOSCA.IT is the first on-going study investigating the head-to-head comparison of adding a sulfonylurea or pioglitazone to existing metformin treatment in terms of hard cardiovascular outcomes. REGISTRATION: Clinicaltrials.gov ID NCT00700856.

The prevalence of Molar Incisor Hypomineralisation (MIH) in a group of Italian school children.

AIM: This epidemiological study in a group of Italian children was undertaken in order to increase our knowledge of the prevalence of Molar Incisor Hypomineralisation (MIH) in different European countries. METHOD: A population of school children aged 7.3 - 8.3 years, living in Lissone, Northern Italy, was examined for the presence and severity of MIH. RESULTS: Of a total of 227 children (113 females), 31 (13.7%) had MIH, the tooth prevalence in the permanent first molars being 5.8%. Fifteen children (6.6%) had demarcated opacities in the incisors with a tooth prevalence of 2.1%. The defects in the molars were mild with the exception of one child who had severe defects. CONCLUSION: MIH was quite common in this Italian town, and the prevalence figures were near those reported in Scandinavian countries but clearly higher than those from Dresden, Germany.

Health status and plasma dioxin levels in chloracne cases 20 years after the Seveso, Italy accident.

BACKGROUND: The Seveso, Italy accident of 1976 exposed a large population to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD or simply dioxin). The accident resulted, mostly among children, in one of the largest ever-reported outbreaks of chloracne, the typical skin disorder due to halogenated-hydrocarbon compounds. OBJECTIVES: Approximately 20 years after the accident, we conducted an epidemiological study in Seveso to investigate (a) the health status of chloracne cases; (b) TCDD-chloracne exposure-response relationship; and (c) factors modifying TCDD toxicity. METHODS: From 1993 to 1998, we recruited 101 chloracne cases and 211 controls. Trained interviewers administered a structured questionnaire assessing, among other epidemiological variables, information on an extensive list of diseases. During the interview, individual pigmentary characteristics were determined. We measured plasma TCDD levels using high-resolution gas chromatography/mass spectrometry. RESULTS: Plasma TCDD was still elevated (> 10 ppt) in 78 (26.6%) of the 293 subjects with adequate plasma samples, particularly in females, in subjects who had eaten home-grown animals, and in individuals with older age, higher body mass index and residence near the accident site. After 20 years, health conditions of chloracne cases were similar to those of controls from the Seveso area. Elevated plasma TCDD was associated with chloracne [odds ratio (OR) = 3.7, 95% confidence interval (CI) 1.6-8.8, adjusted for age, sex and residence]. Chloracne risk was higher in subjects younger than 8 years at the accident (OR = 7.4, 95% CI 1.8-30.3) and, contrary to previous hypotheses, did not increase at puberty onset or in teenage years. Subjects with elevated TCDD levels and light hair colour had higher relative odds of chloracne (OR = 9.2, 95% CI 2.6-32.5). CONCLUSIONS: Dioxin toxicity in chloracne cases was confined to the acute dermatotoxic effects. Chloracne occurrence appeared related to younger age and light hair colour. Age-related dioxin elimination or dilution must be taken into account in interpreting these results.

Contribution of proteomics to the molecular analysis of renal cell carcinoma with an emphasis on manganese superoxide dismutase.

Renal cell carcinoma (RCC) originates in the renal cortex. It accounts for 2-3 percent of all cancers occurring in adults and it is characterised by lack of early clinical manifestations, unpredictable outcome, and absence of effective treatment modalities except early surgery. RCC comprises a heterogeneous group of tumours with various molecular and cytogenetic abnormalities and different histological features as cell types and tumour architecture. Molecular genetic and proteomic tools led to the discovery of potential diagnostic prognostic and therapeutic biomarkers of RCC. In this review we discuss recent developments in understanding genotype-phenotype relationships, with attention to manganese superoxide dismutase, a mitochondrial enzyme related to the redox cycle which affects various regulatory functions of cells. The expression of this protein has been evaluated in numerous human tumour types including RCC, and post-translational modifications are being investigated.

Seveso Women's Health Study: does zone of residence predict individual TCDD exposure?

