Ida M. Schmidt

Human breast milk contamination with phthalates and alterations of endogenous reproductive hormones in infants three months of age.

Phthalates adversely affect the male reproductive system in animals. We investigated whether phthalate monoester contamination of human breast milk had any influence on the postnatal surge of reproductive hormones in newborn boys as a sign of testicular dysgenesis. Design We obtained biologic samples from a prospective Danish–Finnish cohort study on cryptorchidism from 1997 to 2001. We analyzed individual breast milk samples collected as additive aliquots 1–3 months postnatally (n = 130; 62 cryptorchid/68 healthy boys) for phthalate monoesters [mono-methyl phthalate (mMP), mono-ethyl phthalate (mEP), mono-n-butyl phthalate (mBP), mono-benzyl phthalate (mBzP), mono-2-ethylhexyl phthalate (mEHP), mono-isononyl phthalate (miNP)]. We analyzed serum samples (obtained in 74% of all boys) for gonadotropins, sex-hormone binding globulin (SHBG), testosterone, and inhibin B. Results All phthalate monoesters were found in breast milk with large variations [medians (minimum–maximum)]: mMP 0.10 (< 0.01–5.53 μg/L), mEP 0.95 (0.07–41.4 μg/L), mBP 9.6 (0.6–10,900 μg/L), mBzP 1.2 (0.2–26 μg/L), mEHP 11 (1.5–1,410 μg/L), miNP 95 (27–469 μg/L). Finnish breast milk had higher concentrations of mBP, mBzP, mEHP, and Danish breast milk had higher values for miNP (p = 0.0001–0.056). No association was found between phthalate monoester levels and cryptorchidism. However, mEP and mBP showed positive correlations with SHBG (r = 0.323, p = 0.002 and r = 0.272, p = 0.01, respectively); mMP, mEP, and mBP with LH:free testosterone ratio (r = 0.21–0.323, p = 0.002–0.044) and miNP with luteinizing hormone (r = 0.243, p = 0.019). mBP was negatively correlated with free testosterone (r = −0.22, p = 0.033). Other phthalate monoesters showed similar but nonsignificant tendencies. Conclusions Our data on reproductive hormone profiles and phthalate exposures in newborn boys are in accordance with rodent data and suggest that human Leydig cell development and function may also be vulnerable to perinatal exposure to some phthalates. Our findings are also in line with other recent human data showing incomplete virilization in infant boys exposed to phthalates prenatally.

Difference in prevalence of congenital cryptorchidism in infants between two Nordic countries.

BACKGROUND Several investigators have shown striking differences in semen quality and testicular cancer rate between Denmark and Finland. Since maldescent of the testis is a shared risk factor for these conditions we undertook a joint prospective study for the prevalence of congenital cryptorchidism. METHODS 1068 Danish (1997-2001) and 1494 Finnish boys (1997-99) were consecutively recruited prenatally. We also established prevalence data for all newborns at Turku University Central Hospital, Finland (1997-99, n=5798). Testicular position was assessed by a standardised technique. All subtypes of congenital cryptorchidism were included, but retractile testes were considered normal. FINDINGS Prevalence of cryptorchidism at birth was 9.0% (95% CI 7.3-10.8) in Denmark and 2.4% (1.7-3.3) in Finland. At 3 months of age, prevalence rates were 1.9% (1.2-3.0) and 1.0% (0.5-1.7), respectively. Significant geographic differences were still present after adjustment for confounding factors (birthweight, gestational age, being small for gestational age, maternal age, parity, mode of delivery); odds ratio (Denmark vs Finland) was 4.4 (2.9-6.7, p<0.0001) at birth and 2.2 (1.0-4.5, p=0.039) at three months. The rate in Denmark was significantly higher than that reported 40 years ago. INTERPRETATION Our findings of increasing and much higher prevalence of congenital cryptorchidism in Denmark than in Finland contribute evidence to the pattern of high frequency of reproductive problems such as testicular cancer and impaired semen quality in Danish men. Although genetic factors could account for the geographic difference, the increase in reproductive health problems in Denmark is more likely explained by environmental factors, including endocrine disrupters and lifestyle.

