LEAD Action News
LEAD Action News Volume 17 Number 1, September 2016, ISSN 1324-6011
The newsletter of The LEAD (Lead Education and Abatement Design) Group Inc.
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La Oroya sigue siendo la ciudad mas contaminada del mundo

Dr. Godofredo Arauzo Chuco, Médico Cirujano, Ginecólogo Obstetra, Investigador del Medio Ambiente, Master en Medicina, E mail: godo_ara@hotmail.com

Dr. Godofredo Arauzo Chuco, Medical Surgeon, Obstetrician Gynecologist, Environmental Researcher, Masters in Medicine, E mail: godo_ara@hotmail.com

PHOTO of the Doe Run metallurgical system (lead smelter) in La Oroya, Perú: Oroya ciudad más contaminada del mundo. No mas humo, Carajo! Oroya, the most polluted city in the world. No more smoke, Damnit!




Goals. This is an investigation of La Oroya, conducted to determine the degree of pollution.


Materials and Methods. The research is the review of the most outstanding literature on this city.


Results. Although the smoke has been removed since 2009, children are still contaminated with lead since newborn: newborn 19.06 ug/dl, children between 2 and 4 years 38.6 ug/dl, children between 2 and 10 years 33.6 ug/dl, children with more than 10 years 29.05 ug/dl, pregnant 39.49 ug/dl, adult men 39.6 ug/dl; lead in the air 27.53 ug/m3, and households lead levels greater than 2000 mg/kg. .


Conclusion. ‘La Oroya’ metallurgical complex stopped working in 2009, but the people are still contaminated, especially with lead. Besides, water, air, soil and rain have been contaminated, and acid rain has occurred.  Despite the complex is not working since 2009, La Oroya remains the most polluted city in the world.




In La Oroya and its surrounding areas there were 5 ‘haciendas’ and 2 rural communities; the development of this city began with the arrival of the railroad in January 1890, the construction of the railway to ‘Cerro de Pasco’ in 1900-1904, and to Huancayo between 1905 and 1908, the founding of the ‘Compañía Mercantil de La Oroya’ in 1892 and the construction of the smelter in 1922 by the ‘Cerro de Pasco Corporation’.


On 1st January, 1974 the revolution of President Velazco Alvarado nationalized the complex and transferred its management to ‘Centro Min Peru’; in 1997, the American company ‘Doe Run Perú’ acquired at auction the metallurgical complex for 121.5 million dollars. There were then 10000 workers; ‘Doe Run’ then began the collective redundancies till have only 2500 workers when the complex stopped working in 2009. (1).  


By acquiring the refinery, ‘Doe Run’ promised to comply with the provisions with the ‘Program for Environmental Compliance and Management’ (PAMA, by its name in Spanish) (2). In 2009 ‘Doe Run’ declared not to have enough capital to purchase minerals that were processed in the complex. The liquidation process (3) was then initiated. The judge of the 39th Criminal Court of Lima initiated criminal proceedings on charges brought by the Prosecutor against the owner of ‘Doe Run’, Ira Rennert, and its manager, Bruce Neil, for alleged fraud against the State (4). On December 6, 2002, a group of citizens of La Oroya sued the Peruvian government for its inaction to protect the right to health and right to a healthy environment. In the first instance (1st April, 2005) and second instance (11th October, 2005), they decided in favour of the plaintiffs; On May 12th , 2006, the Constitutional Court ordered the government to adopt a series of measures in favour of the inhabitants of La Oroya within 30 days; in addition, the Constitutional Court urged various public entities and private companies, including ‘Doe Run’, to participate in the necessary actions for the protection of the health of workers at La Oroya, as well as the environment (5). On November 21st, 2005, three ‘NGOs’, ‘Inter-American Association for Environmental Defence’ (AIDA, by its name in Spanish), ‘Centre for Human Rights and Environment’- CEDHA, by its name in Spanish-, and ‘EarthJustice’  requested  precautionary measures in favour of the inhabitants of La Oroya to the ‘Inter-American Commission on Human Rights’. In March 2010, the ‘Inter-American Commission’ held a hearing in Washington to discuss the implementation of such precautionary measures; representatives of the applicants complained there about the weakness of the measures taken by the Peruvian government for assisting the inhabitants of La Oroya (6).


