Mercury (inorganic/elemental) in the yard and garden
Moderate risk for your yardInorganic and elemental mercury compounds are classified by IARC as Group 3 (not classifiable as to carcinogenicity in humans) in Monographs Volume 58 (1993), based on inadequate evidence of carcinogenicity in both humans and experimental animals — a sharp contrast to methylmercury (Group 2B) and reflecting the different toxicokinetics and target organ specificity of the two mercury species. Elemental mercury (Hg⁰) is a room-temperature liquid with significant vapor pressure (0.26 Pa at 25°C) that generates mercury vapor at ambient temperatures; inhaled mercury vapor is highly bioavailable (approximately 80% pulmonary retention), rapidly absorbed into blood, and oxidized by catalase to Hg²⁺ in erythrocytes and brain tissue — producing the neurotoxic and nephrotoxic inorganic mercury ion predominantly in the CNS and kidneys. The primary sources of elemental mercury exposure for the general adult population are dental amalgam fillings (each dental amalgam restoration releases approximately 1–5 μg mercury per day as vapor, absorbed during chewing, tooth grinding, and normal oral activity), occupational inhalation in dental offices, chlor-alkali plants, thermometer manufacturing, and gold mining operations (artisanal and small-scale gold mining using mercury amalgamation is the dominant source of mercury exposure for miners in developing countries). Dental amalgam provides a continuous low-level elemental mercury inhalation exposure; for adults with multiple fillings, amalgam-derived daily mercury inhalation of 3–17 μg/day places blood mercury in the range of 2–10 μg/L — within the acceptable range under WHO guidance for inorganic mercury (urine mercury <35 μg/g creatinine as LOAEC), but near the lower end of the range where subtle neurological effects have been reported in occupational studies. WHO urinary mercury guideline: <50 μg/L (guidance for health-based interpretation); occupational health standard (OSHA PEL): 0.1 mg/m³ (8-hr TWA) for inorganic mercury vapor.
What is mercury (inorganic/elemental)?
The IUPAC name is mercury.
Also known as: mercury, Quicksilver, Hydrargyrum, Liquid silver.
- IUPAC name
- mercury
- CAS number
- 7439-97-6
- Molecular formula
- Hg
- Molecular weight
- 200.59 g/mol
- SMILES
- [Hg]
- PubChem CID
- 23931
Risk for people, pets,
Moderate riskInorganic and elemental mercury compounds are classified by IARC as Group 3 (not classifiable as to carcinogenicity in humans) in Monographs Volume 58 (1993), based on inadequate evidence of carcinogenicity in both humans and experimental animals — a sharp contrast to methylmercury (Group 2B) and reflecting the different toxicokinetics and target organ specificity of the two mercury species. Elemental mercury (Hg⁰) is a room-temperature liquid with significant vapor pressure (0.26 Pa at 25°C) that generates mercury vapor at ambient temperatures; inhaled mercury vapor is highly bioavailable (approximately 80% pulmonary retention), rapidly absorbed into blood, and oxidized by catalase to Hg²⁺ in erythrocytes and brain tissue — producing the neurotoxic and nephrotoxic inorganic mercury ion predominantly in the CNS and kidneys. The primary sources of elemental mercury exposure for the general adult population are dental amalgam fillings (each dental amalgam restoration releases approximately 1–5 μg mercury per day as vapor, absorbed during chewing, tooth grinding, and normal oral activity), occupational inhalation in dental offices, chlor-alkali plants, thermometer manufacturing, and gold mining operations (artisanal and small-scale gold mining using mercury amalgamation is the dominant source of mercury exposure for miners in developing countries). Dental amalgam provides a continuous low-level elemental mercury inhalation exposure; for adults with multiple fillings, amalgam-derived daily mercury inhalation of 3–17 μg/day places blood mercury in the range of 2–10 μg/L — within the acceptable range under WHO guidance for inorganic mercury (urine mercury <35 μg/g creatinine as LOAEC), but near the lower end of the range where subtle neurological effects have been reported in occupational studies. WHO urinary mercury guideline: <50 μg/L (guidance for health-based interpretation); occupational health standard (OSHA PEL): 0.1 mg/m³ (8-hr TWA) for inorganic mercury vapor.
