less bats, higher mortality
“…farmers compensated for bat decline by increasing their insecticide use by 31.1%. The compensatory increase in insecticide use by farmers adversely affected health—human infant mortality increased by 7.9% in the counties that experienced bat die-offs.” Eyal G. Frank
A Science article by Eyal Frank got a lot of press last week for linking US bat population plummeting (up to 70%) due to the “white nose syndrom” (an invasive fungus) impacting bats since 2006 (through premature awakening from hibernation) and therefore agriculture, to a huge (8%) rise in infant mortality in the impacted regions, resulting from a jump in the use of insecticides… (The statistical model behind the predicted mortality is a linear model for all dependent outcomes, insecticide use, crop yield, and infant mortality. With plenty of precautions to separate infected counties from non-infected ones and to eliminate exogenous causes.)
September 18, 2024 at 10:53 pm
(Sorry if this appears twice.)
I found the infant mortality rates surprising/fishy and am wondering if you could elaborate on how convincing you find the causal identification strategies … I wasn’t convinced that one could rule out effects of underlying spatial/temporal trends. (More generally, the biological mechanism isn’t discussed at all — what kinds of insecticides are these?) A previous study (Dias et al 2023) estimated a 5% increase in mortality from an overall *tripling* of glyphosate use in Brazil, contrasted with the 31% increase in insecticide use here …)
While the author did post replication materials on Zenodo, unfortunately the infant mortality data are only available by application to the US CDC, and only for use on computers/by researchers within the US (I’m in Canada so …)
Dias, Mateus, Rudi Rocha, and Rodrigo R Soares. “Down the River: Glyphosate Use in Agriculture and Birth Outcomes of Surrounding Populations.” The Review of Economic Studies 90, no. 6 (November 1, 2023): 2943–81. https://doi.org/10.1093/restud/rdad011.
September 19, 2024 at 3:31 pm
I did not look further at the stats, but I agree that the jump is surprisingly strong without further arguments.