ARE THE CURATIVE PROPERTIES OF BLACK MUDFROM THE DEAD SEA DUE TO THE PRESENCE OF BITUMEN

(ASPHALT) OR OTHER TYPES OF ORGANIC MATTER?

ARIE NISSENBAUM1,, JRGEN RULLKTTER2 and YOSEPH YECHIELI31Department of Environmental Sciences and Energy Research, Weizmann Institute of Science,

Rehovot 76100, Israel; 2Institute of Chemistry and Biology of the Marine Environment (ICBM),Carl von Ossietzky University of Oldenburg, D-26111 Oldenburg, Germany; 3Geological Survey

of Israel, Jerusalem 95501, Israel (author for correspondence: tel./fax: +972-8-934-4232;e-mail: arie.nissenbaum@weizmann.ac.il)

Received 1 June 2001; accepted in revised form 8 April 2002

Abstract. Deep black clayey sediments of the Dead Sea, previously covered with water at timesof higher sea level, are being mined for therapeutic purposes and for the preparation of cosmeticproducts under the name Black Mud. It was claimed that the beneficial properties are due to thepresence of bitumen (asphalt) as attested by the colour. Less commonly, the curative properties havebeen ascribed to humic acids or to organic matter derived from algae in the lake. Asphalt from theDead Sea has been of major economic importance to the region and was used as a medication for 2000years until the mid-20th century. Geochemical analysis of the Black Mud showed that it containsrelatively little organic matter (ca. 0.60.8% organic carbon) and that the organic matter is mostlyderived from the land masses surrounding the lake. Asphalt was totally absent and the concentrationof humic acids very low. The black colour of the mud is rather due to the poorly crystallised ironsulphides. Based on this, the therapeutic properties of the mud are ascribed to its content of reducedsulphur species, its physical and chemical properties and possibly its brine content, but not to thepresence of organic matter.

Key words: asphalt, bitumen, Black Mud, Dead Sea, medicine, organic matter, sediments,sulphides

1. Introduction

In recent years, the unique chemical and physical properties of the Dead Sea (witha total salt content of about 320 g L1, high magnesium and bromine content inthe brine and a density of 1.23 g cm3) made it an important centre for the pro-duction of natural medications and cosmetics. In addition to the healing propertiesof the lake water itself, mud from the lake is considered to be of high therapeuticvalue. The mud that is used for this purpose is the so-called Black Mud, a deeplyblack, shiny mud, rich in salts, which is applied to part of or the whole body. TheBlack Mud, when applied as heated mud packs or simply by smearing all overthe body, is used as treatment in case of arthritic diseases. Although it does notprovide a cure, it helps in alleviating the pain suffered by inflammatory and non-inflammatory joint diseases such as psoriatic arthritis or osteoarthritis. In addition,

Environmental Geochemistry and Health 24: 327335, 2002. 2002 Kluwer Academic Publishers. Printed in the Netherlands.

328 ARIE NISSENBAUM ET AL.

the Black Mud has been extensively used as a base for the preparation of soaps,creams and unguents for skin care. The manufacturers of those products claim thatthe mud has major effects on revitalising and toning the skin. Those products areexported today and are sold all over the world.

The mud, when fresh, is shiny black in colour and sheen and very closelyresembles the asphalt (bitumen) blocks, which can be occasionally found alongthe shores of the Dead Sea (Nissenbaum et al., 1980). The reputation of DeadSea asphalt, which has been in use for 10,000 years or so (Nissenbaum, 1994),frequently resulted in assuming that all black materials associated with the DeadSea are asphaltic in nature. Yet, other types of black materials are quite common inthe Dead Sea area. For example, black manganese crusts cover calcium carbonatelayers along the shores (Ehrlich and Zapkin, 1985; Nishri and Nissenbaum, 1993);black flint pebbles abraded from the walls of the Rift Valley, in which the DeadSea is sited, are abundant in the area; deposits of the black so-called oil shales ofSenonian (Upper Cretaceous) age are found in some locations along the coast of thelake and the deeply black, thermally metamorphosed equivalent of this formation,in Arabic called Hajar Musa (the stone of Moses), can easily be confused withasphalt by sight. However, none of those materials contains asphalt, and only theSenonian oil shales contain related organic matter.

