Benzo[a]pyrene, often abbreviated BaP, is everywhere in modern life. It forms whenever organic matter burns incompletely, which means it rises from charcoal grills as fat drips onto hot coals, drifts from cigarette smoke and tailpipes, and accumulates in workplaces such as aluminum smelters, coke ovens and asphalt plants. The International Agency for Research on Cancer classifies it as a Group 1 carcinogen, a category reserved for agents with confirmed cancer-causing activity in humans. Once ingested or inhaled, BaP is metabolically activated by cytochrome P450 enzymes, chiefly CYP1A1 and CYP1B1, into a highly reactive intermediate called BPDE. This compound latches onto DNA to form adducts that can initiate cancer, while the metabolic process itself generates a flood of reactive oxygen species that overwhelm the body’s natural antioxidant enzymes and damage cell membranes, proteins and lipids. Because the liver serves as the body’s principal detoxification organ, it bears the brunt of this chemical assault.

The research team, based at Islamic Azad University in Shahrekord, Iran, set out to test whether dietary intervention could blunt this damage. Seventy male C57BL/6 mice were randomly assigned to fourteen groups of five animals each, with the sample size determined by formal power analysis to satisfy the principles of reduction in animal research. One group received only standard food, another received the olive oil vehicle used to dissolve the chemicals, and a third received 20 milligrams per kilogram of BaP daily by oral gavage for four weeks, a dose previously shown to induce significant oxidative stress and liver and kidney injury in mice without reaching acute lethal levels. A fourth group received vitamin E at 250 milligrams per kilogram, a dose established in earlier studies as antigenotoxic against BaP damage. The remaining groups received chia seed powder mixed into their food at 10, 20 or 30 percent by weight, either alone, alongside BaP simultaneously, or as a two-week pre-treatment before BaP exposure began.

The design allowed the researchers to answer two distinct practical questions. Co-administration tested whether the protective agents could limit damage occurring at the same time as exposure, a scenario relevant to people who cannot avoid contaminated food or polluted workplaces. Pre-treatment tested whether building up the body’s defenses in advance could prevent injury more effectively, a scenario relevant to preventive nutrition. All biochemical analyses were performed in a blinded manner, and the animals were monitored daily for humane endpoints such as excessive weight loss or lethargy, none of which were reached during the study.

The results were unambiguous in one direction and humbling in another. BaP exposure significantly depleted the mice’s total antioxidant capacity and superoxide dismutase activity, raised malondialdehyde, a marker of lipid peroxidation, elevated the liver enzymes AST and ALT, lowered serum albumin, and pushed triglycerides and LDL cholesterol upward. Vitamin E, despite its reputation as a potent fat-soluble radical scavenger, failed to restore antioxidant capacity or superoxide dismutase activity and offered no meaningful protection to the liver enzymes. Chia seeds, by contrast, produced dose-dependent benefits. At 20 and 30 percent dietary inclusion, co-administered chia significantly raised total antioxidant capacity and superoxide dismutase activity while lowering malondialdehyde. Thirty percent chia pre-treatment increased both superoxide dismutase and glutathione peroxidase activities and cut malondialdehyde levels further. Chia co-administration reduced AST at all doses, rescued albumin at the lower doses, lowered triglycerides across the board, and raised protective HDL cholesterol at the higher doses.

The lipid findings were particularly dramatic. BaP exposure drove triglycerides from roughly 1.1 millimolar in controls to 2.44 millimolar, and LDL cholesterol from about 83 to 163 milligrams per deciliter. Chia co-administration at 30 percent brought triglycerides back near baseline while pushing HDL cholesterol to levels well above those of untreated controls. The authors attribute these effects to the seed’s unique biochemical portfolio: alpha-linolenic acid, abundant dietary fiber and a rich array of polyphenols. Mechanistically, chia-derived alpha-linolenic acid appears to activate peroxisome proliferator-activated receptor alpha, boosting fatty acid oxidation, while suppressing sterol regulatory element-binding protein-1, which curbs lipogenesis. Chia components also inhibit fatty acid translocase, known as CD36, limiting fatty acid uptake into tissues, and the seed’s proteins and polyphenols reduce inflammatory signaling through tumor necrosis factor alpha while raising adiponectin.

