1. Introduction
Urban environments have high population densities and are therefore strongly influenced by anthropogenic activities. These activities create high levels of environmental pollutants [
1], which are subsequently transported into the atmosphere or towards the Earth’s surface in both particulate and vapor phases [
2]. The particulates may contain heavy metals derived from different sources in urbanized areas, including vehicular emissions, industrial discharges, and other activities [
3].
Particulate matter denotes particles with size ranging from 1 to 10,000 μm, referred to as dust, which are mostly susceptible to traveling long distances [
4]. Dust is a well-known matrix and is frequently the focus of environmental and human exposure studies. Dust contaminated with heavy metals has drawn public attention due to its high toxicity, persistence, and bioaccumulation [
5]. Additionally, dust particles containing heavy metals—particularly fine particles—can be re-suspended in the atmosphere or consumed by humans through ingestion, inhalation, and dermal adsorption [
6]. Exposure to environmental pollutants results from urban environments fostering economic advancement without always guaranteeing the sustainable development of communities, thus posing potential risks to nearby ecosystems, environmental quality, and public health. The diminished sustainability resulting from environmental pollution threatens the balance between economic growth, environmental conservation, and social well-being, thereby jeopardizing the health and quality of life of the population.
In this regard, highly concentrated pollutants affect the health of children, especially schoolchildren who spend much of their time indoors. Therefore, it is crucial to assess potentially toxic metal(loid)s in sensitive environments such as school classrooms [
7]. The air quality inside schools is a growing concern and has a significant health impact, possibly posing a greater risk than outdoor pollution [
8]. Inside schools, dust can contain various contaminants and trace metals that can be transported into classrooms and affect schoolchildren who spend time in playgrounds, in gardens, and in nearby homes [
9].
Such pollution is relevant for populations of children, who are more susceptible to the adverse effects of pollution due to their still-developing respiratory and immune systems, lower body mass index, and respiratory patterns, causing pollutants to become more concentrated in their systems [
10]. Additionally, children are likely to ingest significant quantities of dust as they commonly put non-food objects in their mouth and repetitively suck on their hands and fingers, leading to a much higher absorption rate of heavy metals [
11]. Therefore, the pollutants that enter and deposit in the environment of a classroom could provide an indirect measurement of air pollution. It is crucial to identify and quantify pollution sources to determine potential health risks for school populations [
12].
Considering that childhood is a critical period for children’s development, exposure to environmental pollutants can affect their respiratory, cardiovascular, and cognitive health, which could impact their neurodevelopment and, consequently, their learning ability [
13]. In this regard, some studies have shown that children exposed to air pollution achieved lower results in neurobehavioral tests [
14], exhibited structural impairment of neurological function [
15], and had lower intelligence quotient (IQ) scores compared to non-exposed children [
16]. Additionally, children exposed to elevated levels of nitrogen dioxide have lower scores in quantitative, working memory, and gross motor skills areas, indicating lower performance in neurobehavioral tests [
17]. Additionally, children exposed to high levels of black carbon had lower verbal and non-verbal intelligence and diminished scores in memory assessments [
16].
It is known that learning—and, consequently, academic performance—in children depends on their cognitive functions [
18], which could be affected through exposure to environmental pollution. Some research has identified that exposure to traffic-related air pollution is linked to cognitive function and, therefore, to the academic performance of children [
19]. Additionally, children with low socioeconomic status (SES), as well as those belonging to ethnic minorities, may exhibit decreased cognitive functions in the face of exposure to environmental pollution in schools [
20].
In this context, the study of Pastor et al. in 2006 evaluated children from impoverished communities in California exposed to environmental pollution, finding low results in standardized tests of academic performance [
21]. Another study, conducted by Moahi et al. in 2011, showed that the majority of children exposed to high levels of air pollution in public schools in Michigan had low performance in state-standardized tests of academic achievement [
22]. In Chile, the standardized test System for Measuring the Quality of Education (SIMCE) is administered every year. SIMCE is an assessment tool for learning applied to students across the country [
23]. At present, there is no published information on whether environmental pollution can affect the academic performance of Chilean children exposed in the Quintero–Puchuncaví area. This information would be crucial for implementing preventive or mitigating measures, especially considering that this Chilean locality is currently designated as a “sacrifice zone”.