While the therapeutic and cosmetic properties of Black Mud from the DeadSea remain unchallenged, the following paper examines the possible presence ofasphalt, and other types of organic matter, as an important constituent of the mud.Organic matter that is occasionally referred to in the advertisements for commercialproducts of Dead Sea mud as tar or simply as organic matter is sometime listed asan active ingredient that may be responsible for some of the claimed cosmetic anddermatological properties of the Black Mud.

1.1. THE BLACK MUD

Black Mud is the common name given to detrital black, fine muds of the Holo-cene Zeelim formation, which is found in the erosional fans of wadis (seasonaldry river beds) along the southern basin of the Dead Sea (Yechieli, 1993). Thebest exposures are in the Zeelim fan where the receding lake level caused theexposure of sediments that were under water for the last several thousand years.The sediment section is at least 7 m thick and ranges in age from the recent untilat least 2500 years BP. The mud is being mined from the top 12 metres of thesediment section.

According to Raz (1993) the Black Mud is mostly formed from detrital matterwhich is brought in by the Jordan River in the north of the Dead Sea and sweptby currents along the western coast of the lake to be deposited in protected bays.The black colour is a result of reductive processes that occur after deposition.Analytical data by Raz (1993) showed that the major components of the water-insoluble fraction of the mud are carbonates such as calcite and dolomite (66%) and

BLACK MUD FROM THE DEAD SEA 329

TABLE IChemical composition of interstitial brines in recent Dead Sea muds (including Black Mud)

Borehole Na+ K+ Ca2+ Mg2+ Cl SO24 Br(g L1) (g L1) (g L1) (g L1) (g L1) (g L1) (g L1)

YM4 (0.1 m) 3.0 7.8 28.2 92.1 326 0.1 10.4YM4 (0.3 m) 31.6 6.9 17.6 45.8 217 0.8 5.7YM4 (0.8 m) 19.4 4.5 6.9 20.5 103 2.2 2.7YDS 20.0 5.5 8.0 20.0 110 0.9 2.6Dead Sea water 39.7 7.6 17.2 42.4 219 0.4 5.3

clays, quartz and feldspars (34%). The water-soluble component is mostly halite.The black mud contains a saline interstitial water with a chemical composition,which is generally similar to that of the Dead Sea brine, but is usually enriched inthe cations Mg2+, Na+ and Ca2+ and the anion Br. The sulphate concentrationis usually higher than that of the Dead Sea water (Yechieli, 1993; Yechieli andRonen, 1997). Table I gives the typical chemical compositions of the interstitialbrines in Dead Sea recent sediments (regular sediments as well as Black Mud)from several locations in the Dead Sea coastal area.

The Black Mud is extensively used in the Dead Sea area for therapeutic pur-poses and is also widely used as a basis for the manufacturing of cosmetic prepar-ations and products that are locally used in spas and exported all over the world.The beneficial effectiveness of Black Mud treatment, especially when combinedwith sulphur baths, against skin diseases and rheumatoid arthritic diseases has beenextensively documented in the medical literature (Sukenik et al., 1990; Sukenik,1996; Elkayam et al., 2000).

1.2. DEAD SEA BITUMEN AS A MEDICATION

Asphalt from the Dead Sea has been extensively used as a remedy since ancienttimes as described by Nissenbaum (1999). (The terms bitumen and asphalt arefrequently used interchangeably, although in the geochemical literature the termbitumen is usually employed to describe organic matter that can be extracted fromsediments by solvents; the term asphalt is retained for native solid organic matterwhich occurs in rocks and sediments). Pliny the Elder (Pliny, 1948), in the firstcentury AD, describes the list of ailments against which bitumen can be employedbecause it is astringent, dispersive, contractive and agglutinating. Although Pliny(1948) does not specifically refer to Dead Sea material, he was well aware of theasphalt production from the lake and indeed mentions about it, as well as bitumenfrom other sources, just before he describes the medical applications of bitumen. Inanother place, he provided a detailed description of the appearance of asphalt in the

