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Evaluation using energy-dispersive X-ray fluorescence spectrometry ofmetal elements in consumer products
Yue Liu, DDS, Shigeru Nakamura, DDS, Yoshihisa Yamabe, DDS, PhD, andHiroyuki Fujii, DDS, PhD
Division of Removable Prosthodontics and Management of Oral Function,
Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
Purpose: Dental metal allergies usually originate in iatrogenic circumstances, or occupational andhousehold environments. Thus, knowing which metallic elements were contained in known and unknown
metal objects is necessary to accurately diagnose and to provide daily life guide for patients with metalallergies. The aim of this study was to identify the metal elements in cosmetic and household products.
Materials and Methods: By energy-dispersive X-ray fluorescence spectrometry (EDXRF), 81 cosmetic
products and 50 household products were analyzed. Solid samples were analyzed intact. Cream samples
and liquid samples were dried to powder or paste before testing with a freeze-dryer. The examination was
carried out in vacuum.
Results: Metal elements were detected in 60 out of 81 cosmetic products and in 39 out of 50 householdproducts. The elements above 1,000 cps X-ray intensity in the cosmetic products were K, Ca, Ti, Fe, Zn,
and Bi; in the household products, the elements found were K, Ca, Fe, Cu, and Zn. In the 23 make-up
cosmetic products, Fe was detected in all, and Ti and Zn were detected in 20 and 19 products, respectively.
Conclusion: The results of this study suggest that when seeking a metal allergen, dermatologists anddentists must pay particular attention to both known and unknown metal objects.
(Int Chin J Dent 2002; 2: 134-142.)
Clinical Significance: In the differential diagnosis and daily life guide to patients with dental metalallergies, those results should be available.
Key words: consumer products, daily life guide, dental metal allergy, differential diagnosis, EDXRF.

INTRODUCTION
Allergies to metal are common, affecting about 10% to 15% of the population.1-4 Dental metal allergies
are usually caused by iatrogenic circumstances, and are aggravated by factors in occupational andhousehold environments.5 Dermal and mucosal contact with and ingestion of metals have been reported tocause immune reactions, which most typically manifest as hives, eczema, redness, and itching.2,6,7 All
metals in contact with biological systems undergo corrosion.8,9 This electrochemical process leads to theformation of metal ions; while not sensitizers on their own, they can activate the immune system by

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forming complexes with endogenous proteins.4,10,11 These metal-protein complexes are considered to be
candidate antigens (or, more loosely termed, “allergens”) for eliciting hypersensitivity responses.
Included in the elements known as sensitizers are: nickel (Ni), cobalt (Co), chromium (Cr), mercury (Hg),gold (Au), palladium (Pd), rhodium (Rh), platinum (Pt), aluminum (Al), manganese (Mn), iron (Fe), zinc(Zn), cadmium (Cd), tin (Sn), copper (Cu), antimony (Sb), iridium (Ir), lead (Pb), zirconium (Zr),molybdenum (Mo), silver (Ag), indium (In) and beryllium (Be). In addition, occasional responses totantalum (Ta), titanium (Ti), and vanadium (V) have been reported.3,6,7,12-19 A Danish population-based
study showed that 19% of females and 12% of males had at least one positive reaction to patch testing.20
At least 10% of women in the Nordic countries were allergic to nickel, but only 1-2% of men.21 Metals areused everywhere and are present in our daily environment at home, at work and at play. In the household
environment, the metal elements contained in known and some unknown metal objects. Understanding
which metal elements are contained in these objects is necessary for making the differential diagnosis andproviding guidelines for daily life to patients with metal allergies.
Because cosmetic and household products are widely used by many people, mainly women, the question
arose whether such cosmetic and household products might contain metallic elements that could provokeallergic responses. The aim of this study was to identify the metal elements in some cosmetic andhousehold products.

MATERIALS AND METHODS
Samples of 81 cosmetic products and 50 household products were obtained from different suppliers inJapan (Table 1). Whenever available, data were recorded concerning material, country of origin, maker,
and product number.
Table 1. Number of materials tested.
Country of manufacturer

Cosmetics

Household products

Japan

66

45

People’s Republic of China

9

1

Malaysia

03Germany20France20Thailand10Indonesia

0

1

U.S.A.