Why did the whole food outperform the purified vitamin? The researchers argue that BaP’s toxicity is multifaceted, attacking membranes, enzymes, lipid metabolism and DNA simultaneously, and that a single antioxidant molecule simply cannot cover all those fronts. Chia seeds deploy a multitarget strategy: their polyphenols and omega-3 fats act synergistically to neutralize reactive oxygen species directly, and they appear to activate the nuclear factor erythroid 2-related factor 2, or Nrf2, signaling pathway, which switches on the cell’s own antioxidant gene program. Vitamin E, by contrast, may influence CYP1A1 and CYP1B1 activity, but the study suggests this mechanism is insufficient against the scale of oxidative assault that BaP delivers. The authors also note that the vitamin E dose, though previously validated, may have been inadequate for this model, or that the four-week treatment window was too short.

Not every organ responded. BaP raised blood urea nitrogen and creatinine, classic markers of kidney injury, but neither chia nor vitamin E significantly reversed these changes. The researchers suggest that renal protection may require longer treatment durations or different therapeutic approaches, pointing to similar findings with lavender extract against lead-induced nephrotoxicity. The study also has acknowledged limitations: the diets were not isocaloric, body weight and food intake were not formally tracked, tissue-level analyses were not performed, and the potentially synergistic combination of chia and vitamin E was never tested, a question the authors flag as a priority for future work.

The pre-treatment versus co-administration comparison carries a clear public health message. Pre-treatment with 30 percent chia preserved superoxide dismutase and glutathione peroxidase activities and kept malondialdehyde low, suggesting that building antioxidant reserves before exposure is the more effective strategy. For the millions of people exposed to BaP through charred food, secondhand smoke or occupational settings such as coke ovens and aluminum plants, where air monitoring has identified BaP as the dominant carcinogenic risk, the implication is that preventive dietary supplementation matters more than trying to repair damage after the fact. The findings also align with a broader shift in nutrition science away from single-molecule supplements and toward whole-food matrices, whose complex mixtures of bioactive compounds often deliver benefits that isolated nutrients cannot replicate.

Cautious interpretation remains essential. These results come from mice receiving deliberately high doses of both toxin and protective agents, and human trials of chia supplementation in healthy and overweight adults have generally shown only modest changes in lipid profiles and inflammatory markers, likely because those studies lacked a specific toxic challenge. The authors emphasize that clinical and mechanistic studies in humans are needed before dietary recommendations can be made with confidence. Still, the study offers a compelling proof of concept that a common, inexpensive whole food can outperform a flagship antioxidant supplement against one of the world’s most notorious environmental carcinogens, and it suggests that what you eat before exposure may matter as much as the exposure itself.

Subject of Research: Dietary protection against benzo[a]pyrene-induced oxidative toxicity in mice using chia seeds and vitamin E

Article Title: Protective Effects of Chia Seeds and Vitamin E Against Benzo[a]Pyrene‐Induced Toxicity in Male Mice: A Comparison of co‐Administration and Pre‐Treatment Strategies

Article References: Rezaei, M., & Karimi‐Dehkordi, M. (2026). Protective Effects of Chia Seeds and Vitamin E Against Benzo[a]Pyrene‐Induced Toxicity in Male Mice: A Comparison of co‐Administration and Pre‐Treatment Strategies. Food Science & Nutrition, 14(10), Article e72405. https://doi.org/10.1002/fsn3.72405

Image Credits: AI Generated

DOI: 10.1002/fsn3.72405

Keywords: benzo[a]pyrene, chia seeds, vitamin E, oxidative stress, hepatotoxicity, polycyclic aromatic hydrocarbons, antioxidants, mice study, lipid profile, food toxicology, pre-treatment, nutrition