330 ARIE NISSENBAUM ET AL.

Dead Sea and its collection by the local people. Josephus Flavius, the 1st centuryAD Jewish historian, provided a description of asphalt collection from the DeadSea (Flavius, 1959) and wrote that this asphalt is used for the cure of mens bodies;accordingly it is mixed in great many medicines. The continuing importance ofDead Sea asphalt in medicine is attested to by the visit of Galen to Palestine in 166AD. Galen, a physician to Emperors and also the most influential medical practi-tioner of the ancient world, went to the Dead Sea to examine two of its products:asphalt and balsam. Galen (according to Matthiolus, 1530, as quoted by Forbes,1959) says that the Dead Sea produces the best bitumen that gives good results insealing fresh cuts and in all things that need to be dried and moderately warmed.The Venerable Bede (Bede, 1896), writing in the beginning of the 8th century AD,in the portrayal of the Dead Sea says that its bitumen is used for the healing ofthe human body. A Moslem physician, El Tamimi, working in Jerusalem at theend of the 10th century, wrote that Jewish Bitumen, collected from the Dead Sea,is used in the preparation of theriac, a medicine in which snake venom was aningredient (Z. Amar, Bar Ilan University, personal communication).

In the 20th century, Dead Sea asphalt also roused interest as medication, prob-ably due to its similarity in colour and smell to the widely used tar products andIchthyol, a dermatological drug extracted by distillation of bituminous shales,particularly near Seefeld, Austria. Blocks of floating asphalt were collected inthe mid-1930s, transported to the Teva Pharmaceutical Industry in Jerusalem anddry-distilled. An odorous blackish liquid with high boiling point, containing 4.6%sulphur (by weight), was separated and was labelled bitupal (Bitumen Palestine).It was used for the treatment of dermatological conditions as pioneered by Prof.A. Dostrovsky, Hadassa Hospital, Jerusalem. A 30% concentration of bitupalin zinc paste was used between 1942 and 1957 to treat 298 inpatients sufferingfrom a variety of skin diseases, such as eczemateous eruptions of several types,neurodermatitis, psoriasis, pruritus and other conditions (Dostrovsky et al., 1959).More than 10,000 outpatients were also treated, but were not included in this report.The conclusions from this study were that bitupal is particularly effective againstresistant dermatoses such as mummular eczema and seborrahic dermatitis, andbeneficial in the treatment of other eczemas. Infantile atopic dermatitis, localisedneurodermatitis and denuded areas of Pemphigus vulgaris also responded verywell to this treatment. The nature of the active ingredient in the bitupal was notinvestigated. It was noted that no side effects were observed in the treated patients.Shannon and Kamnitzer (1959) have made a preliminary clinical evaluation ofbitupal and straight asphalt distillate on pruritus and dermatoses associated withit, as well as comparing it with tar and steroid treatments. The trial group con-sisted of 85 patients, and the results indicated that bitupal had a very strong anti-pruritic effect, equivalent or better than 2.5% cortisone ointment. It also had stronganti-eczemateous and anti-inflammatory properties with very little side effects.

Sulman (1960) investigated for many years the effect of bitupal on caninedermatoses. Bitupal, occasionally in combination with other medications, was used

BLACK MUD FROM THE DEAD SEA 331

to treat 100 dogs suffering from various skin diseases. According to Sulman (1960),all the dogs reacted favourably to the treatment. The advantages of the use ofbitupal are its quick drying action, soothing effect on the skin, its applicationto bare skin, requiring no bandaging, and the speedy healing effect. His conclu-sions were that bitupal is an effective anti-pruritic, anti-eczemteous and anti-inflammatory agent with a wide margin of safety.

Thus, the medical applications of Dead Sea asphalt extended over 2000 years,and it is no wonder that its repute for healing, and in particular for dermatolo-gical diseases, continues as of today and that this reputation is being utilised forcommercial endeavours.

2. Geochemical analysis of Black Mud

The total organic carbon content of bulk Black Mud is low at 0.60.8% organiccarbon (Corg) and is not markedly different from the range of values observed inother sediments from the Dead Sea (Table II). Therefore, if asphalt is present in theBlack Mud, it must be in very low concentration since the asphalt contains about80% Corg (Nissenbaum et al., 1980).

