Dr. Renate Reimschuessel traces melamine–cyanuric acid link to 2007 pet‑food and 2008 infant‑formula kidney injuries

Dr. Renate Reimschuessel, speaking at CDC’s June ZOHU (Zoonoses and One Health Updates) webinar, reviewed laboratory and field investigations that tied the 2007 pet‑food recall and the 2008 infant‑formula crisis to crystalline deposits formed when melamine and related compounds combined in the body.

"If you dose them with both melamine and cyanuric acid, you get many crystals," Reimschuessel said, describing controlled animal studies in which fish, pigs and chickens developed intratubular crystals only after combined exposures. She told attendees that melamine alone and cyanuric acid alone did not produce the same obstructive crystals in tissue sections.

Her presentation summarized the rapid sequence of events in 2007: Menu Foods reported a pending recall of roughly 60 million containers across more than 100 brands after clusters of pets with renal failure. Two weeks after the recall began, melamine was detected in imported wheat gluten; investigators then traced contaminated material through feed mills, rendering plants and onto livestock and aquaculture operations. Reimschuessel described how veterinary pathology reports shared by the field contained unusual needle‑like crystals and how frozen tissue sampling proved pivotal: crystals visible in frozen sections disappeared after routine formaldehyde fixation, which initially obscured chemical detection.

Laboratory work she described included collaborative recuts, frozen‑section examinations, and spectroscopic confirmation. Reimschuessel described Raman microscopy that produced spectra from kidney crystals matching spectra from melamine–cyanuric acid material produced in vitro, strengthening the chemical identification.

She recounted how industry and academic partners aided method development and animal models. "We fed fish melamine alone, cyanuric acid alone, and both of them together, each at 400 milligrams per kilogram of each drug," she said; only the combined dosing produced the characteristic crystals in multiple species. The research led to a joint publication and method validation across laboratories.

Reimschuessel then connected those laboratory and animal results to the 2008 infant‑formula event in China. She said melamine was reported in some powdered infant formulas at levels "as high as 5,000 parts per million." Infants exposed to highly contaminated formula developed melamine‑uric acid kidney stones, which clinicians diagnosed with ultrasound because the stones were radiolucent. She cited an estimate given in the presentation that about six infants died and roughly 300,000 were diagnosed with stones during the global screening response.

She described downstream policy and technical actions: rapid FDA risk assessments, analytical method development, and an expert WHO meeting in December 2008 that contributed to establishing a tolerable daily intake (TDI) for melamine. Reimschuessel emphasized practical lessons for surveillance and response: collect frozen tissue when chemical contamination is suspected, prioritize partnerships among government, industry and academia, provide accessible online reporting for clinicians and the public, and recognize that mixtures of low‑toxicity compounds can combine to produce severe effects.

"Surveillance is essential to be prepared for economically motivated adulteration," she said, and recommended broad collaboration and communication channels to accelerate detection and analysis.

The ZOHU webinar host noted that a recording will be posted on the June ZOHU Call page; attendees were referred to CDC resources and the ZOHU newsletter for links to guidance and publications.

Reimschuessel’s presentation framed the events as a combined laboratory, field and public‑health response that identified a physical mechanism—crystal formation from combined chemicals—behind large‑scale animal and human illness and informed follow‑on toxicology and regulatory work.