Cooking oils were the first items tested by the Consumer Council, soon following its establishment which drew considerable public attention. Subsequent to recent incidents of substandard oils, and growing consumer demand for quality cooking oils, the Council carried out a large-scale test study covering 60 types of cooking oils commonly found in the market. 41 samples were detected containing phthalates; among them, the amounts in 5 samples were higher than the action level in Hong Kong and also above the upper limit of the European Union standard. 2 were found to have residual solvent chloroform. Moreover, contaminant 3-Monochloropropane (3-MCPD) and genotoxic carcinogen glycidol were found in 42 and 46 samples respectively. The Council urges for relevant regulation to be established with safety standards well laid out to strengthen safety.
The Council emphasises that although there is, at present, no specific safety standard for cooking oils in Hong Kong, only by consuming large amounts of the contaminants detected in the test over an extended period would pose health threats generally and reactions to it may also differ from person to person, cooking oils are common ingredients, and can be consumed through different sources. The risk of food safety, therefore, cannot be taken lightly. The Council expects the Government to keep a close eye on the latest risk evaluation on different types of contaminants, and make reference to international standards to establish relevant regulations in Hong Kong. Meanwhile, the Council calls on the industry to actively review their raw materials and manufacturing procedures to avoid having risky contaminants in the oils. Test results revealed that the level of contaminants detected in some samples was lower than others, showing the industry indeed has the ability to improve quality. The Council expects the industry to continuously improve its formulation for the best protection of consumer health.
Tested models included peanut oils (7), corn oils (10), canola oils (11), extra virgin olive oils (11), olive oils (2), olive-pomace oils (2), grapeseed oils (3), sunflower oils (3), rice bran oils (2) and blended oils (9).
In the test, 42 samples were detected 3-MCPD and 3-MCPD released through 3-MCPDE (3-MCPD esters), ranging 150 to 6,800μg/kg; 46 samples were found to contain 67 to 2,000μg/kg genotoxic carcinogen glycidol.
Some cooking oils are manufactured at high temperature and during the process contaminants 3-MCPD and glycidyl esters (GE) may be produced. Some research studies revealed that through hydrolysis of 3-MCPDE and GE in intestinal tracts, 3-MCPD and glycidol would be released respectively. According to reports released by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) and European Food Safety Authority (EFSA), it was confirmed in experiment that animals having long-term consumption of 3-MCPD would be affected in kidneys and male reproductive system. The International Agency for Research on Cancer has classified glycidol as a Group 2A substance, i.e. "probably carcinogenic to humans". Nonetheless, there is currently no legislation or standard to regulate the level of 3-MCPD and glycidol in edible oils and fats in any country or region.
Based on JECFA and EFSA's Provisional Maximum Tolerable Daily Intake (PMTDI) and Tolerable Daily Intake (TDI) for 3-MCPD and 3-MCPDE, 4μg/kg and 0.8μg/kg respectively, a person weighing 60kg can consume maximum 240μg and 48μg every day. Calculating based on the sample detected the highest level (6,800μg/kg), consumption of more than 35g (about 8 tsp) already exceeds JECFA's recommendation, while consumption of more than 7g (about 2 tsp) would exceed the EFSA's recommendation.
The Council also found that product names of blended oils sold in the market, i.e. blending two or more types of cooking oils, could be misleading. According to Food and Drugs (Composition and Labelling) Regulations, ingredients should be listed in descending order of weight or volume. In this test, most models of blended oils cited "virgin olive", "peanut" or "grapeseed" at the front facing, or in bold font. However, on the ingredient lists, canola oil, sunflower seed oil and soybean oil were given the highest placement. The product name of a model, for instance, was "peanut oil", but the highest content on the ingredient list was actually canola oil. The Council calls on the industry to list clearly the content or composition of oils or fatty acids in blended oils, to allow consumers to obtain accurate information for making choices.
There has always been concern over health threats posed by phthalates in foods, which are endocrine disrupters according to studies. Long-term intake has been shown to damage the development of the reproductive systems of laboratory's animals. As phthalates are oil-soluble, plastics containing phthalates should not be used to contain oil products. Consumers who habitually store oil in self-purchased containers should pay extra attention to this.
This test measured the content of 5 kinds of phthalates and found 41 samples containing 1 or more kinds. Among them, 3 samples were detected with di (2-ethylhexyl) phthalate (DEHP) exceeding the local action level by 0.6 to 4.2 times. In 1 sample, the sum of di-isononyl phthalate (DINP) and diisodecyl phthalate (DIDP) content was double the level permitted in action level; and di-butyl phthalate (DBP) content in 1 sample exceeding the action level by 0.7 times.
Consumers however need not be overly anxious, according to the EFSA, for a person weighing 60kg, Tolerable Daily Intake TDI of DEHP is 3mg, DBP is 0.6mg, DINP and DIDP (group TDI) is 9mg. Calculated on the basis of the highest level detected in the samples, health risks may arise only if that person were to consume more than 0.4kg, 1.2kg and 0.5kg cooking oils respectively every day, over an extended period.
In terms of tests on residues of halogenated solvents, 1 sample of extra virgin olive oil was found to contain 0.29mg/kg chloroform, exceeding the international standard set out under the Codex Alimentarius Commission (CAC). Based on the standard, maximum content of 3 types of halogenated solvent in extra virgin olive oils is 0.1mg/kg, and the maximum content of the sum of all halogenated solvents is 0.2mg/kg. Unless consumers consume such product more than 3kg every day and over an extended period, the amount is not likely to cause harm.
The Council reminds consumers, when choosing cooking oils, apart from reading label contents and store oil in suitable containers, they should make choices according to their cooking practices. For instance, virgin olive oil releases smoke in high temperature, so it is suitable only for low-heat cooking; peanut oil, corn oil and canola oil work well for cooking methods like pan-fry or stir-fry. Moreover, high temperatures promote oxidation of oils and may generate carcinogens. As a result, consumers are advised to make minimal use of cooking methods like cooking with high temperature or with too much oil, as a safeguard to their health.
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