The compound, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), is produced as an unwanted by-product of various chemical reactions and combustion processes, including the manufacture of chlorinated phenols and derivatives. In animals, TCDD exposure is associated with toxic, carcinogenic, developmental, and reproductive effects. In 1976, a chemical plant explosion in Seveso, Italy, exposed the residents in the surrounding community to the highest exposure to TCDD known in humans. Materials from an aerosol cloud of sodium hydroxide, sodium trichlorophenate and TCDD were deposited over an 18.1 km2 area. As evidence of the significant level of TCDD exposure, numerous animals died and 193 cases of chloracne were reported among residents of the area. Initially, the contaminated area was divided into three major exposure Zones (A, B, R) based on the concentration of TCDD in surface soils. To date, the majority of epidemiologic studies conducted in Seveso have used Zone of residence as a proxy measure of exposure. The purpose of the present study is to validate the use of Zone of residence in Seveso as a proxy measure of exposure against individual serum TCDD measurement, and to determine whether questionnaire information can improve the accuracy of the exposure classification. Using data collected from the Seveso Women's Health Study (SWHS), the first comprehensive epidemiologic study of the reproductive health of women in Seveso, we determined that Zone of residence is a good predictor of individual serum TCDD level, explaining 24% of the variance. Using questionnaire information could have improved prediction of individual exposure levels in Seveso, increasing the percent of the variation in serum TCDD levels explained to 42%.

Time trends of major coronary risk factors in a northern Italian population (1986-1994). How remarkable are socioeconomic differences in an industrialized low CHD incidence country?

BACKGROUND: The goals are to estimate time trends (1986-1994) of major coronary risk factors in an industrialized low CHD incidence population and to assess education class (EC) differences in risk factor prevalence and in time trends. METHODS: Three population surveys were conducted in 1986-1987, 1989-1990 and 1993- 1994 on independent and two-stage age- and gender-stratified random samples (1906 men and 1941 women) of 35-64 year old residents of Brianza, an affluent region of northern Italy. The protocol for data collection, clinical measurements and biochemical determinations adhered to the WHO MONICA manual and underwent repeated quality control assessments. EC were identified according to gender- and 5-year birth-cohort specific tertiles. RESULTS: In the initial, middle and final surveys 1258, 1259 and 1330 subjects were enrolled, corresponding to participation rates of 70.1%, 70.3% and 74.3%, respectively. Over the 8-year period, in men systolic blood pressure and smoking habits declined, body mass index and serum total cholesterol increased. In women systolic blood pressure showed a constant reduction, total cholesterol and BMI increased and the prevalence of smokers remained stable. Overall inverse associations with EC were found for body mass index, for prevalence of cigarette smokers in men and for systolic blood pressure in women. Decreases in blood pressure were more evident in the lowest EC. Cigarette smoking was on the decline in the higher EC in men. BMI and total cholesterol increased in all EC with the notable exception of the 'low' EC in women. CONCLUSIONS: Favourable changes of the risk factor profile in the low socio-economic classes may have contributed to reduce CHD rates in this population. Specific policies oriented to lowest socio-economic classes are needed to continue to combat the smoking epidemic.

Environmental exposure to dioxin: the Seveso experience.

The toxicity in humans of 2,3,7,8-tetrachlorodibenzo-p-dioxin, a man-made compound and environmental pollutant, is still debated. The industrial accident at Seveso, Italy, in 1976 exposed a large population of both sexes and of all ages to a massive concentration of 2,3,7,8-tetrachlorodibenzo-p-dioxin. Monitoring of soil and measurement of blood samples allowed classification of the exposed population into three categories: A, B and R (high, medium and low exposure, respectively). This article presents data from longitudinal health monitoring of the population, including liver function, immune function, neurological impairment, dermatological effects, reproductive pathology, and mortality.

Human health effects after exposure to 2,3,7,8-TCDD.

In 1949, the first descriptions of human exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD)-contaminated chemicals were reported after a trichlorophenol reactor explosion in Nitro, West Virginia, USA. Reported non-cancer health effects included a range of conditions affecting most systems. Additional reports of the health consequences of exposure continued through the remainder of the century. The majority of effects have been reported among highly exposed groups including occupational populations, such as chemical production workers, pesticide applicators, and individuals who handled or were exposed to materials treated with 2,3,7,8-TCDD-contaminated pesticides, and among residents of communities contaminated with tainted waste oil (Missouri, USA) and industrial effluent (Seveso, Italy). For only six exposed populations were biological measurements of 2,3,7,8-TCDD-contaminated collected and used to examine the relationship between non-cancer health effects and exposure. Of the many non-cancer health effects thought to be associated with 2,3,7,8-TCDD exposure, only chloracne, elevations in GGT and triglyceride levels, and alterations in FSH and LH were related to serum 2,3,7,8-TCDD levels. Mortality from cardiovascular diseases also appeared to be elevated among cohorts of exposed chemical workers and Seveso residents. Continued surveillance of the health of exposed populations will be useful in identifying the long-term effects of both high and low 2,3,7,8-TCDD exposure.

Paternal concentrations of dioxin and sex ratio of offspring.