1

0

Total

81

50

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All samples were analyzed by energy-dispersive X-ray fluorescence spectrometry (EDXRF, SEA2110L,
Element Monitor, Seiko Instruments Inc., Chiba, Japan). All elements can be analyzed by EDXRF fromNa to U (except for Rh) in the periodic table. The accelerating voltage can be set at 5, 15 and 50 kV in thisapparatus. The diameter of the analysis area was set at 10 mm. Solid samples such as lipstick, wereanalyzed intact. With a freeze-dryer (VD-250, Taitec Inc., Saitama, Japan), cream samples and liquidsamples were dried to powder or paste before testing. Powder, or paste sample was placed in a sample
container (XRF Sample Cup, Chemplex, Stuart, FL, USA). The examination was carried out in vacuum.
Under these conditions, elements at levels higher than 200-300 ppm are detectable.22

RESULTSAn example of EDXRF analysis is shown in Fig. 1. The results of the present study are summarized inTables 2-4. Metal elements were detected in 60 out of 81 cosmetic products and in 39 out of 50 householdproducts. In the largest group of products tested, i.e., make-up products, Fe was detected in all 23 samples(100%), and Ti and Zn were detected in 20 (87%) and 19 (83%) products, respectively. The metalelements above 1,000 cps X-ray intensity in the cosmetic products were K, Ca, Ti, Fe, Zn, and Bi, and inhousehold products were K, Ca, Fe, Cu, and Zn.

Fig. 1. An example of EDXRF
analysis of a foundation make-up
cosmetic.

In the current analysis

system, if an element was detected
above 1,000 cps, this element wasconsidered to be one of main
components

of

the

product

quantitatively; and below 100cps,
an amount of the element was aslight and close to the detectionlevel.

23

Ni and Cr were detected in one eyebrow pencil out of 81 cosmetic products (although the X-ray intensity
for the elements was below 100 cps) and in one metal scourer out of 50 household products (within a range
from 100 cps to 1,000 cps X-ray intensity). Hg was detected in one cleaner at less than 100 cps X-ray
intensity. Co was not detected in any products. V was detected in 12 cosmetic products and one householdproduct.

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Table 2. Summary of EDXRF analysis of cosmetic and household products.
Type and number of products

Metal containing productsType and number of products

Number%

Wash (body, hair, and face) 12542DetergentHair dye

2

2

100

BleachHair conditioner

2

2

100

Care (base)

15

2

13

Cosmetics

Metal containing products
Number

%

12

6

50

3

2

67

Deodorant

5

2

40

Metal scourer

4

4

100

Household products

Make-up

23

23

100

Scrub and nylon scourer

4

3

75

Nail cosmetic

5

5

100

Cleaner (sponge)

10

10

100

Lipstick

8

8

100

Brush

2

2

100

Lipliner

3

3

100

Wiper

4

4

100

Toothpaste

4

3

75

Cleaning pad

1

1

100

Bath cosmetic

5

5

100

Cleaning sheet

2

2

100

Body-hair remover

1

1

100

Rubber glove

3

3

100

Nose clear pack

1

1

100

Total

81

60

74

Total

50

39

78

In 23 make-up items, there are seven foundations, six eye colors, eight eyebrow pencils, one eyeliner, and one mascara.
There are four body washes, five shampoos, and three face cleansers in 12 washes.

DISCUSSION
There is a significant number of metal elements, either in free atomic form or as inorganic or organic
compounds, that may be absorbed through the skin or via oral, parenteral, respiratory, conjunctival, andmucosal routes. Dermal and mucosal reactions may take the form of eczema, dermatitis, systemic contact
dermatitis, urticaria or lichen planus, and oral reactions may occur as dental metal eruptions.15,24 It isconceivable that metal ions released from the dental alloys and metal subjects in people’s daily
environments could penetrate the oral and/or intestinal mucosa and the skin, and activate these sensitizedT-cells in vivo. The immune system has many regulatory peptides and receptors that are known to be
expressed in the brain. An activated T-cell might thus cause distant effects.25 The ability of allergenic
metal ions to elicit a reaction in a particular person is dependent upon their concentration, the area of skinor mucosa exposed, and the duration of exposure.26 In some cases, the source of metal contact is known(earrings, jewelry, metal objects), but in others, it is difficult to identify the particular source of contact.
The latter forces the physician to search for less obvious sources of metal contact.
Of the top ten contact allergens found in large prevalence studies conducted among European
populations, four were metal compounds: nickel, chromium, cobalt and mercury. Among these, nickel
consistently ranked as the most common cause of allergic contact dermatitis overall. A random survey of137

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the Danish population showed 11.1% and 2.2% Ni sensitivity for females and males, respectively.27
However, the figure was only 0.67% in a group of male soldiers.28

