Risk Assessment Studies
Report No. 42

Chemical Hazard Evaluation

Safety of Melamine-ware Available for Use on Local Food Premises

November 2010

Centre for Food Safety
Food and Environmental Hygiene Department
The Government of the Hong Kong Special Administrative Region

Correspondence:
Risk Assessment Section
Centre for Food Safety,
Food and Environmental Hygiene Department,
43/F, Queensway Government Offices,
66 Queensway, Hong Kong.
Email: enquiries@fehd.gov.hk

Table of Contents

Risk Assessment Studies
Report No.42

Safety of Melamine-ware Available for Use on Local Food Premises

Risk Assessment Studies –

Safety of Melamine-ware Available for Use on Local Food Premises

OBJECTIVE

              The study aims to

1. examine the level of melamine and formaldehyde migration from melamine-ware available for use on local food premises, and
2. assess the safety of these melamine-ware.

INTRODUCTION

2.            The safety of food contact materials is a matter of public concern. Since the melamine-milk incident, the public has become more aware of the safety of melamine-made tableware and the Centre for Food Safety (CFS) received some public enquiries concerning the safety of this type of products.

3.            Tableware products made of melamine-formaldehyde resins are generally described as melamine-ware. Due to their strong durability, good chemical and heat resistance and low cost, melamine-ware are widely used around the world. Melamine-ware are made by compression-moulding melamine-formaldehyde resin from powder or granular form. The heat and the pressure of the moulding process cures the resin to provide a thermoset plastic. Residual monomer, however, can remain in the plastic after the manufacture and may migrate into foodstuffs coming into contact with the melamine-ware surface.

4.            Previously, the media reported that a survey on melamine tableware in the Mainland revealed some products had problems of decolouration and leaching out excessive amount of formaldehyde. It was suggested that improper use of tableware might also lead to migration of melamine into the foodstuff. In December 2008, General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China conducted a country-wide survey on all types of melamine-ware sold in major shops and supermarkets in the Mainland and reported that all melamine-ware produced by certified manufacturers were tested satisfactory.

5.            In the UK, a study on melamine-ware conducted by the UK Food Standards Agency (FSA) in 2004 revealed that in all 50 samples tested for migration of melamine from the melamine-ware was within the European Union (EU)'s legal limit of 30 mg/kg. However, the migration of formaldehyde were found to be 8 – 76 times above the EU legal maximum (15 mg/kg) in 5 samples.^1,2 The UK FSA stated that consumers' health might have been at risk. A follow-up study released in August 2008 again reported that in 8 out of 50 samples of melamine-ware tested, the level of formaldehyde migration was 6 – 65 times the EU specified legal maximum migration limit.³

6.            In Hong Kong, the Customs and Excise Department has sampled melamine tableware from the market for testing by the Government Laboratory. The results of the safety test, which was released in February 2009, revealed that the level of formaldehyde migration from one model of melamine ladle was 4.3 times the GB permissible hygienic standard (30 mg per litre) for melamine products used as food containers and tableware in the Mainland China (GB9690-88).⁴ It was not known whether the migration of formaldehyde and melamine from the melamine-ware available for use on local food premises would be a cause of potential safety concern to consumers.

HAZARD IDENTIFICATION

Potential hazard of melamine-ware

7.            The migration of impurities and excessive heavy metals could be a problem for any type of food contact materials. However, the major safety concern of tableware made of melamine-formaldehyde resins is the possible migration of excessive melamine and formaldehyde to food.

8.            Melamine is of low acute toxicity. Data from animal studies show that high levels of melamine would cause bladder and kidney stones.  In 2008, high levels of melamine in infant milk and other milk products have led to kidney damage in Chinese children.

9.            Formaldehyde occurs naturally in the environment and can be found naturally in small amounts in a wide range of raw foods, including fruit and vegetables, meat, fish, crustacean, dairy products, etc. Ingestion of a small amount of formaldehyde is unlikely to cause any acute toxicity. However, ingestion of a large amount of formaldehyde can cause severe abdominal pain, vomiting, coma, renal injury and possible death. Animal studies have shown that long-term exposure to formaldehyde in drinking-water might lead to pathological changes in the stomach and increase in kidney weight. Formaldehyde is a carcinogen by inhalation although sustained exposure to a high concentration of formaldehyde would probably be necessary to cause a potential risk to health.