Similar to cities in other developing countries, Puchuncaví and Quintero have many environmental challenges. In Puchuncaví, the Ventanas copper smelter has emitted pollutants (i.e., sulfur dioxide and trace metals) into the atmosphere that could include toxic components which endanger both the environment and the health of school populations. Since the opening of the Ventanas copper smelter in 1964 and until the first environmental regulations in 1991, no measures were taken to mitigate these emissions. Despite the current environmental regulations, the cumulative environmental effects of historical emissions remain latent in the areas surrounding the Ventanas smelter, such as Quintero city, which borders Puchuncaví to the south [
24]. Both locations are called “sacrifice zones” as they correspond to geographic areas with high levels of industrial activity, resulting in substantial economic benefits for the country; however, these activities have had a disproportionate environmental impact, leading to ecosystem degradation, reduced quality of life, and increased health risks for the area’s inhabitants, thus diminishing sustainability. In this context, the Ventanas Industrial Complex—the main cause of the high levels of pollutants in the area—generates a significant portion of the energy supply for the central region of Chile, underscoring its status as a crucial strategic asset for the country. Due to the extent of contamination, population size, social mobilization, and significant health effects resulting from past critical events, Quintero and Puchuncaví represent one of the most emblematic sacrifice zones in the country, with the greatest environmental impact [
25].
Therefore, exposure to trace elements in Puchuncaví and Quintero could pose a risk to human health, which has been evidenced in several studies [
24]. However, no studies have been conducted on exposure to toxic metals in school environments and the associated potential harmful effects on children’s health. Additionally, there are currently no studies indicating whether such exposure can affect academic performance in children. Therefore, the main objective of this research was to determine the distribution of trace metals from various sources present in the dust collected in and around the schools of Puchuncaví and Quintero. As secondary objectives, we determine the potential health risk that exposure to dust (derived from the impact of metals from ultrafine particles that possibly come from the Smelter) poses to schoolchildren through ingestion and dermal pathways, as well as whether the concentrations of these metals could affect their academic performance.
4. Discussion
The main objective of this research was to determine the distribution of trace metals from various sources present in the dust collected inside and outside the schools in the Quintero and Puchuncaví area, which is located in a highly polluted coastal region of the fifth largest region of Chile. Our results indicated that the concentrations of heavy metals are related to the distance of the schools from the source of pollution; they also identified differences between samples obtained from indoor and outdoor areas of the analyzed educational centers. Additionally, in the most-contaminated school in the area, elevated concentrations of metals such as Co, Zn, Cu, As, Se, Pb, Mo, Cd, and Sb were detected.
The first of the secondary objectives of this study was to identify potential carcinogenic and non-carcinogenic risks posed by the analyzed metals to the health of children. In this regard, we did not find evidence of a carcinogenic risk for the health of the exposed students; however, some schools were near the limit values, potentially posing a risk to the children there. Finally, we determined whether the concentration of these heavy metals could affect the academic performance of the exposed children, assessed through the eighth-grade SIMCE test. Our results indicated that, in samples obtained from inside the analyzed schools, the concentrations of manganese, cobalt, arsenic, strontium, and cadmium influenced the academic performance of exposed students. Regarding samples obtained from outside of the analyzed schools, the concentrations of manganese, cobalt, antimony, and vanadium influenced the academic performance of exposed students.