The starting point of the investigation was a computational strategy known as network toxicology, which treats a chemical, its protein targets, and human disease genes as nodes in an interconnected graph rather than as isolated entities. The researchers first assembled a comprehensive list of proteins that benzo[a]pyrene is known or predicted to interact with, drawing on established toxicogenomic databases and target-prediction tools. They then cross-referenced this list with genes associated with prostate cancer. The overlap was striking: 975 shared targets emerged, suggesting that BaP and prostate tumors converge on an unexpectedly large common molecular territory. When these 975 genes were mapped onto known biological pathways, the enrichment analysis pointed decisively toward the PI3K-Akt signaling axis, one of the most frequently hijacked growth and survival circuits in human malignancy, along with related networks governing cell proliferation, apoptosis resistance, and immune modulation.

Identifying 975 candidate genes is a useful beginning, but cancer biology demands sharper focus. To distill the signal, the team applied differential expression analysis to prostate cancer transcriptomic data and then deployed machine learning algorithms to select which of the differentially expressed genes best separated tumor from healthy tissue. Two complementary algorithms converged on four core genes: CAV1, TWIST1, PRKCA, and GDF15. Each of these has an established biography in cancer research. CAV1 encodes caveolin-1, a scaffolding protein of membrane caveolae with documented roles in prostate cancer progression and treatment resistance. TWIST1 is a transcription factor best known for orchestrating epithelial-to-mesenchymal transition, the cellular program that allows stationary epithelial cells to become invasive and migratory. PRKCA encodes protein kinase C alpha, described in recent work as a central node of tumorigenic transcriptional networks in the prostate. GDF15, or growth differentiation factor 15, is a stress-response cytokine whose levels correlate with aggressive and castration-resistant disease.

With the four core genes in hand, the investigators turned to transcriptomic verification. The expression pattern in prostate tumor datasets was coherent and directional: TWIST1 and GDF15 were up-regulated in cancer tissue, while CAV1 and PRKCA were down-regulated. More impressive was the diagnostic performance. When the four genes were combined into a single diagnostic model, the area under the receiver operating characteristic curve reached 0.990, a value approaching the theoretical maximum of 1.0 and indicating near-perfect discrimination between cancerous and non-cancerous samples. The authors emphasize that this four-gene signature could distinguish BaP-relevant molecular states in prostate tissue with a precision that single biomarkers rarely achieve, positioning the panel as both a mechanistic fingerprint of pollutant-driven carcinogenesis and a candidate clinical diagnostic tool.

Because tumors are not merely collections of malignant cells but complex ecosystems of immune, stromal, and epithelial populations, the team next examined how the core genes behave at single-cell resolution. Single-cell RNA sequencing data revealed the specific cellular distribution of each gene within the prostate tumor microenvironment and documented immunological shifts associated with their expression. Immune infiltration analysis at the bulk-tumor level reinforced the connection: the core genes were linked to cellular growth programs and to the recruitment of immune cells into tumors. This immunological dimension matters because previous research has suggested that BaP exposure can play an immunosuppressive role during prostate cancer progression, potentially helping tumors evade surveillance. The new findings place that immune remodeling on a firmer molecular footing, tying it to genes that are themselves responsive to BaP exposure.

To test whether the carcinogen could physically engage its putative targets, the researchers performed molecular docking, a computational technique that predicts how a small molecule fits into the binding pocket of a protein. The docking simulations showed that benzo[a]pyrene binds favorably to the core targets, providing a structural rationale for the associations uncovered by the network analysis. Docking results are inherently approximate and do not prove physiological binding in living cells, but within the study’s multi-layered design they serve as an important plausibility check, bridging the gap between statistical gene associations and the physical chemistry of pollutant-protein interactions.