Regulatory control of melamine food contact materials

10.          In Mainland China, according to the new GB standard established in September 2009 (GB 9690-2009) "Hygienic standard for melamine-formaldehyde products used as food containers and packaging materials", the migration limit for melamine and formaldehyde is 0.2 mg/dm² and 2.5 mg/dm², respectively. ⁵

11.          In the EU, according to the Commission Directive EC No 2002/72, melamine and formaldehyde are approved for use as monomers or additives in plastics with a specific migration limit of 30 mg/kg (5.0 mg/dm2) food for melamine and 15 mg/kg (2.5 mg/dm2) food for formaldehyde.⁶

12.          In the USA, it is specified that the molded melamine-formaldehyde food-contacting articles when extracted with the solvent(s) characterising the type of food in contact and under the conditions as specified in 21 CFR 177, shall yield net chloroform-soluble extracts not to exceed 0.5 mg/in² (~7.8 mg/dm²) of food-contact surface.⁷ However, no specific standards for migration limits of melamine or formaldehyde have been established.

Local situation

13.          Food containers normally supplied for private use or consumption in Hong Kong is controlled under the Consumer Goods Safety Ordinance (CGSO), Cap 456, which is enforced by the Customs and Excise Department while the safety use of utensils/tableware in restaurants is under the ambit of FEHD.

14.          There is no specific regulation governing the safety of utensils /tableware. However, Section 6 of Food Business Regulation, Cap. 132 stipulated that every person who carries on any food business shall at all times ensure that all furniture, articles, equipment and utensils used are kept clean and free from noxious matters and in proper repair and free from cracks or chipping. Furthermore, according to the Preservatives in Food Regulations, Cap. 132 a maximum level of 5 mg formaldehyde per kg of food is allowed, provided that the chemical is from the packaging or containers that are manufactured with formaldehyde-based resins and plastics.

15.          Due to the lack of local data on the level of migration of melamine and formaldehyde from melamine-made tableware available for use on the local food premises, the associated health risk to the local population cannot be assessed. A study is therefore needed to examine the situation in the local scene.

HAZARD CHARACTERISATION

I. MELAMINE

Nature of melamine

16.          Melamine (also known as tripolycyanamide, or 2,4,6-triamino-1,3,5-triazine) is an industrial chemical used for the production of melamine resins, typically by reaction with formaldehyde. Melamine resins or other melamine compounds are used in laminates (e.g. for tabletops), glues, adhesives, molding compounds, coatings, paper (to obtain wet strength), textiles (to obtain shrink resistance, water repellence, stain repellence, fire retardance), flame retardants or superplastisizer for concrete. The end products include countertops, dry erase boards, fabrics, glues, houseware (including kitchen utensils and tableware) and flame retardants.

17.          Melamine is also a major component of pigment yellow 150 (colorant for inks and plastics), fertilizers, derivatives of arsenical drugs for the treatment of African Sleeping Sickness (trypanosomiasis), and a metabolite of the pesticide cyromazine.^8,9,10

18.          Melamine is not allowed in food in any quantity. However, melamine has been found to be illegally used to boost nitrogen levels of food products during protein test. Recent examples include the 2008 melamine milk products incident in Mainland China and the 2004 and 2007 melamine pet foods incident in the USA, Canada and South Africa, causing pathological effects in humans and in pets, respectively. ¹⁵

19.          The structurally related compounds of melamine, namely cyanuric acid, ammelide and ammeline, have raised toxicological concern in the international arena, particularly the possibility of their enhanced toxicity in combination with melamine. Cyanuric acid is a structural analogue of melamine. It may be found as an impurity of melamine. Cyanuric acid is an FDA-accepted component of feed-grade biuret, a ruminant feed additive. It can also be found in swimming pool water as the dissociation product of dichloroisocyanurates used for water disinfection.¹¹

