A study finds that percentage of agricultural lands in three watersheds correlates with testicular oocytes (eggs) in male smallmouth bass. A correlation between testicular oocytes (TO) was found with estrone, a naturally occurring hormone. There is no correlation between actual pesticides used was not studied. Testicular oocytes were not found in two species of suckers.An article in the journal Environmental Monitoring and Assessment covered samples from 16 locations in three major river drainages (Delaware, Susquehanna and Ohio). Fish samples were taken by electroshock during summer (low flow periods) between 2007 and 2010. Grab samples of water and sediment were taken concurrently. Subsequently, water samples were taken during high run off periods by polar organic chemical integrative samplers (POCIS) and semipermeable membrane devices that could collect and concentrate potential contaminants that were below normal detection limits. Endrogenicity was estimated by bioluminescent yeast endrogen screen.
The desired sample size was 10 male and 10 female. That was not always achieved. Estrone, a naturally occurring hormone was the only positive chemical correlation. There was no correlation between TO and being upstream or downstream of a waste water plant. A cumulative effect was alluded to by the authors. There was lower occurrence in Ohio, which also had the lower percentage of agricultural land. The assumption is that the problems are caused by eggs developing in contact with sediment, which has some concentration of chemicals with estrogenic activity.
The study seems be along the lines of a earlier study by FWS and has gotten some press play (here and here.) And, of course, there is a cry for more pesticide reporting by farmers. The type agriculture is not considered or even pesticides that might be used in the drainage. Other than estrone, there seems to be no correlation between pesticides and response. It seems to be one of those studies that interesting and gets folks all excited about chemicals.
The abstract is below.