Is there any risk of botulism from refrigerator pickling or brining? (referring to both meat and slices of vegetables/fruit)  I've read about the subject a fair bit, and know the inherent risks with garlic in oil or items vacuum packed in the fridge for a long time.  However, I recently read about the use of nitrite salt in refrigerator brines for cured ham (a week-long process), which the author claimed was used to maintain the colour of the meat (which darkens without the nitrites) and also prevent botulism growth. But if all the ingredients were at 4°C before going into the fridge, what botulism growth could there be, especially in one week?  Is there something I'm not aware of, or this person uninformed? 
You won't grow significant cultures of clostridium botulinum in temperatures below 50°F. On the flipside, unfortunately, refrigerator temperatures - while retarding growth - do not destroy the bacterium or inactivate or destroy its toxin.  The good news is, normal boiling inactivates present toxins, so even if you have c. botulinum present in the brine but boil it, the combination of both the inactivation of the toxin and the retardation of growth in low temperatures makes brining a pretty safe activity.  Furthermore, c. botulinum really dislikes high acid environments. Brines are usually rather acidic. It's important to note that it takes 250°F over three minutes to cause significant damage to clostridium botulinum. All other means, such as boiling at sea level pressure or refrigerating/freezing only slows culture growth and prevents the production of botulinum toxin. That means even if you cooked, boiled, and froze your food, leaving it out in the danger zone for too long still poses a risk. Obviously pressure-canning does significantly lower it. 