Drinking water quality in areas impacted by oil activities in Ecuador: associated health risks and social perception of human exposure

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Oil production and refining in Ecuador: Historic, economic and legislative context

Oil production in Ecuador began inshore on the Pacific coast in 1911, and lasted concentrated in this region for 60 years (BCE, 1990); at present, this region produces less than 1%, while 99% is concentrated in the Ecuadorian Amazon region, mainly in the provinces of Orellana and Sucumbíos (Bustamante and Jarrín, 2005; EP Petroecuador, 2013). Extraction crude activities in the Northern Ecuadorian Amazon Region (NEAR) began in 1967 with the drilling of the first oil well by Texaco Gulf, becoming economically important in 1972, with a daily production of 300,000 barrels reaching 522,000 barrels in 2017 (BCE, 2018; EP Petroecuador, 2013). Since 1972, crude oil exportation has represented the main source of income for the Ecuadorian economy, exceeding 50% of total exportations from 2004 to 2014 (Figure I), and settling down at 37% in 2017 (BCE, 2010; Calderón et al., 2016; MCE, 2017). In South America, Ecuador is the 4th larger oil producer and the 3rd country with the largest oil reserves (OPEC, 2017).
Oil refining processes in Ecuador have been centered on the Pacific coast since their origin (1926); this region possesses 90% of the total refining production. The country has three refineries: “Esmeraldas”, « Libertad » and the industrial complex “Shushufindi”. The Esmeraldas Figure I. Percentage of total exportations for the main Ecuadorian exporting products from 1990 to 2015. refinery (built in 1977) represents 63% of the total refining capacity (EP Petroecuador, 2013). La Libertad and Esmeraldas are refineries situated on the coast, whereas the Shushufundi refinery is located in the Northern Amazon area.
The oil production infrastructures concentrated in the NEAR and the refining facilities on the Pacific coast have generated many systems of storage and transport of crude oil and derivatives: the Trans-Ecuadorian pipeline (SOTE), the San Miguel-Lago Agrio pipeline (OSLA), the heavy-crude Pipeline (OCP) and the Eden Yuturi-Villano Pipeline. These pipelines collect and transport crude oil from the NEAR, crossing the Andean Cordillera, until the Balao seaport in Esmeraldas (EP Petroecuador, 2013).
Environmental practices related with oil industry in Ecuador remained unregistered until 1972: the first bibliographic reports dated back to the early 1970s and appeared because of the importance of Texaco trial in the last two decades (1990-2010). Some authors pointed out documents from 1972 which explained to employees that only environmental incidents already known by the press or the government should be reported, otherwise they do not have to be registered and the existing reports must be destroyed (Andrade, 2008; Buccina et al., 2013).
Through the 28 years that Texaco Gulf Company with other 12 private oil companies operated in the NEAR, no environmental regulation was enforced by Ecuador Government (BCE, 1990; Narváez, 2000). Oil production in a context of non-environmental policies caused almost 65 billion liters of crude oil spills, 76 billion liters of formation water discharged in the environment, and the burning of 7 million cubic meters of gas. And more than 1000 pools of toxic waste were abandoned (Narváez, 2000). In 1992, Texaco-Gulf transferred all its goods to the state company Petroecuador, without any remediation obligations imposed by the government at that time, and industrial practices remained similar for several years (Kashinsky, 2008).
The historic of the environmental practices related with the refining zones in the Pacific coast since the beginning has not been published; (Narváez, 2000) presents a record (1997-2000) of oil spills, pipeline and fire incidents that affected the Esmeraldas and Teaone rivers since 1997, but not previous information exists. CEPAL (1990) indicates that the obsolescence of infrastructures contributed to chronic pollution of the air, water and soil leaving a favorable scenario for socio-environmental conflicts; in the case of liquid effluents of the REE, they used to be diluted and dispersed in the Teaone and Esmeraldas rivers.
Chachalo (2016) signaled that Esmeraldas refinery (REE) generated more than 30000 tons of dangerous byproducts in August 2014, and that new treatment processes are replacing the old ones since the last renovation in 2015. These kind of improvements were already realized in the refinery facilities in 1987, 1995 and 1997 allowing to increase the refining capacity from 55000 to 110000 barrels per day; but, these technical adjustments have not improved the refinery’s impact on the environment (Cevallos, 2015).
In 2015, the Ecuadorian Ministry of Environment (MAE) inventoried 3 refineries (2 in the Pacific coast and 1 in the NEAR), 2 main oil pipelines, 6383 wells and 1190 platforms while the environmental liabilities were estimated at 1170 oil spills and 2489 waste pits (Ministerio del Ambiente (MAE), 2015a). These liabilities have induced important environmental and social impacts; several indigenous communities were forced to migrate (Buccina et al., 2013) and the pollution of surface and ground waters in Orellana and Sucumbíos provinces affected this rich biodiverse area (Bustamante and Jarrín, 2005; Marx, 2010; Wernersson, 2004).
According to the MAE-PRAS (2015), 97 % of the total environmental liabilities (waste pits and oil spills) is located in the NEAR being the water the abiotic component that local people claim as the most affected by oil activities (Clinica Ambiental and CSS, 2017).
The activities involved in the oil industry are grouped into five main phases: (1) exploration, (2) exploitation or production, (3) storage and transport, (4) refining and (5) commercialization. These activities impacts on the environment mainly affect water sources. However, production and transport phases are the most critical due to the high volumes of formation water (very salty liquid that contains hydrocarbons and metallic elements), drilling mud, process water and the risk of spills (Avellaneda, 2005; Fontaine, 2013). The activities of exploration-exploitation are now in charge of the Petroamazonas public company while the activities of refining, transport and sale are under the control of the Petroecuador public company. Some international-private companies (Chinese, Canadian, etc.) work together with the national enterprises.
Some authors have listed many of the cause-effect variables in the case of oil pollution in the Ecuadorian Amazon region (Buccina et al., 2013; IESC, 2004; Narváez, 2000; Widener, 2007). Some of the current practices mentioned by these authors for the 1972-1993 period, and that can affect negatively the aquatic system are shown in the Figure II, and listed below: – One to three waste pools were built in the vicinity of oil wells to collect byproducts formed by drilling mud, water, oil residues and formation water.

