This morning Howard Oakley submitted a 22-page document to the European Chemicals Agency, his comments to the proposal to ban cadmium pigments in artists’ paints.
We are publishing his comments in their entirety because they are so thorough and well thought out and we hope they add to the discussion about the proposed restrictions of cadmium pigments in artists’ paints. Parts of it are quite technical but he writes in an understandable way and I found I was able to understand most of it. It is long, but there is a summary at the top.
Howard says: “Hopefully it will help the chemists see a little sense and proportion.”
Howard Oakley has recently retired after 35 years as a medical practitioner specialised in environmental and thermal medicine, and has been an enthusiastic painter since childhood. Although he has never been a toxicologist, his medical practice has been concerned with risk and health promotion, and he spent three years working to develop and improve European Standards for Personal Protective Equipment. He declares no conflict of interest beyond his personal love of painting, and appreciation of the value of cadmium pigments in artists’ paints. He has no association with any art supply industry other than as an all-too-frequent customer. These comments have been prepared personally by Dr Oakley, and have not been provided to any other persons or agencies until after they have been supplied to ECA. 30 June 2014.
I have included two paintings by Howard Oakley in this article.
They include just touches of cadmium colours, the bright reds and yellows.
Lac Besson – one of the lakes above Alpe d’Huez, near Grenoble, French Alps, painted from photos and a plein air pastel study, egg-oil tempera on Daler Langton watercolour board, 10 x 14 inches (25 x 36 cm), 2009.
Carisbrooke Chapel – the Chapel at Carisbrooke Castle, Isle of Wight, painted plein air (I think I must be the only plein air egg tempera painter around!), egg-oil tempera on Schoellershammer 4G line & wash board, HP surface, 10 x 14 inch (25 x 36 cm), 18 October 2009.
Comments to Annex XV Restriction Report
Proposal for a Restriction Cadmium and its compounds in Artists’ Paints
by Edward Howard Nigel Oakley
These comments to the proposal for restriction of cadmium pigments in artists’ paints highlight several problems with the arguments put in that proposal. These include:
1. The lower LOAEL values of 1 or 2 (or even 0.5) μg cadmium/g creatinine in urine proposed have methodological issues, are significantly below those published in more recent large studies in Europe, and are at variance with those proposed by other international bodies. They should therefore not be used in this risk assessment until those issues have been resolved.
2. Current estimates of the release of cadmium into waste water from artists’ paints are no more than educated guesses, but are critical to the whole proposal. In the absence of any valid and representative measurements, they are unsound and should not be used.
3. Even if the estimates of release of cadmium into waste water from artists’ paints were accurate, under the mechanism proposed in the report the contribution of that release represents a negligible proportion of the total dietary intake, such that the claimed benefits to health would take an impractically long period to develop, and even after 100 years would be so small as to be unmeasurable if or when achieved.
4. Alternatives currently available to artists are poor substitutes which have significant shortcomings in their properties that would affect the work of many artists. Already adjustments have occurred: market sectors which are more sensitive to price and less concerned with properties such as permanence are changing to alternatives. But those who continue to use cadmium pigments ill be unable to find good substitutes. No consideration is made of the high cost of the development of better substitutes, nor the risk that they may not be found.
5. No serious attempt has been made across Europe to alert artists to the consequences of releasing cadmium into waste water, and no educational campaign has been attempted to improve artists’ practices so as to reduce such release. The report does not evaluate such alternative approaches.
6. Any attempt to impose a restriction could readily result in significant evasion by many individuals, because effective enforcement of a ban on private imports would not be feasible.
7. Considerations of the impact of restriction are purely economic; the great cultural loss which would have important social impact is not assessed.
Taken together these undermine the rationale for the proposal, and I therefore urge rejection of the proposal for restriction. In its place, I suggest measures which hould prove more effective in terms of outcome, including:
1. Multi-centre measurements of the release by artists of cadmium and some other toxic substances to waste water should be made.
2. Techniques to reduce the release of cadmium and other toxic substances from artists’ paints should be developed, and promulgated by education of and engagement (rather than confrontation) with artists.
3. A programme to reduce the release of cadmium from artists’ paints should be integrated proportionately into overall measures aimed at reducing cadmium release.
4. The study of health effects of dietary cadmium intake and strategies to reduce dietary cadmium intake should be co-ordinated throughout Europe, as health improvement measures.
Introduction and general comments
The report establishes a sound intention, which is to reduce unintended release of cadmium compounds into waste water by artists using paints containing cadmium pigments, so as to limit transfer of cadmium into food products, thereby helping reduce human dietary cadmium intake, and bring potential health benefits by reducing the risk of bone fractures and of breast cancers.
Although I intend no criticism at all of that intention, and of the admirable aims of the proposal, there are several serious weaknesses in the evidence put in the report, and of any benefits that might accrue if the proposal is accepted. Whilst I believe that there is clearly improvement which must be made in such inadvertent release of cadmium compounds into waste water, I consider that the adverse effects of any restriction would be considerably worse than envisaged in the report, and the potential benefits to human health – which are already miniscule at best, according to the report – are so small as to be both unmeasurable and insignificant. Accordingly I urge the rejection of the proposal for restriction.
However such a rejection alone would not make any progress in reducing cadmium release into waste water. Instead I urge all agencies to develop programmes of work to educate artists, to provide better processes for concentrations of artists in schools and other educational organisations, and by other means to reduce the release of cadmium.
I also draw attention to the fact that, to a degree, the intention of the proposal has already been achieved voluntarily by the arts supply industry: in part because of the increasing cost of cadmium-based pigments, and in part because of the increasing awareness of the environmental and health hazards of cadmium, most ranges of artists’ paints offered for sale in Europe do not contain cadmium pigments any more. For the remainder of my comments, I refer by section to the report.
My comments to this section arise from those on other later sections, for instance expressing doubt over the claims made in A.2 and A.3 as to the effects of any such restriction, and as to its benefit. I also and most importantly consider that the proposed restriction is not the most appropriate Union-wide measure (A.3.3), as detailed below.
B. Information on hazard and risk
It is generally stated that approximately 10% or 11% of world cadmium consumption is for the production of pigments. However that figure alone does not distinguish those pigments destined for use in fine art painting, i.e. in artists’ paints. I have been unable to obtain any estimate of the proportion of cadmium pigments that are used in artists’ paints, but it is generally held that this is a very small proportion of the total pigment use of cadmium. I believe that artists’ paints account for much less than 10% of the total use in pigments, and suspect that it may be as little as 1% or 2%. Thus the proportion of total cadmium consumption for pigments used by artists’ paints is almost certainly much less than 1%.
