2 School Uniform Samples Detected with Carcinogenic Dyes Suppliers Urged to Exercise Strict Quality Control to Safeguard Student Health

16 July 2018
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2 School Uniform Samples Detected with Carcinogenic Dyes   Suppliers Urged to Exercise Strict Quality Control to Safeguard Student Health

As the school summer holiday gets underway, many parents have started purchasing new school uniforms and textbooks in preparation for the next academic year.  A test carried out by the Consumer Council found the presence of azo dyes in 2 school uniform samples.  These azo dyes can release carcinogenic aromatic amines, and their use have been long banned in many countries and regions.  In Hong Kong, though there is no similar specific legislative control, school uniforms are regulated under the Consumer Goods Safety Ordinance which ensure the products’ general safety.  These test results have since been referred to the Customs and Excise Department for investigation and follow up.  The Council urges school uniform suppliers to check the source of the dyes used for the production of their uniforms and to immediately cease the sale of any uniform if it is found to contain such harmful substances and the Government is also called upon to devise relevant legislation to govern the production of textile products in order to enhance consumer protection.

Furthermore, in addition to the finding of the presence of carcinogenic dyes, 8 samples were found with formaldedyde and 2 samples with pH values exceeding the Mainland standard.  This coupled with the overall unsatisfactory endurance performance of the samples, prompted the Council to strongly propose that school uniform suppliers should exercise strict monitor and control in the quality and safety of their products to ensure fabrics used conform to standards.  On the part of the schools, they should seek more information about the safety of the materials used and conduct regular checks on the quality of school uniforms.  Should any problems arise in relation to any safety aspects of the uniform, they must immediately revert to the suppliers and demand necessary improvement. 

The test included 49 samples of school uniforms sourced from 22 suppliers.  The selection was based on designs and colours that were commonly used in Hong Kong.  The price of the uniforms ranged from $50 for a piece to $280 per set, with the samples comprising 20 samples for boys (shirts and long trousers of 10 each) and 29 samples for girls (16 dresses, 6 two-piece blouses and 7 skirts).

The test carried out included chemical tests, endurance levels, whether the samples contained optical brighteners or fluorescent whitening agents, and labeling information referencing the European EN ISO methodology and using the Mainland GB 18401-2010 and GB/T31888-2015 standards.

The results found, harmful aromatic amines, 4-amino azobenzene, in 2 girl uniform samples - the checkered pattern waist belt of 1 dress sample and the 3 grey cloth embroidered trimmings along the edges of another 1 blouse sample.  They were found to contain 41mg and 173mg per kg 4-amino azobenzene respectively.  In both of these samples, the chemicals contained exceed the Mainland standard of 20mg per kg ie twice the level in the former uniform and by sevenfold in the latter.

4-amino azobenzene, released by azo dyes through a reduction process, poses potential carcinogenic risk to humans or animals.  Years ago, laws were introduced in the Mainland, Europe and Japan to prohibit the use of azo dyes in textiles due to their risks of releasing harmful aromatic amines.

The Council wants to emphasise that although the harmful aromatic amines were only found on the waist belt and the trimmings rather than the main fabric of the garments, the revelation that 2 school uniform samples still used materials containing azo dyes which was banned for use in many countries years ago due to their propensity to release harmful aromatic amines was most unsettling and totally unsatisfactory.  Although the chance of the waist belt or trimmings coming into direct contact with the skin may be relatively small, school uniforms are worn by students practically every day, and when azo dyes are mixed with the perspiration of students, this could trigger a reduction reaction, releasing harmful aromatic amines that can be absorbed by the skin.   The potential risk cannot be taken lightly.

The absorption or contact with excess amount of formaldehyde could cause discomfort to the mouth, nose or skin.  Formaldehyde was found in 8 samples, ranging in concentration from 12mg to 32mg per kg, but all were lower than the Mainland standard of 75mg per kg.

As the human body skin is slightly acidic to prevent the invasion of bacteria infiltration, if the clothing is high in alkalinity, this may tip the PH balance of the skin, resulting in itchiness.  In the test, 1 pair of long trousers and 1 dress sample were found to have a pH value of 8.7 and 8.8 respectively, both exceeding the Mainland pH value limit of 4 to 8.5.  The high alkalinity level could be caused by chemicals such as fabric softener or laundry detergent during the washing process.

As formaldehyde is water soluble and the 2 samples with high pH values adjusted to within the acceptable standard limit after washing them once, it is therefore recommended that new school uniforms be washed before wear to minimise any potential health risks.

Also 35 samples were detected to exhibit fluorescence effect, indicating that over 70% of the samples might have been treated with optical brighteners or fluorescent whitening materials.  Most of the samples involved were white but some were non-white in colour.  Presently, there is no specific international standards or laws regulating the use of fluorescent whitening agents in textiles, and also there is uncertainty as to whether such fluorescent substances can be migrated from the clothing to the body of the wearer.  In general, even with washing, the fluorescent whitening agents in textile products cannot be removed.  People with sensitive skin allergies might be concerned that contact with these substances may trigger adverse reactions. 

In the endurance test, the samples were put through a process of 50 simulated machine washes, including hanging the garments out to dry and ironing.   After the simulation washes, the samples were measured for size which showed little changes.  However, in nearly half (25) of the samples, changes in appearance to various extent were observed, including pilling, puckering, slight color variations and discoloration of the zippers, and this was judged to be “unsatisfactory”.

Furthermore, 6 samples were shown to fare poorly in colour fastness to water and to perspiration leading to colour run and colour stain to other clothes.  Unsatisfactory performance in resistance to pilling, tensile strength of lining and seam strength was found with 1 sample in each of the above categories. 

In respect of labelling, only 14 samples were labelled with the fabric composition; among them, 4 samples were found with discrepancies between the measured values and labelled values which were significantly higher than the acceptable international standard of 3%. The findings have been forwarded to the Customs and Excise Department for follow up.   Less than half of the samples were provided with care labelling, there is clearly much room for improvement.

In many countries and regions, legislation is in place to regulate textile safety as well as the provision of fabric composition and/or care labelling.  There is no similar regulation governing textile industry in Hong Kong.  The Council urges authorities to draw reference from international practice and to devise legislation for textile products to strengthen the protection of Hong Kong consumers’ rights and interests. 

Consumers purchasing school uniforms should take note of the following;

  • Pay attention to the buttons, zippers or other accessories to check if they are sturdy, smooth and without sharp edges;
  • It is advisable to wash new school uniforms once before wear as this helps reduce the chemical residues produced during manufacture;
  • Separately wash white clothing and those with dark colours to prevent colour stain;
  • Avoid the use of bleaching detergent containing chlorine to whiten school uniforms as it may turn the clothing yellowish or damage the fabric fibres. 

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