Academic journal article Environmental Health Perspectives

Maternal Occupational Exposure to Polycyclic Aromatic Hydrocarbons: Effects on Gastroschisis among Offspring in the National Birth Defects Prevention Study

Academic journal article Environmental Health Perspectives

Maternal Occupational Exposure to Polycyclic Aromatic Hydrocarbons: Effects on Gastroschisis among Offspring in the National Birth Defects Prevention Study

Article excerpt

BACKGROUND: Exposure to polycyclic aromatic hydrocarbons (PAHs) occurs in many occupational settings. There is evidence in animal models that maternal exposure to PAHs during pregnancy is associated with gastroschisis in offspring; however, to our knowledge, no human studies examining this association have been conducted.

OBJECTIVE: Our goal was to conduct a case--control study assessing the association between estimated maternal occupational exposure to PAHs and gastroschisis in offspring.

METHODS: Data from gastroschisis cases and control infants were obtained from the population-based National Birth Defects Prevention Study for the period 1997-2002. Exposure to PAHs was assigned by industrial hygienist consensus, based on self-reported maternal occupational histories from 1 month before conception through the third month of pregnancy. Logistic regression was used to determine the association between estimated occupational PAH exposure and gastroschisis among children whose mothers were employed for at least 1 month during the month before conception through the third month of pregnancy.

RESULTS: The prevalence of estimated occupational PAH exposure was 9.0% in case mothers (27 of 299) and 3.6% in control mothers (107 of 2,993). Logistic regression analyses indicated a significant association between occupational PAHs and gastroschisis among mothers z 20 years of age [odds ratio (OR) = 2.53; 95% confidence interval (CI): 1.27, 5.04] after adjusting for maternal body mass index, education, gestational diabetes, and smoking. This association was not seen in mothers < 20 years (OR = 1.14; 95% CI: 0.55, 2.33), which is notable because although young maternal age is the strongest known risk factor for gastroschisis, most cases are born to mothers [greater than or equal to] 20 years.

CONCLUSION: Our findings indicate an association between occupational exposure to PAHs among mothers who are [greater than or equal to] 20 years and gastroschisis. These results contribute to a body of evidence that PAHs may be teratogenic.

KEY WORDS: birth defects, gastroschisis, maternal exposure, occupation, PAHs. Environ Health Perspect 120:910-915 (2012). http://dx.dolorg/10.1289/ehp.1104305 [Online 13 February 2012]

Gastroschisis is a congenital malformation characterized by a herniation of viscera through an abdominal wall defect lateral to the umbilicus. The cause of gastroschisis is unknown; however, suggested mechanisms underlying this condition include vascular disruption (Werler et al. 2009) and failure of mesenchymal differentiation due to early teratogenic exposures (Feldkamp et al. 2007; Sadler and Feldkamp 2008). A recent increase in the prevalence of gastroschisis at birth has led to growing interest in identifying modifiable risk factors (Alvarez and Bard 2007; Benjamin et al. 2010; Mac Bird et al. 2009). Established risk factors for gastroschisis include young maternal age (< 20 years) and cigarette smoking (Mac Bird et al. 2009). Additionally, occupational exposures have been suggested as potential risk factors for gastroschisis (HerdtLosavio et al. 2010; Mac Bird et al. 2009).

Assessing workplace exposures as risk factors for birth defects is of importance because > 95% of employed women in the United States remain employed during pregnancy (U.S. Census Bureau 2009). Furthermore, an increasing number of women are being exposed to potentially teratogenic chemicals in their jobs (Rice and Baker 2007). A prevalent group of toxic chemicals found in the workplace are polycyclic aromatic hydrocarbons (PAHs), which are formed during the incomplete burning of organic substances (Brandt and Watson 2003). Occupational settings where exposure to PAHs is likely to occur include oil and gas production, coal-fired and other power plants, and restaurants [Agency for Toxic Substances and Disease Registry (ATSDR) 1995; Sjaastad and Svendsen 2009].

Occupational exposure to PAHs has been associated with several adverse health outcomes, such as childhood cancer in the offspring of exposed mothers and bladder cancer (ATSDR 1995; Bosetti et al. …

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