TABLE IIConcentration of total organic carbon in Dead Sea sediments

Source of data Year of Water depth (m) Corg (%) Commentscollection

Neev and Emery (1967) 1960 (?) Not given Up to 2 aNissenbaum et al. (1972) 1965 810 0.230.25 bNissenbaum et al. (1972) 1965 165330 0.340.40 bAnderson et al. (1977) 1975 (?) 160330 0.380.87Levy (1987) ca. 1980 (?) Various locations. 0.641.00 c

Mostly in relatively (average= 0.8)shallow water

Oldenburg et al. (2000a) 1998 Surface sediment 0.450.81 dfrom shallow water

Oldenburg et al. (2000a) 1998 Black Mud 0.620.78 d

aLocation unspecified. The value of 2% is quoted as maximum value. The analytical procedure isnot given.bOrganic carbon determined after HCl treatment and drying. Samples run in triplicate.cOrganic carbon determined by combustion and titration. No details of the analytical methods aregiven. Some errors may have been introduced by oxidation of sulphides.dDetermined by coulometry. Sediments collected on land, but they represent sub-aquatic sedimentswhich were exposed due to the lowering of the lake level with consequent receding of the shore line.

332 ARIE NISSENBAUM ET AL.

It is appropriate to comment on the scatter of values for organic carbon valuesthat are reported in Table II. There are three major reasons for this scatter. The firstis that as expected from a narrow, land locked, body of water with very limited pro-ductivity, the distribution of organic carbon in the sediments will be quite variablespatially due to differences in the input of organic matter from the neighbouringland area due to geographical and physiographical variations. Second, the presenceof large amounts of soluble salts in the interstitial water of the sediments, andthe occurrence of halite and gypsum often requires the thorough washing of thesediment with water prior to analysis. The sediment is then dried and analysed.This procedure, however, results in introducing large uncertainty as to the originalweight of the sediment relative to which the organic carbon concentration shouldbe reported. Third, the presence of poorly crystallised iron sulphides in the sedi-ments that reacts with the oxidising solution often used to estimate organic carboncontent (e.g. Levy, 1980) will produce too high organic carbon values. Taking allthis into consideration, the conclusion is that Dead Sea sediments are impoverishedin organic carbon.

A detailed molecular and isotopic geochemical analysis of Black Mud andof underlying sediments from the Zeelim formation by Oldenburg et al. (2000a)indicated the absence of asphalt. For example, the distribution of n-alkanes in as-phalt (Figure 1) is typical for petroleum-related products, while the Black Mudshows an n-alkane distribution which is typical of epicuticular waxes of higher landplants (Eglinton and Hamilton, 1967). The distribution of n-alkanes in sedimentcollected in the central part of the shallow Southern Basin of the lake matchesalmost exactly the pattern of the Black Mud, indicating a common source for

Figure 1. Distribution of n-alkanes in Black Mud, surface sediment from the Southern Basin of theDead Sea and in floating block of Dead Sea asphalt (data from Nissenbaum, 1969; Rullktter et al.,1985; Oldenburg et al., 2000a).

BLACK MUD FROM THE DEAD SEA 333

the n-alkanes. Other geochemical parameters such as the distribution patterns ofn-alcohols, fatty acids, sterols and pentacyclic triterpenoids and the carbon isotopiccomposition of these compounds conclusively point to the organic matter beingmostly derived from terrestrial higher plants, which were swept into the Dead Sea.Evidence for a minor contribution by autochthonous organisms was seen by thecarbon isotopic values of phytol and some sterols (Oldenburg et al., 2000a). Nomolecular geochemical indicators were found which could be ascribed to asphalt.