Perhaps the most consequential portion of the work is its external validation. Computational pipelines in toxicology are sometimes criticized for generating elegant networks that evaporate under experimental scrutiny, so the authors tested their predictions with laboratory and dataset evidence outside the discovery pipeline. The validation confirmed that BaP may promote the progression of prostate cancer and reproduced the expected expression shifts: GDF15 up-regulated and PRKCA down-regulated in prostate cancer contexts linked to BaP exposure. The convergence of the computational prediction and the external evidence strengthens the causal narrative considerably, indicating that the four-gene axis is not an artifact of a single database or analytical choice but a reproducible molecular pattern.

The study arrives amid a growing wave of network toxicology applied to environmental carcinogens in urological cancers. Recent publications have used similar frameworks to implicate polycyclic aromatic hydrocarbons in reproductive health outcomes, to trace the oncogenic pathways of aristolochic acids across prostate, kidney, and bladder cancers, and to dissect the contributions of phthalates such as diethyl phthalate and DEHP to prostate carcinogenesis. Epidemiological work has also lent real-world weight to the hypothesis: occupational exposure to polycyclic aromatic hydrocarbons has been associated with elevated prostate cancer risk in case-control studies. What distinguishes the new paper is the breadth of its validation stack, extending from machine-learning biomarker selection through single-cell immunology to molecular docking and external experimental confirmation, all focused on a single Group 1 carcinogen that nearly every person encounters daily through diet, air, and tobacco smoke.

The implications cut in two directions. Clinically, a four-gene diagnostic panel with an AUC of 0.990 suggests that pollutant-driven molecular signatures could eventually complement prostate-specific antigen testing, which suffers from well-documented problems of overdiagnosis and poor specificity. If GDF15, for example, is already being explored as a circulating marker of response to docetaxel chemotherapy in metastatic castration-resistant prostate cancer, integrating exposure-linked gene panels into diagnostic algorithms could help identify which tumors are environmentally fueled and potentially which patients might benefit from interventions targeting the PI3K-Akt pathway, where several inhibitors are already under investigation in hormone-related cancers. Public health officials, meanwhile, may find in these results additional mechanistic justification for limiting BaP exposure through food preparation guidance, tobacco control, and air quality regulation, since the molecular evidence now traces a plausible route from charred protein and diesel soot to the transcriptional circuits of prostate tumors.

The authors are careful about scope. Their conclusions are framed as BaP potentially promoting prostate cancer development through regulation of CAV1, TWIST1, GDF15, and PRKCA, with causal certainty limited by the correlative nature of much of the transcriptomic evidence and by the approximate nature of docking predictions. The DU145 prostate cancer cell line used in their experiments is commercially available, and the study received support from the Guizhou Provincial Health Commission and related provincial research programs. Still, the work exemplifies a methodological shift that is transforming environmental oncology: instead of asking whether a chemical damages DNA, researchers now map the full network of its molecular conversations with human tissue, then test the strongest nodes experimentally. For a carcinogen as widespread as benzo[a]pyrene, and a cancer as prevalent as prostate cancer, that map may prove to be one of the most valuable public health documents of the decade.

Subject of Research: Molecular mechanisms linking benzo[a]pyrene exposure to prostate cancer

Article Title: Exploring the molecular mechanism of benzo[a]pyrene affecting prostate cancer based on network toxicology and external validation

Article References: Zhu, S., Li, Z., Jiang, K., Sun, F., & Zhu, J. (2026). Exploring the molecular mechanism of benzo[a]pyrene affecting prostate cancer based on network toxicology and external validation. Molecular Diversity. https://doi.org/10.1007/s11030-026-11729-6

Image Credits: AI Generated

DOI: 10.1007/s11030-026-11729-6

Keywords: benzo[a]pyrene, prostate cancer, network toxicology, machine learning, CAV1, TWIST1, PRKCA, GDF15, PI3K-Akt pathway, single-cell analysis, molecular docking, environmental carcinogens