Table 3. Number and type of cosmetic products containing each element.
Element

Intensity (cps)Below 100

Na

3 bat

Mg

3 fod, 5 eyc, 2 eyb, 1 nco, 1 lis, 2 batAl

5 fod, 6 eyc, 6 eyb, 1 eyl, 1 mac, 1 nco, 7 lis,100-1,000

Over 1,000

1 eyb

2 lil, 3 bacSi

2 bwa, 1 hdy, 1 hco, 3 fod, 3 eyb, 1 mac, 4 nco,

2 bco, 4 fod, 6 eyc, 4 eyb, 1 eyl,

8 lis, 3 lil, 5 bat

1 nco, 3 top, 1 hrc

K

1 bwa, 1 hwa, 2 hdy, 4 fod, 2 eyc, 1 eyb, 1 eyl,

1 bwa, 4 eyc, 5 eyb, 3 lis, 3 lil,

2 nco, 4 lis, 1 bat

1 bat

Ca

1 bwa, 1 hwa, 2 hdy, 2 hco, 2 bac, 1 ncp, 5 fod,

1 eyb, 1 eyl, 1 lis

Ti

2 bwa, 2 fod, 1 eyc, 1 mac, 1 nco, 1 top, 2 bat

2 bwa, 2 bat
2 top, 1 hrc

3 eyc, 3 eyb, 1 eyl, 1 mac, 4 nco, 3 lis, 1 topV

3 eyb, 1 mac, 2 lil

Cr

1 eyb

Mn

1 eyc, 1 eyb, 1 nco, 2 lilFe

3 fod, 1 eyc, 1 eyb, 2 nco, 4 lis, 2 top, 1 ncp

Ni

1 eyb

Cu

1 hdy, 2 fod, 4 eyc, 6 eyb, 2 nco,

2 fod, 1 eyc, 1 eyb,

8 lis, 2 lil, 1 hrc

1 lil,

2 fod, 2 eyc, 2 eyb

4 fod, 3 eyc, 1 eyb, 3 nco, 4 lis,

2 eyc, 6 eyb, 1 eyl,

2 lil, 2 bac

1 mac, 2 lil

1 ncp

Zn

1 fod, 2 eyc, 6 eyb, 1 eyl, 1 mac, 1 nco, 2 lis,

Ga

1 eyb

Rb

2 fod, 4 eyc, 5 eyb, 1 eyl, 4 lis, 3 lil

Sr

3 fod, 2 eyb, 1 eyl, 3 lis, 2 top, 1 hrc

Zr

2 fod, 1 eyc, 4 eyb, 1 eyl

1 hwa, 4 eyc

4 fod

1 lil

3 fod

Nb

3 fod, 1 eyc, 3 eyb, 2 lis, 1 lilBa

2 fod, 3 lis

1 fod

Bi

1 eyb

2 eyc

1 eyb

Abbreviations: bwa: body wash; hwa: hair wash; fwa: face wash; hdy: hair dye; hco: hair conditioner; bac: base cosmetic;
ncp: nose clear pack; fod: foundation; eyc: eye color; eyb: eyebrow pencil; eyl: eyeliner; mac: mascara; nco: nail cosmetic;
lis: lipstick; lil: lipliner; top: toothpaste; bat: bath cosmetic; hrc: hair removal cream.

Schubert et al.29 stated that costume jewelry, wristwatches and metal clothing buckles are not only themost important sources of primary nickel sensitization but also of relapses and persistence of the allergy.

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Nickel is found in medicines, fungicides, nickel-plated objects, taps, coins, scissor, zippers, garter clasps,
hairpins, eyelash curlers, metal frames for eyeglasses and costume jewelry.

Because of its special

properties, nickel is still found in dental alloys or in implants such as joint prostheses, plates and screws for
fractured bones, and surgical clips.
Table 4. Number and type of household products containing each element.
Element
Below 100

Na

2 dtg, 1 blc, 1 ddr, 3 cln

Mg

1 ddr, 1 cln, 3 wipAl

2 dtg, 1 blc, 2 cln

Si

2 dtg, 1 blc, 1 mts, 1 scs, 4 cln, 1 wip, 1 clp,

Intensity (cps)100-1,000

Over 1,000

1 dtg, 1 scs, 2 cln, 1 cls

1 cls
K
Ca

2 dtg, 2 blc, 1 cln, 1 cls, 2 rug

1 scs, 1 cln, 1 brs

4 dtg, 1 blc, 2 ddr, 3 mts, 2 scs, 9 cln, 1 brs,

1 rug

4 wip, 2 cls, 1 rugTi

1 blc, 1 ddr, 2 scs, 1 cls, 4 cln, 1 brs, 1 wip,

1 ddr
1 ddr, 1 blc, 1 brs,
1 clp, 1 rug

1 dtg, 1 wip, 1 cls, 2 rug

1 rug
V

1 rug

Cr

1 mts

Mn

2 dtg, 2 mts, 1 cln

Fe

1 mts

2 dtg, 2 blc, 2 ddr, 1 scs, 4 cln, 4 wip, 1 brs,

3 mts

1 clp, 1 rug
Ni

1 mts

Cu

1 dtg, 1 ddr, 1 mts, 1 cln, 1 clp, 1 wipZn

1 dtg, 1 ddr, 1 wip, 1 rug,

Rb

1 mts

Sr

1 ddr, 1 blc, 1 brs, 1 clp

Zr

2 rug

Nb

1 mts

Mo

1 mts

Sn

1 cln

Hg

1 cln

1 mts
1 clp, 2 rug

1 ddr, 1 mts

Abbreviations: dtg: detergent; blc: bleach; ddr: deodorant; mts: metal scourer; scs: scrub scourer; cln: cleaner; brs: brush;
wip: wiper; clp: cleaning pad; cls: cleaning sheet; rug: rubber glove.

