Our research agenda includes taking an ecological approach to problems in human environmental health, especially exposure to arsenic as a non-point source contaminant.
- Arsenic: Kathy is working with Dr. Margaret Karagas and colleagues to assess human exposure to arsenic and other metals. Chronic, low-level exposure to arsenic is associated with skin lesions; skin, lung, and bladder cancer; vascular diseases; low birth weight; increased susceptibility to infection; and reduced IQ. Humans are generally thought to be exposed to the more toxic, inorganic form primarily through drinking water, which is of particular concern in some regions of New Hampshire as well as other parts of the world. In addition, an emerging body of work suggests that elevated concentrations of arsenic in common food items – including rice and rice-based products, fish and seafood, and beer/wine – may pose an additional risk to consumers (see e.g., this update from Consumer Reports). Studying arsenic exposure in food is particularly hard because (1) only some of the arsenic is in the highly toxic inorganic form — and this fraction varies even within types of foods and (2) the toxicity of many organic forms has not yet been established. However, understanding this pathway to exposure is quite important because everyone is exposed to trace amounts of arsenic via food, regardless of the arsenic in their drinking water.
Working as part of the Children’s Center for Environmental Health and Disease Prevention Research at Dartmouth, we are currently quantifying exposure to arsenic via water and food for members of the New Hampshire Birth Cohort (NHBC), a prospective cohort study that recruits pregnant women who drink water from private wells. To date, our work has shown that rice and products made from rice, such as brown rice syrup, may be quite high in arsenic (Jackson et al. 2012a,b) and may be important sources of exposure for the pregnant moms (Gilbert-Diamond et al. 2011), NHBC infants (Carignan et al. 2015), and in U.S. children more generally (Davis et al. 2012, Lai et al. 2015). Importantly, the current Children’s Center project will not only assess exposure as the NHBC children grow from infancy through age 5, but relate those exposures to key health outcomes, including immune function, growth and neurodevelopment.
- Essential elements and other metals: Building from NHBC data, Kathy is working with undergraduate Kassie Amann ’16 on a project to test whether infants who are formula-fed are differentially exposed to other elements than breastfed babies.
- Cholera: Members of the Cottingham lab have studied environmental Vibrio cholerae, the bacterium that causes cholera, in collaboration with Geisel Professor Ron Taylor and his lab on and off since ~2000. V. cholerae is a heterotrophic bacterium that is often an abundant natural component of freshwater and estuarine systems around the world. Kathy first got involved in this line of research because (1) V. cholerae is often found attached to plankton (reviewed in Cottingham et al. 2003) and (2) it has been hypothesized that cholera outbreaks may track plankton blooms (Colwell 1996). From 2001-2006, we studied the interaction between bacterial dormancy and attachment to plankton using laboratory studies of whole-genome expression profiles (microarrays) and field sampling of environmental conditions, plankton community structure, and V. cholerae in two contrasting ponds in Bangladesh.
Around that same time, graduate student Julia Butzler investigated competition between strains of V. cholerae and tested whether lab cultures of V. cholerae were stimulated by association with the colonial cyanobacterium Anabaena, as predicted by the bloom hypothesis.
More recently, undergraduate students have conducted projects to test whether (1) folded t-shirts might be effective at removing V. cholerae from contaminated water sources in Haiti, modeled after the successful interventions with sari cloth in Bangladesh by Rita Colwell and colleagues (they weren’t); (2) V. cholerae may survive passage through Daphnia guts (possibly); and (3) V. cholerae attachment behavior might be stimulated by similar molecules in both the human gut and in the environment (Pruss et al., in prep.). At the moment, no one is working on V. cholerae, but the right questions could spark a revival!