Where do clandestine labs often source phosphorous from?

Phosphorus is commonly sourced from matches and road flares in the context of clandestine labs, particularly in the illicit production of methamphetamine. Matches contain red phosphorus, which is a key substance used in the synthesis of meth. Road flares also contain red phosphorus, making them another readily available source for individuals involved in illegal drug production.

While other options may have limited relevance, they do not provide the same level of practical accessibility or effectiveness in the way that matches and road flares do for those attempting to construct clandestine labs. This is part of why sourcing from matches and road flares is particularly noteworthy in discussions about the precursor chemicals utilized in illegal drug manufacturing.