What follows is an edited version of my most recent essay. References and the full essay can be provided on request.
It is a common practice to use a thin metal core in the centre of a candle wick, to encourage the wick to remain rigid, centred on the candle, to ensure clean (soot-free) and proper burning and to encourage longevity of burn time. Usually zinc, tin or aluminium are used, but occasionally lead is used (CSTEE, 2003). The most common types of candles to use metal cored wicks are container, votive, pillar and tealight candles, particularly those sourced from the Far East. Taper candles do not use metal cored wicks (CSPS, 2003).
The use of lead cored wicks in candles has been explored in several papers and journals in recent years (Van Alphen, 1999; Wasson et al, 2000; Nriagu & Kim, 2000; USEPA, 2001) and has contributed to their banning, both in imports and domestic production, in the United States by the Consumer Product Safety Commission (CSPS) in 2003, in Denmark in 2002 and in Finland (for indoor use) in 2001. There has been a voluntary program in the UK, for British candle producers, since the 1970s (ECED, 2004). There is however no law banning them in the UK and throughout much of Europe and even if most European candle makers do not use lead-cored wicks, there is no way for consumers to find out if they are used in domestically produced candles nor in those imported to the region, as lead testing kits are not readily available.
One company, Abotex, in London, Canada sells the Lead Inspector - a kit for lead testing - and it is this equipment that shall be used to test 19 candles sourced from supermarkets and independent retailers in the Norwich area, to attempt to ascertain the frequency of use of lead cored candle wicks.
The toxicity of lead is well documented. Indeed, in around 25 BCE, the architect Marcus Vitruvius Pollio advised against it's use in water pipes and other elements where it would come into contact with citizens. His warnings were not however heeded and more recently, amongst others Hong et al (1994) suggest that lead poisoning could have contributed to the fall of the Roman empire.
It wasn't until the mid nineteenth century, after centuries of lead use that it's toxic effects began to be accepted and still another century or so before measures were taken to mitigate it's use. The effects of lead poisoning are now well documented and in adults and older children include gastrointestinal discomfort, constipation, anorexia, nausea, fatigue, weakness, personality changes, headache, hearing loss, tremor, lack of coordination and in infants and small children lead poisoning causes irritability, abdominal pain, ataxia, seizures/ loss of consciousness, (chronic) learning deficits hyperactivity and reduced attention span (USEPA, 2001) some of which are irreversible (Nriagu & Kim, 2000) The European Union's maximum safe limit for airborne lead particulates is 2 μg/m³, whilst the World Health Organisation recommends even less at 1.5 μg/m³ (CSTEE, 2003).
In 1999, Van Alphen ignited the debate on lead in candle emissions. His study of candles bought in Adelaide, Australia and manufactured in China found that around twenty per cent of the lead contained in candle wicks was released into the air as a result of combustion in the form of Sodium Lead Carbonate Hydroxide [NaPb(CO)OH]. As this is a lead carbonate, it is readily absorbed through the tissues of the lungs and the gastrointestinal tract. Not only did he find that the airborne lead particulates could be easily inhaled, but also that they would settle on surfaces throughout the house as a fine dust and create a second vector for lead poisoning, particularly for young children who often engage in hand-to-mouth activities. This study suggested that burning one candle in a room for three hours, resulted in average lead in air concentrations of 9.9 μg/m³, with a peak of 42.1 μg/m³, way above any safe levels.
Aidan Luce 0733549
A follow up by Nriagu & Kim (2000), studying candles purchased in Michigan, US, found that lead wicked candles were common in the US as well and recommended legislation to ban their use. This study found that it was principally candles produced in China that contained the most lead and resulted airborne concentrations of lead particulates of between 0.02 μg/m³ and 13.1 μg/m³ after a two hour burn.
In 2002, Wasson et al published another paper on lead in candle emissions, wherein 8% of the candles they purchased were found to contain lead cored wicks, where the wicks themselves were 39-74% lead, the rest being paper or cotton. In all cases, the lead was almost 100% pure. Some candles also contained lead in the coloured coating, although not in large enough concentrations to constitute a health risk by themselves. Wasson et al found that one candle tested, burning for four hours could raise airborne lead concentrations to 19.35 μg/m³ in the source room and 6.37 μg/m³ in the rest of the house. Burning three such candles would raise the levels to 58.06 μg/m³ in the source room and 19.12 μg/m³ in the rest of the house.
As a result of these studies and public pressure, the US CSPS banned outright the production and sale of lead wick candles in 2003. Finland and Denmark had restricted or banned their use and sale in 2001 and 2002 respectively. Slow to respond, the EU published a document through the Scientific Committee on Toxicity, Ecotoxicity and the Environment (CSTEE) on the risks to health from lead wick candles (2003) and in 2004, the European Commission Enterprise Directorate-General (ECED) published another on the risks and benefits of restricting lead use in general, but included an analysis of lead-cored candle wicks. This paper could find no reason not to enforce a ban on the use of lead wicks throughout Europe, but such legislation has still to see the light of day.
According to ECED (2004), the European Association of Candle Makers (AECM) represents 80-90% of European candle manufacture and none of their members uses lead cored wicks in their candles. ECED suggests that any candles with lead cored wicks produced in Europe would be come from east European states. They do warn however that because stricter legislation has been introduced in the US, Canada and Australia and because there are no requirements to declare lead content in candles sold in Europe (and therefore no records or tracking), Far Eastern manufacturers could shift their focus more to these shores and the frequency of lead cored wicks in candles sold within Europe could increase.