The statement (p 13) that cadmium-sulphide based pigments appeared prominently in the paintings of Vincent van Gogh in the late 1800s is not correct. Considerable research has been undertaken on the composition of the paints used by van Gogh, and he, as with most artists of the 19th century, made very little use of cadmium pigments. Most of the stunning yellows that appear in his most famous paintings were in fact accomplished using chrome yellow (Geldof & Megens 2013, Geldof et al. 2013), which unfortunately discolours with age and has posed major problems for conservation.
However among the more famous artists who are thought to have used cadmium pigments in some of their paintings are: Camille Pissarro (seldom), Lucien Pissarro, Vincent van Gogh (seldom), Claude Monet (from about 1880), Paul Gauguin (from about 1896), Paul Cézanne (sometimes), Salvador Dalí, René Magritte, Joan Miró, Max Ernst, Robert Delaunay, Umberto Boccioni, Eugène Delacroix, and Francis Bacon.
The reason widely given for the early unpopularity of cadmium-based paints is their high cost relative to alternatives. For example, Bomford et al. (1990) state that little use of cadmium-based yellow paints was made by the Impressionists in the 1870s because of their high cost relative to competitive colours. Currently the discounted retail cost (Jackson’s 2014) of a typical cadmium yellow oil paint is £0.304 per ml, whilst a non-cadmium yellow oil paint from the same professional range costs £0.157 per ml (52% of the cost of the cadmium), and a non-cadmium yellow from a range aimed at students and amateurs costs £0.078 per ml (26% of the cost of the cadmium). This, and the issues detailed below, accounts for the very low proportion of artists’ paints sold which contain cadmium: the report (p 15) gives estimates of 33-44 tons per year of a total 7 700-11 000 tons per year, approximately 0.4%.
B.5.6 Repeated dosed toxicity
The lower LOAEL values of 1 or 2 μg Cd/g creatinine in urine preferred by EFSA and the Swedish Chemicals Agency must be considered at present to be proposals which lack solid evidence, and until such time as they are more widely accepted, I believe that it is unwise to use them for such a risk assessment.
The meta-analysis cited (EFSA 2009b) and detailed fully in EFSA (2009a) is extensive, covering 54 studies using renal biomarkers, of which most (35) used ß2- MG, which is generally recognised as the most relevant biomarker for the adverse effects of cadmium in this context. However reported values which the authors considered to be outliers were in several cases adjusted and kept in the metaanalysis, rather than rejected. No assessment of the effects of such adjustments was made, although best practice in meta-analysis is to determine the sensitivity of the overall outcome to the inclusion and exclusion of outliers, rather than to attempt to correct them without the explicit involvement of the original authors (Cochrane Collaboration 2002).
A more recent study of 599 workers in Belgium (Chaumont et al. 2011), using both ß2-MG and RBPU biomarkers, determined a BMDL5 (equated to a NOAEL) between 5.5 and 6.6 μg cadmium/g creatinine. The figures in EFSA 2009a (Figures 6 to 9, 11 to 15, 17, 20 to 24) and 2009b (Figures 12 to 14 and 17) clearly show a horizontal (or near-horizontal) line to a breakpoint with a urinary cadmium concentration of approximately 5 μg cadmium/g creatinine, e.g. Table 11 gives an estimate for the breakpoint of 5.24 μg cadmium/g creatinine, with a 95% confidence interval of 4.94– 5.57. Table 19 offers a range of BMD and BMDL estimates based on the focus population from 4.65 to 5.81 (statistical cut-offs) for additional risks of 5% and 10% which similarly appear consistent with other values given and the data displayed in the figures. However, after rejecting the need for any ‘adjustment factor’ to extrapolate from animals to humans, an adjustment factor of 3.9 is then applied, which is “specific to this meta-analysis”. This “factor is valid only for median BMDs (not for BMDLs)” but is then applied to show “that an internal dose of 1 μg/g creatinine of urinary cadmium would preserve at least 95% of European population under cut-offs from the range 100–300 μg/g creatinine of ß2-MG in urine.”
There is an obvious paradox that such an adjustment is applied when performing a meta-analysis, the whole purpose of which is to pool the results of a large number of studies each on a substantial population, thereby reducing the influence of individual variability on its conclusions. Indeed, WHO (2005) states that “the default subfactors for toxicokinetics or toxicodynamics for human variability could be replaced by data that defined the variability in the relevant parameter estimates in healthy human adults, including the influence of any functional genetic polymorphism, as well as the variations between different potentially susceptible subgroups as appropriate.” That would appear to be precisely what the meta-analysis performed, making the additional application of a CSAF a duplication. Although WHO (2005) gives a series of examples using single studies with small numbers of subjects/participants, it does not address the applicability of factors in substantial meta-analyses, nor does it illustrate it.
I consider that as the strength of the meta-analysis is gained by the number and range of different studies which contributed data to it, the overall conclusion is then made unnecessarily more conservative than the conclusions of those studies, by the application of this ‘chemical-specific adjustment factor’ (CSAF, EFSA 2009b p 98). This is particularly relevant here as, without the correction, the LOAEL of 5 μg cadmium/g creatinine of the EU RAR (ECB 2007) is very close to the BMDL5 of 4 μg cadmium/g creatinine reported in EFSA (2009a) and (2009b), and the range of 5.5 to 6.6 μg cadmium/g creatinine found by Chaumont et al. (2011). Yet another adjustment by a different “uncertainty factor” is then used to reduce a later BMDL10 of 2.81 μg cadmium/g creatinine to fit the proposed reference point of 1 μg cadmium/ g creatinine (EFSA 2009b p 100).
In the face of a different approach adopted by JECFA to arrive at its more liberal recommendation for PTMI of cadmium, EFSA (2011) maintained its much lower PTWI based on EFSA (2009b). It is remarkable that JECFA selected a break point value of 5.24 (95% confidence interval 4.94–5.57) μg cadmium/g creatinine in urine as its RP, as given in Table 11 of EFSA (2009a). JECFA then adopted a different and novel approach which appears to have even less of a track record in meta-analysis. There does not appear to be a robust method for deriving such results from metaanalyses which is generally accepted, casting doubt on the validity of those adopted by both EFSA and JECFA. As recommended by EFSA (2011) “the use of probabilistic approaches to model variability and uncertainties in risk characterisation needs to be further developed.”
