An inspection of eggs conducted by the Council of Agriculture (COA) and Ministry of Health and Welfare starting in February showed that two among 54 sample items were found to contain veterinary drug residues, including one from a source that provides eggs to 7-Eleven for hard-boiled tea eggs (茶葉蛋).
The two samples with animal drug residues contained florfenicol, doxycycline and nicarbazin, which are legal for general veterinary use, but are prohibited for use in egg-producing hens, the COA’s Bureau of Animal and Plant Health Inspection and Quarantine said yesterday.
Egg samples from a farm in Chiayi County were found to contain florfenicol and doxycycline. The ranch was fined NT$30,000 (US$984) by the COA for violating the Veterinary Drugs Control Act (動物用藥品管理法).
The other site, in Changhua County, was fined NT$600,000 by the Ministry of Health and Welfare for violating the Act Governing Food Safety and Sanitation (食品安全衛生管理法).
The Chiayi farm provides eggs to 7-Eleven, the nation’s largest convenience store chain, for hard-boiled tea eggs. The contaminated samples came from a batch of about 24,000 eggs that were supplied to 7-Eleven in February.
A ranch spokesperson surnamed Su (蘇) said that the ranch followed drug-use rules on when to stop the drug, but it was possible that the egg-producing hens had slower metabolisms at the time, so the drugs remained in their systems longer than usual.
Su that follow-up inspections did not find drug residue in the eggs.
The inspection bureau said that although the drugs have maximum residue levels established for hens that are not producing eggs, there is no maximum residue limit set for eggs. Therefore, any amount found in eggs is prohibited.
In other hens, the maximum residue limit is 0.1 parts per million (ppm) for florfenicol and doxycycline, and 0.2ppm for nicarbazin.
The bureau said it has discussed the issue with the Ministry of Health and Welfare and will set a maximum residue limit for eggs, so that egg farmers will have a standard to follow when using veterinary drugs.
In addition, the bureau stressed that animal drugs should not be used in the four weeks before hens produce eggs or during the period that they are laying.
Linkou Chang Gung Memorial Hospital toxicologist Yen Tsung-hai (顏宗海) said that excessive intake of florfenicol in humans may cause aplastic anemia, leukemia or even cancer.
The rates of consumption needed for such effects were not specified.