The concentration of total sulphur in the Black Mud is around 0.3% (Oldenburget al., 2000a). Most of the reduced sulphur was in the form of pyrite, but a consid-erable percentage was found as metastable iron sulphides and elemental sulphur.This is different from the findings of Nissenbaum and Kaplan (1976) who didnot detect pyrite or elemental sulphur in surface sediments collected when thesediments were covered by lake water. Nissenbaum and Kaplan (1976) found thatthe reduced sulphur was in the form of AVSs (acid volatile sulphides), presumablyiron sulphides. It is possible that the elemental sulphur and the pyrite are diageneticproducts formed after the sediments were exposed. Sulphur isotopic analysis showsthat the reduced sulphur species were very probably formed by microbiologicalactivity in the sediments (Oldenburg et al., 2000b) as was also found earlier byNissenbaum and Kaplan (1976) for sediments in the shallow and deep parts ofthe lake.

The deeply black colour of the sediments is due to the presence of poorlycrystallised iron monosulphide. This is indicated by the simple test of reacting thesediments with diluted hydrochloric acid. The colour disappears immediately, anda smell of hydrogen sulphide develops at the same time.

Occasionally, it is claimed in commercial advertisements for Dead Sea BlackMud that its main therapeutic properties are due to the presence of large amountsof humic acids that accumulated since the last Ice Age. Analysis by Nissenbaumet al. (1972) showed that humic and fulvic acids in the sediment from the SouthernBasin constitute less than 0.1% of the dry sediment weight. Even in the deep sed-iments, the concentration of humic substances is only about 0.2% of the sedimentweight. Those concentrations are well below values that are found in oceanic andlacustrine sediments.

It has also been claimed that the organic compounds that are medically active inthe sediments are due to contribution from the indigenous algal population of thelake. This is contrary to the findings of Oldenburg et al. (2000a) who showed thatby far the dominant contribution to the total organic matter is from the watershedand that indigenous algal contribution is of minor importance.

3. Conclusions

The Black Mud, which occurs in coastal areas of the Dead Sea that were previ-ously covered by lake water, but are now exposed due to the lowering of lake level

334 ARIE NISSENBAUM ET AL.

during the last 30 years or so, and which is widely used in therapy and cosmetics,is basically not different from other recent sediments of the Dead Sea. There is nogeochemical evidence whatsoever for the presence of Dead Sea asphalt in the BlackMud. The black colour of the mud is due to the presence of poorly crystallisedinorganic iron monosulphide. Neither does it contain significant amounts of humicsubstances, which also have been claimed as a reason for the therapeutic propertiesof the Black Mud. The curative properties of the Black Mud are probably due toits high salt content in the hypersaline interstitial brines, the absorption of sunlightand skin heating by the deep black material and by the interaction of the sulphidesand elemental sulfur with the skin, and not to the presence of asphalt (bitumen) orany other type of organic matter.

Acknowledgements

The authors are very grateful to Mrs. L. Chernobrov, reference librarian, WixLibrary, Weizmann Institute, for the invaluable assistance in collecting some ofthe cited articles.

References

Anderson, M., Kates, M., Baedecker, M.J., Kaplan, I.R. and Ackman, R.J.: 1977, The stereoisomericcomposition of phytanyl chains in lipids of Dead Sea sediments, Geochimica et CosmochimicaActa 41, 13811390.

Bede, T.V.: 1896, Concerning the Holy Places Land (Translated by A. Stewart), PPTS (Reprinted byAMS Press), New York, 91 pp.

Dostrovsky, A., Sagher, F. and Verbi, S.: 1959, Clinical experience with an asphaltite from the DeadSea preliminary report, Antibiotic Medicine and Clinical Therapy 6, 518520.

Eglinton, G. and Hamilton, R.J.: 1967, Leaf epicuticular waxes, Science 156, 13221335.Ehrlich, H.L. and Zapkin, M.A.: 1985, Manganese-rich layers in calcareous deposits along the

western shore of the Dead Sea may have bacterial origin, Geomicrobiology Journal 4, 207221.Elkayam, O., Ophir, J., Brener, S., Paran, D., Wigler, I., Efron, D., Even-Paz, Z., Politi, Y. and Yaron,

M.: 2000, Immediate and delayed effects of treatment at the Dead Sea in patients with psoriaticarthritis, Rheumatology International 19, 7782.

Flavius, J.: 1959, The Jewish Wars (English translation by G.A.Williamson), Penguin Books,New York.