That same meta-analysis (EFSA 2009a) found insufficient good studies of the relationship between urinary Cd levels and osteoporosis to perform a similar metaanalysis for that outcome (EFSA 2009a p 13). However the report bases its risk assessments on the relatively under-researched risks of osteoporosis and breast cancer, which remain controversial and in need of additional good research. It is also notable that 3 of the 8 the studies cited in EFSA (2009b) were on Swedish populations, as were both the more recent studies in SCA (2013): overreliance on single populations such as this is a sure way to arrive at incorrect risk assessments. Those dangers should be apparent from the notes at the foot of Table 4 (p 31), that women with a high dietary exposure to cadmium generally eat “somewhat more nutritious food” than those with lower dietary exposures to cadmium. Across Europe such differences, for example in populations with high intake of seafoods, against those with hardly any fish or shellfish in their diet, are major confounding variables which must be taken into account before conclusions can be applied to European populations.
Indeed the report uses the currently weak and controversial evidence on those to try to justify an even lower LOAEL of 0.5 μg cadmium/g creatinine, which its own meta analysis failed to support (p 27). There appears to be serious statistical perversity in trying to make a case for any LOAEL below 4 μg cadmium/g creatinine on the current evidence.
There are currently insufficient studies for a meaningful meta-analysis: the report (p37) cites a meta-analysis of only 4 studies, which is insufficient, and classification of cadmium as a carcinogen is based on its propensity to result in increased risk of lung cancer in those subject to higher, occupational exposures. I return to consider this in B.11.2 below. The conclusion that the concern is raised is supported, and appears appropriate. However the use of a tentative LOAEL for such effects is at this stage quite inappropriate.
B.5.11 Derivation of DNEL(s)/DMEL(s)
The comments above make the low level proposed here inappropriate.
B.9.3 User Scenario – Release from usage of artists’ paints
Despite clear and at times emotively-expressed concerns in many Swedish sources over the last 15 years, there does not appear to have been any robust quantitative assessment of the release of cadmium salts into waste water by artists. The few studies cited in the report were undertaken using non-quantitative subjective assessments, as part of undergraduate educational studies. None was performed by a qualified researcher, using quantitative techniques of known accuracy and error, and none has been published in the open scientific literature.
The five studies cited – in chronological order and giving the correct citations, Svanberg (1998), Printsmann (1999), Broman (2000) (cited in the report as Enskog 2000), Mimovic & Hammarlund (cited in the report as Hammarlund and Mimovic) (2005), and Weiss (2006) – cross-refer and ultimately are based on several assumptions which are claimed to be “reasonable”, although no reason in fact is given. Key among those assumptions, and repeated in the report, are that 10% of of the cadmium reaching wastewater treatment plants serving Stockholm originates from artists’ paints, and that 1.8-2.2 (Weiss 2006) or 3.5 (Broman 2000) kg cadmium reaching those plants each year originates from artists’ paints. Although treated by the report as factually-based conclusions of those five studies, careful reading of the references cited shows that these were either a priori assumptions or were derived from a priori assumptions without any significant measurements being made.
For example, Annex 6 to Broman (2000) makes clear the evidence used, stating: “Enligt Phillippe Thibalt på ColArt så säljer de konstnärsfärger med totalt 150 kg admium varje år. 30-40 % av deras försäljning är i Stockholm och de uppskattar sin marknadsandel I Stockholm till 70-80 %. I beräkningen antas att 5 % av färgen hamnar i avloppet. Medelvärdet för kadmiummängden som totalt säljs i Stockholm blir ca 70 kg. 5% av detta är 3,5 kg vilket motsvarar ca 10 % av totala kadmiummängden in till reningsverken.”
My rough translation to English renders this as: “According to Phillippe Thibalt of ColArt that company sells artist paints with a total of 150 kg of cadmium per year. 30-40% of their sales are in Stockholm and he estimates its market share in Stockholm to be 70-80%. In the calculation it is assumed that 5% of the paint ends up in the sewer. The mean amount of cadmium in total sold in Stockholm is about 70 kg. 5% of this is 3.5 kg, representing about 10% of the total amount of cadmium in the waste water treatment plants.”
It was assumed in the study by Risk & Policy Analysts Limited (2000) that “5% of cadmium used by artists finds its way into the sewer as a result of brush washing, etc.” No justification was made for that assumption other than (in Figure 4.3 of that report) that it came from “discussions with CEPE”, but the figure of 5% seems to have been inherited without further question by these more recent studies.
It is also very worrying that these weak and insubstantial data are derived from studies on a single Swedish city, Stockholm, which has a relatively high number of art students for its relatively low population, and could I think fairly be described as rather more affluent than most other European cities. No evidence is offered that the conclusions drawn from Stockholm are applicable to other cities across Europe, although many will surely have far smaller proportions of art students, and most of their art students are not be able to afford to buy artists’ quality paints containing cadmium pigments, even if they wished to.
Swedish studies that have attempted a more objective and quantitative approach to tracing the origin of cadmium in waste water, such as Carlsson (2005) for Örebro (sixth largest city in Sweden, population 140,000), who used the passive measuring instrument Ecoscope placed in sewers, have reported the highest concentrations of cadmium in waste water originating from industrial estates. Although some of the activities on those estates were recognised as being likely to discharge cadmium into waste water, in many cases the source was not obvious, but could hardly have been from artists’ paints. This suggests that much more work is necessary to understand which industrial activities are responsible for much of the cadmium in waste water, and that some previously innocent activities may turn out to be substantial sources of cadmium release. Until understanding has been improved by careful quantitative studies of different areas, it would appear premature to make any assumptions about cadmium release across Europe.
In contrast Johnsson (2011), also relying on estimates in her assessment of cadmium release into waste water in northern Stockholm, gives an annual release of 77 g from artists’ studios out of a total of 9166 g cadmium. That is 0.8% of the total cadmium load at the treatment plant in Käppala, the same plant studied by Mimovic & Hammarlund (2005). Curiously the report does not consider her more recent work, nor whether it might support a marked reduction in cadmium use among artists in more recent years, as I suggest here.