Considering the distribution of trace metals from various sources present in the dust collected inside and outside the schools, the concentrations of trace elements reported in this study are higher than those in dust samples from general school environments worldwide. For example, the mean concentrations of As, Cu, and Mo in dust collected inside the Greda School were higher by factors of 20, 1500, and 50, respectively, when compared to those reported by De Miguel et al., 2007 (Spain) [
52] and Abdul et al., 2020 (Pakistan) [
7]. Similarly, the concentrations of Zn, Pb, V, Cr, and Ni in the studies of Olujimi et al., 2019 in Nigeria [
53] and Chen et al., 2014 in China [
34], were up to 10 times lower than those reported in this study. In addition, V and Cr were higher in the Faro and Santa Filomena schools and Ni and Sr were higher in the Faro School than in the other schools sampled. Faro and Santa Filomena are located six kilometers from the industrial complex in the area (see
Table S1) and are also close (less than 700 m) to a bus terminal and a company dedicated to boarding and disembarking ships, which could be sources of vanadium in the schools as this element is enriched in emissions from crude or heavy oil used in large ships and automobiles [
54]. The average Co, Zn, Cu, As, Se, Pb, Mo, Cd, and Sb concentrations were higher in the Greda (Alerces) and Greda schools (located less than 3.3 km from the industrial complex) than in the other schools sampled. The high levels of these trace metals inside the schools likely derive from external sources (e.g., industrial activities and vehicular emissions) and may be transported into the schools on the schoolchildren.
Regarding the concentrations of trace elements in the outdoor dust, our results indicated higher mean concentrations of V (427 mg/kg) and Cr (591 mg/kg) in the summer at the Santa Filomena School than at the other schools. Moreover, the mean concentrations of Ni, Zn, Se, and Sr in dust around the schools were higher at the Horcón School than at the other schools, possibly because Horcón is a popular tourist location, suggesting a greater influence of anthropogenic sources such as motor vehicles. At the Greda (Alerces) and Greda schools, the average concentrations of Cu, As, and Mo in the dust samples collected outdoors were 60, 3, and 10 times higher, respectively, than those at the other schools sampled, and the concentrations of Cu, Co, Zn, As, Se, Sb, Mo, Cd, and Pb in both indoor and outdoor dust were highest among the sampled schools, suggesting the influence of anthropogenic sources.
Next, we determined the chemical species profiles and the contribution of each factor to the total mass per sample (mg/kg) through PMF and found that the first component—labeled “industrial”—explained 64% of the total variance and was primarily associated with the contents of Cu, Mo, Cd, Sb, Pb, As, Zn, and Se. The chemical profile of this factor suggests contamination from the nearby copper smelter near the schools, with the most-affected schools being the Greda (Alerces) and Greda schools, likely due to their proximity to industrial complexes in the area and the trajectory of the prevailing winds (northeasterly). These results are similar to those reported in other studies, such as [
55], in which the sources of heavy metal contamination in urban dust in a continental city in eastern China were determined, where Cu and Zn originated from emissions from the local smelting industry. Similarly, other studies have found metal smelting to be one of the most important anthropogenic sources of heavy metal emissions [
56]. During the smelting process, the heavy metals in minerals are evaporated from the matrix and eventually transported to the atmosphere if pollution control technology is not applied [
57]. In addition, it has been reported that Cu is released during industrial activities such as metal processing and smelting [
58,
59].
Regarding the second component, our results showed that 36% of the total variance was explained by the “traffic + crustal” component. The chemical profile of this factor was characterized by Li, Be V, Cr, Mn, Co, Ni, Zn, As, Se, Sr, and Tl. The greatest contributions to this factor were found in the Faro, Santa Filomena, Inglés, Politécnico, Chocota, and Horcón schools. The presence of Mn, Ni, and Zn could be associated with vehicular sources (related to brake and engine wear), which has also been reported in other studies [
60,
61]. The trace elements Zn, As, and Se have two possible sources: industrial (copper smelter) and vehicular [
26].
The trace elements Zn, Cr, Ni, Sr, and Co are related to traffic, as they are present in vehicle exhaust [
62,
63,
64,
65]. These results are comparable with those of a similar study [
66] investigating the composition of dust in indoor and outdoor school classrooms in Kuala Lumpur, in which it was found that the highest contribution was exhaust emissions containing Cr and Ni. Similarly, Cr, Ni, V, and Co have been reported as markers of either exhaust emissions or brake and clutch wear in other studies, such as [
54,
67].