Toxicity of melamine and its structural analogues

20.          The Joint Food and Agriculture Organization (FAO) / World Health Organization (WHO) Expert Committee on Food Additives (JECFA) has not evaluated the safety of melamine and its structural analogues. Little human data on oral exposure to melamine were available before the 2008 outbreak of the infant kidney stone cases in the Mainland. WHO convened an expert meeting in December 2008 to review the toxicological aspects of melamine and cyanuric acid. A tolerable daily intake of 0.2 mg/ kg body weight was established for melamine.

Kinetics and metabolism

21.          Melamine can be degraded by hydrolysis by three successive deamination reactions to ammeline, ammelide and cyanuric acid in bacteria.¹⁰ After oral administration of a single dose of melamine labelled by isotope, 90% of the administered dose was excreted within the first 24 hours into urine in rats. Only slight differences in levels of radioactivity between blood, liver or plasma were observed, suggesting that melamine is distributed in the body water. Radioactivity levels were much higher in the kidney and the bladder compared to plasma. It is considered that bladder levels were highest, probably due to either back diffusion from urine or a contamination of the bladder tissue with urine.¹⁰ However, a study with oral application in rats indicates that melamine is not metabolised and is rapidly eliminated via urine, with an elimination half-life in plasma of about 3 hours.

22.          The rapid clearance from the body shows that melamine and its analogues do not accumulate in mammalian tissues. The US Food and Drug Administration (FDA) in 2007 also considers that melamine is metabolically inactive or inert (i.e. it does not readily undergo any type of metabolic change) and there is a reasonable probability that all monogastric species eliminate the originally ingested substance, melamine or its analogues, and not a metabolite.

23.          A US patent for the use of melamine as a source of non-protein nitrogen for cattle (melamine may be utilizable by the rumen microorganisms) was filed in 1970.⁶ However, a study to determine the effectiveness of melamine as a non-protein nitrogen source for ruminants published in 1978 concluded that melamine may not be an acceptable non-protein nitrogen source for ruminants because melamine may not be hydrolysed in the rumen at a rate sufficient to promote maximum ruminal protein synthesis and the incompletely hydrolysed fractions may be absorbed and voided in the urine.¹² There is no official information to-date that melamine is currently approved for use in animal feed.

Acute toxicity

24.          Melamine is of low acute toxicity. The reported oral median lethal dose (LD50) values were 3100 - 3300 mg/kg of body weight (bw) in rodents.^8,10,11 Melamine produced diuresis and crystalluria (i.e. excretion of crystals in the urine) in rats and dogs given a single oral dose of 2400 mg/kg. Signs of toxicity following lethal doses to mice included lacrimation, dyspnea, intermittent tremors and coma preceding death.

Genotoxicity and carcinogenicity

25.          The International Agency for Research on Cancer (IARC) of the WHO (1999) evaluated the carcinogenicity of melamine and considered that there was inadequate evidence in humans for the carcinogenicity of melamine and there was sufficient evidence in experimental animals for the carcinogenicity of melamine under conditions in which it produces bladder calculi (i.e. stones). IARC classified melamine as Group 3 agent, i.e. not classifiable as to its carcinogenicity to humans.¹³

26.          IARC also noted that melamine was not genotoxic in experimental system and the non-DNA-reactive mechanism by which melamine produced urinary bladder tumours in male rats occurred only under conditions in which calculi were produced.¹³

27.          The European Food Safety Authority (EFSA) in 2007 also considered that melamine is not genotoxic or carcinogenic.¹⁰

Chronic toxicity

28.          The most commonly observed effects in animal experiments where melamine was administered orally include reduced food consumption, body weight loss, bladder stones, crystalluria, epithelial hyperplasia of urinary bladder and lowered survival rate. However, no kidney failure or clinical symptoms of kidney failure were observed. The lowest no-observed-adverse-effect-level (NOAEL) noted in published literature was 63 mg/kg bw/day for stone formation in a 13-week rat study.¹⁴ EFSA considered that melamine is not teratogenic.¹⁰

Observation in Human

29.          With reference to the data from the 2008 Chinese incident, it showed that infant formula contaminated mainly with melamine can result in stone formation if sufficient concentrations are present. Limited data indicate that stones are composed of uric acid and melamine at a molar ratio ranging from 1.2:1 to 2.1:1, without evidence of the presence of cyanuric acid or other melamine analogues.

