The Cullen Criteria

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MCS was first described by Theron Randolph in 1959, and since then has been defined with a variety of similar but inconsistent criteria for both clinical practice and research purposes. In 2025, the Marilyn Brachman Hoffman Foundation issued our first competitive request for applications. One of the challenges we encountered was selecting the right framework for identifying “cases” of MCS in clinical research populations.  Following a careful review of the literature, we determined that the Cullen Criteria (Cullen, 1987) would provide the best clinical research framework for this initial RFA. These criteria are: 

1. “Disorder is acquired in relation to some documented environmental exposure, insult, or illness.”

2. “Symptoms involve more than one organ system.”

3. “Symptoms recur and abate in response to predictable stimuli.”

4. “Symptoms are elicited by exposures to chemicals of diverse structural classes and typically known toxicologic modes of action.”

5. “Symptoms are elicited by exposures that are demonstrable.”

6. “Exposure that elicits symptoms must be very low.”

7. “No single available test of organ systems function can explain syndrome.”