Forbes, R.J.: 1959, in: More Studies in Petroleum History, Brill, E.J. (publisher) Leiden.Levy, I.: 1980, The Dead Sea hydrographic, geochemical and sedimentological changes during the

last 25 years (19591984), Israel Geological Survey Bulletin, Jerusalem, February 1987, 61 pp.(in Hebrew).

Neev, D. and Emery, K.O.: 1967, The Dead Sea, Bulletin 41, Israel Geological Survey, Jerusalem,147 pp.

Nishri, A. and Nissenbaum, A.: 1993, Formation of manganese oxyhydroxides on the Dead Sea coastby alteration of Mn-rich carbonates, Hydrobiologia 267, 6173.

Nissenbaum, A.: 1969, Studies in the Geochemistry of the Dead Sea Jordan River System,Unpublished PhD Thesis, University of California, Los Angeles, 288 pp.

BLACK MUD FROM THE DEAD SEA 335

Nissenbaum, A.: 1994, Utilization of Dead Sea asphalt throughout history, Reviews in ChemicalEngineering 9, 365383.

Nissenbaum, A.: 1999, Ancient and modern medicinal applications of Dead Sea asphalt (bitumen),Israel Journal of Earth Sciences 48, 301308.

Nissenbaum, A. and Kaplan, I.R.: 1976, Sulfur and carbon isotopic evidence for biogeochemicalprocesses in the Dead Sea, in: Nriagu, J.O. (ed.) Environmental Biogeochemistry, Ann ArborScience Publishers, Ann Arbor, MI, pp. 309325.

Nissenbaum, A., Baedecker, M.J. and Kaplan, I.R.: 1972, Organic geochemistry of Dead Seasediments, Geochimica et Cosmochimica Acta 36, 709727.

Nissenbaum, A., Aizenshtat, Z. and Goldberg, M.: 1980, The floating asphalt blocks of the Dead Sea.in: Douglas, A.G. and Maxwell, J.R. (eds), Advances in Organic Geochemistry 1979, PergamonPress, Oxford, pp. 157161.

Oldenburg, T.B.P., Rullktter, J., Bttcher, M.E. and Nissenbaum, A.: 2000a, Molecular and isotopiccharacterization of organic matter from recent and sub-recent sediments from the Dead Sea,Organic Geochemistry 31, 251265.

Oldenburg, T.B.P., Rullktter, J., Bttcher, M.E. and Nissenbaum, A.: 2000b, Addendum: Molecularand isotopic characterization of organic matter from recent and sub-recent sediments from theDead Sea, Organic Geochemistry 31, 773774.

Pliny: 1948, Natural History (English translation by H. Rackham), Harvard University Press,Cambridge, MA.

Raz, E.: 1993, The Dead Sea Book (in Hebrew), Nature Reserve Authority, Jerusalem.Rullktter, J., Spiro, B. and Nissenbaum, A.: 1985, Biological marker characteristics of oils and

asphalts from carbonate source rocks in a rapidly subsiding graben, Dead Sea, Israel, Geochimicaet Cosmochimica Acta 49, 13571370.

Shannon, J. and Kamnitzer, S.: 1959, Topical therapy with a new distilled bituminous asphaltite fromthe Dead Sea, American Medical Association Archives of Dermatology 79, 592594.

Sukenik, S.: 1996, Balneotherapy for rheumatic diseases at the Dead Sea area, Israel Journal ofMedical Sciences 32(supplement), 916.

Sukenik, S., Buskilla, D., Neumann, L., Kleiner-Baumgarten, A., Zimlichman, S. and Horowitz, J.:1990, Sulphur bath and mud pack treatment for rheumatoid arthritis at the Dead Sea area, Annalsof the Rheumatic Diseases 49, 99102.

Sulman, F.G.: 1960, Therapeutic properties of bituminous asphaltite, Veterinary Medicine 55(4),5457.

Yechieli, Y.: 1993, The Effects of Water Level Changes in Closed Lakes (Dead Sea) on the Surround-ing Groundwater and Country Rocks, Unpublished PhD Thesis, Weizman Institute of Science,Rehovot, Israel.

Yechieli, Y. and Ronen, D.: 1997, Early diagenesis of highly saline lake sediments after exposure,Chemical Geology 138, 93106.