A toddler has been treated in hospital after drinking a commercially available product for treating aquarium fish parasites.
The three-year old girl drank up to two ounces of Wardley Ick Away, a medication based on 0.075% malachite green, which is designed for treating whitespot and fungus on aquarium fishes.
She was found with blue lips and nails by her father and taken to casualty, where she was awake and crying, with signs of a medical condition called cyanosis; a disorder which causes the skin and mucus membranes to turn blue due to a decrease in blood oxygen levels.
The girl's head, hands, arms, feet and legs had turned blue and she was also suffering from methemoglobinemia (MetHb) - a higher than normal presence of a non-oxygen carrying form of haemoglobin in the blood.
She was treated with methylene blue (coincidentally another chemical also used to treat fungal diseases in fish) and responded rapidly by turning pink, making a recovery after 20 hours in intensive care.
Henry Spiller, George Rodgers, Danetta Willias and George Bosse of the Kentucky Regional Poison Center and Janice Sullivan of the University of Louisville reported in the journal Clinical Toxicology that the case was believed to be the first documented case of human injury following ingestion of malachite green, and the first case of methemoglobinemia after ingestion of the chemical.
Malachite green is the most widely used constituent of aquarium anti-parasite and anti-fungi medications.
It forms a chemical called leucomalachite green which accumulates in fish tissues. Studies on rats have suggested that the chemical is a carcinogen (causes cancer).
It is now banned from use in aquaculture, but remains on sale in the aquarium hobby, where few viable alternatives exist for the treatment of the target diseases.
For more information see: Spiller H, Rodgers G, Willias D, Bosse G, Sullivan J (2008) - Methemoglobinemia due to malachite green ingestion in a child. Clinical Toxicology, 2008, April, 46(4): 320-1.