Polycyclic aromatic hydrocarbons (PAH) are organic compounds of petrogenic and pyrogenic origin that are ubiquitous, persistent, bioaccumulative in adipose tissue, and proven to be carcinogenic. The Cagarras Islands Natural Monument (MONA) is a protected area located 4,5 km from the city of Rio de Janeiro, whose potential sources of PAH to the site include the Ipanema Outfall, Guanabara Bay, the transit of large and small vessels, and atmospheric deposition from high traffic of vehicles and industrial emissions. Considering that bivalve mollusks are effective biomonitoring organisms of exposure to PAH, in Feb/22 (C1) and Jul/22 (C2), approximately 240 mussels of the species Perna perna were collected from three MONA islands to assess the input of PAHs from anthropogenic activities. Composite samples (3-5 animals) were extracted in triplicate using accelerated solvent extraction (ASE) with purification in the cell, and additional purification by column chromatography. The PAH fraction was determined by gas chromatography-mass spectrometry (GC-MS). The concentrations of (summation)39PAH ranged from 236 to 1378 ng g-1, with the highest values found in C1, similar to previous studies with P. perna in the region of Guanabara Bay and some of the MONA islands (68-6271 ng g-1), but characterized by an increase in input over the last 10 years. The general profile of contaminants demonstrates a mixture of pyrolytic and petrogenic sources in the MONA region, with probable sources being fossil fuel combustion in the metropolitan region and chronic oil input, including irregular leaks, from the constant traffic of vessels and anchoring near the MONA. The concentrations of Benzo[a]pyrene, the (summation)4PAH – benzo[a]anthracene, chrysene, benz[b]fluoranthene, and benzo[a]pyrene – and the Toxic Equivalent Quotient of Benzo[a]pyrene (TEQ BaPy) were below the thresholds of 5 ng g-1, 30 ng g-1, and 18 ng g-1, respectively, but higher in the sampling performed in summer, suggesting a potential risk to the quality of seafood (mollusks) and the human population. The scenario provided by a limited data set (only two samplings) reinforces the need for a biomonitoring program in the Cagarras Islands Natural Monument that includes PAHs and other classes of organic contaminants, such as polychlorinated biphenyls (PCBs) and pesticides.