Health

Health: What the Evidence Does and Does Not Show

The health case here does not rest on claiming this plant will make Plainfield sick. It rests on two firmer foundations: what the pollutants in the ash are, by authoritative classification, and what fine-particle pollution does to mortality across the general population. The near-plant disease studies are presented as what they are — inconsistent, and weak for most outcomes.

Part one

What the Pollutants in the Ash Are

The fly ash, bottom ash and process residues of waste-gasification and incineration plants are documented in the peer-reviewed literature to carry dioxins and heavy metals — lead, cadmium, arsenic, mercury and others. (The composition record is set out on the Water & Land page.) What those specific substances are, in the judgment of the world’s health authorities, is not a matter of dispute.

Dioxins: a known human carcinogen

• The International Agency for Research on Cancer (IARC), the World Health Organization’s cancer body, classifies 2,3,7,8-TCDD — the reference dioxin of the class found in this ash — as Group 1, “carcinogenic to humans,” its highest tier, and has described it as a multi-site carcinogen.¹ The WHO’s public fact sheet restates this and explains the toxic-equivalency (TEF/TEQ) framework regulators use to weigh dioxin mixtures.³
• The U.S. EPA’s Integrated Risk Information System sets an oral reference dose for TCDD of 7 × 10⁻¹⁰ mg/kg per day — one of the lowest (most potent) reference doses in the entire IRIS database — a high-confidence value based on effects on sperm and on neonatal thyroid function.⁴ The federal ATSDR toxicological profile ties dioxin exposure to developmental, reproductive, liver and immune toxicity as well as cancer.⁶

Arsenic and cadmium: also Group 1

• IARC classifies arsenic and cadmium (and their compounds) as Group 1, carcinogenic to humans — the same top tier as dioxin.² These are not trace curiosities; they are among the metals the peer-reviewed literature identifies as enriched and leachable in municipal-waste incineration fly ash.

Lead: no known safe level

• In 2021 the U.S. Centers for Disease Control and Prevention lowered the childhood blood-lead reference value from 5.0 to 3.5 micrograms per deciliter and states plainly that there is no known safe blood-lead level in children.⁵ The ATSDR lead profile identifies the nervous system as the main target, with low-level exposure decreasing children’s mental development, learning, IQ and behavior; lead is an EPA probable carcinogen and IARC Group 2A.⁷

These classifications describe the pollutants themselves. They do not, on their own, quantify the risk from any one plant — but they establish that the substances in the ash are genuine hazards, not an inert list of chemical names.¹²

Part two

Fine Particles and Death: The Dose-Response

The strongest population-level health evidence relevant to any combustion facility is not about incinerators specifically — it is about fine particulate matter (PM2.5), the sub-2.5-micron particles that combustion produces and that lodge deep in the lungs. Here the epidemiology is large, replicated, and consistent.

• The chart above draws on the Harvard Six Cities cohort, whose 35-year follow-up found that each 10 µg/m³ of long-term PM2.5 raised all-cause mortality by 14%, cardiovascular mortality by 26%, and lung-cancer mortality by 37% — with the association holding below 18 µg/m³ and no safe floor identified.¹² The original 1993 Six Cities study first established the higher mortality in the most-polluted city and became the basis for regulating PM2.5 as a mortality risk.¹³
• An independent cohort — the American Cancer Society study of roughly 1.2 million adults — confirmed the direction and scale: each 10 µg/m³ PM2.5 raised all-cause mortality about 4%, cardiopulmonary about 6%, and lung-cancer about 8%.¹⁴ The two landmark cohorts point the same way.
• Regulators have moved with the evidence toward lower and lower thresholds. In February 2024 the U.S. EPA tightened the annual PM2.5 standard from 12.0 to 9.0 µg/m³, the current binding federal health benchmark;⁹ the WHO in 2021 halved its annual guideline from 10 to 5 µg/m³, citing demonstrated harm at progressively lower levels.⁸ EPA’s own weight-of-evidence assessment finds the long-term PM2.5–cardiovascular-mortality relationship to be causal, not merely correlational.¹⁰

A new large combustion source does not need to be an outlier to matter: the mortality evidence finds no exposure level demonstrated to be safe.¹²⁸

Part three

The Near-Facility Epidemiology, Honestly

Mixed evidence — mostly null

The question residents most want answered — do people who live near these plants get sick more often? — has the weakest evidence base on this page. The studies disagree, most outcomes show no significant effect, and study quality is often low. Honesty requires presenting the specific findings and the null results side by side, without a headline that the record does not support.