30.          Most children with stones developed in the urinary tract did not have clinical signs of illness. Overt clinical symptoms only occurred in severe cases of renal failure and/or blockage.

II. FORMALDEHYDE

Nature of formaldehyde

31.          For industrial uses, formaldehyde is produced by catalytic, vapour-phase oxidation of methanol. Formaldehyde is used mainly in the production of phenolic, urea, melamine and polyacetal resins. These materials have wide uses as adhesives and binders for the wood products, pulp and paper, and synthetic vitreous fibre industries and in the production of plastics and coatings as well as in textile finishing. Formaldehyde is often used as preservative in cosmetics. In addition, formaldehyde has been used as a fumigant in wheat and oats, as well as in some other plants and vegetables.^16,17,18

Routes of human exposure

32.          The general population is exposed to formaldehyde during release from combustion (e.g. from cigarettes and cooking) and emission from some building materials. They may also get exposed via the application of consumer products containing formaldehyde as a preservative and the consumption of food containing formaldehyde either naturally or as a preservative. A survey conducted in Canada indicated that daily intake of formaldehyde via ingestion of foodstuffs was consistently higher than via inhalation. Nevertheless, the focus of human health assessment is airborne exposure, due primarily to the lack of representative data on concentration in media other than air and limited data on effects following ingestion.¹⁶

Kinetics and metabolism

33.          Following ingestion, formaldehyde is readily absorbed from the gastrointestinal tract and converted to formate, which is further oxidised to carbon dioxide or incorporated into nucleic acids and amino acids.^17,19 Excretion of formate in the urine is the other major route of elimination of formaldehyde.¹⁶ Formaldehyde also shows dose-dependent toxicity in cell cultures.¹⁸ However, the bioavailability of formaldehyde in various foods following ingestion is not known.¹⁶

Acute toxicity

34.          It has been reported that oral LD50 s of 800 and 260 mg/kg body weight for rats and guinea pigs.¹⁶ Also, there is evidence that formaldehyde can induce irritation to the forestomach in experimental animals after high-dose oral exposure.¹⁸ Human deaths have also been reported after ingestion of 517-624 mg/kg body weight of formaldehyde (in form of formalin containing 37% formaldehyde).¹⁹ Generally speaking, ingestion of large amounts of formaldehyde can cause severe abdominal pain, vomiting, coma, renal injury and possible death.^17,19

Carcinogenicity

35.          The International Agency for Research on Cancer (IARC) re-evaluated the carcinogenicity of formaldehyde in 2004 and considered that there was sufficient evidence for carcinogenicity in both humans and experimental animals. IARC re-classified formaldehyde from Group 2A (probably carcinogenic to humans) to Group 1 (carcinogenic to humans). After reviewing the epidemiological data in humans upon occupational exposure, IARC concluded that:¹⁸

1. there is sufficient epidemiological evidence that formaldehyde causes nasopharyngeal cancer in humans;
2. there is strong but not sufficient evidence for a causal association between leukaemia and occupational exposure to formaldehyde;
3. there is limited epidemiological evidence that formaldehyde causes sinonasal cancer in humans; and
4. there is insufficient epidemiological evidence for a causal role for formaldehyde in relation to other cancers including the oral cavity, oro- and hyophayrynx, pancreas, larynx, lung and brain.

