MedPT: A Massive Medical Question Answering Dataset for Brazilian-Portuguese Speakers

While large language models (LLMs) show transformative potential in healthcare, their development remains focused on high-resource languages, creating a critical barrier for others as simple translation fails to capture unique clinical and cultural nuances, such as endemic diseases. To address this, we introduce MedPT, the first large-scale, real-world corpus for Brazilian Portuguese, comprising 384,095 authentic question-answer pairs from patient-doctor interactions. The dataset underwent a meticulous multi-stage curation protocol, using a hybrid quantitative-qualitative analysis to filter noise and contextually enrich thousands of ambiguous queries. We further augmented the corpus via LLM-driven annotation, classifying questions into seven semantic types to capture user intent. Our analysis reveals its thematic breadth (3,200 topics) and unique linguistic properties, like the natural asymmetry in patient-doctor communication. To validate its utility, we benchmark a medical specialty routing task: fine-tuning a 1.7B parameter model achieves an outstanding 94\% F1-score on a 20-class setup. Furthermore, our qualitative error analysis shows misclassifications are not random but reflect genuine clinical ambiguities (e.g., between comorbid conditions), proving the dataset's deep semantic richness. We publicly release MedPT to foster the development of more equitable, accurate, and culturally-aware medical technologies for the Portuguese-speaking world.

ToxSyn-PT: A Large-Scale Synthetic Dataset for Hate Speech Detection in Portuguese

We present ToxSyn-PT, the first large-scale Portuguese corpus that enables fine-grained hate-speech classification across nine legally protected minority groups. The dataset contains 53,274 synthetic sentences equally distributed between minorities groups and toxicity labels. ToxSyn-PT is created through a novel four-stage pipeline: (1) a compact, manually curated seed; (2) few-shot expansion with an instruction-tuned LLM; (3) paraphrase-based augmentation; and (4) enrichment, plus additional neutral texts to curb overfitting to group-specific cues. The resulting corpus is class-balanced, stylistically diverse, and free from the social-media domain that dominate existing Portuguese datasets. Despite domain differences with traditional benchmarks, experiments on both binary and multi-label classification on the corpus yields strong results across five public Portuguese hate-speech datasets, demonstrating robust generalization even across domain boundaries. The dataset is publicly released to advance research on synthetic data and hate-speech detection in low-resource settings.