Social and health context in oil activities zones in Ecuador

The petroleum production zones in Ecuador constitute an interesting case of study because it reflects the historical evolution of the land and natural resources use. It is possible to visualize the relations economy-society-environment and identify a group of four actors that define this dynamic: 1) the native inhabitants 2) the extractive companies, 3) the local and international organizations and 4) the Ecuadorian State (Juteau-Martineau, 2012). This latter has been the main integrator (positively or negatively) among the other actors during the stages of the development of the country before the agrarian reform (Juteau-Martineau et al., 2014), during the first and second agrarian reform period (1964-1979) and in the petroleum era (since 1973).
Before the agrarian reform, in the Amazon rainforest, the relationships between the native inhabitants and Nature were based in an itinerant small-scale agriculture and other productive practices preserving the ecological equilibrium and the conservation of natural resources in the long term (Varea et al., 1995). The Ecuadorian economy was based on the exportation of raw agriculture products coming from the coastal region (banana and cocoa) and the rural population generally served as workforce in these activities (Acosta, 2006).
During the first agrarian reform period (1964-1972), only Pichincha and Esmeraldas (where access roads existed) and Morona Santiago (where roads were built to encourage migration to the Southern Amazon) showed important new areas of colonization (Gondard and Mazurek, 2001). During this period, the petroleum industry, centered on the Pacific coast, was minimal (EP Petroecuador, 2013). But, a strong colonizing boom occurred since the issuance of the second agrarian reform law, which coincided with the start of oil production in the NEAR (1972) and the construction of the refinery (1975) in the Esmeraldas province (Wasserstrom and Southgate, 2013). As a consequence of these events and of the mining activities, the colonization of Amazonian provinces and Esmeraldas increased exponentially (Figure III).
When the road Quito-Lago Agrio was completed (1972), the NEAR became more accessible. The Ecuadorian government advanced with the colonization of zones considered uninhabited (ignoring the right of original groups regarding the land occupation) and the oil companies were asked to build complementary facilities (roads and bridges) (Wasserstrom, 2013). The companies that exploited natural resources (wood, petroleum, etc.) with the complicity of the government forced the displacement of ethnic groups, and the confrontation between “colonos” and indigenous people became usual (Jarrín et al., 2016). The petroleum, logging or agro-industrial companies were based on economic interests extracting the natural resources with the minimum investment in workforce and technology; the “colonos” who became the main local workforce in the companies, expanded the agriculture for their self-consumption or to supply the local market (Gondard and Mazurek, 2001; Varea et al., 1995). In these productive schemes, neither environmental nor socio-cultural aspects were considered.