On the other hand, due to the relationship between nickel and vanadium, the source of these trace elements could be vehicular fuel combustion, which has been reported in other studies [
68,
69]. Likewise, the elements Li, Be, and Tl could be attributed to lithogenic sources [
46,
70,
71].
In the dust samples collected outdoors from the analyzed schools, PMF was applied to determine the chemical species profiles and the contribution of each factor. In this regard, two factors were identified: the first component—named “industrial”—explained 28% of the total variance and was associated with the contents of Cu, Sb, Cd, Zn, As, Se, Mo, and Pb, which are attributed to copper smelting contamination. The second component explained 72% of the variance and was characterized by the presence of Li, Be, V, Cr, Mn, Co, Ni, Zn, As, Se, Sr, and Tl in the samples collected outside the schools. This high percentage is logical as these outdoor samples were collected in front of the schools, where there were high contributions from vehicular and lithogenic sources.
According to the above results, the sampled dust particles contained pollutants with an anthropogenic origin, including an industrial source and traffic sources (e.g., related to brake and wear).
Therefore, the sources of contamination inside these schools could be external; that is, external atmospheric particles were carried in by the wind or on the children themselves, originating from the copper smelter and vehicular sources.
Subsequently, we determined the children’s exposure to trace metals in the school dust collected inside and outside selected schools in the cities of Quintero and Puchuncaví, either through ingestion, inhalation, or dermal contact, using Equations (1)–(9).
The hazard quotient (HQ) and hazard index (HI) were computed for nine hazardous metals (V, Cr, Ni, Zn, As, Sr, Cd, Pb, and Cu) for a non-carcinogenic health risk assessment. Simultaneously, a carcinogenic health risk assessment focused on five toxic metals (As, Cd, Cr, Ni, and Pb) was also conducted, assessing their potential health impacts [
48,
49].
The HQ and ƩHI for all exposure routes in the Faro, Santa Filomena, Ingles Quintero, Politécnico, Basica Chocota, and Basica Horcón schools were below 1, indicating that there were no significant non-carcinogenic health risks posed by the trace metals in all samples collected (indoor or outdoor dust). In the Greda (Alerces) and Greda schools, the ƩHI value exceeded 1, indicating a potential risk for non-cancerous effects. Among the three routes of exposure, the HQ for the dermic pathway was the highest for As in indoor dust collected in the Greda Alerces (2.09) and Greda (1.13) schools. Because these HQ values exceed 1, the children currently studying at Greda School are at potential risk of non-cancerous effects from As.
Among the dust samples collected from other schools, V, Cr, Cu, Pb, and As presented the highest non-carcinogenic risk of the nine heavy metals, while Zn showed the lowest non-carcinogenic risks both indoors and outdoors. Dermal contact was identified as the primary route of toxic metal exposure for children in the selected schools, followed by inhalation and ingestion.
The assessment of heavy metal concentrations in dust was conducted through the utilization of integrated hazard index (ΣHI) values, reflecting real-life scenarios of children’s exposure to a mixture of heavy metals, rather than individual metal exposure [
51].
Considering the ΣHI values for all of the schools, the children encountered the highest non-cancerous risk inside Greda School, being at risk of experiencing non-cancerous effects such as nausea, loss of appetite, and headache.
According to the obtained values for the different exposure pathways, even though the HI values for the six schools fell within the safe range, the high concentrations of some elements that could be emitted from anthropogenic sources pose a risk to the health of children, especially considering the greater susceptibility of children due to their body weight [
72,
73].
Likewise, we evaluated the carcinogenic health risks among the schoolchildren. Due to the unavailability of reference slope factors, we assessed the cancer risks (CR) associated with As, Cd, Cr, Ni, and Pb specifically for inhalation exposure.
