How to Cite
Harrison, E. O., & Melford, C. M. (2026). Multisystem Toxicological Effects of Petroleum Hydrocarbon Exposure in Chickens: A Sex- And Duration-Dependent Analysis. International Journal of Research, 13(1), 147–157. https://doi.org/10.26643/eduindex/ijr/2026/9
Authors:
Eruotor Ogheneochuko Harrison¹* and Chinwebudu M. Melford²
¹ Department of Biochemistry, Faculty of Science, University of Port Harcourt, Rivers State, Nigeria
ORCID: https://orcid.org/0009-0000-9415-2993
² Department of Medical Technology, College of Allied Medical Sciences, Cebu Doctors’ University, Mandaue City, Cebu, Philippines
ORCID: https://orcid.org/0009-0005-0654-5479
Corresponding Author (post-publication):
Eruotor Ogheneochuko Harrison
Email: harrisoneruotor2014@yahoo.com
ABSTRACT
Petroleum hydrocarbon contamination remains a persistent environmental challenge in regions with sustained oil exploration and production, where chronic exposure frequently occurs alongside heavy metal co-pollution. Unlike acute toxicity, long-term environmental exposure may induce progressive and interconnected disturbances across multiple physiological systems. This study evaluated the multisystem toxicological effects of chronic petroleum hydrocarbon exposure in chickens using an integrated analytical framework. Chickens exposed to a petroleum hydrocarbon-contaminated environment for 6 and 12 months were compared with unexposed controls, with analyses stratified by sex and exposure duration. Endocrine, hepatic, renal, cardiovascular, hematological, oxidative stress, inflammatory, and heavy metal parameters were jointly assessed to characterize systemic toxicity. Chronic exposure was associated with coordinated disturbances across all evaluated systems, including endocrine dysregulation, hepatorenal impairment, cardiovascular injury, hematological abnormalities, antioxidant depletion, lipid peroxidation, inflammatory activation, and accumulation of chromium, lead, and zinc. Oxidative stress and inflammation emerged as central mechanisms linking multisystem dysfunction, while heavy metal burden further amplified toxicological effects. Sex-dependent differences were evident, with females exhibiting greater endocrine, oxidative, and inflammatory disturbances and males showing more pronounced cardiovascular injury and metal accumulation. Toxicological severity increased with exposure duration, indicating cumulative effects of prolonged environmental contamination. This integrated multisystem evaluation demonstrates that petroleum hydrocarbons induce systemic toxicity through interacting biological pathways rather than isolated organ-specific mechanisms. The findings highlight chickens as sensitive sentinel species and underscore the ecological, food safety, and public health implications of chronic petroleum hydrocarbon contamination.
Keywords: Petroleum hydrocarbons, Multisystem toxicity, Oxidative stress, Inflammation, Heavy metals, Chickens, Nigeria
INTRODUCTION
Petroleum hydrocarbon contamination remains a major environmental and public health concern in regions with sustained oil exploration, production, and transportation activities. Chronic release of petroleum-derived compounds into soil and water ecosystems results in prolonged exposure of resident organisms to complex mixtures of hydrocarbons and associated co-pollutants, including heavy metals. Unlike acute toxic exposure, chronic environmental contamination exerts its effects gradually, often through subtle but cumulative disruptions across multiple physiological systems, leading to long-term biological consequences that may not be immediately apparent (Cleveland Clinic, 2025; Harvey, Sharp, & Phillips, 1982).
Emerging evidence indicates that petroleum hydrocarbons do not target isolated organs but instead induce multisystem toxicity involving coordinated dysfunction of endocrine regulation, metabolic processes, cardiovascular integrity, hematopoietic function, immune responses, and redox balance. These effects are mediated through interconnected mechanisms such as oxidative stress, inflammatory activation, endocrine disruption, and bioaccumulation of toxic metals. As these pathways interact, injury in one physiological system may exacerbate dysfunction in others, resulting in compounded biological consequences over time and progressive loss of homeostatic control (Dey et al., 2015;Liu et al., 2025).
Sex-related differences further complicate the toxicological impact of petroleum hydrocarbon exposure. Variations in hormonal regulation, antioxidant capacity, immune responsiveness, and metal metabolism between males and females may influence susceptibility, adaptive responses, and severity of toxic effects. In addition, duration of exposure plays a critical role in determining toxicological outcomes, as prolonged exposure permits cumulative tissue damage, persistent inflammation, endocrine imbalance, and sustained oxidative stress, thereby amplifying systemic dysfunction (Oleforuh‑Okoleh et al., 2023; Fowles et al., 2016).