BACKGROUND: 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD or dioxin), is commonly considered the most toxic man-made substance. We have previously shown that high serum concentrations of TCDD in parents from Seveso, Italy, were linked to their having a relative increase in the number of female births after the parents exposure to a release of dioxin in 1976. We have continued the study to determine whether the parents' sex and/or age at exposure affected the sex ratio of their children. METHODS: We measured the TCDD concentrations in serum samples from potentially exposed parents collected in 1976 and 1977, and investigated the sex ratio of their offspring. FINDINGS: Serum samples were collected from 239 men and 296 women. 346 girls and 328 boys were born to potentially exposed parents between 1977 and 1996, showing an increased probability of female births (lower sex ratio) with increasing TCDD concentrations in the serum samples from the fathers (p=0.008). This effect starts at concentrations less than 20 ng per kg bodyweight. Fathers exposed when they were younger than 19 years of age sired significantly more girls than boys (sex ratio 0.38 [95% CI 0.30-0.47]). INTERPRETATION: Exposure of men to TCDD is linked to a lowered male/female sex ratio in their offspring, which may persist for years after exposure. The median concentration of dioxin in fathers in this study is similar to doses that induce epididymal impairments in rats and is about 20 times the estimated average concentration of TCDD currently found in human beings in industrialised countries. These observations could have important public-health implications.

Heat shock proteins in human cancer.

The heat shock proteins (hsp) are ubiquitous molecules induced in cells exposed to sublethal heat shock, present in all living cells, and highly conserved during evolution. Their function is to protect cells from environmental stress damage by binding to partially denatured proteins, dissociating protein aggregates, to regulate the correct folding, and to cooperate in transporting newly synthesized polypeptides to the target organelles. The molecular chaperones are involved in numerous diseases, including cancer, revealing changes of expression. In this review, we mainly describe the relationship of hsp expression with human cancer, and discuss what is known about their post-translational modifications according to malignancies.

Seveso Women's Health Study: a study of the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on reproductive health.

Although reproductive effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure have been reported in numerous investigations of animals, studies of this association in humans are limited. In 1976, an explosion in Seveso, Italy exposed the surrounding population to among the highest levels of TCDD recorded in humans. The relatively pure exposure to TCDD and the ability to quantify individual level TCDD exposure from sera collected in 1976 for the Seveso cohort affords a unique opportunity to evaluate the potential dose-response relationship between TCDD exposure and a spectrum of reproductive endpoints. The Seveso Women's Health Study (SWHS) is the first comprehensive study of the reproductive health of a human population exposed to TCDD. The primary objectives of the study are to investigate the relationship of TCDD and the following endpoints: (1) endometriosis; (2) menstrual cycle characteristics; (3) age at menarche; (4) birth outcomes of pregnancies conceived after 1976; (5) time to conception and clinical infertility; and (6) age at menopause. Included in the SWHS cohort are women who were 0-40 yr old in 1976, who have adequate stored sera collected between 1976 and 1980, and who resided in Zones A or B at the time of the accident. All women were interviewed extensively about their reproductive and pregnancy history and had a blood draw. For an eligible subset of women, a pelvic exam and transvaginal ultrasound were conducted and a menstrual diary was completed. More than 95% of the women were located 20 yr after the accident and roughly 80% of the cohort agreed to participate. Data collection was completed in July 1998, serum TCDD analysis of samples for analysis of endometriosis as a nested case-control study was completed in October 1998, and statistical analysis of these data should be completed in early 1999. Serum samples are now being analyzed in order to relate TCDD levels with the remaining reproductive outcomes.

Modified expression of plasma glutathione peroxidase and manganese superoxide dismutase in human renal cell carcinoma.

Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) is a powerful tool to separate thousands of polypeptides and to highlight the modification of protein expression in malignant diseases. By applying 2-D PAGE to ten normal human kidney and ten homologous renal cell carcinoma (RCC) tissues, we found two peptides in all ten normal tissues but not in RCCs and, conversely, two peptides were detected in all RCCs but not in normal tissues. Using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and internal sequence analysis, the two first peptides were identified as two isoforms of plasma glutathione peroxidase (GPxP). The two other peptides isolated in all RCCs but not in normal tissues were identified by N-terminal sequence analysis as multimeric forms of manganese superoxide dismutase (Mn-SOD). No multimeric Mn-SODs and only two monomeric forms were detected in normal tissues. GPxP and Mn-SOD are metallo-enzymes encoded on chromosome 5q32 and on chromosome 6p25, respectively. Their regions are within the locus 5q21-->qter and 6q21-6q27 on which deletions and translocations are described in some cytogenetic studies of RCC transformation. Therefore, our results might suggest a correlation between the modified expression of GPxP and Mn-SOD in tumor tissues and chromosomal modifications, and that the two proteins may be putative markers for diagnosis of RCC.

Exposure assessment: serum levels of TCDD in Seveso, Italy.