All of the values determined for the ILTCR inside and outside the schools were lower than or very close to 1 × 10
−6 and were therefore within the safe limit established by regulatory and environmental agencies [
40]. These results were similar to those of other studies, where the values for carcinogenic risk were found to be lower than 1 × 10
−6 [
50,
66,
74]. However, for carcinogenic health risks, only Cr and As presented higher ILTCR values in all dust samples collected inside and outside the selected schools in Quintero and Puchuncaví (
Table 7). This suggests that local environmental authorities should pay attention to a potential carcinogenic risk at Greda School, where the detected value for As was 5.98 × 10
−8, whereas it was lower (3.7 × 10
−8) in the outdoor dust samples collected at the same location. Similarly, at the Santa Filomena and Faro schools, the ILTCR values for Cr were 5.44 × 10
−7 and 4.82 × 10
−7, respectively. This trend in the Cr-associated carcinogenic risk assessment for children was similar to those reported in other studies on pollution and health risk assessments of trace elements in indoor dust in classrooms [
7,
53].
Finally, through the use of an economic model, we determined whether the concentrations of heavy metals inside and outside the classrooms of eighth-grade students at schools in Quintero and Puchuncaví could predict their academic performance. Our results indicated that, in the dust collected from inside the classrooms, higher concentrations of Mn, As, Sr, and Cd were associated with lower academic performance assessed through the SIMCE test. Meanwhile, higher concentrations of Co predicted better academic performance for eighth-grade students. In dust samples collected outside the children’s classrooms, high concentrations of Mn, Sb, and V predicted lower academic performance, while high concentrations of Cd could indicate higher academic performance.
In this regard, Mn is a crucial element for the proper development of mammals throughout their lives, but elevated concentrations of this compound can lead to health disturbances [
75]. In children, it has been observed that exposure to manganese can impact neurodevelopment, learning, and, consequently, academic performance. Our results support this statement and align with the conclusions of other authors. Various authors have assessed the relationship between exposure to high concentrations of Mn in children aged 6 to 13 from different countries and alterations in IQ [
76], scores in intelligence test (Wechsler Intelligence Scale for Children, WISC-IV) [
77], scores in cognitive functions (Raven’s Progressive Color Matrices Scale, PCM) [
78], mathematics test scores [
79], and scores on memory and attention tests [
80]. The results of these studies have consistently shown that higher concentrations of Mn to which children are exposed are associated with lower performance in learning assessments and academic achievement. Furthermore, our results indicate that, both inside and outside the classroom, higher levels of Mn decreased the academic performance of the analyzed eighth-grade students, leaving them exposed in their entire school environment to the effects of this element.
Similar to Mn, various studies have observed that exposure to elevated levels of As in children aged 6 to 13 is associated with lower IQ scores [
81], diminished cognitive abilities (Wechsler Intelligence Scale for Children, WISC-IV) [
82], low scores in mathematics tests [
83], and decreased visuospatial skills [
84], as well as a reduction in vocabulary and the assembly of objects and images [
85]. Our results align with those of the mentioned authors, but only in our indoor model (specifically, within the classroom). Considering this result, it appears that exposure to As (arsenic) during the school day inside the classroom may negatively affect the learning ability of the assessed children. On the other hand, most of the mentioned studies have assessed As levels in the urine or blood of children; in contrast, our study demonstrated that an invasive procedure is not necessary to identify the effect of As concentration on the academic performance of exposed students.
On the other hand, Sr (strontium) is a metal that can be found in the air, soil, and water. Our results showed that elevated levels of Sr in the indoor model predicted lower academic performance in the evaluated students. In this regard, we conducted a search for possible relationships or associations of Sr with cognitive function, neurodevelopment, IQ, or academic performance in children, but no information on the subject was found. Some studies have demonstrated possible relationships between Sr levels in water and certain pathologies in the population. In this regard, it has been shown that Sr levels in drinking water could prevent cavities in children when the concentration was 5–6 mg/L [
86]. It has also been observed that the levels of Sr are negatively correlated with the incidence and mortality of cardiovascular diseases [
87] and positively correlated with longevity [
88]. Furthermore, Sr (strontium) levels are related with a hazard index (HI) above 1, indicating evident non-cancerous risks [
89]. Considering the above, it is possible that elevated Sr levels could affect the cognitive function of children and, consequently, their academic performance; however, further research is needed in this regard.
