case 2 of paleopathology case reviews

Chronic Arsenic Poisoning in a Valley of Northern Chile

Image Directory:
1 Mummy w/Arsenic Sulfide Face Paint from his turban
2 Camarones Mummy
3 Hyper- & hypopigmentation
4 Extent of Severe Skin Pathology
5 Arsenic Lesions in the Lungs
6 Arsenic Levels in Nails, Ribs & Skin (pre-Columbian)
7 Arsenic Levels in Nails & Hair (modern)

Tables 1-4

Mummy with arsenic sulfide face paint from his turban The Camarones Valley, 100 km. south of the city of Arica in Northern Chile, is a rich archaeological site with prehistoric populations going back 10,000 years or more. It has a small stream that receives melting snow and rain from the highlands in good years, and empties into the Pacific Ocean. Plans were made in the 1980's to build a fishing port at the mouth of the valley. The Department of Anthropology at the University of Tarapaca decided to salvage what archaeological material it could prior to construction.  Two areas were excavated. One contained the graves of early people from 5,000 or more years before present (BP). Another consisted of later groups dating from just prior to the European invasion, around 1500 to 1600 BP. This is a mummy with arsenic sulfide face-paint from his turban.
Camarones mummy This area showed evidence of Inca and European contact into the colonial period. Venetian beads, iron and Spanish cloth were found. The late pre-Columbian and colonial dwellers of the Camarones Valley belonged to a coastal culture known as the "Gentilar." They became acculturated after the Inca conquest. They supplied the Inca with marine products, copper, possibly corn and hot peppers in exchange for cloth and pottery. Apparently they were making none of their own anymore.
Hyper- & hypopigmentation The earliest individuals excavated (5,000 or more BP) showed extensive sign of trauma with wounds from projectile points and fractures, but no signs of skin lesions. The later people (1500-1600 BP) were essentially free of trauma, but had extensive skin lesions from chronic arsenic poisoning. The lesions were not pox-like. They were areas of hyper- and hypopigmentation. On consultation with University colleagues it was discovered that several faculty in the Department of Biochemistry had been studying the arsenic content of water, foodstuff, and animals in the valleys of Northern Chile, including Camarones Valley. The skin lesions were compatible with those of chronic arsenic poisoning.
Extent of severe skin pathology Thirty two mummies were studied: 11 children from 0-15 years old, fifteen adults from 16-40 years old, and six geriatric adults over 40 years of age. On physical examination, 27 were found to have skin lesions compatible with chronic arsenic poisoning. This was graded as severe, moderate and mild in the various locations. Table 1 shows the distribution of skin lesions in 27 individuals with chronic arsenic poisoning and the presence of Mees lines on the nails. Fifty two percent had Mees lines on the nails. Table 2 shows the distribution on the skin according to age.
Arsenic lesions in the lungs The internal organs with lesions are seen in Table 3. These were recorded as positive for the mummies with organs. Some of the mummies did not have all their organs. The image on the right shows arsenic lesions in the lungs.
Arsenic levels in nails, ribs & skin (pre-Columbian) A chemical analysis of nails, ribs and skin is shown according to age in Table 4. We could only assume in retrospect that arsenic levels on these ancient people was similar to what they are in the valley's modern inhabitants. A further study was undertaken on modern inhabitants of the valley and their foodstuffs and fresh water sources. The modern rural people were living under very similar conditions to those of their pre-Columbian ancestors.
Arsenic levels in nails & hair (modern) River water in the Camarones valley today has an arsenic level of 0.45 mgs/liter at the mouth where it enters the Pacific Ocean, and 1.09 mgs/liter high up in the valley. River water from a similar control valley 100 kms to the north was 0.088, 15 kms from the Pacific. Both valleys had springs with arsenic levels below 0.06. While an admissible daily dose of arsenic is 0.31mgs., a calculated daily dose in Camarones for humans was 2.0 - 2.5 mgs and in the control valley, 100 kms to the north, it would be around 0.13 mgs. Examination of the modern inhabitants for stigmata of arsenic poisoning revealed 59% with lesions attributable to arsenic, while no one from the control Valley had lesions of this nature. In Camarones there was a single case of skin cancer due to arsenic in each of the pre-Columbian and modern inhabitants studied.