Nickel is also found in kitchen utensils, e.g., cans and tins, pots and pans, electric kettles, and cutlery.
Water taps, pipes, sinks and bathtubs can all contain and release nickel.24,30 Modern formulations ofconsumer products, with the possible exception of mascara, contain only trace levels of nickel.2 Current
good manufacturing practice ensures that traces of nickel, cobalt and chromium concentrations in consumer

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products are less than 5 ppm of each metal. It has been recommended that this amount be adopted as astandard for maximum concentrations and that the target should be to achieve concentrations as low as 1
ppm.2,31
A series of studies related to the safety of cosmetics for consumers were reported.31-33 Eye shadow is atypical example of a group of cosmetic products in which the significance of pigments is great. Some toxic
elements and their compounds are water-soluble, and moist skin can, therefore, promote the percutaneousabsorption of elements occurring as impurities in pigments. The excipients used also affect the absorption
through the skin.2,27,31 For indeed, the frequency of administration of cosmetic formulations is generally
scheduled on a daily basis, and in some instances, several cosmetic products, such as lipstick or hand cream,
can be applied to the body two or more times a day. Because eyebrow pencil is a “leave-on” cosmetic
product, i.e., it is applied to the body repeatedly and left on the skin for a relatively long period of time, thesame problem may be expected as occurred with eye shadow and mascara. Foundation is a leave-on
cosmetic product in contact with the skin up to approximately 10 hours every day. Make-up such as
lip-liner and lipstick products are leave-on cosmetic products and are applied undiluted to the skin/mucosa.
A low concentration of allergenic metal has the risk of eliciting a response for such long durations andlarge areas of exposure to skin/mucosa. Although the traces found in these consumer products will not be
the primary cause of sensitization to these metals, they could be sufficient to maintain an allergy.2 Products
such as shampoo and nose cleaning packs are “wash-off” cosmetic products; since they are rapidly dilutedand quickly rinsed off during use, the level of allergenic metal will be very low on the skin/mcosa.
Nonetheless, in areas where the product can be trapped (ear canals, under rings), such wash-off products
can cause allergies. Thus, it is important that the content labelling is shown for all cosmetic products, sothat consumers can avoid the use of the products containing specific chemical(s) that they cannot tolerate.
Furthermore, dermatologists and dentists can use the content labelling on cosmetic products as a guide to
identify specific chemical(s) in cosmetic products that may be the cause of skin/mucosa reactions in certain
people. All household products should also have this content labeling.
A large segment of the public is exposed to metal-containing compounds, potentially resulting in theirunintentional absorption through the skin. Of course, both finished products and ingredients, including
metal compounds, are designed to be biologically inactive and nontoxic, and are formulated to minimize
their absorption. However, present knowledge of percutaneous absorption and pharmacokinetics teach thatsuch criteria cannot be viewed in absolute terms.27 The authors suggest when seeking a metal allergen,dermatologists and dentists must pay particular attention to both known and unknown metal objects.

CONCLUSION
In 81 cosmetic products tested in this study, 21 elements were detected. In 23 make-up cosmetic
products, Fe was detected in all, and Ti and Zn were detected in 20 and 19 products, respectively.
Twenty-one elements were detected in this study from 50 household products tested. These results areimportant for the differential diagnosis of allergic reactions as guidelines for patients being treated for140

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metal allergies.

ACKNOWLEDGMENT
This study was partly supported by Grant-in-Aid for Scientific Research (B)(2) No.11470419 from The
Japanese Ministry of Education, Science, Sports and Culture.

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Reprint request to:
Dr. Shigeru Nakamura
Division of Removable Prosthodontics and Management of Oral Function
Nagasaki University Graduate School of Biomedical Sciences
1-7-1, Sakamoto, Nagasaki 852-8588, Japan
FAX: +81-95-849-7694
E-mail: basser@net.nagasaki-u.ac.jp
Received on October 8, 2002. Revised on November 11, 2002. Accepted on November 18, 2002.
Copyright ©2002 by the Editorial Council of the International Chinese Journal of Dentistry.

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