• Porta et al. (2009), systematic review. Reviewing solid-waste-management health studies, it reported small excess risks within 3 km of incinerators — all-cancers relative risk 1.035 (95% CI 1.03–1.04), lung 1.14, colorectal 1.11, liver 1.29, non-Hodgkin lymphoma 1.11 — and within 10 km, facial-cleft RR 1.30 and renal dysplasia RR 1.55. It judged the respiratory evidence inadequate and inconsistent.¹⁵
• Bottini et al. (2025), the most current meta-analysis. It found a small but significant asthma association — hazard ratio 1.02 (95% CI 1.00–1.05) per 1 ng/m³ of incinerator PM10 — and flagged individual high-exposure studies (one French cohort with ~2.3× non-Hodgkin lymphoma; one Italian study with leukemia OR 4.12, CI 1.82–9.32, at high dioxin exposure). But it found the birth and reproductive evidence inconsistent and no consistent robust signal for most outcomes.¹⁶
• Elliott et al. (1996), the largest study by scale. Covering more than 14 million people near 72 British incinerators, it found cancer risk declining significantly with distance from the plants (all cancers and stomach, colorectal, liver and lung), the liver gradient largest at roughly a 37% excess in the nearest band. The authors themselves caveated the finding as possibly reflecting diagnostic misclassification or residual confounding rather than a plant effect.¹⁷
• Parkes et al. (2019), Imperial College birth-outcomes study. Examining 219,486 births within 10 km of 10 modern incinerators, it found no risk linked to modeled PM10, but did find, per 1 km closer to a plant, congenital-heart-defect odds ratio 1.04 (CI 1.01–1.08) and genital-anomaly OR 1.07 (CI 1.02–1.12). Both were statistically significant, and the authors did not exclude a causal effect — nor confirm one.¹⁸
• Baek, Park & Kwak (2022), the null result. Pooling 11 studies, this meta-analysis found no significant excess for breast, colorectal, liver, lung, lymphohematopoietic, stomach, bladder, central-nervous-system, or all cancers combined (pooled RR 1.00, CI 0.94–1.06). The single exception was female laryngeal cancer (RR 1.82, CI 1.10–3.01). This is the clearest statement of how much of the near-plant cancer literature comes back null.¹⁹

Read together, these are not a proof of local harm and should not be presented as one. They are a body of mostly-null and inconsistent evidence with a few significant signals — asthma, some birth anomalies, scattered high-dose cancer findings — that neither confirms nor rules out an effect near a modern plant.

Part four

The Counter-Position: “No Clear Evidence”

A page that only cited the positive findings would be doing exactly what it criticizes. So here is the strongest official argument against a local-health claim, stated plainly.

• The UK Health Security Agency (formerly Public Health England) holds that modern, regulated municipal-waste incinerators add so little to local air pollution — on the order of a thousand times below background PM10 — that “it is not possible to rule out adverse health effects… completely, but any potential damage to health is likely to be very small, if detectable.” UKHSA states there is no clear evidence of associations with cancer, respiratory disease, or adverse birth outcomes.¹¹
• Two honest caveats sit alongside that position. First, the UKHSA opinion concerns modern, well-regulated plants operating within permit limits, and much of the underlying study base involves older-generation facilities; it is a statement about what studies have detected, not a guarantee of harmlessness. Second, and more important, the UKHSA position does not touch the two firmer foundations of this page: it does not reclassify the Group 1 carcinogens in the ash, and it does not overturn the general PM2.5 mortality dose-response.¹¹²

The defensible health argument is narrow and true: the pollutants are known hazards, fine particles kill at every measured level, and the near-plant disease evidence is unsettled. Not “this plant will give Plainfield cancer.”¹¹¹⁹

Questions and answers

Frequently Asked Questions

Will this plant cause cancer in Plainfield?

No one can say that, and this page does not claim it. The studies of people living near incinerators are mixed and mostly null — the most recent cancer meta-analysis found no pooled excess for most cancers. What can be said with citation is that the pollutants documented in this class of ash are classified as known human carcinogens, and that fine-particle air pollution raises mortality with no safe threshold identified.¹⁹¹¹²

Are the pollutants in the ash actually dangerous?

By the judgment of the world’s health authorities, yes. IARC classifies dioxin, arsenic and cadmium as Group 1 — carcinogenic to humans. The CDC states there is no known safe blood-lead level. The EPA’s reference dose for dioxin is among the lowest for any substance in its database.¹²⁵⁴

Does fine-particle pollution really raise the death rate?

Yes, and this is among the best-replicated findings in environmental health. In the 35-year Harvard Six Cities cohort, each 10 µg/m³ of long-term PM2.5 raised all-cause mortality 14%, cardiovascular 26%, and lung-cancer 37%, with no safe floor found; the American Cancer Society cohort of 1.2 million adults confirmed the pattern. The EPA judges the long-term PM2.5–cardiovascular-mortality link to be causal.¹²¹⁴¹⁰

The developer says modern incinerators are safe — is that true?

The UK Health Security Agency does state there is no clear evidence linking modern regulated incinerators to cancer, respiratory disease or birth outcomes, because they add very little to local air pollution. That position is presented in full above. It does not, however, reclassify the carcinogens in the ash or overturn the general PM2.5 mortality evidence, and its study base leans on older-generation plants.¹¹

What is the honest bottom line?

The strong, defensible health facts are the hazard classifications of the pollutants and the PM2.5 mortality dose-response. The near-facility disease epidemiology is unsettled and should not be used as proof of local harm. Both halves of that are on this page, sourced.¹¹²¹⁹