Herculaneum, Missouri city in the United States, is a city in which a cast of ‘Doe Run’ processes several metals. In August 2011, the ‘Doe Run’ companies Fluor Corp and A.T. Massey Coal, were sentenced to pay 358.5 million dollars (38.5 million as compensation for exposure to air emissions of lead, and 320 million intended to compensate citizens for damages to their health from lead contamination between 1986 and 1994. The state of Missouri ordered that ‘Doe Run’ released to air only half a kilo of lead per ton of refined lead. (3). In 2010, ‘Doe Run’ initiated an international arbitration, alleging the violation of its rights as foreign investor, guaranteed by the Free Trade Agreement between Peru and the United States, and claimed to be a victim of unfair and inequitable treatment, claiming a compensation for expropriation of 800 million dollars. (7).


In 2016 the commission of the arbitration took, unanimously, the wise and historic step of rejecting this demand (7a). In March 2012 the U.S. Congress MPs urged the State Department and the Treasury Department to refrain from any support for the company in the arbitration proceedings, based on the F.T.A. with the government of Peru; where appropriate, the U.S. government should require ‘Doe Run’ the withdrawal of the claim.


The metallurgical complex in La Oroya was rated as the metallurgical capital of Peru and South America; it was one of the 4 major refineries in the world, along with ‘Hoboken’ in Belgium, Roonskar in Sweden, and Dowe Roonskar in Japan (8), and considered by Blachsmith among the 10 most polluted cities in the world.

This research was performed in order to determine the contamination with lead and other substances to the population after its closing down.




The Metallurgical Complex of La Oroya (CMLO, for its name in Spanish) was composed of a set of smelters and refineries specially designed to refine the polymetallic ores of the Peruvian Central Andes: copper, zinc, silver, lead, indium, bismuth, gold, selenium, tellurium and antimony, and nine sub products: zinc sulphate, copper sulphate, acid sulphate, arsenic trioxide, oleum, sodium bisulphate, zinc oxide, zinc powder, zinc concentrate, in order to extract from them high value elements such as silver, indium, bismuth, and others (10). The technology used in casting follows the same process since the foundation of the Complex in 1922; since then, only minor modifications (7) were carried out.


According to the Program for Adequacy of the Environment (PAMA, for its name in Spanish), written by ‘Centro Min’, the toxic liquids were released without treatment through 40 effluents into the Mantaro River, and there were released to the air 1000 tons of sulphur dioxide, 2500 tons of lead, 2500 tons of arsenic, 20 tons of cadmium, and 20 tons of particulate matter, on average per day, only through the highest chimney, 167.5 meters, without the counting of the toxic contaminants that were released through 95 small chimneys, the industrial incinerator and the Malpaso reservoir (8); in total there were 160000 tons of toxics eliminated per day (Chuqimantari 1962). The airborne concentrations of lead, cadmium, arsenic, sulphur dioxide and others were increased substantially after ‘Doe Run’ took over: 1163% lead, 606% arsenic, and 1990% cadmium (12). Not only the above mentioned heavy metals were increased, but also the 11 metals and 9 by products.


The area affected by the fumes of La Oroya reached the extraordinary extension of 7000,000 hectares around Oroya, the best area of central Peru; officially, only 14,000 hectares (12) is the area recognized. The city is a living laboratory; its inhabitants are contaminated by the synergy of toxic heavy metals and their by-products. What happens to children in Oroya is a crime (14) and it’s an oversight function of the Peruvian government. The quality sampling and monitoring analysis employed by the company are doubtful; there is no certainty that the information provided to the Ministry of Energy and Mines (MEM, for its name in Spanish) is accurate, reliable and adequate; data given to MEM could be considered as an approximation, and can be undervalued; they are not electronic of graphed data; all the air quality

Parameters  had deteriorated dramatically since ‘Doe Run’ took over the complex (15).


The pollution generated by La Oroya was not only confined to this city, but also it contaminated markedly distant areas as the city of Concepcion which is 100 km from La Oroya (16). The refinery of La Oroya also contaminated the rain with the production of acid rain (pH 5.6 or less) from the 1,000 tons of sulphur dioxide (SO2) which it produced per day, and that was the highest concentration in the world (17). The 48% of the rain falling in the Mantaro Valley was acidic; in Concepcion 98%, and in La Oroya it was extremely acidic: pH 3.5 to 4.2 (18). In August 2008 (13-08-2008) the SO2 concentration reached the historical and horrifying limit of 27,000 ug/m3; a few days later Blacksmith visited La Oroya and that day the concentration of SO2 was 0 (zero) (19); the permitted concentration is 200 ug/m3.  




