Measuring and Mitigating Toxicity in Large Language Models: A Comprehensive Replication Study

TL;DR

This study evaluates DExperts, an inference-time technique for reducing toxicity in large language models, revealing high effectiveness against explicit toxicity but vulnerabilities with implicit hate speech and significant latency costs.

Contribution

It provides a comprehensive empirical assessment of DExperts, highlighting its strengths and limitations in mitigating both explicit and implicit toxicity in LLMs.

Findings

DExperts achieves 100% safety on explicit toxicity benchmarks.

The method's safety drops to 98.5% against implicit hate speech.

Latency increases tenfold, impacting real-time deployment.

Abstract

Large Language Models (LLMs) trained on web-scale corpora inherently absorb toxic patterns from their training data. This leads to toxic degeneration where even innocuous prompts can trigger harmful outputs. This phenomenon poses significant risks for real-world deployments. Thus, necessitating effective mitigation strategies that should maintain model utility while ensuring safety. In this comprehensive replication study, we evaluate the efficacy of DExperts (Decoding-time Experts), which is an inference-time mitigation technique that steers generation without requiring model retraining. We structured our research into three systematic phases: (1) establishing baseline toxicity measurements using RealToxicityPrompts on standard GPT-2 models; then (2) implementing and evaluating DExperts to mitigate explicit toxicity; and finally (3) stress-testing the method against implicit hate speech using the adversarial ToxiGen dataset. Our empirical results confirm that while DExperts achieves near-perfect safety rates (100%) on explicit toxicity benchmarks, it exhibits brittleness against adversarial, implicit hate speech, with safety rates dropping to 98.5%. Furthermore, we quantify a critical trade-off. The method introduces a 10x latency penalty (from 0.2s to 2.0s per generation), posing challenges for real-time deployment scenarios. This study contributes to the growing body of work on AI safety by highlighting the robustness gap between explicit and implicit toxicity mitigation. We emphasize the need for more sophisticated approaches that generalize across diverse hate-speech patterns without incurring prohibitive computational costs.