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Environmental and human risk assessment

Many tools are proposed to evaluate the risk of PAHs distribution in the environment. All these tools are based on different “toxicity reference values” (TRVs) like the quality guidelines/reference concentrations, reference doses, toxic units and toxic equivalent factors(Anses, 2018; European Commission, 2012).
Environmental quality guidelines, as defined by the US Environmental Protection Agency, are the highest concentrations of contaminants in a specific compartment (water, sediments, soil, air) that are expected not to pose a significant risk to most of the species in a given environment (US EPA, 2015b, 2018a). Different water quality guidelines (WQG) for PAHs have been developed at local and international levels; among them, the Canadian (CCME, 2018) and European (European Commission, 1998) guidelines seem the most complete, and propose quality guidelines for individual components, while Ecuadorian (RAOHE) and US-EPA guidelines are defined by the sum of different molecules. A compilation of different surface water regulations is presented in Table SI-2.
The sediment quality guidelines (SQG) are defined as numerical limits from which toxicity tests on benthic environments ensure the protection of the aquatic life from adverse effects (CCME, 1999); Keshavarzi et al. 2015) sets SQG in several ranges : “Effect range low” (ERL) and “threshold effect level” (TEL) defined by concentrations below which adverse effects are improbable and infrequently expected; “effect range median” (ERM) and “probable effect level” (PEL) that define the concentration at which adverse effects are more probable to occur. Other values like NOEL (no observed effect level) and LOEL (lowest observed effect level) are also considered in Canadian sediment quality guidelines (CCME, 1999). In the case of Ecuador, there is no regulation for PAHs contents in river sediments, but a recent amendment (TULSMA, 2015) allows the use of international SQGs except for oil activities monitoring (where RAHOE applies). We used the ERL/TEL and PEL/ERM for assessing the environmental quality of the different basins. References doses (RfD), According to the Environmental Protection Agency (US EPA, 2019) RfD is a numerical estimate of a daily oral exposure to the human population that is not likely to cause harmful effects during a lifetime. This concept is extrapolated for other exposure pathways as dermal or inhalation, and can be used for evaluating acute or chronic human risk (A human risk analysis based on reference doses related to water by dermal and ingestion pathways is presented in the Chapter 2).
Toxic units (TU) is defined as concentration of a chemical divided by a standard measure of its toxicity TEL, PEL , ERL and ERM are typical values used as standard measures of toxicity (US EPA, 2019). The addition of the individual TUs (accumulated toxicity) is considered as the toxic units accumulated (TUA), and the mean is known as the  » mean SQG quotient » (mSQGQ) .We used the approach developed by Soliman et al. (2015) in assessing the Ecological Risk to obtain two mSQG quotients based on the TEL and ERM, respectively; and estimate the potential acute toxicity of the PAHs.
Toxic equivalent Factor (relative potency factors) this method allows to represent a group of molecules with similar mechanisms of action as the concentration of a single molecule with a well characterized toxicity. In the case of PAHs, multiplying the measured concentration of the individual hydrocarbon by its corresponding TEF gives the concentration of the molecule in terms of BaP, since BaP is considered the most well defined in terms of carcinogenicity and toxicity; the addition of individual concentrations results in a total concentration of BaP defined as the toxic equivalent quantity (TEQ) (Keshavarzi et al., 2015; Nisbet and LaGoy, 1992).
Alternatively, cartographic methods are also of current use for mapping hazards and risks (Baynard et al., 2013; Cuba et al., 2014; Durango-Cordero et al., 2018; Finer et al., 2008). To determine the hydrocarbon pollution hazard we combined the surface runoff estimated with the IRIP (Intensive Rainfall Runoff) method(Cadot et al., 2016). Since this method is based on the environmental characteristics (geology, nature of soils, relief, land use, etc.) and takes into account the multiplicity of sources, it was used only for the NEAR. In addition, the software Qgis and Arcmap 10.4 were used to define the number of oil facilities (oilwells and flares) and pollution sources (pits and pools, and oil spills) affecting each one of the sampling sites. These results were integrated to our database and used for analyzing the correlation with the molecules analyzed.