36.          However, it should be noted that IARC's consideration was mainly based on studies of occupational exposures in workers. ¹⁸ In establishing the guideline value for formaldehyde in drinking water, the World Health Organization (WHO) in 2005 considered that the weight of evidence indicates that formaldehyde is not carcinogenic upon ingestion. ²⁰

Genotoxicity

37.          In its evaluation in 2004, IARC considered that formaldehyde is genotoxic in multiple in vitro models and in exposed humans and experimental animals. ¹⁸

Chronic toxicity

38.          Animal studies showed that long-term exposure to formaldehyde in drinking-water might lead to pathological changes in the stomach and increase in kidney weights. ²⁰ There have been epidemiological studies examining the reproductive effects upon occupational exposures to formaldehyde but the results are inconsistent. ¹⁸

Safe reference intakes

Formaldehyde in Foods

RISK ASSESSMENT

Scope of study

Methodology

Sampling

Phase I Study (May – October 2009)

Phase II Study (October 2009 – February 2010)

Laboratory analysis

RESULTS

56.          A total of 61 samples from 7 categories of melamine-made tableware covering 9 brands were sampled and analysed. Detailed records of the individual results of melamine migration and formaldehyde migration are presented in Annex II and Annex III, respectively. Tables 1, 2, and 3 summarize the study results according to various categories, brands and sources of melamine-ware samples obtained, respectively. The overall mean level of melamine migration from melamine-ware (LOQ = 0.003 mg/dm²) was 0.027 mg/dm² (range: ND – 0.190 mg/dm²) under the GB test and 0.050 mg/dm² (range: ND – 0.280 mg/dm²) under the EU test. The overall mean level of formaldehyde migration from melamine-ware (LOQ = 0.044 mg/dm²) was 0.090 mg/dm² (range: ND – 0.407 mg/dm²) under the GB test and 0.217 mg/dm² (range: ND – 0.750 mg/dm²) under the EU test.

Table 1: Migration of melamine and formaldehyde from various categories of melamine-ware samples

Number in bracket ( ) denotes the number of melamine-ware samples.
ND: not detected; i.e. level of melamine < 0.003 mg/dm² or level of formaldehyde < 0.044 mg/dm².
The value of 1/2 LOQ was assigned to non-detects (results below LOQ) for the calculation of mean levels.

Table 2: Migration of melamine and formaldehyde from various brands of melamine-ware samples

Number in bracket ( ) denotes the number of melamine-ware samples.
ND: not detected; i.e. level of melamine < 0.003 mg/dm² or level of formaldehyde < 0.044 mg/dm².
The value of 1/2 LOQ was assigned to non-detects (results below LOQ) for the calculation of mean levels.

Table 3: Migration of melamine and formaldehyde from melamine-ware samples obtained from various sources

Number in bracket ( ) denotes the number of melamine-ware samples.
ND: not detected; i.e. level of melamine < 0.003 mg/dm² or level of formaldehyde < 0.044 mg/dm².
The value of 1/2 LOQ was assigned to non-detects (results below LOQ) for the calculation of mean levels.

DISCUSSION

58.          In this study, according to the GB and EU testing methods, sample analysis needs to be carried out on new unused melamine-ware for the purpose of standardisation which would best reflect the quality of the melamine-ware under test.

Table 4: GB and EU limits for migration of melamine and formaldehyde

61.          The low levels of migration of melamine and formaldehyde detected in all melamine-ware samples tested in this study under the worst-case scenario indicate that these melamine-ware samples are not expected to pose health concern to consumers under normal food use.

62.          The levels of migration of melamine and formaldehyde measured in this study (melamine migration: ND – 0.280 mg/dm²; formaldehyde migration: ND – 0.750 mg/dm², under the EU test) were much lower compared to those reported in the UKFSA studies conducted in 2004 and 2008. In the 2004 UKFSA study, the reported melamine and formaldehyde migration ranged from 0.051 – 0.90 mg/dm² and 0.055 – 190 mg/dm², respectively. In the UK studies, for the 13 samples that showed formaldehyde migration level exceeding the EU limit (5/50 samples in 2004 study and 8/50 in 2008 study), Turkey was the country of origin for one sample, China for two samples and the country of origin was not given for the remaining 10 samples. No samples of the brands of the non-compliant samples in the UK studies were available for this study.