Impaired Reproductive Development in Sons of Women Occupationally Exposed to Pesticides during Pregnancy

OBJECTIVES The aim of this prospective study was to investigate whether occupational pesticide exposure during pregnancy causes adverse effects on the reproductive development in the male infants. DESIGN AND MEASUREMENTS Pregnant women employed in greenhouses in Denmark were consecutively recruited, and 113 mother-son pairs were included. The mothers were categorized as occupationally exposed (91 sons) or unexposed (22 sons) to pesticides during pregnancy. Testicular position and volume, penile length, and position of urethral opening were determined at 3 months of age using standardized techniques. Concentrations of reproductive hormones in serum from the boys were analyzed. RESULTS The prevalence of cryptorchidism at 3 months of age was 6.2% [95% confidence interval (CI), 3.0-12.4]. This prevalence was considerably higher than among Danish boys born in the Copenhagen area (1.9%; 95% CI, 1.2-3.0) examined by the same procedure. Boys of pesticide-exposed mothers showed decreased penile length, testicular volume, serum concentrations of testosterone, and inhibin B. Serum concentrations of sex hormone-binding globulin, follicle-stimulating hormone, and the luteinizing hormone:testosterone ratio were increased compared with boys of nonexposed mothers. For individual parameters, only the decreased penile length was statistically significant (p = 0.04). However, all observed effects were in the anticipated direction, and a joint multivariate test showed that this finding had a p-value of 0.012. CONCLUSIONS Our findings suggest an adverse effect of maternal occupational pesticide exposure on reproductive development in the sons despite current greenhouse safeguards and special measures to protect pregnant women.

Height of conscripts in Europe: is postneonatal mortality a predictor?

The height of conscripts has increased steadily during recent decades in Europe. We have collected data on conscript height from 11 European countries to examine if this trend is continuing. In the Scandinavian countries and The Netherlands the increase in height reached a plateau during the 1980s, while the trend towards increasing adult height continued in the middle and southern European countries. There are still large differences between the countries (1990: The Netherlands 181.2 cm and Portugal 170.3 cm), with a marked trend for the tallest conscripts to be in the north and the shortest in the shortest in the south. It has been suggested that the secular increase in adult height is mainly determined by an increase in growth during the first years of life. We examined postneonatal mortality (PNM) as a proxy for adverse environmental factors, mainly poor nutrition and infections, affecting growth during infancy, and related it to conscript height in the European countries. The general pattern was a rapid decrease in PNM until a low level was reached, after which it remained low, or decreased only very slowly. In countries where the increase in conscript height has levelled off, PNM reached a low and stable level (about 3-5 per thousand) approximately two decades before this stagnation. We speculate that the increase in height will continue in the rest of the European countries until approximately two decades after PNM has reached the same low level.

Secular change in adult stature has come to a halt in northern Europe and Italy

AIM To investigate whether the increase in adult stature in European countries is continuing. METHODS The secular trend in growth after 1990 for various European countries was assessed by national conscript data. RESULTS In Scandinavia and the Netherlands, the height has reached a plateau at 179-181 cm, and in Italy a plateau at 174 cm. In Belgium, Portugal and Spain, height continued to increase. CONCLUSION Only in the northern European countries and Italy height has ceased to increase.

Lower birth weight and increased body fat at school age in children prenatally exposed to modern pesticides: a prospective study

BackgroundEndocrine disrupting chemicals have been hypothesized to play a role in the obesity epidemic. Long-term effects of prenatal exposure to non-persistent pesticides on body composition have so far not been investigated. The purpose of this study was to assess possible effects of prenatal exposure to currently used pesticides on childrens growth, endocrine and reproductive function.MethodsIn a prospective study of 247 children born by women working in greenhouses in early pregnancy, 168 were categorized as prenatally exposed to pesticides. At three months (n = 203) and at 6 to11 years of age (n = 177) the children underwent a clinical examination and blood sampling for analysis of IGF-I, IGFBP3 and thyroid hormones. Body fat percentage at age 6 to11 years was calculated from skin fold measurements. Pesticide related associations were tested by linear multiple regression analysis, adjusting for relevant confounders.ResultsCompared to unexposed children birth weight and weight for gestational age were lower in the highly exposed children: -173 g (-322; -23), -4.8% (-9.0; -0.7) and medium exposed children: -139 g (-272; -6), -3.6% (-7.2; -0.0). Exposed (medium and highly together) children had significantly larger increase in BMI Z-score (0.55 SD (95% CI: 0.1; 1.0) from birth to school age) and highly exposed children had 15.8% (0.2; 34.6) larger skin folds and higher body fat percentage compared to unexposed. If prenatally exposed to both pesticides and maternal smoking (any amount), the sum of four skin folds was 46.9% (95% CI: 8.1; 99.5) and body fat percentage 29.1% (95% CI: 3.0; 61.4) higher. There were subtle associations between exposure and TSH Z-score -0.66(-1.287; -0.022) and IGF-I Z-score (girls: -0.62(-1.0; -0.22), boys: 0.38(-0.03; 0.79)), but not IGFBP3.ConclusionsOccupational exposure to currently used pesticides may have adverse effects in spite of the added protection offered to pregnant women. Maternal exposure to combinations of modern, non-persistent pesticides during early pregnancy was associated with affected growth, both prenatally and postnatally. We found a biphasic association with lower weight at birth followed by increased body fat accumulation from birth to school age. We cannot rule out some residual confounding due to differences in social class, although this was adjusted for. Associations were stronger in highly exposed than in medium exposed children, and effects on body fat content at school age was potentiated by maternal smoking in pregnancy.

