Current Grant-funded Projects
Lateral view of a zebrafish developmentally-exposed to nonylphenol ethoxylate and aged to 30 days. Nile Red stain fluorescently labels the fat cells throughout the fish.

Metabolic Disruption by Common Surfactants

Funded through a K99/R00 award from NIEHS, this project aims to explore the potential metabolic disruption potential of alkylphenol and alcohol polyethoxylates, a group of common surfactants added to hard surface cleaners, detergents, paints, and other common consumer products. Our goals are to:
1) Identify potential metabolic health impacts (adiposity, altered growth) on developmentally-exposed zebrafish. 
2) Identify potential causal mechanisms through which these chemicals exert their effects on metabolic health.
3) Assess the relative contribution of these chemicals to metabolic impacts of environmental mixtures.

You can listen to a webinar that I gave on this topic here.

Metabolic Disruption Potential of Organic and Inorganic ​Contaminant Mixtures

Funded via an NIEHS P30 Center Pilot award through the Center for Urban Responses to Environmental Stressors. This project aims to explore the potential hormone receptor activation/inhibition and metabolic disruption of organic and inorganic pollutant mixtures relevant to Michigan. Our goals were to:

1) Characterize concentrations of inorganic pollutants in household dust and examine associations with organic pollutants/bioactivities. 
2) Assess adipocyte development and receptor disruption following exposure to select organic/inorganic contaminants and mixtures.
3) Assess adipocyte/adipose tissue development following exposure to select organic/inorganic contaminants and mixtures in zebrafish.

​You can listen to a webinar I gave on related mixture research here.​​
Visualization of differentiated 3T3-L1 pre-adipocytes. Green = Nile Red lipid stain; blue = Hoechst DNA stain (cell number).
Visualization of differentiated 3T3-L1 pre-adipocytes. Yellow = Nile Red
lipid stain; blue = Hoechst DNA stain (cell number).

Interrogation of Existing Toxicological Mixture Models through Metabolic Disruption Contaminant Mixture Testing

Currently funded via an EPA STAR award to rigorously assess available toxicological models (e.g., concentration addition, independent action) through controlled testing of mixtures with increasing complexity. We'll test using a mixture of metabolic disrupting chemicals working through 1) a single, shared mechanism, 2) single mechanisms across six metabolic pathways, and 3) six overlapping mechanistic pathways, with chemicals activating multiple rather than just one.  

We'll pursue this and actual environmental sample testing through use of human mesenchymal stem cells and the zebrafish model. 
​
You can listen to a webinar I gave on related mixture research here.

Endocrine Disrupting Toxicity Associated with
Artificial Turf Materials and Use
We have been funded through pilot grant from the New York University (NYU) Collaborative Center in Children's Environmental Health Research & Translation and the WSU CURES P30 Center.

We recruited a small cohort of Detroit-area youths and are measuring diverse semi-volatile contaminant exposures associated with playing on artificial turf fields versus natural grass fields. We also profiled the endocrine toxicity of these mixtures as well as extracts derived from diverse artificial turf products, filler materials, and padding samples and working to better characterize toxicity following developmental exposures in the zebrafish model.

We're interested in better characterization of the endocrine disruption potential and toxicity associated with artificial turf materials. We are also interested in better understanding the chemical mixture exposures potentially experienced by the people playing on and/or using this material in their daily lives.
Artificial turf is increasingly used in both sports and residential environments, yet the chemicals used to produce this product and the potential exposures to humans using these surfaces has not been well-studied. 
Liquid crystal monomers (LCMs) are chemicals used in liquid crystal device (LCD) screens and have been shown to leach out and end up in both humans and the environment (sediment, household dust, etc.). 

Characterizing Liquid Crystal Monomer Toxicity

We were funded through a Wayne State One Health Initiative pilot grant to better understand environmental exposures and toxicity of these emerging contaminants.

​Samantha Heldman has been working to characterize the endocrine toxicity and metabolic disruption potential of chemicals used in the LCD screens of your favorite devices. ​Samantha's first project profiled endocrine activity across diverse nuclear hormone receptors and examined the ability to promote fat cell development in a pre-adipocyte cell model. Our future projects intend to dig into mechanisms, metabolism of these chemicals, effects in a zebrafish model, and trying to better understand human exposure to these chemicals in the US. 

Other Projects/Broad Research Interests

Assessing Health Risks from Exposure to
​Environmental Contaminant Mixtures

I have great interest in pursuing endocrine disrupting chemical mixtures and their potential impacts on human/animal health.

​This work has previously focused on using whole environmental samples or extracts (unconventional oil and gas wastewater, municipal wastewater, residential household dust, silicone wristband extracts, and human serum). We work to measure biological activities (e.g., receptor activation or inhibition, adipocyte development) and associate these activities with human and animal health outcomes. We previously demonstrated that the extent of house dust-induced fat cell development was significantly associated with the BMI of residents.

​We utilize whole mixture testing in cell-based assays and animal models (primarily zebrafish) along with CRISPR to identify outcomes and understand how mixtures act. We also collaborate with statisticians to better model mixtures and outcomes.​
Humans and animals are regularly exposed to complex mixtures of hundreds/thousands of chemicals, most of them not regulated, with uncertain health effects.
A natural gas well in Garfield County, Colorado, an extremely dense unconventional oil/natural gas production region.

 Identifying and Characterizing Endocrine Disrupting Chemicals and Mixtures

I have a great interest in pursuing novel endocrine disrupting chemicals and their mechanisms of action. 
​
​This work has previously focused on novel environmental sources of endocrine disruptors like unconventional oil and gas production and residential household dust, and we have several novel projects actively developing in the lab!

We utilize cell-based reporter gene assays, cell-free receptor binding affinity assays, and adipogenesis bioassays to identify the molecular mechanisms and functional consequences of these chemicals and mixtures, as well as evaluating the causal chemicals responsible for these effects.

You can listen to a webinar I gave on this topic here.