LIMITATIONS

CONCLUSION AND RECOMMENDATIONS

67.          This study investigated the levels of migration of melamine and formaldehyde from commonly used melamine-ware categories of brands available for use on local food premises. The study results show that even under experimental conditions that simulate the worse-case scenario, all melamine-ware samples tested had low levels of migration of melamine and formaldehyde which were well below the GB and EU specified migration limits, indicating that all melamine-ware samples tested were of the quality suitable for food use. Based on the satisfactory analytical results, the melamine-ware samples tested are not expected to pose health concern to consumers under normal food use. There is no cause for alarm.

68.          It is noted that instructions on the recommended conditions of use of the melamine-ware are often specified on the package or provided at the manufacturer's company website. Most manufacturers specify a temperature of -30 ^oC to +120 ^oC while some specify a temperature of up to +140 ^oC. General instructions for safe use include not to use the melamine-ware for cooking, holding hot oil or highly acidic foods, and in particular, not to use melamine-ware for heating in microwave or conventional oven. Based on the product information provided by the manufacturers, the following recommendations on the safe use of melamine-ware are formulated.

General Advice for Using Melamine-ware

• Use melamine-ware according to product specifications and instructions.
• Do not use melamine-ware that is broken or damaged on its surface
• Do not heat or cook foods in melamine-ware.
• Do not use melamine-ware in microwave oven or conventional oven.
• Do not use melamine-ware to hold hot oil or highly acidic foods.
• If melamine-ware is to be used for holding hot deep-fried foods, cool the foods down before putting in the melamine-ware.
• For cleaning, do not use abrasive detergent and cleaning tools or strong chemicals which will damage the surface.

Advice to Food Businesses

• Restaurants and food businesses should obtain melamine-ware from reliable manufacturers and suppliers and use melamine-ware of suitable quality to serve food to customers.
• Use melamine-ware according to the product specifications and instructions.

Advice to Manufacturers and Suppliers

• Manufacturers should adopt good manufacturing practices in making melamine-ware for food use.
Manufacturers are advised to provide instructions on its intended use.
• Suppliers should obtain melamine-ware products from reliable manufacturers and ensure the products are of suitable quality for food use.

REFERENCES

1 UK FSA. Chemicals used in plastic materials and articles in contact with food: Compliance with statutory limits on composition and migration –year 2. London: May 2004. Available from: URL: http://www.food.gov.uk/multimedia/pdfs/monomerssurvey.pdf

2 Bradley EL et al. (2005). Survey of the migration of melamine and formaldehyde from melamine food contact articles available on the UK market. Food Addit. Contam. 22(6): 597 – 606

3 UK FSA. Surveys on chemical migrants from food contact materials and articles and formaldehyde from melamine-ware. London: August 2008. Available from: URL:
http://www.food.gov.uk/science/surveillance/fsisbranch2008/chemicalmigration

4 GB 9690-88: Hygienic standard for melamine products used as food containers and tableware. 中華人民共和國國家標準 《食品包裝用三聚氰胺成型品衛生標準》

5 GB 9690-2009: Hygienic standard for melamine-formaldehyde products used as food containers and packaging materials. 中華人民共和國國家標準 《食品容器、包裝材料用三聚氰胺-甲醛成型品衛生標準》

6 EC. Commission Directive 2002/72 of 6 August 2002 relating to plastic and articles intended to come into contact with foodstuffs. L.220/18. 15.8.2002. Available from: URL:
http://faolex.fao.org/docs/pdf/eur34651.pdf

7 US Code of Federal Regulations, 21 CFR 177, as of 1 April, 2003. Available from: URL: http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfCFR/CFRSearch.cfm?CFRPart=177

8 OECD. Melamine – OECD Screening Information Data Set (SIDS) for High Production Volume Chemicals. UNEP; June 2002. Available from: URL: http://www.inchem.org/documents/sids/sids/108781.pdf

9 US National Library of Medicine. Melamine: Hazardous Substances Data Bank. In: Toxicology Data Network (Toxnet). Bethesda; US National Library of Medicine. Available from: URL: http://toxnet.nlm.nih.gov

