MINNEAPOLIS – Prenatal exposure to traffic-related toxins may increase the risk for Wilms tumor, the most common form of childhood kidney cancer, the results of a study suggest.
Furthermore, findings suggest that different toxins may be potent at different pregnancy periods, Anshu Shrestha reported in a poster presentation at the annual meeting of the Society for Pediatric and Perinatal Epidemiologic Research.
The main culprits – formaldehyde, lead, and chromium VI – all have been shown to increase the risk of kidney cancer in adults, but little is known about their relationship to childhood renal cancers.
Wilms tumor occurs in 1 in 200,000-250,000 children, typically striking at about 3 years and rarely developing after age 8 years. The cure rate is about 90%, if the tumor has not metastasized.
The population-based, case-control study included 84 children in the California Cancer Registry who were aged 5 years and younger at the time of diagnosis with Wilms tumor, and 25,222 controls who were randomly selected from a birth registry and matched by birth year. Cases and controls lived within a 5-mile radius of a California Air Resources Board monitoring site, which measures 24-hour averages of air toxic concentrations every 12 days. Trimester-specific averages were calculated for 20 air toxins that were selected for carcinogenic property and sufficient sample size. Logistic regression analysis was adjusted for birth year, maternal age, maternal race/ethnicity and census-based socioeconomic status.
Third-trimester exposure to formaldehyde increased the risk of Wilms tumor by nearly 1.5-fold (odds ratio, 1.43), said Ms. Shrestha, an epidemiology doctoral student at the school of public health, University of California, Los Angeles.
Exposure to chromium VI in the first trimester and to lead in the second trimester also increased the odds of Wilms tumor, although to a lesser degree (OR, 1.10 and 1.27).
Positive associations were suggested for first-trimester exposure to lead, selenium, and benzene, but not for 1,3-butadiene, styrene, and ortho-dichlorobenzene.
Ms. Shrestha said that the data are preliminary and require more work to confirm that they are not due to chance alone.
Nearly half (47.6%) of the cases were Hispanic, 52.4% lived at the two lowest socioeconomic levels, and 55% had mothers aged 20-29 years at the time of their birth. Only 10.7% of cases lived at the highest socioeconomic level (defined by a combination of seven census indicators, including education and median household income).
The study was supported by grants from the National Institute of Environmental Health Sciences. Ms. Shrestha did not provide conflict of interest information.