Benzo[a]pyrene, often abbreviated BaP, belongs to the polycyclic aromatic hydrocarbons, a family of compounds assembled from fused aromatic rings and generated mainly by the combustion of fossil fuels, plant biomass, and petroleum derivatives. These molecules are persistent, highly lipophilic, and notorious for their affinity for particulate surfaces. In aquatic organisms they are associated with narcosis, cardiac dysfunction, mutagenicity, and carcinogenicity, and BaP in particular ranks among the most potent genotoxic and bioaccumulative agents known in aquatic toxicology. Microplastics, meanwhile, have become so widespread that measuring their effects in isolation increasingly misses the point. Contaminants in rivers and lakes rarely arrive alone, and microplastic particles, with their vast hydrophobic surface areas, are prime candidates to interact chemically with hydrocarbons dissolved in the water.

The research team, led by Yuuri Gabriel de Souza Santos of Universidade Santa Cecília together with colleagues from Universidade Santa Cecília and the Universidade Federal de São Paulo, designed a full-factorial exposure experiment to disentangle these interactions. Cultures of Raphidocelis subcapitata were exposed for 72 hours under tightly controlled conditions of temperature, light, and agitation to low-density polyethylene microplastics at three concentrations: 5, 50, and 500 milligrams per liter. The lowest of these reflects concentrations actually reported in freshwater environments, while the higher doses were intended to simulate more extreme pollution scenarios. Each microplastic treatment was tested alone and in combination with the median effective concentration of BaP, the dose that inhibits algal growth by fifty percent, which the team first determined experimentally for this species.

That determination produced a sobering baseline. The calculated EC50 for BaP in R. subcapitata was approximately 21 micrograms per liter, with a 95 percent confidence interval of 20 to 25 micrograms per liter. Even the lowest concentration tested, 3 micrograms per liter, caused statistically significant growth inhibition, marking it as the lowest observed effect concentration under the study’s conditions. At the highest dose of 39 micrograms per liter, growth inhibition approached 90 percent. The estimated EC50 falls squarely within the range of BaP concentrations documented in contaminated freshwater systems worldwide, where water column values typically span from less than a hundredth of a microgram to roughly 2.4 micrograms per liter, and sediments can hold far higher burdens. In other words, the toxicological benchmark established in the laboratory is uncomfortably close to what polluted rivers actually deliver.

The mechanism behind BaP’s damage to algae is thought to involve both photosynthetic disruption and direct membrane interactions. As a lipophilic compound, BaP binds readily to the lipid bilayers of algal cells, and polycyclic aromatic hydrocarbons can drive excessive production of reactive oxygen species through interference with cellular electron transport. Prior work has also shown that high hydrocarbon loads impair chlorophyll production, starving cells of photosynthetic capacity. Intriguingly, during routine microscopic examination the researchers occasionally observed clumps of lipids forming on the outer surfaces of BaP-exposed cells, a response consistent with previous reports that green algae increase membrane lipids as a defensive strategy against cytotoxic hydrocarbon damage.

When the microplastics were tested on their own, the results defied simple dose-response logic. At 5 and 50 milligrams per liter, the polyethylene particles significantly reduced algal density, an effect the authors attribute largely to chemical additives incorporated into the polymer, such as plasticizers, antioxidants, UV stabilizers, lubricants, and pigments. Because these additives are not covalently bound to the plastic matrix, they can leach into the surrounding water and exert their own toxicity; benzotriazole UV stabilizers, for example, have previously been shown to harm the freshwater alga Chlamydomonas reinhardtii. Yet at 500 milligrams per liter, toxicity vanished entirely and algal biomass actually exceeded the control by 3.7 percent, surpassing the lower-dose treatments by more than 40 percent. The most plausible explanation is that the enormous particle surface area at high concentrations provided an ideal substrate for biofilm formation, effectively turning the plastic into a growth platform for the microorganisms it would otherwise harm.

