Final answer:
The 'big milk contamination incident' may refer to an outbreak of listeriosis in 1983, linked to unpasteurized milk, causing 630 confirmed cases. A case-control study associated the bacterium Listeria monocytogenes with contaminated milk. The 1986 amendments to the Safe Drinking Water Act were important in improving detection and response to such incidents in the future.
Step-by-step explanation:
The student asked about the details of the big milk contamination incident in 1985. During this incident, various sources of food such as unpasteurized milk and undercooked ground beef, among others, were found to be contaminated leading to widespread health issues. Although the student's query refers specifically to 1985, the incident that matches the description and had significant consequences transpired in 1983. It involved the bacterium Listeria monocytogenes, which caused a considerable outbreak of listeriosis. There was an epidemiological investigation that confirmed 630 cases across 11 states.
The source of the bacteria was identified through a case-control study by comparing foods consumed by infected patients with those consumed by healthy controls. The result pointed strongly to contaminated milk as a primary vehicle for the bacteria.
Unfortunately, the provided references do not specifically mention a milk contamination incident in 1985 but discussing the 1983 outbreak and other environmental crises helps us understand the severity and impact such contamination events can have. It is also important to note that amendments made to the Safe Drinking Water Act in 1986, like the establishment of Maximum Contaminant Level Goals (MCLGs), were important steps towards protecting public health from contaminated food and water sources.