## Facts

- Members of the Community of San Mateo de Huanchor, a rural community in Huarochirí, Lima, alleged serious environmental and health impacts from a nearby toxic mine tailings (sludge) dump known as “Mayoc,” associated with a private mining company.
- Petitioners alleged Peru authorized, allowed, or tolerated the dump’s operation and continued presence despite studies reporting high concentrations of heavy metals in environmental media and in residents’ blood, particularly children.
- Reported findings included elevated rates of lead, cadmium, and mercury exposure, and alleged medical conditions among children such as dermatitis, liver dysfunction, hearing loss, and malnutrition; petitioners also alleged a heightened risk of severe dermatological outcomes if the dump was not relocated.
- Petitioners asserted contamination harmed agricultural production and interfered with community ties to land and environment, affecting both subsistence and collective interests.
- Petitioners claimed domestic judicial and administrative responses were ineffective due to delay, inadequate protective measures, and financial and structural barriers for a rural community confronting mining-related harms.
- Peru objected that domestic remedies were not exhausted because a related criminal proceeding was pending when the petition was filed (Feb. 28, 2003).
- While the admissibility determination was pending, the Commission issued precautionary measures (Aug. 17, 2004) directing Peru to implement health assistance—especially for children—and to develop a plan to remove or neutralize the toxic waste.

## Issues

1. Whether the Commission had jurisdiction (ratione personae, materiae, temporis, and loci) over the alleged harms linked to toxic contamination affecting protected rights.
2. Whether the petition satisfied admissibility requirements under Articles 46 and 47 of the American Convention, including exhaustion of domestic remedies (or applicable exceptions) and timeliness.
3. Whether the alleged facts, if proven, could characterize violations of the invoked Convention rights, warranting merits review.

## Decision

- The Commission issued an admissibility report (Oct. 15, 2004) finding the petition admissible in part, without prejudging the merits.
- The petition was declared admissible regarding alleged violations of Articles 4 (life), 5 (humane treatment), 8 (fair trial), 17 (family), 19 (rights of the child), 21 (property), 25 (judicial protection), and 26 (progressive development), in conjunction with Articles 1(1) and 2.
- The Commission declined, at the admissibility stage, to proceed on other invoked provisions (including Articles 7, 11, 16, 22, 23, and 24).
- The Commission rejected Peru’s inadmissibility objection based on non-exhaustion, concluding the petition satisfied Articles 46 and 47 (including through exhaustion or applicable exceptions).
- The Commission ordered notice to the parties, publication in its annual report, and continuation to the merits phase on the admitted claims.

## Legal Principles

- At admissibility, the Commission determines jurisdiction and whether a petition satisfies Articles 46 and 47; this assessment is preliminary and does not decide whether violations occurred.
- The exhaustion requirement may be satisfied either by completion of effective domestic remedies or by exceptions when remedies are unavailable, inadequate, or ineffective in the specific circumstances.
- A petition is admissible when alleged facts are not manifestly groundless and, if proven, could characterize violations of protected rights.
- Severe environmental contamination and related health impacts may be analyzed through Convention rights such as life, personal integrity, child protection, property, and judicial guarantees/protection, and may also implicate Article 26 duties concerning economic, social, and cultural rights.
- Precautionary measures may be issued when there is a serious and urgent risk of irreparable harm, including directions for medical monitoring/care and remediation planning.

## Conclusion

The Commission allowed the case to proceed to the merits on a defined set of rights, concluding that alleged toxic contamination and ineffective domestic responses could, if proven, constitute violations of life, integrity, due process, property, child and family protections, judicial protection, and Article 26 obligations, notwithstanding the State’s non-exhaustion objection.


Cmty. of San Mateo de Huanchor & Its Members v. Peru, Case 504/03, Inter-Am. Comm'n H.R., Report No. 69/04 (2004)