How did regulations start?
As people moved to the cities, the milk supply became unhealthy. Milk had to be transported longer distances and was held at higher temperatures for longer times. As a result, many people, especially children, became sick and died after consuming contaminated milk.
In the late 19th century, public health reformers started working toward a safer milk supply. One such reform was, in 1910, the city of Chicago required milk to be pasteurized. Farmers and sellers sued the city stating that requirement was unnecessary and costly. In 1914, the Illinois Supreme Court decision in Koy vs City of Chicago required pasteurization of milk sold in the city. By 1920, regulations regarding milk had spread across the nation.
This proved to be a public health victory. In 1938, disease outbreaks from milk counted for 25% of all outbreaks from food and water. As of 2002, that number was down to 1%.
In 1924, the United States Public Health Service (USPHS), a branch of the FDA, developed what is now known as the Pasteurized Milk Ordinance (PMO). The PMO contains provisions governing the production, processing, packaging and sale of Grade “A” milk and milk products. This includes the barns, equipment, water, testing, cleaning, etc. The 2013 PMO is over 430 pages.
The PMO is the basic standard used in the Voluntary Cooperative State – USPHS/FDA program for the Certification of Interstate Milk Shippers (IMS). To be involved with Grade “A” milk, you must be “listed” in the IMS. This includes dairy processors, laboratories, container and closures companies. All 50 states, DC and US territories participate in the IMS program. Forty-six states have adopted the PMO for their own milk safety rules. The other 4 states have passed laws very similar.
Federal law prohibits the interstate sale of raw fluid milk. In 1987, the FDA banned the state-to-state shipping of raw milk. They mandated the “pasteurization of all milk and milk products in final package form for direct human consumption.”
Why pasteurize?
The leading human illnesses attributed to milk before pasteurization were brucellosis, diphtheria and tuberculosis. These are well-controlled or virtually eliminated in modern dairy herds in the United States. They do still occur in other countries.
Predominant illnesses today from raw milk and raw milk products are normally caused by Salmonella sp, Campylobacter sp, E. coli and Listeria sp.
RAW MILK OUTBREAKS in unpasteurized (raw) milk and raw milk products, United States 1998 – 2013 (15 years)
136 total outbreaks
102 were from fluid milk
28 were from raw milk cheese.
6 wer from multiple raw dairy products.
2,468 total illnesses, 2 deaths
1,803 fluid milk-related illnesses.
608 cheese-related illnesses, 2 deaths
57 illnesses from multiple raw dairy products.
From January 2015 to March 2016 (15 months), there were 15 recalls of unpasteurized milk. The states include California (4), Pennsylvania (3), New York (3), Washington (2), Idaho, Tennessee and Indiana.
The contaminates were Campylobacter sp. (7), Salmonella sp. (2), E. coli 0157:H7 (4), Listeria sp. (4), and Cryptosporidium (1). Two recalls were for more than one contaminant. Some recalls were in response to routine testing that yielded positive results. Others were due to illnesses related to the consumption of raw milk. In states that allow the sale of raw milk, there are mandatory testing requirements of the raw milk that vary from state to state. Some states require routine pathogen testing, while others do not until there is a complaint or outbreak.
How does raw milk get contaminated?
There are many avenues for contaminates to get into the raw milk. It can come from the processing equipment such as the milking equipment, lines, tanks and containers. 
Environmental factors can include dirt, mud, fecal matter in the straw, and standing water in the area.
Rodents, including mice, rats, insects and chicken and poultry can contaminate the area and the milk.
Other avenues can come from the humans on their boots, gloves, hands and soiled clothing. 
The animals themselves can be the source of contamination due to the inadequate cleaning of the udders, broken skin or illness.
What testing is done? Report to follow.
