The Effects of Arsenic Poisoning in the early inhabitants of the Azapa Valley, Chile

Gwyn Madden1 and Bernardo Arriaza2 (1Grand Valley State University, 2University of Tarapaca).

AcknowledgementsResearch and Development, GVSUPadnos International Center, GVSUDepartment of Anthropology, GVSUUniversity of Tarapaca, Arica, Chile

Museo Arqueologica San Miguel de Azapa, Arica, Chile Tim Elrod, GVSU student assistant

AbstracttArriaza (2005) hypothesized the possibility that the Chinchorro of ancient Chile began mummification of the dead due to high numbers of infant death. The Arica Region is understood to have maintained a high level of natural arsenic in the ground water from prehistory through the present. Between the San Jose and Camarones Rivers the arsenic levels range from 20-100 times over that considered acceptable by the World Health Organization. This project investigated evidence of arsenic poisoning and the affects on mortality of 30 infants (neonate to 18 months) from five cemeteries in the ancient Azapa Valley. Arsenic poisoning is known to cause miscarriage, stillbirth, and potentially several birth defects including polydactyly, syndactyly, spina bifida, cleft palate, cleft lip, club foot, orbital malformations, and disjoined hip. Obvious differential diagnoses exist in terms of miscarriage, stillbirth, infant death, and all noted birth defects. Although increased frequency in any one or all of these would be suggestive of arsenic poisoning. The Chinchorro mummies were so extensively reconstructed that observation of their remains specifically were not possible; as well as radio-opacities due to the clay used in their construction. Therefore, naturally mummified remains of their Azapa Valley descendents were observed radiologically in their place. As the level of arsenic has remained high through time, the morbidity and mortality seen in the Chinchorro descendents mirror that seen in the Chinchorro themselves. Our findings indicate that ancient Arica populations faced high levels of perineonatal mortality, although congenital defects are not seen at a high frequency. We suggest that ancient infants of similarages from the Azapa Valley and the Camarones site in particular be tested for arsenic intake as further evidence to support or reject the arsenic hypothesis put forward by Arriaza (2005).

BackgroundThe Chinchorro of Chile’s Atacama Desert were the first culture known to practice artificial mummification from 5000 BC to 1100 BC (Arriaza 1995; Aufderheide et al. 1993; Standen 1997). A great deal of research has been undertaken to describe the culture in terms of subsistence, technology, health, methods of mummification, and reasons behind creating these very intricate mummies. Three potential driving factors have been postulated in the search to understand why the Chinchorro chose to partake in this energy intensive task, including religion, social rank, and love of children. As these were sedentary hunter-gatherers, it is believed that status would likely not have had much of an affect on the decision to mummify. Many of the mummies are children, which is also unusual outside of societies using ascribed status to rank individuals. Religion is always a possibility, however unlike Egyptian mummification, there was no written or pictoral evidence left to define the potential religious purpose of mummification. That leaves the love of children theory to be explained. Arriaza (2005) has suggested that the Chinchorro mummified their deceased children as part of the grief process. As many Chinchorro children were mummified, a potential cause for the increased mortality was sought. In 2005, Arriaza put forward the hypothesis that high levels of natural arsenic may have been responsible for this increase in infant mortality. In the Camarones Valley where artificial mummification first began, arsenic rates are around 1000 ug/L. The World Health Organization states that up to 10 ug/L are acceptable. It is understood that levels of arsenic over 800 ug/L affect fetal growth and cause an increase in stillbirth and infant mortality. As fetal growth is affected, it is assumed that an increase in birth defects would also be present including polydactyly, syndactyly, spina bifida, cleft palate, cleft lip, club foot, orbital malformations, and disjoined hip. The current study was conducted to search for indicators which suggest arsenic poisoning may have been a motivator for artificial mummification.

MethodologyRadiographic analysis of 11 mummies and 20 mummy bundles was undertaken searching for age at death and presence or absence of birth defects (polydactyly, syndactyly, spina bifida, cleft palate, cleft lip, club foot, orbital malformations, and disjoined hip). Thirty one infants were selected from five sites including Camarones, Azapa, Lluta, Playa Miller, San Lorenso, and three individuals of unknown provenience (Table 1). Age of the individuals in the sample was determined using dental calcification (Mincer et al. 1993) when possible, and length of long bones (Johnston 1962). Long bone length was taken on exposed bones, excluding the epiphyses, in mm with digital Mitutoyo calipers.

