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Over 60% Foldable Silicone Food Containers and Cups Exceeded Limits for Volatile Organic Matter Selecting Safe and Reusable Utensils Helps Reduce Waste Plastics at its Source

  • 2021.09.15

Jurisdictions around the world have implemented policies to slash plastic waste, and many consumers have also responded to the initiatives by bringing their own reusable containers for takeaway food and beverages. In recent years, various foldable silicone food containers and cups have emerged, boasting various benefits such as pliability, lightness, being easy to fold and carry. However, the Consumer Council tested 14 models of foldable silicone food containers and cups on the market and found that over 60% of the models contained levels of volatile organic matter that exceeded German limits. In view of the Government’s plans to regulate disposable plastic tableware, the Council opines that apart from progressive control of the selling and use of disposable plastic cutlery, the Government should also take prompt action to set safety standards for reusable products, so as to ensure product quality and increase the public’s confidence in using such products.

Silicone is a type of compound, being a hybrid between synthetic rubber and synthetic plastic. Different manufacturing processes can produce silicone with varying properties to be used for a variety of goods, such as personal care products, construction sealants, electronic and computer products, soft medical tubing, etc. Its high temperature resistance and stable nature makes it very popular for cooking and dining utensils, but generally such silicone materials need to be of higher quality food grade and the products must meet safety regulations related to food contact materials, such as those laid out by the Food and Drug Administration (FDA) of the United States, the German Food Consumer Goods and Animal Feed Act (LFGB) or the GB4806.11-2016 standard of the Mainland, etc.

The test included 9 models of foldable food containers and 5 models of foldable cups. The food containers had labelled capacities from 600ml to 1L, and retail prices ranging from $29 to $130; the 5 cup models showed a greater variance in retail price, ranging from $12 to $200, amongst which 4 models had labelled capacities from 130ml to 470ml, while 1 model did not declare its capacity. Test items included overall migration for 3 food simulants, potassium permanganate consumption, colour migration when soaked in liquids, volatile organic matter (VOM), total lead and cadmium levels, food colouring residue and durability, while the labelling information on the packaging was also examined.

Based on the results of the migration test, the soaking liquid for all of the models did not show any colour transfer, cloudiness, sediment or odour. The silicone body of all test models of food containers and cups were able to meet the Mainland standard requirements for overall migration onto 3 food simulants, as well as the potassium permanganate consumption. Besides, the total cadmium and total lead contents also met the requirements of the German LFGB standard. In the durability test, all models had satisfactory performance and showed no breakage after being folded for 1,000 times using dedicated test equipment.

Siloxanes are main VOMs found in silicone materials. When siloxane levels are in excess, they may migrate onto the food and affect food safety. According to the LFGB standard, the VOM limit for food-contact silicone products is 0.5%. The test results revealed that over 60% of the models (9 models) exceeded the VOM limit, while only 3 food container models and 2 foldable cup models met the requirements. Amongst the models that exceeded the limit, 6 were food containers which had VOM levels from 0.76% to 1.3% for the body and sealing ring materials; the remaining 3 were foldable cups which had VOM levels from 0.8% to 1.4%. Research has indicated that long-term contact with high dosages of siloxanes may adversely affect the liver health of test animals. As Hong Kong currently does not have any regulations for the VOM levels of food-contact silicone/rubber products, the Council urges the Government to establish relevant standards promptly to safeguard the health of consumers.

Many office workers bring their own lunch and reheat it in the microwave oven before eating. All silicone food container models in this test claimed to be microwavable. However, consumers should be mindful that as the lid of some products may be made from different plastic materials or come in different shapes and designs, it should not be assumed that they could all be microwaved. Consumers should peruse the labelling information before use to avoid damaging the product or even cause accidents due to misuse. Upon inspection of the labelling information of the test models, it was found that 6 out of the 9 food containers had a non-microwavable lid, which should be removed before reheating; 2 models claimed to be microwavable, while 1 model did not clearly specify its suitability.

When selecting a silicone food container, aside from its product safety when reheating food, another deciding factor is whether it is easy to clean. As part of the test, 2ml of curry sauce and 2ml of tomato sauce were placed in each model separately, heated in a microwave oven, then the sauce was removed and the containers were cleaned in a designated dishwasher once to examine the food colouring residue. The results showed that 7 models of food containers had colour stains even after washing. For curry sauce, only 2 models performed relatively better, yet only received a rating of 3 points (out of 5), while the remaining models had unsatisfactory performance and scored 2 points to 2.5 points. As for tomato sauce, 2 models performed better and did not show any obvious stains after washing, thus received the highest rating of 5 points. The remaining models performed inconsistently and were left with clear tomato sauce stains, thus were rated 2 points to 3 points only. Consumers are reminded to promptly soak and clean silicone food containers that have been used to hold pigmented food and reheated in the microwave, so as to prevent staining.

On the other hand, the models of foldable cups were not found to have major issues. In the test, the models were filled with hot coffee at 90°C and grape juice at room temperature respectively, emptied after 2 hours and cleaned in a dishwasher. Apart from 1 model which had coffee stains after washing and thus received a 3-point rating, the other models were not found to be stained and were all rated 5 points.

Product labels should display instructions for correct use and precautions in both Chinese and English, to let consumers easily understand and use the product as intended, so as to prevent accidents. Upon reviewing the labelling information, it was found that 5 models displayed information in both Chinese and English; 7 models had information in either English or Chinese; 2 models did not bear safety warnings in Chinese and/or English. The Council has passed the relevant information to the Customs and Excise Department for follow-up action.

With regards to the suitable temperature range, 6 food container models displayed their suitable temperature range, which ranged from -40°C to the highest of 240°C, implying that they could be chilled in a freezer. Amongst them, only 2 stated that they were oven-safe. The remaining 3 models did not indicate a suitable temperature range. Consumer should pay heed and avoid misuse. Amongst the silicone cups, only 1 model was labelled as microwave-safe excluding its accompanying lid, 2 models stated they were not suitable for microwave heating, and the remaining 2 did not have any labelled instructions.

When purchasing and using foldable silicone food containers and cups, consumers can take note of the following recommendations:

  • Before purchasing, check the product labels for information or logos indicating compliance with safety standards, such as FDA, LFGB or GB standards, or the symbol for food-safe materials;
  • Carefully read the labels to understand important information such as the suitable temperature range, whether the body and lid are microwave-safe, etc.;
  • Newly purchase silicone products should be thoroughly washed and cleaned before use;
  • Do not clean silicone products with wire scourers or scouring pads to avoid scratching the surface. Instead, gently clean using a soft sponge or cloth with a small amount of dishwashing liquid, rinse and air dry to prevent mould;
  • For microwave-safe food containers with an air vent on the lid, keep the vent open during microwave heating to release the steam and prevent build-up of pressure;
  • Refrain from storing dark-coloured or strong-smelling food in silicone food containers for long periods to avoid staining or leaving an odour in the container;
  • Try to remove stains or odours from food containers by soaking it in baking soda paste or diluted citric acid for a period of time, then thoroughly rinsing it;
  • Silicone cups with a smaller capacity may become soft after holding hot drinks or heating in the microwave, and may cause spillage of hot beverages. Pay extra heed if the cup is used by a child to prevent scalding.

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