Surprisingly, given that lack of evidence, the report rejects the default worst case release factor used by the CSRs (1%), and does not use that in the report, preferring to assume a release to waste water of 5% of paint used, as first suggested by Risk & Policy Analysts Limited (2000) without any measurement evidence. I do not consider that, at present, there is an estimate of the release to waste water that is any more reliable than an educated guess. This casts great doubt over all subsequent calculations made in the report, in particular the claimed benefits of any restriction. I consider that this is the single weakest link in the case for restriction made in the report, and that it alone is sufficiently weak as to render the case unscientific and untenable.
B.22.214.171.124 Indirect exposure of humans via the environment
The calculations made here are based on the underlying assumption, which is not stated explicitly, that all artists’ paints sold are consumed, in the sense that they are emptied from their tubes and either applied to paintings or lost in waste. For example, I currently have three complete sets of oil paints (one for high-quality studio work, one for painting outdoors, and one consisting of alkyd paints). There is a total of 814 ml of cadmium-based oil paints in those, of which I have actually used approximately 10 ml in the last 5 years. Although I have 4 sets of watercolour paints, none of those many pans or tubes contains a single cadmium-based paint.
Many, if not most, artists hold a stock of paints that is considerably greater than that used by them over a year. Usage varies greatly by the type of paint, the style of the artist, the genres or types of work (portraits, landscape, etc.) painted, and in different individual works. I am not aware of many studies that cast any useful light on the consumption of paints by amateur or professional artists, but one (Russell 2010) has recently been completed as part of a PhD thesis. Russell examined the documentary records of paint purchases made by a popular and prominent oil painter, Francis Bacon, over the 14 years from 1976 to 1980. Although this still does not give direct estimates of his usage (or, even better, wastage to waste water) of cadmium-based paint, it perhaps gives better insight than the unrealistic assumptions inherent in the report.
Over those 14 years, Francis Bacon purchased 1813 ml of titanium white, 1110 ml of lamp black, 962 ml of permanent rose (a red which does not contain cadmium), but a total of only 185 ml of colours using cadmium as the pigment. Making the assumption that he used as much as he purchased, his total annual consumption of cadmium-containing paints was therefore 13 ml per year, over a period in which he painted regularly as a full-time professional. Using the average contents given in Table 16 of the report (and allowing for the fact that 3 of the tubes of cadmium paint that he bought were not oils but acrylics), he therefore consumed approximately 3.6 g cadmium in pigments per year. Even assuming that 5% of that went to waste water (which I consider to be incorrect, see above and below), his average annual release to waste water would have amounted to no more than 180 mg. In contrast, using the assumptions of Weiss (2006), he would have been expected to have released 960 mg per year of cadmium to waste water.
Furthermore Table 17 (p 48) makes the assumption that the proportion of each paint type that is lost to waste water is the same. Given the major differences in the way that different types of paint (known to artists as different media) are used, and differences in cleaning practices between them, that assumption is not valid, and any calculations based on it are also invalid.
Most oil paints sold in Europe are not ‘water miscible’ (i.e. emulsions of oil and pigment in water), but are based on vegetable oils, the most common of which remains linseed oil. It is not possible to clean those traditional oil paints using aqueous media, but organic solvents such as turpentine or other less hazardous mineral spirits must be used. Whilst in the past some artists may have casually discarded used solvents into waste water, increasing environmental awareness and education have steadily changed that practice, and artists now avoid discharging any waste from cleaning of oil paints into waste water. It is possible that very small amounts may still be released, for example when cleaning small residues from the skin or clothes.
Another confounding factor which makes the assumptions underlying the figures in Table 17 unreliable is the differential use of cadmium pigments according to medium. Painters in oils or acrylics normally work with a range of transparent and opaque paints, according to the precise manner in which that particular section of the painting is being worked. Paints which contain cadmium pigments are largely opaque, irrespective of their type or medium. Colours such as yellow may be required in a transparent paint, for example to apply a thin transparent layer of colour (a ‘glaze’), or in opaque form, for example to paint a yellow building on the background of a green field. Because of their opacity, cadmium-based paints are of very limited use in glazes, but greatly preferred for opaque work.
Painters in watercolour are much more likely to use an ‘English technique’, in which the colours that they use are all, or almost all, transparent, to allow the bright white of the underlying paper to make the painting appear colourful and lively. Thus for most artists who use watercolours, cadmium-based paints are little used, because of their opacity. That is not true of gouache paints, which are generally opaque and cannot be used with ‘English technique’.
Ironically, in recent years, particularly in art schools and other educational uses of artists’ paint, there has been a move away from the use of oil paints, with their complicated health and safety issues involving exposure to organic solvents, to acrylic paints. Whilst all responsible oil painters now should be following best practice in the disposal of waste paint almost entirely in solid waste, acrylics use water as their solvent and practices commonly involve frequent washing of brushes to waste water. Accordingly a move to try to address potential health and safety concerns has probably inadvertently increased the release of cadmium to waste water.
I therefore consider that the use of simple market share to estimate the quantity of cadmium sold by medium (‘type of colour’) in Table 17 is not valid. I think that it is much more likely that the overwhelming majority of cadmium-based paints used are oils or acrylics. Thus the quantities of cadmium given per year (the last column of Table 17) overestimate the amount from watercolours, and underestimate those from oils and acrylics. This is particularly important in view of my comments above on cleaning practices for oil paints, as I believe that in conjunction with the low release from oil paints to waste water, it leads to a substantial overestimate of the total release of cadmium per year from artists’ oil paints. Coupled with the other factors given above, I believe that the effect is to further reduce the effective proportion of cadmium released to waste water, and that the total of 0.43 tpa given at the top of page 49 of the report could easily be incorrect by an order of magnitude, thus that the actual cadmium release to waste water could be as little as 0.04 tpa. However much more work needs to be done before any figure can be deemed sufficiently accurate as to form the basis for major policy decisions. I note that my arguments here are similar to those already available in Risk & Policy Analysts Limited (2000), and am surprised that the report does not consider them.
Even so, and using the total given at the top of page 49, it is manifest that such an overestimate of release of cadmium to waste water from artists’ paints is a small fraction of the total release, at most less than 10% of that from car washing and degreasing, and possibly less than 1% if my lower suggestion above is correct. Using the total figure derived in Table 20, the range of cadmium recycled in sludge to agriculture in the EU 27 would therefore be from 0.01 part per million dry (lower level suggested above) to 0.1 part per million dry (total at the top of page 49 of the report).