In this study, polydactyly is defined as the presence of more than the usual 10 digits on the hands and feet, while syndactyly is the absence of one or more of the usual 10 digits. Spina bifida refers to lack of closure of the neural arches of the sacrum, S1-S3 (S4 and S5 are normally open). Failure to close completely at the midline of the palate is characteristic of cleft palate. Cleft lip can occur alone or with cleft palate, but is represented as a lack of closure of the soft tissue in the naso-maxillary area. Orbital malformations are more subjective, but may be associated with Trisomy 21 (Aufderheide and Rodriguez-Martin 1998). Finally, disjoined hip is a congenital disorder in which the affected individual displays aplasia of the lunate surface of the acetabulum, a false acetabulum, flattening of the femoral head, and shortening of the femoral neck (Aufderheide and Rodriguez-Martin 1998:69).

ResultsWhile miscarriage, stillbirth, or neonate (28 days following birth) mortality may be suggestive of arseniasis in this sample, it seems that there is no increase in the number of birth defects. However, a few of the birth defects are not recognizable in individuals of such young ages including spina bifida and disjoined hip due to fusion occurring in later age groups. Given disarticulation, flexion of the body, and lack of development of the femur head and vertebrae, spina bifida disjoined hip was unobservable in most cases. No cases of spina bifida or disjoined hip were noted. Polydactyly, syndactyly, and club foot were not observable in many cases; mummified tissue may be present within the bundles but disarticulation of the skeletons was noted on radiography. In those cases where the hands and feet were observable, no cases of polydactyly, syndactyly, or club foot were noted. Individual AZ 141 T35 shows a potential case of cleft palate, while Lluta 54 T28 (Figure 11) represents a possible case of cleft lip. In the case of Lluta 54 T28, skin shrinkage may be a differential for the soft tissue change. One case of malformed orbits was present, AZ 6 T9 (Figure 13). One individual of 31 presents with a malformation and two others with potential birth defects from three separate cemeteries. This represents a total of 97% of the sample population free from birth defects.

ConclusionThe next step is three fold, first to determine the number of infants present in each population to calculate infant mortality rates. The second step will be to sample older children and adults to widen the search for the birth defects described in the study. It is possible that individuals suffering from birth defects may not have died around the time of birth. This will allow us to have a better understanding of the potential association of birth defects and arsenariasis. The final step will include sampling of skeletal tissue to determine the amount of arsenic present in the bone. This final study will be carried out by Arriaza and colleagues at the University of Tarapaca.

Figure 3. Playa Miller 7 radiograph, inset shows the mummified remains.

Figure 5. Camarones 9 T25 radiograph, inset shows mummified remains.

Figure 7. Camarones 8 T25 radiograph, inset shows mummified remains.

Figure 2. Morro 1-5 14, Chinchorro radiograph

Figure 4. Camarones 8 T22 radiograph

Figure 13. Azapa 6 T9 radiographFigure 12. Azapa 141 Desc 07 radiograph

Figure 11. Lluta 54 T28 radiograph

Figure 8. Lluta 54 T25 radiograph Figure 9. Lluta 54 T13 radiograph

Figure 10. Azapa 6 T190 radiograph

Figure 6. Camarones 8 T19A radiograph

ReferencesArriaza, BT2005 Arseniasis As An Environmental Hypothetical Explanation For The Origin Of The Oldest Artificial Mummification Practice In The World. Chungara 37:255-260.1995 Beyond Death. The Chinchorro Mummies of Ancient Chile. Smithsonian Institution Press, Washington D.C.Aufderheide, A, I Munoz, and B Arriaza1993 Seven Chinchorro Mummies and the Prehistory of Northern Chile. American Journal of Physical Anthropology 91:189-201.Aufderheide, A and C Rodriquez-Martin1998 The Cambridge Encyclopedia of Paleopathology. Cambridge University Press, Cambridge.Johnston, FE1962 Growth of the Long Bones of Infants and Young Children at Indian Knoll. Human Biology 23:66-81Mincer, HH, EF Harris, and HE Berryman1993 The A.B.F.O. Study of Third Molar Development and its Use as an Estimator of Chronological Age. Journal of Forensic Sciences 38:379-90.Standen, V1997 Temprana Complejidad Funeraria en la Cultura Chinchorro: Norte de Chile. Latin American Antiquity 8:134-156.World Health Organization2005 Http://www.who.int/mediacentre/factsheets/fs210/en/

