title: Gastric mucosal irritation following oral exposure to sodium metabisulphite: A reproducible effect?
abstract: Sulphiting agents, such as sodium metabisulphite (SM), are used in food as bleaching agents and to prevent browning reactions. A 1972 repeat dose study in rats found that dietary sulphites caused irritation of the stomach with inflammation, hyperplasia and bleeding. We conducted a 7-day dietary study in rats to confirm that stomach lesions were the most sensitive toxicological endpoint. Rat feed was prepared daily with 0%, 0.25%, 0.5%, 1% or 4% (w/w) SM. Parameters included clinical signs, feed and water intake, bodyweight gain, haematology, serum protein chemistry, necropsy findings and gastrointestinal histopathology. There were no treatment-related clinical signs or gastrointestinal lesions. Mean bodyweight gain was markedly decreased in the 4% (w/w) SM group although feed consumption was marginally depressed. Slightly lower mean values for RBC, Hb, Hct, total WBC and lymphocyte count were observed in the 4% SM group with no evidence of compensatory haematopoiesis. The gastric lesions in rats observed in a 1972 study of dietary SM for 10-56 days could not be replicated. These findings create uncertainty around the most relevant toxicological endpoint to establish a suitable health based guidance value, which can only be overcome if a robust long-term dietary study is undertaken.
authors.affiliation: Food Standards Australia New Zealand, Level 3, 154 Featherston Street, Wellington, 6011, New Zealand. Electronic address: rosalind.dalefield@foodstandards.govt.nz.
authors.forename: Rosalind R
authors.initials: RR
authors.lastname: Dalefield
authors.affiliation: Food Standards Australia New Zealand, Boeing House, 55 Blackall St., Barton, ACT, 2600, Australia. Electronic address: utz.mueller@apvma.gov.au.
authors.forename: Utz
authors.initials: U
authors.lastname: Mueller
mesh_terms: D000284:Administration, Oral; D000818:Animals; D015415:Biomarkers / Q000097:blood; D004032:Diet; D004334:Drug Administration Schedule; D004435:Eating / Q000187:drug effects; D005503:Food Additives / Q000008:administration & dosage / Q000633:toxicity*; D005753:Gastric Mucosa / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D007509:Irritants / Q000008:administration & dosage / Q000633:toxicity*; D008297:Male; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D018570:Risk Assessment; D013447:Sulfites / Q000008:administration & dosage / Q000633:toxicity*; D013997:Time Factors; D023382:Toxicity Tests, Acute; D015430:Weight Gain / Q000187:drug effects
chemical_list: D015415:Biomarkers; D005503:Food Additives; D007509:Irritants; D013447:Sulfites; C005200:sodium metabisulfite
keywords: Sodium metabisulphite; Sulphite