Identification of PAHs sources

From the main anthropogenic sources of PAHs, we can distinguish the pyrogenic PAHs originated from the incomplete combustion of coal, petroleum and biomass, and the petrogenic PAHs presented in petroleum products found in fossil fuels and crude-oil spills (Amiard, 2017; Sun et al., 2017). The use of molecular ratios of isomeric PAHs in bottom sediments allow to reduce the misinterpretation due to volatility, water solubility, adsorption, etc; this method has been developed and widely used for source identification of PAHs contamination (Budzinski et al., 1997; Sun et al., 2017, 2010, Yunker et al., 2014, 2002). This method is based on the fact that low molecular weight (LMW) and alkylated PAHs are mainly present in petrogenic sources, while pyrogenic sources are mostly formed by high molecular weight (HMW) parent PAHs (Raza et al., 2013).
The ratios Phe-A and Fa-Py has been traditionally used to distinguish petrogenic and pyrolytic sources; Phenanthrene is considered as the most thermodynamically stable among the LMW-PAHs (Budzinski et al., 1997) and the presence of Phe, Flu and Py is related with a pyrolytic origin of the pollution (Stogiannidis and Laane, 2015). Since naphthalene, is highly volatile and hydrophilic (Douben, 2003) it is relatively unstable in sediments, thus it was not considered in the analysis of sources.
For each site, different isomeric ratios were calculated and we considered that samples from a common origin present similar isomeric ratios, they were used in a Hierarchical Cluster Analysis (HCA) and PCA in order to trace de different sources in function of its nature. This is a new approach proposed here that allows to treat all the isomeric ratios in an only one analysis, instead of using the traditional bi-plot analysis.

Table of contents :

I.1.1. Production et raffinage du pétrole en Équateur : contexte historique, économique et législatif
I.1.2. Contexte social et sanitaire dans les zones d’activités pétrolières en Équateur
I.1.3. Contexte socio-scientifique du projet MONOIL
I.2.1 Les spécificités de la région amazonienne
I.2.2 Les spécificités de la côte Pacifique
I.1.1. Oil production and refining in Ecuador: Historic, economic and legislative context
I.1.2. Social and health context in oil activities zones in Ecuador
I.1.3. Socio-scientific context of the MONOIL project
I.2.1 Amazon Region: specificities
I.2.2 Pacific Coast: specificities
CHAPTER 1. Tracing oil activities sources by PAHs distribution in surface water and sediments of the Amazonian and coastal regions of Ecuador Forewords Polycyclic aromatic hydrocarbons (PAHs) in surface water and sediments at oil exploration and refining sites in Ecuador: concentrations and source distribution
1. Introduction
2. Materials and methods
2.1 Study Area
2.2 Sample Collection
2.3 Chemical analysis
2.4 Statistical analysis
2.5 Environmental and human risk assessment
2.6 Identification of PAHs sources
3. Results and discussion
3.1 Distribution of PAHs concentrations in surface freshwater
3.2 Concentrations of PAHs in bottom sediments
3.3 Oil activities tracing (source tracing)
4. Conclusions
Supplementary Information 1
CHAPTER 2. Oil pollution hazards and health quality of drinking waters in Ecuador Forewords
Drinking water quality in areas impacted by oil activities in Ecuador: associated health risks and social perception of human exposure
1. Introduction
2. Materials and Methods
2.1 Study area
2.2 Water sample collection
2.3 Analytical methods
2.4 Sociological methods
2.5 Health risk assessment
2.6 Statistical analysis
3. Results
3.1 Physico-chemical parameters
3.2 Major and TME concentrations
3.3 PAHs concentrations
3.4 Bacteriological results
3.5 Human health risks assessment
4. Discussion
4.1 Impacts of oil activities on drinking water quality
4.2 Drinking water risks due to low mineralization
4.3 Limits of Ecuadorian Regulations
4.4 Social perception of the risk and human exposure
5. Conclusion and recommendations
Conclusion Générale
Recommandations et perspectives
General Conclusion
Recommendations and perspectives


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