Botulism toxins — relative human toxicity among types A, B, and C Among the listed botulinum neurotoxin serotypes, which is considered less toxic to humans under typical foodborne exposure scenarios?

Introduction / Context:
Clostridium botulinum produces several neurotoxin serotypes (A–G). Human foodborne botulism most often involves types A, B, E, and, less frequently, F. Awareness of relative human toxicity guides risk assessment across food categories and animal reservoirs.

Given Data / Assumptions:

• Serotypes listed: A, B, C (and others).
• Question: which is less toxic to humans?
• Context: human foodborne disease patterns.

Concept / Approach:
Human cases predominantly involve types A, B, and E. Type C is much more associated with animal/bird botulism (avian botulism), with relatively fewer and atypical human cases. Thus, relative to A and B, type C is considered less toxic or less clinically significant to humans in typical foodborne exposure contexts.

Step-by-Step Solution:
Rank serotypes by human clinical prevalence: A/B/E > F > C (rare in humans).Compare options A, B, C; choose the serotype least implicated in human disease.Select type C as less toxic to humans.

Verification / Alternative check:
Epidemiological data show A and B dominate US/European foodborne botulism; E is linked to marine foods; C is primarily veterinary.

Why Other Options Are Wrong:
Types A and B are highly potent for humans; “none of these” contradicts established patterns; type F is uncommon but still recognized in humans.

Common Pitfalls:
Assuming equal human relevance across all serotypes; overlooking host range differences.

Final Answer:
Type C.