Gestational Exposure to Volatile Organic Compounds (VOCs) and Trace Metals in a Region of Intensive Hydraulic Fracturing for Natural Gas Exploitation
Bibliographic record
Abstract
Background: The Peace River Valley (Northeastern British Columbia, Canada), located on the Montney formation, is an area of intensive hydraulic fracturing for natural gas exploitation. Hydraulic fracturing operations can release contaminants that have been associated with adverse birth outcomes. Recent studies in the United States found associations between density and proximity of natural gas wells and birth defects, small birth weight and preterm birth. However, no exposure assessment studies have been carried in Northeastern British Columbia.Objective: To evaluate exposure to benzene, toluene and a suite of trace metals in 29 Indigenous (13) and non-Indigenous (16) pregnant women from the Peace River Valley.Methods: Enrolled participants collected urine samples over five consecutive days and provided one hair sample. We measured metabolites of benzene (trans,trans muconic acid (tt-MA), S-phenylmercapturic acid (S-PMA)) and toluene (S-benzylmercapturic acid (S-BMA)) in pooled urine samples from each participant. We measured trace metals in pooled urine samples and in the two centimeters of hair closest to the scalp.Results: The median urinary tt-MA level was 3.5 times higher (182 μg/g creatinine) than that from the general Canadian population (48 μg/g creatinine); in Indigenous participants, the median level was 6 times higher (319 μg/g creatinine). Median urinary and hair levels of barium (1.52 μg/L and 4.48 μg/g of hair), aluminum (7.60 μg/L and 4.37 μg/g of hair), strontium (148.40 μg/L and 4.47 μg/g of hair), and manganese (0.49 μg/L and 0.16 μg/g of hair) were higher in participants than reference median levels established in non-occupationally exposed volunteers.Conclusion: Our results suggest elevated gestational exposure to contaminants in our study population compared to the general population. Documenting gestational exposure to environmental chemicals in this region is paramount to assessing health risks and developing exposure mitigation strategies.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".