Avian species, particularly chickens, represent valuable sentinel organisms for assessing multisystem environmental toxicity. Their close interaction with contaminated soil, water, and feed, combined with physiological sensitivity to endocrine, oxidative, cardiovascular, and inflammatory disturbances, makes them suitable models for evaluating integrated toxicological effects. Moreover, because chickens are directly linked to human food systems, multisystem toxicity observed in these animals may serve as an early warning indicator of broader ecological and public health risks associated with petroleum hydrocarbon pollution.
While previous studies have largely focused on individual toxicological endpoints, such as reproductive dysfunction, hepatic injury, oxidative stress, immune alterations, or cardiovascular effects, there remains a paucity of studies adopting an integrated multisystem approach that simultaneously evaluates endocrine, hepatorenal, cardiovascular, hematological, oxidative, inflammatory, and heavy metal–related effects within the same exposed population. Such an approach is essential for capturing the full biological burden of chronic petroleum hydrocarbon exposure and for identifying sex- and duration-dependent vulnerability patterns that may otherwise remain obscured when systems are examined in isolation.
Against this background, the present study was designed to evaluate the multisystem toxicological effects of chronic petroleum hydrocarbon exposure in chickens by integrating endocrine, hepatic, renal, cardiovascular, hematological, oxidative stress, inflammatory, and heavy metal parameters within a single analytical framework. The study sought to characterize how prolonged exposure to a petroleum hydrocarbon-contaminated environment disrupts physiological homeostasis across multiple organ systems and biological pathways, and to determine whether the magnitude and pattern of multisystem toxicity vary according to sex and duration of exposure (6 months versus 12 months). It was anticipated that chronic petroleum hydrocarbon exposure would result in concurrent endocrine disruption, hepatorenal impairment, cardiovascular injury, hematological dysregulation, oxidative stress, inflammatory activation, and heavy metal accumulation in exposed chickens when compared with unexposed controls. Furthermore, it was hypothesized that these toxicological effects would be significantly modulated by sex and exposure duration, with prolonged exposure and sex-specific physiological differences contributing to increased vulnerability and severity of multisystem dysfunction. Through this integrative approach, the study aimed to provide a comprehensive assessment of systemic toxicity and to advance understanding of the complex biological consequences of long-term exposure to petroleum hydrocarbon-contaminated environments.
MATERIALS AND METHODS
This study adopted an integrated comparative experimental design to evaluate the multisystem toxicological effects of chronic exposure to a petroleum hydrocarbon-contaminated environment in chickens. The analysis synthesized endocrine, hepatorenal, cardiovascular, hematological, oxidative stress, inflammatory, and heavy metal parameters to provide a comprehensive assessment of systemic toxicity. Exposed chickens were compared with unexposed controls, with stratification by sex and duration of exposure (6 months and 12 months) to evaluate sex-dependent susceptibility and cumulative toxicological effects.
Chickens in the exposed group were obtained from an environment with sustained petroleum hydrocarbon contamination resulting from prolonged hydrocarbon-related activities, while control chickens were sourced from a comparable environment without documented petroleum hydrocarbon pollution. All birds were maintained under similar husbandry conditions, including access to feed and water, to minimize confounding influences unrelated to environmental exposure. A total of eighteen chickens were included in the study, comprising twelve exposed birds and six controls. The exposed group consisted of chickens exposed for 6 months (male, n = 3; female, n = 3) and 12 months (male, n = 3; female, n = 3), while the control group included chickens maintained for 6 months (male, n = 2; female, n = 2) and 12 months (male, n = 1; female, n = 1).
Blood samples were collected aseptically from each chicken via venipuncture under standard laboratory conditions. Samples were processed to obtain serum and whole-blood fractions as required for biochemical, immunological, hematological, and heavy metal analyses. All samples were handled, stored, and analyzed according to established laboratory protocols to preserve analytical accuracy and integrity.
Multisystem assessment incorporated validated biomarkers across seven physiological domains. Endocrine evaluation included reproductive and thyroid hormones to assess hypothalamic–pituitary–gonadal and hypothalamic–pituitary–thyroid axis function. Hepatic and renal function were evaluated using standard liver enzyme activities, protein indices, bilirubin fractions, renal electrolyte concentrations, and nitrogenous waste markers. Cardiovascular integrity was assessed using cardiac injury and stress biomarkers alongside hematological indices reflecting oxygen-carrying capacity, immune status, and hemostatic balance. Oxidative stress status was determined through antioxidant enzyme activities and lipid peroxidation indices, while inflammatory responses were evaluated using cytokines, acute-phase proteins, and nitric oxide levels. Heavy metal burden was assessed by measuring serum concentrations of chromium, lead, and zinc as representative co-pollutants commonly associated with petroleum hydrocarbon contamination.