The combined exposures produced the study’s most consequential findings. BaP alone at 21 micrograms per liter inhibited roughly 57.6 percent of algal growth. But when the same BaP concentration was paired with 50 or 500 milligrams per liter of microplastics, inhibition dropped sharply to about 34.9 and 22.8 percent respectively, both statistically distinct from BaP alone. The interpretation is that at these higher particle densities, the hydrophobic hydrocarbon preferentially sorbs onto plastic surfaces, sequestering it away from the water column and lowering its effective bioavailability to the algae. This protective sorption effect mirrors previous observations in gammarids, cladocerans, sea urchins, and mysids, and echoes a study of juvenile common gobies in which microplastics delayed pyrene-induced mortality from 48 to 60 hours. Plastic, in these scenarios, acts as a temporary chemical sponge.

At the environmentally relevant concentration, however, the picture reversed into genuine concern. When just 5 milligrams per liter of microplastics accompanied the BaP, inhibition remained essentially unchanged from BaP alone, at about 58.3 percent, and both treatments were significantly more toxic than controls. This dose of plastic was evidently too low to strip a meaningful fraction of BaP from solution, leaving the hydrocarbon free to attack cell membranes. Since 5 milligrams per liter reflects concentrations documented in real freshwater systems, the message for regulators is troubling: at realistic pollution levels, microplastics do nothing to buffer hydrocarbon toxicity, while the plastic itself independently inhibits growth at that same dose.

The authors emphasize that this is the first study to evaluate combined BaP and microplastic effects in Raphidocelis subcapitata, and that their generalized linear model analyses confirmed a statistically significant interaction between the two contaminants, meaning the impact of each depends on the level of the other. The relationship is explicitly nonlinear: microplastics can either enhance or mitigate BaP toxicity depending on their concentration, rendering simple additive assumptions obsolete. Fourier transform infrared spectroscopy confirmed the test particles were linear low-density polyethylene, the polymer characteristically identified by split methylene peaks and methyl-group bands in its spectrum, matching the manufacturer’s specification.

The ecological stakes extend well beyond a single algal species. As primary producers, freshwater microalgae drive oxygen production, nutrient cycling, and energy transfer through food webs, and both microplastics and hydrocarbons can bioaccumulate in algal cells before moving to higher trophic levels. Green algae such as R. subcapitata are also valued agents of PAH bioremediation, and the new results raise questions about whether plastic contamination could undermine that cleanup capacity by altering hydrocarbon bioavailability. The authors acknowledge limitations: BaP adsorption onto the particles was not directly quantified, and responses such as chlorophyll content, oxidative stress, and gene expression were not measured. Notably, prior work on marine invertebrates found that even when survival appeared unaffected by combined exposures, surviving organisms carried DNA damage and elevated lipid peroxidation, hinting that growth-based endpoints may understate harm. The team calls for future research on chronic effects, trophic transfer, and additional freshwater species under environmentally realistic conditions, and concludes that microplastics cannot be treated as inert particles in aquatic systems. Their concentration, not merely their presence, may determine whether they worsen or mask the toxicity of the organic pollutants they travel with.

Subject of Research: Interactive toxicity of low-density polyethylene microplastics and benzo[a]pyrene in the freshwater microalga Raphidocelis subcapitata

Article Title: Interactive effects of low-density polyethylene microplastics and benzo[a]pyrene on the growth of the freshwater microalgae Raphidocelis subcapitata

Article References: de Souza Santos, Y. G., Choueri, R. B., Nobre, C. R., Simões, F. R., & Gusso-Choueri, P. K. (2026). Interactive effects of low-density polyethylene microplastics and benzo[a]pyrene on the growth of the freshwater microalgae Raphidocelis subcapitata. Ecotoxicology, 35(7), Article 161. https://doi.org/10.1007/s10646-026-03143-3

Image Credits: AI Generated

DOI: 10.1007/s10646-026-03143-3

Keywords: microplastics, benzo[a]pyrene, Raphidocelis subcapitata, freshwater ecotoxicology, polycyclic aromatic hydrocarbons, low-density polyethylene, algal growth inhibition, bioavailability, sorption, additive leaching, biofilm formation, ecological risk assessment