The research conducted by the Yale University in 2009 with the complex already paralysed found that the lead levels in the air were up to three times higher than the maximum permitted limits; likewise, the concentration of sulphur dioxide (SO2) was exceeded in 4,500 times; with respect to cadmium, this heavy metal was exceeded in 45% of the records, and the highest value was up to three times the maximum permissible limit (LMP, by the initials in Spanish). The research used information provided by ‘Doe Run’ and the medical centre of La Oroya between December 2009 and February 2014.


(20-21). The population is still polluted by the gases that were released by the heavy metals that are deposited in the soil. The consultants ‘Ground Water International’, ‘Science Integrity’, and ‘Knight Piesold Consulting’ asked by the state agency ‘Activos Mineros’ (Activ Miners, in English) have carried out a magnificent study of the extent of the pollution generated by the metallurgical complex since the beginning of its activities, and they have concluded that the foundry has affected 2,700 square km around  La Oroya, especially with lead and arsenic, a total area equivalent to the 83% of metropolitan Lima. This has affected not only the province of Yauli and La Oroya, but also the provinces of Junin, Tarma, Jauja and Concepcion. The most affected area is the Old Oroya, more than 2 km to the south. The highest concentration of heavy metals was found in the first 10 cm deep and the concentration decreases till the 80 cm deep. They say that these toxic heavy metals remain unchanged as oxides and hydroxides. Even up to 3 km from the complex there were found lead levels between 3,000 and 16,000 ug/kg (7.5 to 40 times higher than the permitted limit), and arsenic level between 500 and 5,700 ug/kg (1.5 to 114 times higher than the permitted). The risk of cancer from this high concentration of lead and arsenic is 2.2 cases per 100: it is unacceptable. The newspaper ‘El Comercio’ said that 2,700 km2 of land around La Oroya are poisoned by lead and arsenic (22).


After 2009, when the La Oroya smelter ceased operations, lead levels in maternal blood, in newborns and in placentas were investigated; there were found in maternal blood, 27.4 ug/dL, in newborns 19, ug/dL, and in placentas 319 ug/100gm (23).


In 2009 the metallurgical complex of La Oroya stopped working, and in the years 2011 to 2015 the Health Center of La Oroya, belonging to the Health Network Yauli Oroya conducted a research of the lead levels in the blood of children and pregnant women, which are plotted in Figures 1, 2, 3 and 4, where high lead levels can be seen in the blood of children and pregnant women (24) produced by the emanation of gases of lead accumulated in the soils of La Oroya and nearby. 














It is reiterated that the La Oroya refinery ceased operations in 2009. From 2009 to 2014 the University of Yale in the U.S. studied the Oroya by using information from Doe Run and the Health Centre of La Oroya, and found that the level of lead in the air was three times higher than the allowable maximum limit (LMP, by its initials in Spanish), the concentration of sulphur dioxide (SO2) exceeded in 4,500 times the LMP, and the concentration of cadmium exceeded 300% that LMP.


The consultants Ground Water International, Science Integrity, and Knight Piesold Consulting, at the request of the Peruvian government, made a magnificent study of the extent of the pollution generated by the metallurgical complex since it began its activities. They have concluded that the Foundry has affected 2,700 km2 around La Oroya, especially with lead and arsenic; not only the provinces of Yauli and La Oroya, but also the provinces of Junin, Tarma, Jauja, and Concepcion. The most concentration of heavy metals was found in the first 10 cm deep, and there were lesser amounts of them up to 80 cm from the surface of the soil; and the consultants state that these toxic metals remain unchanged as oxides and hydroxides. Up to 3 km from the resort they found lead in the soil between 3,000 and 16,000 ug/dL (7.5 to 40 times the allowable limit), and arsenic from 500 to 5,700 ug/kg (1.5 to 114 times more than allowed). The risk of cancer by this high concentration of lead and arsenic is 2.2 cases per 1000, which is unacceptable. 


The people of La Oroya began their pollution since the refinery began operating, in 1922; it is the most polluted city in the world; its inhabitants are contaminated with a mixture of heavy metals which do not degrade; it is a living laboratory; it is a crime experienced by children. The environment pollution by mining companies can be decreased when it is put into effect an updated technology for mineral processing, and the universal principle put also into effect since 1972 by the countries of the Organization for Economic Cooperation and Development (OECD): THE POLLUTER PAYS (25-26).


