Thank you for your inquiry. There are several parts, including a couple nested assumptions I can address. First, just to clarify: Non-native, invasive species of rats (Rattus rattus and Rattus norvegicus) and house mice (Mus musculus) are not wildlife species. Next, your concern about effects of rodenticides on wildlife species is certainly valid, and is an area of active research - not necessarily by members of OSU's Dept of FWCS nor of the state wildlife agency (see end of my reply). However, research on the problem (risks of rodenticides to wildlife) applies regardless of where the study system is located.

You've mentioned anticoagulant rodenticides, which are certainly one area of concern if wild animals (or pets, etc.) contact them, but other modes of action are employed in rodenticides, too https://npic.orst.edu/factsheets/rodenticides.html
One of the very active centers of commensal rodent mgmt with regards to rodenticide (and other) effects is the University of California Natural Resources (UCANR). Here's a landing site article - https://ucanr.edu/blog/pests-urban-landscape/article/management-urban-rats-and-mice. I'm recently returned from the biennial international Vertebrate Pest Conference that UCANR organizes and can assure you that these issues are areas of active research, worldwide. 

Further background: Both species of Rattus were introduced in the Pacific NW by the end of the 16th century, so unfortunately they are ubiquitous in and around all of our human communities - and can be found well beyond city/town boundaries into forests and rangelands, too. This far pre-dates urban chicken-keeping as we currently know it. There is a huge (!) amount of scholarship around issues of commensal rodents (rodents located in and around human-settlement), factors driving population abundance, effects (or non-effects) of rat-eradication efforts, etc., etc. I recommend pulling up Google, and then entering Scholar in the search window to access the search term window for GoogleScholar, which will allow you to search the published research (worldwide) according to the terms you enter. For example, one fairly recent article: 
https://www.science.org/doi/full/10.1126/sciadv.ads6782

On your concern about chickens, particularly: 
Poorly-managed (i.e., not rodent-proofed) food and water for chickens, pet, and wild birds, along with downed fruit and garden products, all can act as food sources supporting existing populations of rats. Beyond food, hiding/harborage resources around homes (e.g., dense ivy, ground cover, piles of stored building materials/equipment/etc.) support rat populations abundance, but certainly location of food and/or harborage resources can affect the visitation (and sighting) rate at a particular house. If your local/neighbor chicken-keepers don't store and distribute (i.e., feeders in rat-proof runs that are closed at night after chickens roost in the coop portion) their feed in appropriate ways, then reducing their feed $ loss to rats could be an excellent conversation point. This article might provide food for thought for those losing feed to rats: https://extension.okstate.edu/fact-sheets/rodent-control-in-the-poultry-house
However, the conversation must also be had with those whose wild bird feeders are not equipped to preclude access (e.g., climbing, stretching from fence) to the feeder or spillage. And similarly, many neighbors likely don't realize their unharvested garden produce is also providing a free source of meals to rats (but also habituating and food-conditioning raccoons, skunks, deer, etc.).

 

As to use of rodenticides: The label on the product is the actual law. It may not be top of mind to folks buying "rat bait", etc., but the label tells extremely specifically for which species, in what settings (e.g., exterior vs. interior of a home or in a particular crop in a particular season), and in what manner (e.g., inside burrows, inside locked bait stations, etc.) the product can legally be used. If you know of someone violating the label/law, you can report them  - The Oregon Department of Agriculture pesticide division has means of doing that, or depending on the particular product, they might refer you to a different enforcement agency. 
However, it is also true that even legal and best-practices-compliant uses of rodenticides can "travel" into areas used by wild animals, such as when a baited rat survives long enough to be predated by a wild bird, mammal, or snake. I understand that these are the cases about which we all share concern.

Finally, I notice your letter is addressed to OSU's Dept of FWCS (I am a member of the Dept's faculty), whereas the state's wildlife management agency is Oregon Department of Fish and Wildlife (ODFW; https://www.dfw.state.or.us/ ). Although both are involved in wildlife research, the ODFW is the managing agency and is involved in policy, regulation-setting conversations with the OR legislature (about wildlife - not rats, nor chickens), and the very similar unit names cause a lot of understandable confusion. You also express an interest in engaging in advocacy - Because wildlife professionals, whether academic researchers or agency wildlife managers, are very aware of the risks, your greatest impact can likely be had by engaging in constructive conversations with the neighbors, and hopefully some of the information and resources I've provided can support you in undertaking that important dialogue.