A Participatory Science Approach to Evaluating Factors Associated with the Occurrence of Metals and PFAS in Guatemala City Tap Water.

Limited information is available regarding chemical water quality at the tap in Guatemala City, preventing individuals, water utilities, and public health authorities from making data-driven decisions related to water quality. To address this need, 113 participants among households served by a range of water providers across the Guatemala City metropolitan area were recruited as participatory scientists to collect first-draw and flushed tap water samples at their residence. Samples were transported to the U.S. and analyzed for 20 metals and 25 per- and polyfluoroalkyl substances (PFAS). At least one metal exceeded the Guatemalan Maximum Permissible Limit (MPL) for drinking water in 63% of households (n = 71). Arsenic and lead exceeded the MPL in 33.6% (n = 38) and 8.9% (n = 10) of samples, respectively. Arsenic was strongly associated with groundwater while lead occurrence was not associated with location, water source, or provider. One or more PFAS were detected in 19% of samples (n = 21, range 2.1-64.2 ppt). PFAS were significantly associated with the use of plastic water storage tanks but not with location, water source, or provider. Overall, the high prevalence of arsenic above the MPL in Guatemala City tap water represents a potential health risk that current water treatment processes are not optimized to remove. Furthermore, potential contaminants from premise plumbing and storage, including lead and PFAS, represent additional risks requiring further investigation and public engagement.

Private demand for a HIV/AIDS vaccine: evidence from Guadalajara, Mexico.

The private demand for a hypothetical vaccine that would provide lifetime protection against HIV/AIDS to an uninfected adult was measured in Guadalajara, Mexico, using the concept of willingness to pay (WTP). A 91-question survey instrument was administered by trained enumerators employing contingent valuation techniques to 234 adults, aged 18-60. Our estimates of private demand indicate that individuals anticipate sizable personal benefits from such a vaccine, and that they would be willing to allocate a substantial portion of their income to be protected in this way from HIV infection. A conservative estimate of the mean WTP of adults in the Guadalajara sample is 6358 pesos (669 US dollars) and the median is 3000 pesos (316 US dollars). A multivariate statistical analysis of the determinants of individuals' WTP shows that individuals with higher incomes, with spouses or partners, and with higher perceived risks of becoming infected with HIV are willing to pay more for the vaccine. Older respondents are willing to pay less. These results suggest that there is likely to be a potentially large private market for a HIV/AIDS vaccine in the middle-income developing countries such as Mexico. These findings have important implications both for the level of R&D effort that is devoted to a vaccine and, assuming these efforts are successful, for future policies to make the vaccine available to the public.