According to the maximum value for cadmium that may be added annually to agricultural land (Council Directive 86/278/EEC, given at the foot of page 50 of the report), the total contribution from artists’ paints could be added to 267 to 2 867 ha of agricultural land without breach of that directive. With its low proportion of sludge recycled to agriculture, the maximum contribution of cadmium from inadvertent release from artists’ paints to agricultural land in Sweden must be even more insignificant. The overview figures given in Table 23 (p 55) only serve to reinforce the insignificance of artists’ paint in adding cadmium to agricultural land, and B.9.4 shows how small those are relative to other sources of cadmium. I note that Risk & Policy Analysts Limited (2000, p 154) concluded that “Emissions to the environment during use of products containing cadmium stabilisers and pigments” (which included the use of artists’ paints) “were determined and were found to be of negligible proportions.”
B.9.7 Human exposure via food
Table 29 illustrates the very wide range of levels of cadmium found in different types of food. Surprisingly high levels of cadmium (largely unaccounted for by any issues over which the report is concerned) are found in seaweeds (which form a significant part of the diet of many people in Japan, Wales, and elsewhere), oilseeds (which are also consumed in high quantities in some regions of Europe), horse meat (which is banned in some countries, but widely consumed in others), shellfish (with marked regional variation in consumption), fungi (regional variations), and chocolate (a heavily-promoted manufactured product which meets no dietary need, and which many health and dietary experts consider is consumed to excess across much of Europe). Curiously no study on the possible risks associated with high levels of dietary cadmium intake appears to have made use of these marked variations, which would be expected to result in noticeable regional variations in the incidence of renal damage, osteoporosis, breast cancers, etc.
Consumption of one 100 g chocolate bar each day would be sufficient to add about 10 μg to the total daily consumption of an individual, a weekly load of 70 μg, or to add an extra 51% to their mean weekly dietary exposure to cadmium (according to the figures given at the top of p 67 of the report). Someone who currently consumes a single 100 g chocolate bar every day, but who then stops eating chocolate, would therefore reduce their intake immediately by 10 μg cadmium per day. In that context, the potential reductions in intake that might be expected from the elimination of cadmium from artists’ paints after 100 years (Table 39) of 0.004 to 0.04 μg cadmium per day are insignificant.
According to Divine Chocolate (2014), the British population apparently purchases more than 660 000 tons of chocolate per year (I suspect very little of which goes into storage, almost all of which is eaten), giving an approximate annual consumption of 11 kg per person per year, or 30 g daily. If every person in Britain were to stop eating chocolate, aside from many other health benefits, there would be an immediate reduction in their cadmium intake by 3 μg per day, nearly 100 times the maximum reduction envisaged in the report 100 years after the prohibition of cadmium in artists’ paints.
Of course substantial reduction in total dietary cadmium intake – much greater than that achievable by the proposed restriction – would drive a ‘positive feedback loop’, in which it would reduce faecal and urinary cadmium output, which in turn would result in much greater reduction in cadmium concentrations in sewage sludge. It is not clear whether this has been considered in current models of cadmium transfer.
B.10.1.1.3 Indirect exposure of humans via the environment
The forecast figures here (foot of p 89 of the report) are so small that, even 150 years after the introduction of a prohibition on cadmium in artists’ paints, the effect cannot be measured in the general noise of the health data. Indeed there can be no doubt that, just as over the last 150 years, other changes in public health, agriculture, diet, climate, etc., would drown any tiny secular change as a result of this small reduction in cadmium loss to waste water.
It is puzzling that this report chose not to consider kidney effects in the quantitative risk assessment, given the extensive studies, and thorough meta-analysis of those studies (EFSA 2009a). Instead it chose to focus on osteoporosis and breast cancer, where there are still insufficient good studies on which to base a meta-analysis, and many of the studies published to date have been confined to the Swedish population (see above, B.5.6 and B.5.8).
Cho et al. (2013) attempted a meta-analysis of the relationship between dietary cadmium intake and the risk of cancer, finding only 8 articles which met the criteria for inclusion in such a meta-analysis. Of those, only 3 examined breast cancer, one being on a Japanese population, one US American, and one Swedish. The 95% confidence intervals for the risk ratios of the 3 studies were 0.76–2.00, 0.72–1.41, and 1.07–1.36, making firm conclusions impossible. The authors concluded that “we cautiously suggest that chronic exposure to cadmium and other metalloestrogens may partly explain the risk of developing hormone-related cancers, particularly in Western populations. To reduce cadmium-induced cancer risk, it is important to identify the high-risk population (e.g., vegetarians; Fe-, Ca-, Zn-deficient individuals; smokers) and to provide an appropriate medical intervention. Although this metaanalysis of epidemiological studies suggests a link between cadmium and hormonerelated cancers, more experimental and epidemiological studies using diverse populations are needed to establish a causal association, as well as to verify the
Likewise Åkesson et al.’s (2014) extensive review of non-renal effects of environmental cadmium exposure concluded that, whilst they should be considered critical effects in the health risk assessment of cadmium, and that exposure to low concentrations of cadmium is associated with effects on bone including osteoporosis, information currently available is still too limited “for appropriate use in quantitative risk assessment” of other effects, particularly cancers. Of the 21 studies with osteoporosis or fractures as outcome which they reviewed, 10 had been conducted on Swedish populations, 4 on Belgian populations, and only one on other European populations.
C. Available information on alternatives
C.2 Assessment of alternatives
Over the last 15 years or so, as the campaign in Sweden to eliminate the use of cadmium in artists’ paints has developed, artists in other countries have become more aware of and more sensitive to environmental concerns, including the inadvertent release of cadmium (although that is not the only such environmental concern among artists). Increasingly stringent measures to protect the health and safety of art students have also led to changes in practice in art schools and other educational establishments. Manufacturers have responded to those, and rises in the cost of cadmium pigments, by removing cadmium pigments from all except for their premium or professional paint ranges (a market-driven action which will have significantly reduced the use of cadmium in artists’ paints, but which is not examined in the report). For example, at present Winsor & Newton (2014) offers in Europe the following colours in their paint ranges:
Only 6 months ago, their Griffin range of alkyd oil paints included 8 colours based on cadmium pigments. Other manufacturers are similar, with some now offering no colours containing cadmium pigments at all. Both manufacturers and artists of all levels have therefore developed practical experience of the alternatives.