There seems to have been no more study of the subject for several years, except for the odd paper which references the ones mentioned herein. Thus it would appear to be necessary to ascertain the amount of lead-cored wicks on sale in the UK and in Europe and hopefully this paper could go some way to revealing this.
This study sampled nineteen candles bought at supermarkets Sainsbury's, Tesco, Asda, Morrison's and Waitrose, as well as some smaller retailers - Neal's Yard, Evolution, Head in the Clouds, Whistlestop (99p Store) and QD.
Tealights and pillar candles were purchased at each store, except Neal's Yard, where only tealights were purchased. Incidentally, Neal's Yard were the only retailer who were able to confirm that their candles did not contain lead-cored wicks. According to their in-house product guide their tealights are aluminium cored. Twelve of the candles did not display a country of origin, three of those that did were European made and hopefully will be lead-free, confirming the ECED study. The rest were of Far Eastern origin, three from China and one from Thailand.
The lead testing kit used, Lead Inspector (US patent #1,256,782) is produced by Abotex and is used by the US Food and Drug Administration (FDA) and Health Canada in lead screening procedures. The active ingredient in the Indicator Solution is Sulphide anions (S--). When mixed with water, reacts with lead cations (Pb++) to produce a distinctive brownish-black color. The chemical equation is as follows: Na2S + H2O + Pb++ > PbS + Na+ + OH- + H2S (Abotex, n.d.)
In each case, a 20mm long length of wick was cleaned and soaked in 4ml of a mild (clear) vinegar liquid for eighteen hours. If any lead were present, molecules would leach into the vinegar. After enough time had passed, 1.5ml of the vinegar was put into a test tube and four drops of the sodium sulphide indicator solution were added. The test tube was agitated. The liquid would change colour if lead was present. The resulting colour would be compared with a colour chart which denotes the approximate concentration of lead in parts per million (ppm) within the vinegar, as follows:
Faint yellowish tint 
1-3 ppm
Light brown 5 ppm
Medium brown 10 ppm
Dark brown 25 ppm
Black Over 50 ppm
A control would have no wick. Equipment used would be rinsed in tap water between tests.
This study did not test the candles for emissions. The previous studies have shown that lead cored candle emissions are harmful and this does not need to be re-examined. The purpose of this study was to discover if the ECED (2004) study was accurate in it's prediction of possible increased frequency of lead-cored candle wicks in Britain (and Europe), to get some idea of the scale of the problem and perhaps to provide a stepping stone to further research.
The leachate from the candle wicks was quite minimal, and as a result only returned results in the 1-3 ppm range. Reading accurately was quite difficult and therefore these results can only be advisory. However, of all the nineteen wicks tested, eleven were found to contain traces of lead This is 57.89% of the candles, quite a substantial share of the sample group. All the identified Far Eastern candles yielded traces of lead and all the candles manufactured in Europe did not. Six of the candles that tested positive were pillar candles and five were tealights.
It would seem that lead cored wicks may be in use an awful lot in the UK and even Europe. With nearly sixty per cent of all candles containing lead, this could present a huge risk to people's health and seriously affect indoor-air quality.
Based on the ECED (2004) figures for candle consumption and this share of the market, in the years 2000 to 2002, nearly 30,000 tonnes of candles sold could have had lead cored wicks. In the EU15, the total would be 270,285 tonnes, but this is unlikely. What is more likely is that the legislation applied in the US, Canada, Australia et al has had the effect of increased sales and consumption of lead-cored wicks in countries where there is no legislation against them, as the ECED (2004) feared. For example, if we assume that Wasson et al's (2002) finding that eight per cent of candles they purchased had lead wicks can be applied to the global market at the time, then we can see that in the intervening five or six years since laws banning lead wick candles came into force, their production has not altered perceptibly, just that all the bad candles are going to fewer customers. ECED (2004) cited Potera (2000) who found that only 3% of 285 candles bought had lead cored wicks, if we make this assumption with this percentile, then the picture becomes even more bleak.
The non-leaded candles could also be fetching higher prices in the countries where they are the only ones which can be sold.
Of course there were limitations in the experiment and the results are by no means conclusive. The test results were ultimately decided at the discretion of the person conducting the experiment. Trying to ascertain a slight yellowish tint in a 5ml plastic test tube, could easily lead to misjudgement and is not as accurate as direct detection of lead, for example through mass spectroscopy or through analysing the candle emissions, but shows that further research needs to be done to ascertain the true extent of the use of lead cored candle wicks in Britain and Europe today.
Despite the fact that the test tube and the sample transfer equipment was washed after each sample was tested, there could be the possibility of cross-contamination spoiling the results.
Considering the results of this experiment, it is advisable to be extremely cautious. ECED (2004) suggested that 53% of Europe's candles come from China. As all our identified Chinese candles contained lead and it is also not unlikely that some of the candles of unknown origin were manufactured there, avoiding Chinese and other Far Eastern made candles is recommended. Because of the uncertainty of source, due to the lack of regulation of the market, it is most advisable to only source your candles from 'safe' sources. Most European manufacturers do not use lead wicks, so you'd decrease you chance of exposure to lead. However, to truly know that you are buying a safe candle, the best source countries would be those that have already banned lead cored candle wicks: US. Canada, Australia; Denmark, Finland or those that can confirm they do not use leaded wicks.