For the purposes of this multisystem analysis, individual biomarker results were evaluated both independently and collectively to identify convergent patterns of toxicity. Parameters were interpreted within and across physiological systems to assess interactions among endocrine disruption, organ dysfunction, oxidative stress, inflammation, and metal accumulation. Emphasis was placed on sex- and duration-specific comparisons to identify differential vulnerability and cumulative toxicological effects.
Data were analyzed using appropriate statistical software. Descriptive statistics were expressed as mean ± standard deviation. Inferential analyses included independent-sample t-tests to compare exposed and control groups and one-way analysis of variance to evaluate differences based on sex and duration of exposure, with post-hoc testing applied where appropriate. Statistical significance was set at p < 0.05. To avoid redundancy and ensure publication integrity, this multisystem analysis emphasized integrative interpretation and pattern synthesis rather than repetition of system-specific statistical outcomes reported in companion papers.
All experimental procedures involving animals were conducted in accordance with internationally accepted ethical guidelines for the care and use of experimental animals, and all efforts were made to minimize animal stress and discomfort throughout the study.
RESULTS AND DISCUSSION
Chronic exposure of chickens to a petroleum hydrocarbon-contaminated environment produced coordinated toxicological disturbances across multiple physiological systems, demonstrating true multisystem toxicity rather than isolated organ-specific effects. Endocrine disruption, hepatorenal impairment, cardiovascular injury, hematological dysregulation, oxidative stress, inflammatory activation, and heavy metal accumulation occurred concurrently, reflecting interconnected pathogenic mechanisms driven by prolonged environmental exposure. The convergence of these alterations underscores the systemic biological burden imposed by petroleum hydrocarbons and associated co-pollutants.
Endocrine disturbances observed in exposed chickens, including altered reproductive and thyroid hormone profiles, appeared closely linked to oxidative and inflammatory stress. Disruption of gonadotropin secretion, sex steroid balance, and thyroid regulation suggests impaired hypothalamic–pituitary control. Oxidative stress is known to interfere with hormone synthesis, transport, and receptor signaling, while pro-inflammatory cytokines can suppress endocrine gland function, indicating that redox imbalance and immune activation likely amplified endocrine toxicity in exposed birds (Movahedinia et al., 2018; Dey et al., 2015; Huang et al., 2017).
Hepatic and renal dysfunction further contributed to systemic toxicity. Elevated liver enzymes, altered protein indices, increased bilirubin fractions, and deranged renal electrolytes and nitrogenous waste markers reflect compromised detoxification and excretory capacity. Impairment of these organs may exacerbate endocrine and cardiovascular toxicity by reducing clearance of petroleum hydrocarbons, hormones, and inflammatory mediators. Such dysfunction facilitates bioaccumulation of toxic metabolites and heavy metals, reinforcing a cycle of cumulative toxicity (Thomas et al., 2021; Lala, Zubair, & Minter, 2023).
Cardiovascular injury was evident through elevations in cardiac troponin I, creatine kinase-MB, and natriuretic peptides, indicating myocardial injury and hemodynamic stress. These changes were accompanied by hematological abnormalities, including anemia, leukocytosis, elevated erythrocyte sedimentation rate, and platelet alterations. Hematological dysregulation may worsen tissue hypoxia and inflammatory burden, thereby increasing cardiac strain. The parallel occurrence of cardiovascular and hematological disturbances suggests that altered blood composition and immune activation contribute to hydrocarbon-induced cardiac injury (Lawal et al., 2019; Miller, 2022).
Oxidative stress and inflammation emerged as central mechanistic pathways linking multisystem toxicity. Depletion of antioxidant enzymes, increased lipid peroxidation, and elevated inflammatory mediators collectively indicate persistent redox imbalance and immune activation. These processes disrupt cellular membranes, impair enzyme function, and alter gene expression, thereby affecting endocrine glands, liver, kidneys, heart, and hematopoietic tissues simultaneously. Chronic inflammation likely potentiated oxidative injury, establishing a self-perpetuating toxicological cascade (Altanam, Darwish, & Bakillah, 2025; Bellanti et al., 2025).
