Introduction

FDA has temporarily suspended its Grade “A” milk lab proficiency testing program, an annual check on laboratory accuracy, due to staffing shortfalls​. This is not an end to milk safety inspections or routine testing. All the usual milk safety tests from farm to shelf continue unchanged​. Milk at farms, trucks, and processing plants is still being tested multiple times as normal​. Consumers can remain confident in dairy safety while the FDA works on a backup plan for monitoring lab performance​.

Milk and Dairy Testing in Wisconsin

Milk in Wisconsin undergoes rigorous testing at every step – from the farm bulk tank, during transport, at the processing plant, and in finished dairy products. Some tests are required by federal/state regulations, while others are voluntary quality checks by farmers or processors. Below is a mapped timeline of when and how often milk is tested, and who is responsible at each stage, from cow to consumer:

On the Dairy Farm (Raw Milk Production)

Cows are milked under sanitary conditions, and the milk is rapidly cooled in a bulk tank. Visual and Odor Check: Each batch of milk is inspected for any visible issues or off-odors – milk with abnormalities or bad smell is rejected​. Cooling: Milk must be cooled to 45 °F (7 °C) or lower within 2 hours of milking (a Grade A requirement under the Pasteurized Milk Ordinance) to inhibit bacterial growth. Farmers and milk haulers monitor cooling equipment to ensure this standard is met. On-Farm Antibiotic Control: Farmers avoid shipping milk from cows treated with antibiotics (they “withhold” that milk). Many farms test treated cows’ milk with rapid kits before commingling it, as a precaution (voluntary good practice). State Inspection: Farms are periodically inspected by state officials for hygiene and milk handling, including checks on cooling and storage; inspectors might also review farm records or perform a brucellosis ring test on milk (a surveillance test for cow disease, done periodically on bulk tank milk in some states).

At Milk Pickup (Bulk Transport)

A licensed bulk milk hauler visits the farm (often daily or every other day) to collect milk. Sampling: Before pumping milk from the farm’s tank, the hauler takes a sample of that farm’s milk​. This sample represents the farm’s milk and is labeled with the farm ID, date, and temperature​. It’s kept cold on the truck​. Temperature Check: The hauler measures and records the milk’s temperature in the farm tank; if it’s above the legal limit (45 °F), the milk may be rejected on the spot. Sensory Check: The hauler also visually inspects the milk and may smell it for any sour or unusual odor (an additional quality check). Measurement: The volume of milk is measured for farmer payment. Haulers must be licensed (Wis. Stat. §97.17) and follow strict procedures for sampling and sanitation during collection​.

Bulk Tanker Testing (Before Unloading at Plant)

When the milk tanker truck arrives at the dairy plant, a composite sample from the entire truckload is tested for antibiotics before the milk is unloaded or mixed​. This is required for every load of milk under Appendix N of the Grade A Pasteurized Milk Ordinance​. A rapid drug residue test (e.g., SNAP or Delvotest) is used, sensitive at least to beta-lactam antibiotics (the most common residue of concern)​. The test must be done immediately, and the load cannot be commingled or processed until a clear result is confirmed​.  Who tests? Typically, plant receiving personnel or a certified lab technician tests the bulk load sample. If Positive: If the tanker sample pops positive for a drug residue, it’s considered a presumptive positive. The same sample is tested again (confirmatory test) to rule out any error​. If confirmed positive, the entire truck of milk is rejected (dumped) and not allowed into the food supply​. Then, follow-up testing is done on the individual farm samples from that load to find out which farm’s milk caused the positive​. The dairy plant or a certified lab tests each farm’s sample for the specific drug, doing duplicate confirmatory tests on any positive farm​.  The offending farm is reported and regulatory action is taken (the farm’s milk license is usually suspended until the issue is corrected, and they may face financial penalties for the lost milk). This Appendix N process happens for every tanker of milk – ensuring no truckload with antibiotics enters the plant.​

Routine Producer Milk Testing (Laboratory Quality Tests)

In addition to per-load screenings, each farm’s milk undergoes routine lab tests at least once per month for quality metrics, as required by regulations. The farm samples collected by haulers are delivered to a certified milk testing laboratory (which may be operated by the dairy plant, a cooperative, or a state agency)​. Key tests include:

At the Dairy Processing Plant (Intake and Processing)

Once farm milk passes incoming tests, it is unloaded into the plant’s raw milk storage (silos). Commingled Raw Milk Testing: The plant may test silo milk (which is commingled from many farms) for quality. For example, Grade A commingled raw milk in a silo must be ≤300,000 CFU/mL bacteria​; if higher, it suggests a problem and could trigger investigation or additional pasteurization steps. Plants often check raw milk acidity or perform rapid bacteria tests as milk arrives – high acidity or rapid spoilage can indicate a farm issue or cooling failure. Pasteurization: Milk for fluid use must be pasteurized. Pasteurization itself isn’t a “test,” but a process monitored under strict controls. Time and temperature charts are recorded for each batch. Pasteurizer seals and thermometers are inspected regularly by state officials. After pasteurization, a phosphatase test is done periodically on milk to verify no active enzyme remains (meaning pasteurization was effective)​. The legal limit is <350 milliunits/L alkaline phosphatase in pasteurized milk​. Plants also do equipment tests (like cultures on pasteurizer plates) to ensure the system is working and clean.