Samples of nails, hair and urine were analyzed for arsenic from modern inhabitants of Camarones and the control Valley. The acceptable normal values for nails is 4.0 mgs, hair 1.92 mgs and urine 0.22 mgs. It was noted the arsenic concentration varied with age, with the highest levels in children and the geriatric populations, a variation similar to that seen in the pre-Columbian and Colonial mummies.

Adlai Stevenson referred to our planet Earth as a "Little spaceship" on which we travel together dependent on its vulnerable supplies of air and soil. Numerous people elaborate on the gross pollution of our surroundings by urbanization and industry, but they fail to mention that many natural poisons and toxic agents were present before the industrial age. Problems with these agents had begun even before man was present on this earth.

One important toxic agent found everywhere in nature is arsenic. This agent in its nontoxic metal form and its highly toxic trivalent form are found on the surface, while its pentavalent form, generally less toxic, is found deep in the soil. In volcanic areas of our earth they are found in heavy concentration; for example in New Zealand they may reach a concentration in the soil of 10,000 parts per million. This leaches into the water where it may reach 1000 parts per million.

The toxicity of arsenic is a double-edged sword. In fact, it is not toxic for most animals, and man has used it as a medicine for nearly 3,000 years. It has been used in the treatment of amoebiasis, syphilis and fungal infection of man and plants. In Austria it is still used by mountain dwellers who mix the metallic arsenic with lard and eat it spread on bread to prevent mountain sickness, to stimulate the appetite, and to give the skin a rosy complexion. The extent of this health problem will vary depending on the daily dose of arsenic and its accumulation.

Most people, unlike animals, cannot handle the toxic arsenic oxides. Most of the world's studies involving sublethal doses include a number of exposed individuals who show no evidence of intoxication. The initial manifestations of the disease can be easily overlooked since its symptoms--gastrointestinal nausea or a cold with hoarseness--are also the symptoms of a virus. In addition, individuals usually live in areas of exposure for months, or even several years, before skin lesions appear. In the mummies, a calculated daily dose before the appearance of skin lesions was 2.9 mgs over 4 years. In one Mexican study, the daily dose was 2.6 mgs in eight years, with an accumulation of 12 to 18 gms over 11 to 16 years.

It should be mentioned here that the severity of individual lesions is not reflected since over 53% of the mild lesions occurred under the age of 40. The more dangerous lesions, such as ulceration of the palms of the hands and soles of the feet with horny growths on the skin, were seen mainly in people over 40 who experienced an accumulated dose over 30 gms. There is also a selective preference for the trunk and nails which may be due to higher sulfur compounds in these locations. It is also possible that arsenic is recirculated within the body for 10-15 years. Unfortunately, removal of the source after long exposure does not guarantee protection against the development of skin or other forms of cancer . Among both the mummies and the modern inhabitants a single case of skin cancer was present, which in general requires an exposure of 18 to 25 years.

The following conclusions were drawn from this study:

1. A certain number of exposed individuals do not develop clinical disease when exposed to chronic arsenic poisoning.
2. After the development of clinical disease there is a period in which the disease subsides and the individual shows tolerance to arsenic.
3. Individuals, when they reach the geriatric age, have an increased severity of the disease with a series of new medical problems such as pneumonias and cancers due to arsenic.
4. One of the encouraging environmental factors is that subterranean water springs with acceptable arsenic levels are readily available in all the valleys. Unfortunately, the people prefer to drink the arsenic-poisoned river water, claiming it tastes better. Thus educational programs are necessary and the digging of wells should be encouraged. Problems must still be faced when it comes to shrimp and certain foodstuffs that concentrate arsenic.

Updated March 7, 2006