10 EFSA. EFSA's provisional statement on a request from the European Commission related to melamine and structurally related compounds such as cyanuric acid in protein-rich ingredients used for feed and food. Parma; 7 June 2007. Available from: URL: http://www.efsa.eu.int/cs/BlobServer/Statement/efsa_statement_melamine_en_rev1.pdf?ssbin ary=true

11 WHO. Melamine and Cyanuric acid: Toxicity, Preliminary Risk Assessment and Guidance on Levels in Food. Geneva: WHO; 25 September 2008, updated 30 October 2008. Available from: URL: http://www.who.int/foodsafety/fs_management/Melamine.pdf

12 Newton GL and Utley PR. Melamine as a dietary nitrogen source for ruminants. 1978. Journal of Animal Science; 47:1338-1344.

13 IARC. Summaries and evaluation - Melamine. Lyon: IARC; 1999. Available from: URL: http://monographs.iarc.fr/ENG/Monographs/vol73/volume73.pdf

14 US FDA. Interim Melamine and Analogues Safety / Risk Assessment. College Park; FDA; 25 May 2007.

15 WHO. Expert meeting to review toxicological aspects of melamine and cyanuric acid – In collaboration with FAO and supported by Health Canada. Ottawa Canada, 1-4 December 2008. Available from: URL: http://www.who.int/foodsafety/fs_management/conclusions_recommendations.pdf

16 International Programme on Chemical Safety. Concise International chemical Assessment Document 40: Formaldehyde. Geneva: World Health Organization; 2002. Available from: URL: http://www.inchem.org/documents/cicads/cicads/cicad40.htm

17 International Programme on Chemical Safety. Environmental Health Criteria 89: Formaldehyde. Geneva: World Health Organization; 1989. Available from: URL: http://www.inchem.org/documents/ehc/ehc/ehc89.htm

18 International Agency for Research on Cancer. Formaldehyde – Monograph Vol. 88. Lyon: IARC; 2004

19 Agency for Toxic Substances and Disease Registry. Toxicological profile for formaldehyde. Atlanta: ATSDR; July 1999. Available from: URL:
http://www.atsdr.cdc.gov/toxprofiles/tp.asp?id=220&tid=39

20 World Health Organization. Formaldehyde in Drinking-water: Background document for the development of WHO Guidelines for Drinking-water Quality. Geneva: WHO; 2005.

21 Agency for Toxic Substances and Disease Registry. Minimum risk levels for hazardous substances. Atlanta: ATSDR; December 2009. Available from: URL:
http://www.atsdr.cdc.gov/mrls/mrllist.asp#39tag

22 Lagace L., Guay S. and Martin N. Level of endogenous formaldehyde in maple syrup as determined by spectrofluorimetry. Journal of AOAC International 2003; 86(3): 598-601

23 Canadian Food Inspection Agency. Fish Products Standards and Methods Manual – Approved therapeutics for aquaculture use. Ottawa: CFIA; 2003.

24 EN 13130-1:2004 Materials and articles in contact with foodstuffs - Plastics substances subject to limitation - Part 1: Guide to test methods for the specific migration of substances from plastics to foods and food simulants and the determination of substances in plastics and the selection of conditions of exposure to food simulants.

25 EC. Commission Directive of 18 October 1982 laying down the rules for testing migration of the constituents of plastic materials and articles intended to come into contact with foodstuffs (82/711/EEC).

Annex I

Reference standards

Annex II

Level of melamine migration from melamine-ware samples

Note:

ND: not detected; i.e. level of melamine < 0.003 mg/dm² or level of formaldehyde < 0.044 mg/dm².
The value of 1/2 LOQ was assigned to non-detects (results below LOQ) for the calculation of mean levels.

Annex III

Level of formaldehyde migration from melamine-ware samples

Note:

ND: not detected; i.e. level of melamine < 0.003 mg/dm² or level of formaldehyde < 0.044 mg/dm².
The value of 1/2 LOQ was assigned to non-detects (results below LOQ) for the calculation of mean levels.