Authors
Mendola P, Robinson LK, Buck GM, Druschel CM, Fitzgerald EF, Sever LE, Vena JE.

Title:
Birth defects risk associated with maternal sport fish consumption: potential effect modification by sex of offspring.

Journal:
Environmental Research 97(2):134-141, 2005.

Summary:
Consumption of contaminated sport fish from Great Lakes results in exposure to a variety of toxic substances. These substances include chemicals such as polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and pesticides such as dichloroethane (DDE) hexachlorobenzene & mirex. These chemicals are lipophilic and have a tendency to bioaccumulate with continued exposure. Moreover, their ability to cross the placental barrier results in fetal exposure to these potentially endocrine disrupting substances. Teratogenic effects of these substances, observed in laboratory animals and wildlife, has raised concerns about human health effects.

In this study, the relationship between maternal consumption of sport fish and the risk of major birth defects was assessed. The analysis was based on the New York State Angler Cohort Study that was conducted in 1991 to identify potential reproductive and developmental effects of contaminated sport fish meals. The cohort is comprised of subjects aged 18 to 40 years, who were licensed anglers from one of the 16 New York State counties surrounding Lake Erie and Lake Ontario, and completed the study questionnaire. The analysis was limited to 2,237 first born children of cohort members, born between June 1986 and June 1991, with complete data on exposure, outcome and confounding variables. Exposure to sport-caught fish meals was assessed using a food frequency approach, based on information from mothers in the cohort. The exposure was categorized into: no meals (reference), less than or equal to 1 meal per month, and 2 or more meals per month during pregnancy, which represents acute exposure. Duration of exposure was defined using number of years of sport fish intake by the mothers from 1955 to birth of the first child, representing chronic body burden. Duration of exposure was categorized into three groups: none (reference), ate contaminated sport fish for 5 years or less, and ate contaminated sport fish for 6 years or more. Children born with birth defects were ascertained from newborn medical records and New York State Congenital Malformations Registry. A case was defined as "any registry match or confirmed newborn medical record notation of a congenital anomaly (ICD 9 740.0-759.9) after application of the Metropolitan Atlanta Congenital defect program exclusion criteria for minor anomalies".

A total of 125 cases (5%) with major birth defects were identified. The analysis revealed no significant relationship between maternal sport fish consumption during pregnancy and risk of major birth defects. Upon stratification by gender, a significant three fold increase in risk of birth defects was observed in male children of women who ate > 2 meals of sport fish/month during pregnancy. No such relationship was observed in females. Analysis by duration of sport fish consumption revealed no significant relationship with birth defects.

In summary, this study found no significant relationship between maternal sport fish consumption and risk of birth defects overall. However, an elevated risk of birth defects was found among male infants compared to female infants at the same exposure levels. This effect is biologically plausible given the importance of fetal androgens in male development and the endocrine disrupting properties of some chemicals in contaminated sport fish. A number of studies have examined pregnancy outcomes following maternal fish consumption, with most reporting no significant effects on fetal death, birth weight and size and only modest effects on time to pregnancy. This is the first study in North America to specifically assess the relationship between sport fish consumption and birth defects. This study used questionnaire responses from mothers to assess fish consumption rather than using geographic area as a proxy measure. However, risk associated with individual chemical exposure could not be assessed. Lack of information on the actual contamination profile of sport fish consumed by women during pregnancy, and the timing of consumption is a limitation of this study. Moreover, limiting the analysis to major birth defects excluded cryptorchidism, which has been suggested to be an adverse outcome associated with exposure to endocrine disrupting chemicals. Only infants that survived major birth defects were analyzed as there was no information on spontaneous losses and elective terminations which further limits the study findings.