Accurate exposure assessment is an important step in both risk assessment and epidemiologic studies involving potential human exposure to environmental toxicants. Various methods have been used to assess human exposure. These methods include models based on one's temporal and spatial nearness to the source, environmental levels of toxicant, and biological measures. We believe that the latter measure is the "gold standard." In this article we present the serum 2,3,7,8-tetrachlorodibenzo-p-dioxin levels in residents of the contaminated zones in Seveso, Italy, in 1976, and delineate these data by age and gender. Some of these serum levels are among the highest ever reported and thus this population serves as a benchmark for comparison of human exposure and potential adverse health effects. One such potential population is that population consuming potentially contaminated fish.

[Seveso: biological monitoring of dioxin pollution. An example of environmental medicine. Multicentric and interdisciplinary applied research]. / Seveso--Monitoraggio biologico di inquinamento da Diossina: Esempio di Medicina Ambientale. Ricerca Applicata Multicentrica e Interdisciplinare.

In 1976 the population of an area including Seveso (about 30,000) affected by the fallout of a toxic cloud containing 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) started a health monitoring plan which lasted until 1985. Smaller groups were monitored until 1997. The large number of people and the different toxic effects on organs have gathered different discipline experts including informatic. This work has permitted the not easy observation both of minor and bigger effects during two decades.

Plasma apolipoproteins A-I and B in survivors of myocardial infarction and in a control group.

The values of apolipoproteins (apo) A-I and B were determined in a population sample of hospital outpatients with a standardized method to verify if the cutpoints calculated in a cross-sectional study in the US are usable with other populations. We also tested the apolipoproteins' ability to discriminate between healthy people and survivors of myocardial infarction. In the studied population the apo A-I value corresponding to the HDL-cholesterol decisional centile is 1.12 g/L for males and 1.17 g/L for females; the apo B value corresponding to the LDL-cholesterol decisional centile is 1.23 g/L for males and 1.14 g/L for females. These values are quite close to the cutpoints proposed for the American population (1.20 g/L for both apolipoproteins). In comparison with the LDL- and HDL-cholesterol decisional concentrations, the cutpoints for apolipoproteins allow a correct classification of a greater percentage of postmyocardial infarction patients (16% higher for apo B and 5% for apo A-I). Standardized assays coupled with a reference database allow a better clinical use of apolipoprotein measurements.

2,3,7,8-Tetrachlorodibenzo-p-dioxin plasma levels in Seveso 20 years after the accident.

In 1976, near Seveso, Italy, an industrial accident caused the release of large quantities of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) into the atmosphere, resulting in the highest levels of the toxicant ever recorded in humans. The contaminated area was divided into three zones (A, B, R) corresponding to decreasing TCDD levels in soil, and cohort including all residents was enumerated. The population of the surrounding noncontaminated area (non-ABR) was chosen as referent population. Two decades after the accident. plasma TCDD levels were measured in 62 subjects randomly sampled from the highest exposed zones (A and B) and 59 subjects from non-ABR, frequency matched for age, gender, and cigarette smoking status. Subjects living in the exposed areas have persistently elevated plasma TCDD levels (range = 1.2-89.9 ppt; geometric mean = 53.2 and 11.0 ppt for Zone A and Zone B, respectively). Levels significantly decrease by distance from the accident site (p = 0.0001), down to general population values (4.9 ppt) in non-ABR, thus validating the original zone classification based on environmental measurements. Women have higher TCDD levels than men in the entire study area (p = 0.0003 in Zone B; p = 0.007 in non-ABR). This gender difference persists after adjustment for location within the zone, consumption of meat derived from locally raised animals, age, body mass index, and smoking. There is no evidence for a gender difference in exposure, so variation in metabolism or elimination due to body fat or hormone-related factors may explain this finding. Elevated TCDD levels in women may contribute to adverse reproductive, developmental, and cancer outcomes.

Controlling persistent organic pollutants-what next?

Within the context of current international initiatives on the control of persistent organic pollutants (POPs), an overview is given of the scientific knowledge relating to POP sources, emissions, transport, fate and effects. At the regional scale, improvements in mass balance models for well-characterised POPs are resulting in an ability to estimate their environmental concentrations with sufficient accuracy to be of help for some regulatory purposes. The relevance of the parameters used to define POPs within these international initiatives is considered with an emphasis on mechanisms for adding new substances to the initial lists. A tiered approach is proposed for screening the large number of untested chemical substances according to their long-range transport potential, persistence and bioaccumulative potential prior to more detailed risk assessments. The importance of testing candidate POPs for chronic toxicity (i.e. for immunotoxicity, endocrine disruption and carcinogenicity) is emphasised as is a need for the further development of relevant SAR (structure activity relationship) models and in vitro and in vivo tests for these effects. Where there is a high level of uncertainty at the risk assessment stage, decision-makers may have to rely on expert judgement and weight-of-evidence, taking into account the precautionary principle and the views of relevant stake-holders. Close co-operation between the various international initiatives on POPs will be required to ensure that assessment criteria and procedures are as compatible as possible.