With respect to Cd, our results indicated that, in the indoor model, high levels of Cd predicted lower academic performance in the evaluated students; meanwhile, in the outdoor model, the results indicated the opposite. Cadmium is a rare element in nature; however, the main sources of cadmium exposure in children are food, cigarette smoke, and dust [
90]. Furthermore, Cd is toxic to organs such as the lungs, kidneys, liver, digestive system, and bone tissue, and can cause cancer and neurotoxicity [
91]. Pre- and post-natal exposure to this element has a detrimental effect on the child’s neurological development, primarily due to increased oxidative stress that could induce neuronal apoptosis [
92]. Regarding the effects on the neurodevelopment of children exposed to elevated Cd levels, Tian et al. (2009) have assessed 4-year-old children, and their results indicated that IQ was lower when children had higher levels of Cd in the blood [
93]. Gustin et al. (2018) have also identified an association between Cd exposure and a decrease in IQ [
94]. Lui et al., in 2022, assessed mothers and children during pre- and post-natal stages (2–3 years old), examining the presence of 22 heavy metals in serum and urine and their relationship with the neurocognitive development of the children using the Gesell Developmental Diagnosis Scale (GDDS; Chinese version). Their findings indicated that higher pre-natal exposure to Cd was associated with a lower Gesell Developmental Quotient (DQ) score, indicating lower cognitive levels in the gross motor area; furthermore, in the post-natal stage, increased Cd exposure was linked to a lower DQ score in language [
95]. On the other hand, some studies in children aged 2 to 14 years did not find relationships or associations between Cd levels and neurodevelopmental assessments in children [
91,
96]. Considering this information, more data are necessary to determine the effects of Cd on cognitive functions, IQ, neurodevelopment, and academic performance in children.
Regarding Co, in our indoor model, high concentrations of this metal predicted better academic performance in the evaluated children. In this regard, no published information was found on the effects of Co on learning, academic performance, cognitive function, or IQ in children. However, there is information indicating that exposure to high concentrations of Co in children aged 6–11 years was associated with a higher overall health score [
97]. On the other hand, Boraa et al., in 2019, demonstrated that Co concentrations >5 μg/L were associated with low scores in memory tests in children under 18 years old [
98]. Due to the inconsistency in the published information and the limited amount of research available, it is necessary to continue investigating the effects of Co on cognitive function, learning, and neurodevelopment in exposed children.
Antimony is commonly found in the form of antimony trioxide, and is present in the environment due to industrial activities or the weathering of rocks and soil runoff [
99]. Our results showed that elevated levels of antimony outside classrooms of the analyzed schools predicted lower academic performance. In this regard, no information was found regarding the effect of antimony on cognitive function, learning, academic performance, or neurodevelopment in exposed children. Some research, such as that of Cao et al. in 2016, has associated its ingestion in children with non-carcinogenic and carcinogenic risks 100 times higher than the acceptable level in an integrated analysis of Pb, Cr, Cu, Zn, As, Se, Cd, and Sb [
100]. The study of Cheung et al. in 2008 demonstrated that, in secondary-level students, the levels of antimony—along with other heavy metals ingested through the diet—posed low health risks [
99]; furthermore, the study of Jiang et al. in 2021 showed that children are more susceptible to the non-cancerous effects of antimony [
101]. These studies indicate that high concentrations of Se may impact the overall health of children, but there is a lack of information regarding its effects on cognitive function and learning. It is necessary to continue investigating the potential effects of Se in children, particularly those exposed to elevated levels of this metal due to living in highly contaminated industrial areas.
Finally, our results indicated that vanadium levels in dust samples collected outside children’s classrooms predicted lower academic performance. Vanadium (V) is found in the environment as a byproduct of the petrochemical industry, automobile manufacturing, fertilizer production, and steel manufacturing [
102]. The population is exposed to V primarily through alcohol consumption, water, diet, and inhalation of contaminated air [
103]. Some studies have shown that exposure to V can cause adverse health effects, such as neurotoxicity and cognitive deficit in rats [
104], reproductive and developmental alterations [
105], and adverse birth outcomes [
106], related to cognitive and neurodevelopmental alterations in children. No studies were found that have assessed its effects on learning and academic performance in children. Considering its effects on neurodevelopment and the described birth outcomes, it is possible that its effects on variables associated with academic performance could be similar; however, more information is needed in this regard.
