FRIENDS Children's Environmental Health Center

University of Illinois, Urbana-Champaign

FRIENDS Children's Environmental Health Center
Susan Schantz, Ph.D.
schantz@uiuc.edu

Project Description

The overall research objectives of the FRIENDS Children's Environmental Health Center are to: (1) study the impact of exposure to polychlorinated biphenyls (PCBs) and methylmercury (McHg) on cognitive, sensory and motor development of children, (2) develop effective educational strategies to reduce exposure to these neurotoxic contaminants, and (3) undertake laboratory studies to better understand the mechanisms by which these contaminants induce neurological deficits in children. The Center builds on several long-standing research collaborations and is organized around an exposure cohort. The cohort consists of Hmong and Laotian refugees who are consuming PCB- and MeHg- contaminated fish from the Fox River in northeastern Wisconsin. The Center includes an administrative core, a community-based project, two biomedical research projects and an analytical toxicology core. The two primary goals of the community-based project are: (1) to evaluate the impact of PCB and MeHg exposure on reproductive health and child development and (2) to provide families with practical information that will help them to reduce their exposure to PCBs and MeHg. The assessments of the children focus on specific aspects of behavioral and sensory function that have not been adequately addressed in previous human studies. These goals are being accomplished in partnership with community resource groups in the area. The biomedical research projects complement the community-based project by characterizing the cognitive, sensory, motor and neurochemical effects of exposure to PCBs alone, MeHg alone or PCBs and MeHg combined in a rodent model. Moth projects use a mixture of PCBs that models the PCB congener profile in Fox River fish, and a ratio of PCBs to MeHg similar to that found in the fish. The findings from the animal studies guide the selection of additional behavioral and sensory endpoints for use in the children exposed to PCBs and MeHg via maternal consumption of Fox River fish. The analytical toxicology helps formulate the PCB mixture to be used in the animal studies and provide congener specific PCB analysts, heavy metal analysis, and pesticide analysis in human and animal samples from the three research projects. The administrative core provides oversight, coordination and integration of all Center activities.

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Project Highlights

Center investigators found that rats exposed to the Fox River PCB mixture during development exhibited a striking dose-dependent deficit in auditory function that persisted into adulthood.  In these studies Center investigators used distortion product otoacoustic emissions (DPOAEs) to directly measure the functional integrity of the cochlea and auditory brain stem responses to measure the function of the auditory nerve (Powers et al., 2006). Unlike the commercial PCB mixture, Aroclor 1254, which had previously been shown to cause low-frequency hearing loss in laboratory rats, the hearing deficits following exposure to the Fox River PCB mixture extended to the mid- and high-frequency ranges as well.  The pattern of effects was indicative of damage at the level of the cochlea.  Importantly, preliminary results from research currently in progress suggest that concurrent exposure to MeHg does not exacerbate the effects of PCBs on auditory function. 

Complementary neurochemical and neurobehavioral studies conducted by collaborating FRIENDS Center scientists have revealed that the pattern of neurochemical and cognitive deficits following developmental PCB exposure closely parallels the pattern of deficits seen in children with attention deficit hyperactivity disorder (ADHD). That is, PCB-induced hypofunctionality of brain dopamine systems appears to cause animals to have difficulty performing various cognitive tasks that require inhibitory control for their successful execution (Bemis and Seegal, 2004; Sable and Schantz, 2006; Sable et al., 2006). Studies on the interactive effects of the Fox River PCB mix and MeHg on cognitive function are currently underway. An important aim of the Center’s future laboratory studies is to further understand the mechanisms through which PCBs, MeHg and also the polybrominated diphenyl ethers (PBDEs), which are structurally similar to PCBs, alter brain dopamine function, as well as how these changes in brain dopamine impact cognitive function.  Because of the parallels with ADHD, Center research has the potential to contribute significantly to the understanding of this common childhood disorder.

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