Case Number Age Polydactyl Spina Bifida Cleft Palate Club Foot Eye Malformations Syndactly Disjoined Hip

AZ 6 T190 fetal to newborn Absent Not Obs. Not Obs. Absent Absent Absent Not Obs.

AZ 6 T9 1 year Absent Absent Absent Absent Present Absent Possible

AZ 6 T170 Y 4/4 newborn Absent Not Obs. Absent Absent Not Obs. Absent Not Obs.

AZ 6 T-28 I 1/1 newborn to 6 months Not Obs. Not Obs. Not Obs. Not obs Absent Not Obs. Not Obs.

AZ 115 T3 6 months Absent Not Obs. Absent Absent Absent Absent Not Obs.

AZ 115 T12 6 months Absent Not Obs. Absent Absent Absent Absent Not Obs.

AZ 115 T3 A newborn Not Obs. Not Obs. Absent Not obs Absent Not Obs. Not Obs.

AZ 71 T140 6 months Absent Absent Absent Absent Absent Absent Absent

AZ 71 T310 fetal to newborn Absent Not Obs. Not Obs. Absent Absent Absent Not Obs.

AZ 71 T167 6 mon Absent Not Obs. Not Obs. Absent Not Obs. Absent Not Obs.

AZ 75 T86 9 months-1 year Absent Absent Not Obs. Absent Not Obs. Absent Absent

AZ 140 T54 6 months Absent Not Obs. Absent Absent Absent Absent Not Obs.

AZ 141 Desc 07 newborn Absent Absent Absent Absent Not Obs. Absent Absent

AZ 141 T54 12-18 months Not Obs. Absent Absent Not obs Absent Not Obs. Absent

AZ 141 T47 A 4-6 months Absent Not Obs. Not Obs. Absent Absent Absent Not Obs.

AZ 141 T42 newborn Absent Absent Not Obs. Absent Absent Absent Absent

AZ 141 T40 1 year Absent Absent Absent Absent Absent Absent Absent

AZ 141 T35 1-2 years Absent Absent Present Absent Absent Absent Absent

Lluta 54 T13 6 months-1 year Not Obs. Not Obs. Not Obs. Not obs Absent Not Obs. Not Obs.

Lluta 54 T18 newborn to 6 months Not Obs. Not Obs. Not Obs. Not obs Not Obs. Not Obs. Not Obs.

Lluta 54 T25 fetal Absent Absent Not Obs. Absent Absent Absent Absent

Lluta 54 T28 6 month Not Obs. Not Obs. Present Not obs Absent Absent Not Obs.

San Lorenzo 6 months-1.5 years Not Obs. Not Obs. Not Obs. Not obs Absent Not Obs. Not Obs.

PLM 7 6094 newborn to 6 mon Not Obs. Not Obs. Not Obs. Not obs Not Obs. Not Obs. Not Obs.

Cam 8 T25 1 year Absent Absent Absent Absent Absent Absent Absent

Cam 8 T19 A fetal Not Obs. Not Obs. Not Obs. Not obs Not Obs. Not Obs. Not Obs.

Cam 8 T22 fetal Absent Not Obs. Not Obs. Absent Not Obs. Not Obs. Not Obs.

Cam 9 9 months-1 year Absent Absent Absent Absent Possible Absent Absent

BN 273 indeterminant Not Obs. Not Obs. Not Obs. Not obs Not Obs. Not Obs. Not Obs.

BN 1263 newborn to 6 months Absent Absent Absent Absent Absent Absent Absent

S/Ref 1972 fetal to newborn Not Obs. Not Obs. Not Obs. Not obs Not Obs. Not Obs. Not Obs.

Figure 1. (Above) Map of sites in the study.

Table 1. (Right) Age and presence or absence of birth defects observed in the study group.