Gender difference in breast tissue size in infancy: correlation with serum estradiol.

Breast tissue in newborn infants is considered to be physiologic and mainly related to exposure to maternal hormones in utero or through breast-feeding. However, controversy exists as to whether breast tissue in later infancy is under the influence of endogenous hormones. Children at 2–4 mo of age have a surge of reproductive hormones, including estradiol, which may affect the mammary gland. In a prospective cohort study of 1126 healthy, 3-mo-old infants, breast tissue size and reproductive hormones were measured. We found that palpable breast tissue (diameter ≥3 mm) is a common physiologic condition present in 78.9% of children, significantly more frequent (p < 0.001) and larger (p < 0.001) in girls than in boys. Girls had significantly higher median estradiol levels than boys (30.0 versus 21.0 pmol/L, p < 0.001). In a multiple regression model including breast tissue size given as quartiles as the dependent variable and weight for gestational age, subscapular skinfold, weight at 3 mo of age and serum estradiol as independent variables, a gender difference was shown. In girls, the estradiol level was positively (p < 0.03) correlated to breast quartile. In boys, no correlations were found. Whether the stimulation of the mammary gland in infancy represents a developmental window that is of biologic significance for breast development and pathology in adulthood remains to be defined.

Early breast development in girls after prenatal exposure to non-persistent pesticides

Contemporary American and European girls experience breast development at earlier ages compared with 15-20 years ago. Alterations in BMI alone cannot account for these changes. Several currently used pesticides possess endocrine disrupting properties and may interfere with reproductive development, but human data are sparse. We examined girls whose mothers worked in greenhouses in the first trimester of pregnancy to assess the long-term effects of prenatal pesticide exposure on puberty. Mothers were prenatally categorized as exposed or unexposed to pesticides. We studied the offspring of these greenhouse workers, and evaluated the anthropometry, pubertal staging in the girls, and blood samples were drawn at 3 months of age (n = 90) and again once at school age (6-11 years, n = 83). No clinical and biochemical differences were found between the exposed and unexposed girls at 3 months of age. Mean onset of B2+ was 8.9 years (95% CI: 8.2; 9.7) in prenatally exposed girls, compared with 10.4 years (9.2; 17.6) in the unexposed (p = 0.05), and 10.0 (9.7-10.3) years in a Danish reference population (p = 0.001). Exposed girls had higher serum androstenedione levels (geometric means: 0.58 vs. 0.79 nmol/L, p = 0.046) and lower Anti-Müllerian Hormone (AMH) compared with the unexposed (geometric means: 16.4 vs. 21.3 pmol/L, p > 0.05) and the reference group (20.2 pmol/L, p = 0.012). Levels of testosterone, estradiol, prolactin, FSH, LH, SHBG, DHEAS, DHT, Inhibin A and Inhibin B did not differ between the groups. In conclusion, our findings suggest that prenatal exposure to currently approved pesticides may cause earlier breast development in girls. This association appeared not to be because of changes in gonadotropins, but rather to higher androgen levels, which indirectly may increase oestrogens through aromatization. In addition, lower serum AMH levels indicated a reduced pool of antral ovarian follicles. The long-term consequences of our findings with regard to establishment of future reproductive function still remain unknown.

Effect of gender and lean body mass on kidney size in healthy 10-year-old children

Abstract When evaluating renal abnormalities, kidney volume is an important parameter. Most reference materials on kidney size in children are based on data from pediatric patients examined for non-uronephrological problems. Renal size is traditionally related to body height, weight, or surface area, but not to body composition. As part of a prospective cohort study we have examined 102 healthy 10-year-old children measuring kidney volume by ultrasonography, body composition by dual energy X-ray absorptiometry, and body height and weight. Boys had significantly larger kidneys than girls. The strongest predictor of kidney volume was lean body mass, overruling height, weight, and surface area. When total kidney volume was related to lean body mass as a ratio, the gender difference in kidney size was no longer significant. A strong negative correlation was found between fat body mass and kidney volume. In conclusion, the strongest predictor of kidney volume in healthy 10-year-old children is lean body mass. The correlation is likely to reflect an association between metabolic active tissue, renal solute load, and kidney volume. We have currently no explanation for the negative correlation between fat body mass and kidney volume.

Secular change in adult stature has come to a halt in northern Europe and Italy: Secular change in adult stature across Europe

Aim: To investigate whether the increase in adult stature in European countries is continuing.Methods: The secular trend in growth after 1990 for various European countries was assessed by national conscript data. Results: In Scandinavia and the Netherlands, the height has reached a plateau at 179–181 cm, and in Italy a plateau at 174 cm. In Belgium, Portugal and Spain, height continued to increase.