Distribution and Retail

Milk and dairy products are generally sealed at the plant. En route, milk tanker trucks (hauling raw milk or pasteurized bulk) must maintain temperature. At retail, there isn’t routine testing of milk in stores except as part of periodic inspections. State agencies may do spot checks – e.g., testing random milk cartons from grocery coolers for proper pasteurization, bacteria counts, and truth-in-labeling (fat content). Also, expiration date management is checked to ensure products are fresh. If consumers complain about a product (e.g. “this milk was bad before the date”), regulators can sample and test that product. Responsible entities: Retail dairy inspections in Wisconsin are often handled by DATCP or local health departments as agents, who ensure stores keep dairy at safe temperatures and remove expired products.

Summary of Responsibilities

In Wisconsin, farmers are responsible for producing clean, cool, unadulterated milk. Milk haulers (licensed by the state) are responsible for proper sampling and immediate quality observations during pickup​. Dairy processors are responsible for testing incoming milk and their products to meet all standards – they usually operate the labs or contract labs for routine testing​. Certified laboratories (including the Wisconsin Dairy Science labs or private labs) actually perform many tests and must follow strict methods and annual proficiency checks. State regulators (DATCP) oversee the whole chain: they license farms, haulers, plants, and labs, set testing requirements (often mirroring FDA’s PMO), and audit compliance. The FDA provides oversight for interstate milk shipments, primarily by ensuring Wisconsin’s program meets the national standards (FDA often audits state programs and sometimes runs its own tests or inspections as a double-check). In addition, industry organizations (co-ops, etc.) impose voluntary quality programs: for instance, a co-op may reward farmers with extra pay for low bacteria count or butterfat above a baseline, thus encouraging extra quality testing by the farmer and continuous improvement. All these layers of testing – on farm, truck, plant, and shelf – work together so that by the time dairy reaches consumers, it has been tested or monitored at least half a dozen times for safety and quality​.

Policies and Regulations Governing Milk Testing

Multiple federal and state regulations ensure milk and dairy testing is done thoroughly. Below is a list of key policies/laws, and notes on how the FDA’s proficiency testing (PT) suspension might impact compliance:

Grade “A” Pasteurized Milk Ordinance (PMO)

Federal (FDA/USPHS). This is the cornerstone regulatory code for milk safety, adopted by Wisconsin and all states shipping Grade A milk. The PMO outlines all required tests and standards for Grade A milk production and processing – for example, the required monthly tests for bacterial counts and SCC on farms, the requirement to test every bulk milk tanker for antibiotics (Appendix N)​, and pasteurized milk standards (bacteria, coliform, etc.)​. It also mandates the annual laboratory evaluation program (Section 6 and Appendix I of the PMO) – requiring that each lab analyst is evaluated (often via proficiency tests) to ensure they can accurately perform the tests​. Impact of PT Suspension: The FDA’s PT program was a primary tool to fulfill this PMO requirement of annual lab competency testing​. With it suspended, FDA is looking for alternative ways to meet the PMO’s mandate​. States like Wisconsin may rely on their own proficiency test schemes or third-party providers to ensure labs/analysts still get evaluated, so they remain in compliance with the PMO’s standards despite the federal program pause​.

Food, Drug, and Cosmetic Act (FD&C Act)

Federal law. This broad law deems food unsafe if it’s “adulterated” or “misbranded.” For milk, adulteration includes things like drug residues or added water, or unsanitary production leading to contamination. Selling adulterated milk is illegal (21 U.S.C. §331). Enforcement: The FDA can enforce recalls or plant closures under this act if milk products violate safety standards. This law underpins why we test for antibiotics (residues make the milk adulterated by law) and why high bacterial counts or pathogens are taken seriously (milk with pathogenic contamination is adulterated). Impact of PT Suspension: None directly – routine testing for adulterants must continue regardless. If anything, the pause in the PT program heightens the importance of each lab’s other quality controls to ensure no adulterated product slips by.