The study by Castro and Cols in 2003, when the complex had already been stopped for 4 years, showed that children were being born contaminated with lead: 19 ug/dL. The World Health Organization (WHO) sets a limit of 10 ug/dL of lead. The Centre for Disease Control U.S. (CDC) reports that the level of lead in the blood should not be greater than 5 ug/dL (27), and it is shown that there is no safe level in the blood (28). The average life of lead in the blood is one to two months, and, once deposited in the bones or teeth, it has an average life of 20 to 30 years.


AIDA has spent over a decade working and monitoring the situation in La Oroya; during these years it has seen the gravity of the damage to health that the residents of La Oroya have suffered because of the pollution to which they have been exposed, and still they are, by the fumes of the toxics accumulated in soils; the government must assume its obligations and comply fully with the precautionary measures of the IACHR, which are valid at the moment.




1.- Barja A. Historia de una Villa que Hoy es Gran Ciudad La Oroya. Revista Pluma Digital 2015.


1.- Barja A. History of a Villa which is Today  The Great City of La Oroya. Magazine ‘Pluma Digital’ 2015.


2.- RPP Noticias. Doe Run: Una historia de contaminación y acuerdos incumplidos http://rpp.pe/economia/economia/doe-run-una-historia-de-co.


2.- RPP News. Doe Run: A History of pollution and unfulfilled agreements. http://rpp.pe/economia/economia/doe-run-una-historia-de-co.


3.- Mantaro Revive, 20 de noviembre de 2011. http://elmantarorevive.blogspot.com/2011/12/indecopi-reconoce-doe-run-cayman-como_01.html.


3.- Mantaro Revives, November 20, 2011. http://elmantarorevive.blogspot.com/2011/12/indecopi-reconoce-doe-run-cayman-como_01.html.


4.- http://www.larepublica.pe/03-12-2011/juez-abre-proceso-propietario-de-doe-run-ira-rennert-por-credito-fraudulent0.


5.- Sentencia del Tribunal Constitucional, cf.



5.- Constitutional Court Ruling, ef. http://www.tc.gob.pe/jurisprudencia/2006/02002-2006-AC.html


6.-  Comisión de Derechos Humanos (http://www.aida-americas.org/es/project/laoroya_en y el vídeo de la audiencia: http://vieo.com/10469416


6.- Human Rights Commission (http://www.aida-americas.org/es/project/laoroya_en and the video of the hearing http://vieo.com/10469416


7 SERVINDI- Perú: FIDH Presenta Informe sobre La Oroya, una de las Ciudades más Contaminadas del Mundo 2013 Http://www.servindi.org/actualidad/86904.


7.- SERVINDE- Peru: FIDH Presents Report on La Oroya, one of the most Polluted Cities in the World, 2013. Http://www.servindi.org/actualidad/86904.


 7a.-  SemanaEconòmica.com. El Perú ganó arbitraje a Renco Group por caso La Oroya 2016. http://semanaeconomica.com/article/economia/medio-


7ª.- SemanaEconómica.com. Peru won the arbitration against ‘Renco Group’ 

  in case of La Oroya, 2016.

8.- Programa de Adecuación  de Manejo Ambiental  (PAMA).Complejo Metalúrgico de la Oroya 1996.


8.- Environment Management Improvement Program (PAMA, by its initials in Spanish). La Oroya Metallurgical Complex, 1996.


9.-Arauzo G- La Oroya la Ciudad más Contaminada del Mundo. Lead Action News  2009;9(2) . 



9.- Arauzo G- La Oroya, the most Polluted City in the World. Lead Action News, 2009; 9(2). http://www.connuestroperu.com/actualidad/2097-la-oroya-la-ciudad-mas-contaminada-del-mundo.


10.- DOE RUN PERÛ. Operaciones /Complejo Metalúrgico de la Oroya/ Descripción.  http://www.doerun.com.pe/content/pagina.php?pID=90


10.- DOE RUN PERU. Operations/Metallurgical Complex of La Oroya/ Description. http://www.doerun.com.pe/content/pagina.php?pID=90


11.- Garcia C. El Plomo de Doe Run 2005.



11.- García C. Doe Run’s Lead, 2005. www.paginadigital.com.ar/articulos/2005/2005terc/noticias7/intoxicacion-plomo-061205.asp


12.- Portugal C, Hurtado W y Aste J. Los Humos de Doe Run. 2003-


12.- Portugal C, Hurtado W and Aste J. The Doe Run’s fumes, 2003.


13.- Pajuelo J. Medio Ambiente y Salud de la Oroya, 2006.


13.- Pajuelo J. Environment and Health of La Oroya, 2006.