Heavy metal accumulation further intensified multisystem toxicity. Elevated concentrations of chromium, lead, and zinc in exposed chickens reflect environmental bioavailability and biological uptake from contaminated ecosystems. Heavy metals can directly generate reactive oxygen species, inhibit antioxidant enzymes, and modulate immune responses, thereby amplifying oxidative and inflammatory damage initiated by petroleum hydrocarbons. The coexistence of hydrocarbon exposure and heavy metal burden therefore represents a compounded toxicological threat under chronic exposure conditions (Javed et al., 2025; Aljohani, 2023).
Sex-dependent differences were evident across multiple systems. Female chickens generally exhibited greater endocrine disruption, oxidative stress, and inflammatory responses following prolonged exposure, whereas males demonstrated relatively higher heavy metal accumulation and more pronounced cardiovascular markers. These differences may be attributed to sex-specific hormonal regulation, metabolic capacity, antioxidant defenses, and metal handling pathways. Such findings highlight the importance of sex-stratified analyses in environmental toxicology to avoid masking vulnerable subpopulations (Hao, Xie, & Li, 2025; Ebrahimi, Ebrahimi, & Shakeri, 2023).
Duration of exposure emerged as a critical determinant of toxicity severity. Chickens exposed for 12 months consistently demonstrated more pronounced multisystem alterations than those exposed for 6 months, emphasizing the cumulative nature of petroleum hydrocarbon toxicity. Prolonged exposure permits progressive oxidative damage, persistent inflammation, endocrine exhaustion, and organ dysfunction, ultimately resulting in systemic failure rather than adaptive compensation.
Overall, these findings demonstrate that petroleum hydrocarbon exposure induces integrated multisystem toxicological effects in chickens, mediated through interacting pathways involving oxidative stress, inflammation, endocrine disruption, organ dysfunction, and heavy metal accumulation. The observed sex- and duration-dependent patterns provide important insight into vulnerability dynamics and reinforce the value of chickens as sentinel species for assessing complex environmental toxicity.
CONCLUSION
This study provides compelling evidence that chronic exposure to petroleum hydrocarbon-contaminated environments induces profound multisystem toxicological effects in chickens. Integrated assessment revealed concurrent disruption of endocrine regulation, hepatic and renal function, cardiovascular integrity, hematological homeostasis, redox balance, immune responses, and heavy metal accumulation. The simultaneous occurrence of these alterations confirms that petroleum hydrocarbons exert systemic toxicity through interconnected biological pathways rather than isolated organ-specific mechanisms.
Oxidative stress and inflammatory activation emerged as central mediators linking multisystem dysfunction. Depletion of antioxidant defenses, increased lipid peroxidation, and sustained elevation of inflammatory biomarkers likely contributed to endocrine disruption, organ injury, cardiovascular damage, and hematological abnormalities. Heavy metal accumulation further intensified toxicity by amplifying oxidative and inflammatory pathways and impairing detoxification capacity, resulting in a cumulative toxicological burden that worsened with prolonged exposure.
Sex- and duration-dependent differences highlight differential vulnerability to petroleum hydrocarbon toxicity. Female chickens showed greater endocrine, oxidative, and inflammatory disturbances with prolonged exposure, whereas males exhibited more pronounced cardiovascular and metal-related alterations. Collectively, these findings underscore the importance of incorporating sex-specific and temporal analyses in environmental toxicology and highlight chickens as sensitive sentinel species for assessing ecological, food safety, and public health risks in petroleum-impacted regions.
LIMITATIONS AND FUTURE DIRECTIONS
Despite the robustness of the multisystem findings, certain limitations should be acknowledged. The relatively small sample size may limit broad generalization, although the consistency of toxicological patterns across multiple physiological systems supports the biological relevance of the results. Environmental exposure conditions did not permit precise characterization of individual petroleum hydrocarbon fractions or metal speciation, which may influence toxicity profiles. In addition, the absence of histopathological and molecular analyses limited confirmation of mechanistic pathways at the tissue and cellular levels.
Future studies should incorporate larger sample sizes, controlled exposure models, and detailed chemical characterization of environmental contaminants. Histopathological evaluation of endocrine glands, liver, kidney, heart, and hematopoietic tissues would strengthen mechanistic interpretation, while molecular analyses of oxidative, inflammatory, and endocrine signaling pathways would further elucidate cross-system interactions. Longitudinal investigations assessing reversibility of toxicity following environmental remediation would also provide valuable insight into recovery potential and long-term health outcomes.
Funding Statement
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
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