21 CFR §1240.61 (Interstate Pasteurization Requirement)

Federal regulation. This regulation prohibits the sale of raw (unpasteurized) milk across state lines for direct consumption. It effectively means Grade A milk in commerce is pasteurized, and it ties into testing by ensuring raw milk must eventually be pasteurized unless used on-farm or in-state under specific conditions. Indirectly, it emphasizes the need for robust pasteurization and verification testing (like phosphatase tests, pathogen tests on products, etc., to ensure pasteurization is working).

Food Safety Modernization Act (FSMA) & Preventive Controls for Human Food (21 CFR Part 117)

Federal law/regulation. Dairy food processors (like cheese, ice cream plants, etc.) must follow FSMA’s Preventive Controls rule, which requires a hazard analysis and risk-based preventive controls. For ready-to-eat dairy, this often means companies must have plans to control hazards like Listeria or Salmonella. Testing under FSMA: While FSMA doesn’t list specific tests, it may require environmental monitoring (e.g., swabbing for Listeria in a ice cream plant) or product testing as verification if those are appropriate controls for identified hazards. Wisconsin dairy plants implement these as part of their food safety plans. Impact of PT Suspension: None on FSMA requirements – those are independent of the FDA milk lab program. However, the accuracy of lab tests (for pathogens or contaminants) remains crucial, so labs might use non-FDA proficiency programs to ensure they meet ISO or AOAC standards even without the FDA’s PT samples.

Wisconsin Statutes (Chapter 97, Food Regulation)

State law. Wisconsin Statutes §97.20 covers licensing of dairy plants, §97.22 covers Grade A milk permits, and related provisions require adherence to safety standards and regulations. For example, to hold a Grade A permit in Wisconsin, a producer must meet the PMO standards (which are enforced under state law). Raw milk sales: Wisconsin law (generally §97.24) prohibits selling raw milk to consumers (except limited farm-owner use), aligning with federal intent for pasteurization. Milk contractor law: There’s also regulation (Chapter 126) ensuring dairy farmers get paid correctly, which ties into the accuracy of component testing. Impact of PT Suspension: State law requires that dairy plants follow rules that include lab testing. If the FDA PT program is suspended, Wisconsin may invoke its own authority to require labs to participate in a state-run proficiency program (which Wisconsin already has in place​), thereby satisfying state law obligations even in the absence of the FDA program.

Wisconsin Administrative Code (ATCP 65: Milk and Milk Products)

State regulations. This comprehensive rule is essentially Wisconsin’s detailed implementation of the PMO and other dairy regulations. It covers farm requirements, milk quality standards, testing frequencies, and plant operations. For example:

Wisconsin Administrative Code (ATCP 77: Laboratory Certification)

State regulations. This rule requires that any lab testing milk (or food, water, etc.) for official purposes in Wisconsin be certified by DATCP. To be certified for dairy testing, labs must use approved methods and successfully participate in proficiency testing. ATCP 77 assigns Laboratory Evaluation Officers (LEOs) who periodically audit labs and oversee proficiency sample distribution. Impact of PT Suspension: Labs still must meet ATCP 77 requirements. DATCP’s LEOs will likely accept alternative proficiency results (e.g., from the state’s own program or third-party providers) in lieu of FDA-run test results. The bottom line is that labs cannot simply skip proficiency – the mechanism to do it might shift from an FDA-run test to a state-facilitated one. Wisconsin has indicated it will continue to require and facilitate these proficiency tests, so labs remain certified and consumers protected.

Industry Guidelines and QA Programs

In addition to laws, there are industry standards (e.g., those by the National Conference on Interstate Milk Shipments, NCIMS) and programs like the Interstate Milk Shippers (IMS) List – a FDA/state program that lists approved shippers of Grade A milk. To stay on the IMS list (which allows interstate commerce of milk), states and dairies must adhere to the PMO including all testing requirements. Private standards (e.g., ISO 17025 for lab accreditation or Safe Quality Food (SQF) certification for plants) often require proficiency testing and rigorous QA. Impact of PT Suspension: Organizations like NCIMS and industry groups have been discussing how to ensure continued compliance. The International Dairy Foods Association (IDFA) has reassured that milk testing frequency and oversight are unchanged​ and that many labs have other proficiency checks to rely on​. So, industry QA programs provide a safety net – many dairy labs also do proficiency tests through groups like ADPI or AOAC. Thus, even with FDA’s program on hold, other policies and programs fill the gap to maintain testing integrity in the short and intermediate term.

Conclusion

In summary, federal and Wisconsin regulations form a safety net that mandates testing of milk at multiple points. The FDA’s proficiency testing program was one piece of ensuring those tests are done accurately (a lab oversight function). Its suspension does not suspend the underlying laws – all dairy testing laws are still in force, and Wisconsin is still requiring all the usual tests (and finding ways to keep labs checked). Regulators and the industry are adjusting via state programs and third-party proficiency testing to remain compliant with the letter and spirit of the law despite the FDA program’s hiatus​.

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