14.- Saravia G. Médico Denuncia Contaminación por Metales Pesados y el Estado le hace la Vida Imposible 2015. Ideele Revista 2015




14.- Saravia G. A Doctor Reports Heavy Metal Pollution and the state makes his life impossible, 2015.


15.- Cederstav A y Baranadiaran A. La Oroya no Espera 2002.


15.- Cederstav A and Baranadiaran A. La Oroya does not wait, 2002.


16.- Universidad de San Luis de Missouri USA. Estudio Sobre la Contaminación Ambiental de los Hogares de La Oroya y Concepción y sus Efectos en la Salud de sus Residente 2005.


16.- University of St. Louis, Missouri, U.S.A. A study of the Environmental Pollution of the Households of La Oroya and Concepcion, and its effects on the health of their residents, 2005.


17.- NASA.Earth Observing  System (EOS) AURA 2006. http.//www.aura.gsfc.nasa.gov/science/top10_smelter.


17.- NASA.Earth Observing  System (EOS) AURA 2006.



18.- Arauzo G. La Lluvia Acida en el C entro del Perú 2010 http://www.ecoportal.net/Temas-speciales/Contaminacion/la_lluvia_acida_en_el_centro_del_peru)speciales/Contaminaciòn/la_lluvia_acida_en_el_centro_del_peru.


18.- Arauzo G. The Acid Rain in Central Peru, 2010. http://www.ecoportal.net/Temas-speciales/Contaminacion/la_lluvia_acida_en_el_centro_del_peru)speciales/Contaminaciòn/la_lluvia_acida_en_el_centro_del_peru.


19.- El Comercio. La Concentración del SO2 Llegó a Nivel Histórico y Espeluznante, 2008.



19.- El Comercio. The Concentration of SO2 reached an historical, horrifying level, 2008. www.elcomercio.com.pe/ediciononline/HTML/2008-08-19/azufre-aire-oroya-supero-niveles-historicos.html


20.- Sociedad Peruana de Derecho Ambiental (SPDA). 2016



20.- Peruvian Society for the Environmental Law, 2016. http://www.actualidadambiental.pe/?p=18872


21.- CQPPER. CQPPER. La Oroya: Registros de Metales Pesados en el Aire Cuando el Complejo Metalúrgico no Operaba 2016.  http://www.cqpperu.org/noticias/143-la-oroya-registraron-metales-pesados-en-el-aire-cuando-complejo-metalurgico-no-operaba)


21.- COPPER. COPPER. La Oroya: Records of Heavy Metals in the Air When the Metallurgical Complex didn’t work, 2016. http://www.cqpperu.org/noticias/143-la-oroya-registraron-metales-pesados-en-el-aire-cuando-complejo-metalurgico-no-operaba)


22.- El Comercio 11-11-2009.


23.- Castro J, Chirinos D, Ríos E. Rev. Perú. med. exp. salud pública 2013;30(3).


23.- Castro J, Chirinos D, Ríos E. Rev. Perú. med. exp. Public Health,  2013;30(3).


24.- Oscanoa B. Metales Pesados.  Centro de Salud de La Oroya Red de Salud Yauli La Oroya Dirección Regional de Junín 2016.


24.- Oscanoa B. Heavy Metals. Health Center La Oroya, Health Network Yauli La  Oroya,  Junin Regional Management, 2016.


25.- Leyva M. Quien Contamina Paga; un Principio de Derecho Internacional




25.- Leyva M. Polluter Pays; a Principle of International Law. http://www.monografias.com/trabajos37/quien-contamina-paga/quien-



26.- Garcia T. Perspectiva Jurídica del Principio Quien Contamina Paga. Dereito 2001; 10(1):49.


26.- García T. Legal Perspectives of the ‘Polluter Pays’ principle.

Dereito 2001; 10(1):49.


27.- Centers for Disease Control and Prevention (CDC). Childhood Lead Poisoning Prevention Program 2016. http://www.cdc.gov/nceh/lead/acclpp/blood_lead_levels.htm


28.-  Qui J, Wang K, Wu X, et al. Blood Level in Children 0-6 Years Old in Hunan Province, China From 2009-2013. PLOS One 2015;10(4).


29.- Vazquez. E, Maldonado E, Vedagary F,y Col. Intoxicación por Plomo. Reporte de un Caso y Revisión de la Literatura. An Med Asoc Med Hosp ABC 2002;47(1):33.


29.- Vazquez  E, Maldonado  E, Vedagary F, and Col. Lead Poisoning. Case Report and Review of Literature. An Med Asoc Med Hosp ABC 2002;47(1):33.




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