Regulatory consensus
12 regulatory and scientific bodies have classified Mercury (inorganic/elemental). The classifications differ — that's the data.
| Agency | Year | Classification | Notes |
|---|---|---|---|
| OSHA | — | Occupational exposure limit | |
| EPA CTX / IRIS | — | D (Not classifiable as to human carcinogenicity) | |
| EPA CTX / IARC | — | Group 3 - Not classifiable as to its carcinogenicity to humans | |
| EPA CTX / Health Canada | — | Group 3: IARC (not classifiable as to its carcinogenicity to humans) Group C: IRIS (possible human carcinogen) | |
| EPA CTX / EPA OPP | — | Group D Not Classifiable as to Human Carcinogenicity | |
| EPA CTX / Skin-Eye | — | Skin Sensitization: Sh (score: high) | |
| EPA CTX / Skin-Eye | — | Eye Irritation: Category 2 (score: high) | |
| EPA CTX / Skin-Eye | — | Skin Sensitization: Category 1 (score: high) | |
| EPA CTX / Skin-Eye | — | Skin Sensitization: Category 6.5B (Category 1) (score: moderate) | |
| WHO | 2024 | major_concern | Top 10 chemicals of major public health concern. |
| EU_REACH | 2024 | restricted | EU Mercury Regulation. Minamata Convention. |
| US_EPA | 2024 | MCLG_0.002 | Drinking water standard: 0.002 mg/L |
Regulators apply different standards of evidence — animal-data weighting, exposure-pattern assumptions, epidemiological power thresholds — which is why two scientific bodies can review the same data and reach different conclusions. The disagreement is the data.
Where your yard encounter mercury (inorganic/elemental)
- Contaminated Water — Mining site runoff, Industrial discharge areas, Drinking water from old infrastructure
- Soil Contamination — Industrial sites, Smelter areas, Battery recycling facilities
- Food Chain — Fish from contaminated waters, Shellfish from polluted areas, Crops grown in contaminated soil
Safer alternatives
Lower-risk approaches that achieve a similar outcome to Mercury (inorganic/elemental):
-
Process controls to minimize degradant formation
Trade-offs: Additional manufacturing costRelative cost: 1.2-2×
Frequently asked questions
Is mercury (inorganic/elemental) safe for your yard?
Inorganic and elemental mercury compounds are classified by IARC as Group 3 (not classifiable as to carcinogenicity in humans) in Monographs Volume 58 (1993), based on inadequate evidence of carcinogenicity in both humans and experimental animals — a sharp contrast to methylmercury (Group 2B) and reflecting the different toxicokinetics and target organ specificity of the two mercury species. Elemental mercury (Hg⁰) is a room-temperature liquid with significant vapor pressure (0.26 Pa at 25°C) that generates mercury vapor at ambient temperatures; inhaled mercury vapor is highly bioavailable (approximately 80% pulmonary retention), rapidly absorbed into blood, and oxidized by catalase to Hg²⁺ in erythrocytes and brain tissue — producing the neurotoxic and nephrotoxic inorganic mercury ion predominantly in the CNS and kidneys. The primary sources of elemental mercury exposure for the general adult population are dental amalgam fillings (each dental amalgam restoration releases approximately 1–5 μg mercury per day as vapor, absorbed during chewing, tooth grinding, and normal oral activity), occupational inhalation in dental offices, chlor-alkali plants, thermometer manufacturing, and gold mining operations (artisanal and small-scale gold mining using mercury amalgamation is the dominant source of mercury exposure for miners in developing countries). Dental amalgam provides a continuous low-level elemental mercury inhalation exposure; for adults with multiple fillings, amalgam-derived daily mercury inhalation of 3–17 μg/day places blood mercury in the range of 2–10 μg/L — within the acceptable range under WHO guidance for inorganic mercury (urine mercury <35 μg/g creatinine as LOAEC), but near the lower end of the range where subtle neurological effects have been reported in occupational studies. WHO urinary mercury guideline: <50 μg/L (guidance for health-based interpretation); occupational health standard (OSHA PEL): 0.1 mg/m³ (8-hr TWA) for inorganic mercury vapor.
What products contain mercury (inorganic/elemental)?
Mercury (inorganic/elemental) appears in: Mining site runoff (Contaminated water); Industrial discharge areas (Contaminated water); Industrial sites (Soil contamination); Smelter areas (Soil contamination); Fish from contaminated waters (Food chain).
Why do regulators disagree about mercury (inorganic/elemental)?
Mercury (inorganic/elemental) has been classified by 12 agencies including OSHA, EPA CTX / IRIS, EPA CTX / IARC, EPA CTX / Health Canada, EPA CTX / EPA OPP, with differing conclusions. Regulators apply different standards of evidence (animal data weighting, exposure-pattern assumptions, epidemiological power thresholds), which is why two scientific bodies can review the same data and reach different conclusions. See the regulatory consensus table on this page for the full picture.
See Mercury (inorganic/elemental) in the outdoor app
Look up products containing mercury (inorganic/elemental), compare to alternatives, and explore the full data record.
Open in outdoor View raw API dataSources (1)
- IARC Monographs Volume 58: Beryllium, Cadmium, Mercury, and Exposures in the Glass Manufacturing Industry — Methylmercury Compounds Group 2B; Inorganic Mercury Compounds Group 3 (1993) (1993) — regulatory
Reference data, not professional advice. Aggregates publicly available regulatory and scientific data; not a substitute for veterinary, medical, legal, or regulatory advice. Why we built ALETHEIA →