It is also worth noting an unfortunate side-effect of improving health and safety (given at B.126.96.36.199 above). Whereas painting in oils was very widely taught in art schools in the past, concerns over the toxicity of the organic solvents used as diluents and for cleaning have reduced the amount of oil painting undertaken in schools and art schools, with a shift towards acrylics. Whilst artists should not release much cadmium from oil paints (see above), it is much harder to limit release of cadmium from acrylic paints. As they dry very quickly, artists painting in acrylics have to wash brushes and other equipment frequently in water, so releasing more paint into waste water than they would have done if they had been painting in oils.
Within any given medium, there are several important qualities determined by the pigment used, of which the visible colour is but one. Although ‘tinting power’, that is the amount of paint required to achieve a given change in the colour of a mixture of paints, is important, as was made clear above (B.188.8.131.52), another major consideration is the opacity of the paint. Some pigments produce transparent colours, required for glazing and other techniques, whilst others produce opaque colours, which are essential when overpainting other colours, for example when scumbling (applying a superficial layer of opaque paint).
Although substitute pigments and mixtures of pigments can produce very similar colours to those provided by cadmium pigments, there are many remaining differences which would have a major impact on many paintings, particularly those of professionals and the better amateurs. The two major shortcomings of substitutes re in opacity and permanence.
In general, organic compounds such as the bright modern pigments based on pyrroles, etc., produce transparent colours. The only pigments that have established themselves as being suitable alternatives and can be opaque include:
PY53 (containing nickel and titanium)
PY184 (containing bismuth)
PY216 (containing titanium, tin, zinc, and antimony)
PO73 (pyrrole, but generally rated as semi-transparent rather than opaque)
PR254, PR255, PR264 (pyrroles which can be manufactured into transparent or opaque paints).
The great majority of the pigments listed in Table 49 of the report as examples of alternative pigments make transparent paints, except for the pyrroles noted above.
There is no satisfactory generic way to transform a transparent colour into an opaque one. Inorganic pigments are much more likely to be opaque, or be capable of being presented in an opaque paint. However the potential substitutes that are inorganic would present their own problems with toxicity and environmental issues, as given above but not fully in Appendix 7 of the report.
Historically the most serious problem with non-cadmium pigments for yellows, oranges, and reds is their tendency to fade over time. I have already pointed out the huge conservation problems that have resulted from van Gogh’s exuberant use of chrome yellow. Although impossible to render in terms of economic loss, the cultural loss if his famous sunflower paintings were to fade into grey would be devastating. Many of the substitute pigments are not as resistant to fading over time, being rated in class II or lower by the internationally-accepted ASTM test method. It is good practice for artists who are creating works for sale or other future enjoyment to use only those paints rated class I according to the ASTM method.
Of the pigments listed in Table 49, many have inferior permanence in comparison with cadmium-containing pigments, and several are notoriously fugitive, including PY1 (ASTM II-III), PY1:1 (ASTM II), PY3 (ASTM II), PY13 (ASTM II-III), PY97 (ASTM II), PO13 (ASTM II), PR3 (ASTM II-IV), PR4 (ASTM II-IV), and PR170 (ASTM I-III) (Gottsegen 2006 and various online sources). This major issue is not considered in the report, or even in Appendix 7 of the report, where it appears to be assumed that those fugitive pigments would be acceptable alternatives. For many artists, they are not.
Another important feature of cadmium pigments is their very broad range of hues, from the very palest of lemons to rich and deep reds. This enables artists to select paints formulated with those pigments to exactly the right colour for their purposes, rather than having to mix pigments or paints. Many artists consider it important to use, as far as possible, paints containing single pigments rather than a combination of two or more. This is because, as they mix paints to achieve the precise hue and tone required, the more pigments that are brought into that mixture, the greater the tendency for the resulting paint to become grey or muddy. To match the current range of colours offered using cadmium pigments, most artists would be forced to use paints containing mixtures of pigments (as has been used to create alternative paints termed ‘hues’ in current ranges), and their ability to mix those without adverse effects on the hue of the resulting mixture would thus be severely limited.
In practice, therefore, for most of the current applications of paints containing cadmium pigments, there would not be an alternative which had similar opacity, similar (or better) lightfastness, fewer toxic environmental effects, and contained just one rather than a mixture of pigments. Thus the assertions in C.2.4.1 and surrounding sections do not give an accurate picture of the very serious effects on artists of the removal of pigments containing cadmium. The user would indeed search for solutions, and would not find them. If there is to be a derogation for those restoring works of art and historic buildings, in recognition of the impossibility of finding good substitutes, then the same argument should also apply to many artists.
C.2.4.2 Economic feasibility
I have discussed cost differences above (B.2.2). However if a non-cadmium paint with matching properties does not exist, the cost of the required paint is not finite. Given the extremely small size of the artists’ paint market, the cost of trying to develop new pigments specifically for that market should be considered as an alternative. I strongly suspect that the cost of bringing direct replacements for the 8 or 9 colours generally provided in professional paint ranges by cadmium pigments, with near-identical properties, would be far in excess of any potential economic benefits to be achieved by the proposal.
E. Justification why the proposed restriction is the most appropriate Unionwide
E.1.1 Risk to be addressed – the baseline
I have addressed my concerns with this argument in my comments above.
E.1.3 Other Union-wide risk management options than restriction
Given the lack of appreciation of the importance of reducing the inadvertent release of cadmium into waste water among the art schools and artists consulted during the work reported by Weiss (2006), for example, I consider that there is great potential for risk reduction by methods here discussed as ‘voluntary agreements’. Whilst there is uncertainty over the effectiveness of such measures, given the long time scale required for such small reductions in cadmium intake, and the great uncertainties inherent in several of the arguments put in the report, it is wholly inappropriate to proceed straight to total ban of cadmium in artists’ paints without taking a little time to assess the situation better and to try voluntary measures, monitoring their effectiveness as part of the process of obtaining better evidence to inform good decision-making.
It is also quite inappropriate to consider that uncertainty in effectiveness is lack of effectiveness. As I have stated in several places above, I believe that there is considerable uncertainty in the effectiveness of the proposed restriction (uncertainty which is inadequately evaluated in the report); it would be equally wrong to dismiss that uncertainty in effectiveness as lack of effectiveness.
