| Evidence population/year | Observation | Interpretation and limitations | Sources |
|---|---|---|---|
| Jiangsu pneumoconiosis registry, China, 2011–2023; analysis published 2024 | Graphite pneumoconiosis accounted for 2 of 5,791 deceased pneumoconiosis patients (0.03%). | This is the graphite-diagnosis share **among registered deceased pneumoconiosis patients**, not population prevalence, incidence, case-fatality, or graphite-specific mortality. The two cases are too few for disease-specific survival inference. | (pqac-00000015, pqac-00000021, pqac-00000049) |
| NIOSH survey, Asbury Graphite Mills, United States, 1993; report published December 1994 | Among 47 current workers, 3 (6.4%) had chest radiographs consistent with simple pneumoconiosis; 8 (17.0%) had below-normal spirometry—6 mild obstructive and 2 mild restrictive patterns. | Cross-sectional, small, all-male workforce; no unexposed control group and former workers did not participate. Silica measurement was analytically unsuccessful, but graphite feedstock contained silica and potential silica overexposure was demonstrated, preventing attribution to graphite alone. | (pqac-00000016, pqac-00000046) |
| Historic CT series of 19 graphite workers, reported in a 2006 review | CT showed small nodular hyperattenuating areas in 17/19 (89.5%), interlobular septal thickening in 11/19 (57.9%), and large hyperattenuating areas in 10/19 (52.6%). | Small selected series rather than a screening population; findings resemble coal-workers’ pneumoconiosis and are not specific for graphite. Exposure composition and frequencies among all graphite-exposed workers were not established. | (pqac-00000017, pqac-00000047) |
| Historic review of 639 reported graphite-pneumoconiosis cases, published 1983 | Histopathology or autopsy material confirmed only 39/639 reported cases (6.1%); detailed dust-exposure information was available for only 14 cases. | The evidence base was dominated by radiographic reports with limited pathological and exposure verification. The reviewer judged most adequately described cases to be mixed-dust reactions, commonly involving mineral impurities such as quartz or mica. | (pqac-00000000, pqac-00000017) |
| Fischer-344 rat acute inhalation study, published 1989 | After one 4-hour exposure, synthetic graphite containing <0.1% quartz at 1–100 mg/m³ did not produce the persistent inflammatory and macrophage changes seen with 100 mg/m³ silica. At 500 mg/m³, graphite produced transient inflammation and macrophage activation lasting about 24–48 hours; particles remained in macrophages for up to 3 months without reduced lavage-cell viability. | Animal, acute, very high-concentration exposure; it demonstrates macrophage uptake and a dose-dependent transient response, not chronic human pneumoconiosis. It neither excludes delayed effects of prolonged exposure nor resolves the contributions of graphite, silica impurities, and particle overload in workers. | (pqac-00000019, pqac-00000024, pqac-00000029) |


*Table: Compact evidence table separating human registry, workplace, imaging, pathology, and experimental findings. It highlights denominator constraints, silica confounding, and the limits of extrapolating acute rat responses to chronic occupational disease.*