Response to: Comment on “Association of Lead in Drinking Water With Head and Neck Cancer in the United States”

We appreciate the suggestion and agree that geographic variation in HPV-related cancers is an important risk factor in the epidemiology of head and neck cancer. However, the data presented by Burus et al1 reflect the incidence of HPV-associated cancers rather than the underlying prevalence of HPV infection. Because HPV-associated cancer incidence is a downstream outcome influenced by multiple factors, including latency periods, healthcare access, and demographic variation, it may not accurately represent regional HPV exposure. As such, classifying regions as “HPV high” or “low” based solely on cancer incidence could introduce misclassification and potentially bias the analysis. While datasets containing HPV infection prevalence do exist, such as the National Health and Nutrition Examination Survey, these data are not available at the geographic resolution required for county-level ecological analyses and cannot be directly linked to cancer registry data such as the Surveillance, Epidemiology, and End Results (SEER) Program. To our knowledge, there is currently no dataset that provides population-level HPV infection prevalence with sufficient spatial granularity to be meaningfully integrated into this type of analysis. For these reasons, we believe that currently available ecological proxies do not adequately capture its distribution in a way that would meaningfully reduce confounding in our analysis. None. None.