In the context of the most probably very small reduction in cadmium content of sewage sludge which could be achieved by its prohibition in artists’ paints, considerations of stricter limit values in the sewage sludge directive (p 105 of the report) are inappropriate: I have examined this in my comments to B.184.108.40.206 above, and even taking the highest level claimed in the report (that cadmium from artists’ paints accounts for 2% of the total cadmium in EU produced sludge, p 55), it is hard to see how eliminating that completely would achieve a limit value of around 1–3 mg cadmium/kg dry matter, which the report states would have to be considered “for a revised limit value on cadmium to have any effect” (top of p 106). Indeed the wording of that statement underlines the negligible benefits that would be accomplished by the proposed restriction on cadmium pigments in artists’ paints, and the need for much more effective measures capable of resulting in major reductions in the concentration of cadmium in sludge.
E.220.127.116.11 Risk reduction capacity
The figures given here demonstrate the very long period required to have an unmeasurably small predicted benefit, even using the favourable assumptions made in the report: hence the tiny predicted effect, and miniscule effectiveness. Expressed as a percentage change in the number of cases of fractures and breast cancers, these would not even be detectable in the morbidity statistics of the European population, and will no doubt be drowned by much greater changes resulting from other trends and changes over that long period. Using the figures provided in B.10.1.1.3 of the report, after 150 years:
• a reduction in female fractures of 47 cases/yr of a forecast total of 4.6 million fractures in women over 50 years of age = 0.0001% reduction
• a reduction in male fractures of 13 cases/yr of a forecast total of 2.4 million fractures in men over 50 years of age = 0.0005% reduction
• a reduction in breast cancers of 16 cases/yr of a forecast total of 374 200 cases in postmenopausal women = 0.004% reduction.
I hope that I do not need to elaborate how tiny these reductions would be in health terms, and how they could not be detected in epidemiological data. There is some strength in the argument that health improvements that are unmeasurable are therefore illusory.
I offer comments on matters relating to costs above, and below. I emphasise that the costs of developing closer-matched alternatives to current artists’ paints would be very substantial, and are not considered in the report.
Even given the optimistic predictions in the report, it is remarkable how small is the estimated benefit per year, as shown in Table 53, when spread across the whole European population and its economy. These figures should better be set in the context of other measures that could reduce dietary intake of cadmium, for comparison.
Given the very small size of the current market for cadmium-based artists’ paints, the ease of purchase of such products from online sources, and the lack of any proposed restrictions in the single largest market for artists’ paints in the world (the USA), it is probable that any restriction on sales within Europe would result in artists ordering cadmium-based artists’ paints from US suppliers. This likelihood is neither addressed in terms of developing effective enforcement measures, nor in the effect that such illegal importation and use would have in reducing the effectiveness of restriction.
If that contingency appears unlikely, consider the history of the pigment ultramarine. For centuries ultramarine was derived from crushed lapis lazuli, mined only in remote locations in the inhospitable Badakhshan area of Afghanistan, and its price per gram in Europe was greater than that of gold. Despite the huge difficulties and cost of obtaining supplies of ultramarine pigment before it was mined elsewhere and later manufactured, artists employed it extensively in many of the greatest paintings of the past. Indeed in many respects the cost and difficulty in obtaining ultramarine enhanced its desirability in paintings, among both artists and their clients/patrons.
E.4 Main assumptions used and decisions made during analysis
• 5% is assumed to be released to waste water I have detailed above (B.9.3) my serious concerns with the evidence from which this assumption is derived.
• no change in composition of diets is assumed over 100 years To assume no change because change is unpredictable invites gross error. Given the significant contribution made by some foods such as chocolate, discussed above (B.9.7), this is another major weakness in the report which appears insoluble.
• The Swedish epidemiological study on cadmium in food and breast cancer is relevant for EU I have considered this above (B.5.6 and B.11.2). Again there is no evidence presented that Swedish data represent the whole of the population of the EU, but the
report relies on that.
F. Socio-economic Assessment of Proposed Restriction
The evidence presented here is purely economic. There is no consideration of the cultural damage that could be done as a result of the loss of these major pigments to artists – an issue that is surely at the heart of the social impact of the proposed restriction.
Although as I have pointed out van Gogh’s most famous paintings of sunflowers used chrome yellow rather than cadmium yellow (B.2.2), millions of visitors each year to the National Gallery and others exhibiting them leave with a deep impression created by his masterful use of yellow paint. Preventing today’s and future generations of artists from using cadmium paints would stifle similar artistic expression, and deprive current and future Europeans of that experience. Social and economic assessments of the arts remain an underdeveloped area (Reeves 2002), but even when expressed in crude economic terms can be surprisingly substantial.
The impact of great paintings on the viewer cannot be reckoned in economic terms. But to commit to an act which would prevent all such works by European artists for the next 150 years, in the vain hope that a tiny and unmeasurable reduction in osteoporotic fractures and breast cancers might occur, is surely the most destructive act of weak science on vulnerable art. It would be an act of cultural vandalism.
What should be proposed?
I would not wish to leave these comments on such a negative note, given the potential importance of the issues which the proposal is concerned. However I think that it would be much better for artists and for the health of the people of Europe to try the following first, before considering the removal of cadmium pigments from artists’ paints:
1. Conduct robust multi-centre research to quantitate the amount of cadmium being discharged into waste water by artists. This should not only include a spread of art schools (which could perhaps adopt effective measures to reduce their release of cadmium into waste water), but individual artists working in their own studios (who are likely to be more limited in actions they could take to reduce release). I suggest that this study should extend to include some other significantly toxic pigments including cobalt and nickel, in anticipation of future concerns and to aid the assessment of effectiveness of remedial measures.
2. Conduct studies of simple practical techniques and equipment which could be used either in art schools or in small studios, to reduce the release of cadmium into waste water. Although better and more recent books describe some measures (e.g. Gottsegen 2006, pp 19-20), there is a pressing need to develop simple but effective techniques which artists can use, and to publicise them and educate artists. The latter can of course be accomplished by art schools, manufacturers, and the specialist press. These techniques will also be necessary to anticipate future concerns over release to waste water of other toxic pigments, something that the proposed restriction does not contemplate, but which is likely to become increasingly important as the European states address environmental problems. Today’s cadmium could readily be tomorrow’s cobalt.
