Associations between congenital cryptorchidism in newborn boys and levels of dioxins and PCBs in placenta

H E Virtanen,E Sundqvist,J J Koskenniemi,N E Skakkebaek,J Tuomisto,M Viluksela,T Vartiainen,J Toppari,J T Tuomisto,H Kiviranta,K M Main

doi:10.1111/j.1365-2605.2011.01233.x

Abstract

In animal studies, exposure to dioxins has been associated with disrupted development of the male reproductive system, including testicular maldescent. Some polychlorinated biphenyls (PCBs) have also dioxin-like effects. In addition, one previous case–control study has reported an association between congenital cryptorchidism and colostrum PCB levels. We performed a case–control study to evaluate whether congenital cryptorchidism in boys was associated with increased levels of dioxins or PCBs in placenta reflecting foetal exposure. In addition, associations between placenta levels of these chemicals and reproductive hormone levels in boys at 3 months were studied. Placentas were collected in a Danish–Finnish joint prospective cohort study on cryptorchidism (1997–2001). The boys were examined for cryptorchidism at birth and at 3 months. Altogether, 280 placentas [112 Finnish (56 cases, 56 controls) and 168 Danish (39 cases, 129 controls)] were analysed for 17 toxic polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and 37 PCBs (including 12 dioxin-like PCBs). Infant serum samples taken at 3 months were analysed for reproductive hormones. No significant differences between cases and controls were observed in either country in dioxin WHO-TEq levels (median 9.78 vs. 8.47 pg/g fat, respectively, in Finland, and 11.75 vs. 10.88 pg/g fat in Denmark) or PCB WHO-TEq levels (median 2.12 vs. 2.15 pg/g fat in Finland, 2.34 vs. 2.10 pg/g fat in Denmark) or total-TEq levels (median 11.66 vs. 10.58 pg/g fat in Finland, 13.94 vs. 13.00 pg/g fat in Denmark). Placenta WHO-TEq levels of dioxins were not associated with infant reproductive hormone levels at 3 months. In Finland, PCB WHO-TEq levels in placenta associated positively with infant LH levels. WHO-TEq levels of dioxins and PCBs and total-TEq levels were higher in Danish than Finnish samples. In conclusion, no association between placenta levels of dioxins or PCBs and congenital cryptorchidism was found. Significant country differences in chemical levels were observed.

Highlights

Cryptorchidism, i.e. undescended testis, is one of the most common genital abnormalities in newborn boys
Congenital cryptorchidism & dioxins and PCBs dibenzofurans (PCDFs)] and polychlorinated biphenyls (PCBs) are persistent environmental chemicals, which tend to accumulate in tissue lipid and in the food chain (Laisi et al, 2008; Linden et al, 2010)
Study population There were no significant differences between cases and controls in maternal age, body mass index (BMI) or weight for gestational age in either country (Table 1)

Summary

Introduction

Cryptorchidism, i.e. undescended testis, is one of the most common genital abnormalities in newborn boys. During the last two decades, the reported incidence of cryptorchidism in newborn boys with a birth weight ‡2500 g has varied between 2.1 and 8.4% in prospective studies using similar and clearly defined criteria (Virtanen & Toppari, 2008). Environmental chemicals with endocrine disrupting activities have been hypothesized to play a role in the increasing incidence of problems of male reproductive health (Sharpe & Skakkebaek, 1993; Toppari et al, 1996; Sharpe, 2003). Congenital cryptorchidism & dioxins and PCBs dibenzofurans (PCDFs)] and polychlorinated biphenyls (PCBs) are persistent environmental chemicals, which tend to accumulate in tissue lipid and in the food chain (Laisi et al, 2008; Linden et al, 2010). Some PCBs have dioxin-like effects (Linden et al, 2010). The developing immune, nervous and reproductive systems seem to be most sensitive to the adverse effects of dioxins

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