Undoubtedly, the impact of pollution on children must be factored into the governmental policies of the region and the country. Chile has made strides in managing environmental pollutants in the Quintero and Puchuncaví area following numerous instances of environmental alerts and the poisoning of residents, particularly children. These incidents, largely stemming from emissions from local industries, prompted action from the Chilean Ministry of the Environment. Their Atmospheric Prevention and Decontamination Plan for the municipalities of Concón, Quintero, and Puchuncaví (D.S. N°105/2018) has led to a reduction in pollution levels. However, this plan primarily addresses air pollutants, overlooking soil and water contaminants, which pose challenges due to their prolonged presence. Despite a decrease in critical events, these pollutants persist, indicating that current measures—though significant—remain insufficient. We advocate for the incorporation of our findings into public health policies and strategies at regional and national levels. This should involve comprehensive control of pollution, encompassing not just air quality but also soil and water management in affected areas. Given the elevated risks posed to children’s health and education by soil contamination, interventions within and around schools are particularly crucial. We urge relevant Chilean ministries to consider these recommendations for effective risk reduction, especially for vulnerable populations such as children. In particular, considering that dust is a major reservoir of pollutants that can enter children through various pathways, it is necessary to continue conducting thorough research on the risks associated with carcinogenic contaminants present in schools and their potential hazards. Therefore, it is imperative to seek support from governmental entities to implement development and pollution mitigation plans targeted at anthropogenic activities, such as installing and maintaining adequate ventilation systems inside classrooms, as well as promoting green environments (including gardens and recreational areas) in schoolyards and nearby locations.
Limitations
One limitation of this research was its sole focus on the Quintero and Puchuncaví zones, which constitute only one of the five sacrifice zones in Chile. We chose to concentrate on Quintero and Puchuncaví due to the significant population affected by severe environmental pollution, resulting in numerous critical health incidents such as vomiting, fainting, headaches, and respiratory crises, affecting both children and adults, including vulnerable groups such as the elderly and pregnant women. This level of impact is more intense and frequent in Quintero and Puchuncaví compared to other sacrifice zones in Chile, leading to various social movements advocating for the regulation of industrial pollution levels. Consequently, Quintero and Puchuncaví are emblematic sacrifice zones in the country with the most significant environmental and social repercussions. The Ventanas Industrial Complex is a major pollution source in the area, playing a vital role in regional and national contexts as it hosts significant port activities, copper and heavy metal smelting, energy generation, gas reception and distribution, and other operations. It contributes substantially to the energy supply of Chile’s central area, making it a key strategic location for the country geopolitically.
This sacrifice zone likely mirrors others in Chile and worldwide, characterized by exposure to high levels of contaminants from industries that make essential economic contributions but come with significant environmental costs.
As for limitations related to academic performance, we first identify the number of schools analyzed. We analyzed approximately 50% of the schools in the area, but it would be interesting to consider all of the schools located in this sacrifice zone in future research, providing a comprehensive overview of public, subsidized, and private schools. On this occasion, our analysis was conducted only in public and subsidized schools. Another potential limitation is that some schools only offer basic education, while others only offer secondary education. Therefore, it was not possible to compare the results of heavy metal measurements with the same academic performance test for all students. Consequently, in the analysis of academic results, we did not include all the schools from which dust samples were taken, but only those teaching the eighth grade. In future research, it would be beneficial to analyze or contrast the results of standardized academic performance tests conducted at different educational levels or to consider other indicators of academic performance and learning. In such cases, it would be valuable to differentiate the analyses based on the sociodemographic characteristics of the children and their families, such as parents’ educational level, family socioeconomic status, gender, etc.