3. Co-ordinate focussed work to reduce cadmium release from artists’ paints with other existing programmes, including those on NiCad batteries and car cleaning, which should achieve even greater reductions in cadmium release to the environment. There seems little point in targeting only the smaller sources of cadmium release without co-ordinating work on artists with much larger developing programmes appropriate for much larger releases.
4. Co-ordinate with a Europe-wide research programme, linked to a health improvement programme, to first establish the health benefits to be achieved by reducing dietary cadmium intake, and then to develop programmes which will bring about the required reduction in intake. Currently the rather fragmentary results of research would suggest that marked reductions in cadmium intake would directly reduce risk of several important and costly medical conditions. Europe-wide studies need to be undertaken to examine this more robustly: this is not just an issue of environmental chemistry, but has potentially major impact on dietary advice and even the production of foods. For instance, chocolate is high in cadmium content but seems unavoidably popular, particularly in certain populations and age groups. As a processed food, it should not be difficult to develop chocolate which has a much lower cadmium content, which could have major health benefits. Agricultural scientists have already identified strains of economically significant plants which accumulate less cadmium (Clemens et al. 2013), and that is another important area which should be integrated into this programme.
Åkesson A, Barregard L, Bergdahl IA, Nordberg GF, Nordberg M & Skerfving S (2014) Non-renal effects and the risk assessment of environmental cadmium exposure. Environ Health Perspect 122:431–438.
Bomford D, Kirby J, Leighton J & Ray A (1990) Art in the Making. Impressionism. Pp 61-62. The National Gallery & Yale University Press, New Haven.
Broman LE (2000) Kadmium – miljö- och hälsoaspekter vid slamspridning. Stockholm Vatten R nr 2.
Carlsson M (2005) Spårning av tungmetaller i Örebros spillvattenledningsnät. Civil engineering dissertation, Luleå Technical University, Luleå, Sweden.
Chaumont A, De Winter F, Dumont X, Haufroid V & Bernard A (2011) The threshold level of urinary cadmium associated with increased urinary excretion of retinolbinding protein and ß2-microglobulin: a re-assessment in a large cohort of nickelcadmium battery workers. Occup Environ Med 68, 257-264.
Cho YA, Kim J, Woo HD & Kang M (2013) Dietary cadmium intake and the risk of cancer: a meta-analysis. PLoS ONE 8(9): e75087. doi: 10.1371/ journal.pone.0075087.
Clemens S, Aarts MGM, Thomine S & Verbruggen N (2013) Plant science: the key to preventing slow cadmium poisoning. Trends Plant Sci 18(2), 92-99.
Cochrane Collaboration (2002) Further issues in meta-analysis. Sensitivity analysis. http://www.cochrane-net.org/openlearning/html/mod14-2.htm accessed 26/06/2014.
Divine Chocolate (2014) www.divinechocolate.com/uk/about-us/research-resources/ resources/chocolate-facts accessed 19/06/2014.
EFSA (2009a) Meta-analysis of dose-effect relationship of cadmium for benchmark dose evaluation. EFSA Scientific Report 254, 1-62.
EFSA (2009b) Cadmium in food. Scientific opinion of the panel on contaminants in the foot chain. The EFSA J 980, 1-139.
EFSA (2011) Statement on tolerable weekly intake for cadmium. EFSA J 9(2):1975.
Geldof M & Megens L (2013) Van Gogh’s Dutch palette. Pp 226-237 in Van Gogh’s Studio Practice, ed. Vellekoop M, Geldof M, Hendriks E, Jansen L & de Tagle A. Van
Gogh Museum and Yale University Press, New Haven.
Geldof M, Megens L & Salvant J (2013) Van Gogh’s palette in Arles, Saint-Rémy and Auvers-sur-Oise. Pp 238-255 in Van Gogh’s Studio Practice, ed. Vellekoop M, Geldof M, Hendriks E, Jansen L & de Tagle A. Van Gogh Museum and Yale University Press, New Haven.
Gottsegen MD (2006) The Painter’s Handbook. Watson-Guptill, New York.
Jackson’s (2014) www.jacksonsart.com accessed 19/06/2014.
Johnsson C (2011) Flödesanalys av spårelement från källa till slam. Dissertation, University of Uppsala, Sweden.
Mimovic D & Hammarlund L (2005) Kadmium från konstnärsfärger. Källor till kadmiumutsläpp och konstnärsfärgers bidrag vid Käppalaverket. Dissertation,
Stockholms Miljöcenter, Stockholm, Sweden.
Reeves M (2002) Measuring the economic and social impact of the arts: a review. http://culturability.org/wp-content/blogs.dir/1/files_mf/
1271761227measuringtheeconomicandsocialimpactofthearts.pdf accessed 29/06/2014.
Risk & Policy Analysts Limited (2000) The risks to health and environment by cadmium used as a colouring agent or a stabiliser in polymers and for metal plating. Final report prepared for the European Commission, DG Enterprise. Loddon, Norfolk. Available at http://www.rpaltd.co.uk/documents/J316-Cadmium.pdf, accessed 25/06/2014.
Russell, Joanna E (2010) A study of the materials and techniques of Francis Bacon (1909-1992). Doctoral thesis, Northumbria University. pp 113-114.
SCA (2013) Economic cost of fractures caused by dietary cadmium exposure. Report No. 4/13, Swedish Chemicals Agency, Stockholm.
Weiss J (2006) Rening av tvättvatten från konstnärer – kadmium. Dissertation, Stockholms Miljöcenter, Stockholm.
WHO (2005) Chemical-specific adjustment factors for interspecies differences and human variability: guidance document for use of data in dose/concentrationresponse assessment. IPCS harmonisation project document no. 2. WHO, Geneva.
Winsor & Newton (2014) http://www.winsornewton.com/uk/ accessed 29/06/2014.
Index of major comments
artists’ paints result in a small fraction of the total cadmium release p.10
assumption of LOAEL values of 1 or 2 μg Cd/g creatinine in urine p.4
assumption that all artists’ paints sold are consumed p.8
cadmium pigments wasted according to medium p.9
cost to develop alternative pigments p.15
cultural damage p.18
dietary reduction in cadmium intake p.11
opacity of alternatives p.14
permanence of alternatives p.14
pigments provide a broad range of hues p.14
proportion of paint types that is lost to waste water p.9
release of cadmium salts into waste water by artists p.6
risk of cancer p.12
risk of osteoporosis p.5
voluntary agreements not explored p.15