1. Your kitchen sponge. Flickr: gosheshe / Via Creative Commons When you should replace it: Every week — unless you kill germs on your sponge by microwaving it on high for one minute or cleaning it in the dishwasher.Here's why: Uncleaned sponges can accumulate millions of bacteria that put you at risk for food poisoning. And while cleaning techniques (like microwaving a damp sponge for a minute) will get rid of most bacteria, regularly replacing your sponges is still a good idea. 2. Your pillows. Flickr: jbozanowski / Via Creative Commons When you should replace it: Every 18 months.Here's why: Old pillows accumulate all kinds of unpleasant things like mold, dead skin cells, and dust mites, which can trigger illness and allergies. 3. Your loofah. dimpipatelnd / Via instagram.com When you should replace it: Every 3 months — although in the interim, you should clean them properly by rinsing them with super hot water and letting them dry outside the shower in between uses. Here's why: Loofahs are a breeding ground for bacteria, and can contain fungal organisms that lead to skin infections. 4. Your bra. liveslow / Via ThinkStock When you should replace it: Every 6-12 months — although they can last longer if you regularly rotate your bras.Here's why: Older bras offer less support (which can lead to back pain) and can even cause skin discomfort. 5. Your herbs and spices. Flickr: somegeekintn / Via Creative Commons When you should replace them: If stored correctly, most herbs and spices should be replaced after 1 year. Dried, whole spices generally last up to 3 years.Here's why: Herbs and spices don't go "bad," but they do lose their flavor (which can seriously hurt your cooking game). 6. Your car seat. Flickr: raes_antics / Via Creative Commons When you should replace it: Generally 5-6 years after the date of manufacturing, depending on your car seat's expiration date (yes, car seats have expiration dates). You should replace a car seat after you have an accident, too.Here's why: The parts in your car seat degrade, warp, and wear over time making your kid more susceptible to harm in a crash. 7. Your contact lens case. Flickr: lenore-m / Via Creative Commons When should you replace it: At least every three months.Here's why: Keeping a case longer than you should increases your chances of developing an eye infection. 8. Your toothbrush. Flickr: sidewalk_flying / Via Creative Commons When you should replace it: "Every 3-4 months or sooner if the bristles become frayed from use," according to the American Dental Association. Kids' toothbrushes may need to be changed even sooner.Here's why: The biggest reason is because older toothbrushes are less effective in cleaning your teeth, but they also develop bacteria and other microorganisms over time. There isn't really any clinical evidence proving these microorganisms are harmful to you, but still — nasty. 9. Your beauty products. Jenny Chang / Via BuzzFeed Design When you should replace it: Anywhere from 2 months to 3 years (as detailed above).Here's why: Expired beauty products can cause a whole host of problems including inflammation, rashes, and allergic reactions that can be really severe. 10. Your eyelash curler. @kealseyanne / Via instagram.com When should you replace it: At a minimum every twelve months, but many recommend that you change it every 6 months. You will also need to change the pads every 3 months.Here's why: The change may be imperceptible over time, but an eyelash curler loses its precision performance after continued use. 11. Your smoke detector. Flickr: topquark22 / Via Creative Commons When you should replace it: Every ten years. That may sound like a long time, but do you know for sure how old the smoke detectors are in your home? If not, replace them. Here's why: It might literally save your life and most smoke detectors cost just ten bucks or less. 12. Your baby's pacifier. Flickr: timothykrause / Via Creative Commons When you should replace it: Every 2 months.Here's why: The older the pacifier, the more likely it has been contaminated with biofilms that can increase the risk of developing colic or ear infections, plus more serious conditions as well. An older pacifier is also more apt to break and become a choking hazard. 13. Your HVAC air conditioning filter. Chesterland / Flickr: ivydawned / Via Creative Commons When you should replace it: Every 1-3 months depending the type of filter.Here's why: Dirty filters make your air conditioner less efficient, costing you serious coin. 14. Your cat's litter. Jeremy Pippa / Via instagram.com When you should replace it: Twice weekly for non-clumping litter, monthly for clumping litter.Here's why: If the litter box is dirty your cat might stop using it — and start going elsewhere in the house. 15. Your non-stick cookware. Flickr: cjp24 / Via Creative Commons When you should replace it: Every 2 years, but if your pan is chipped or scratched you should immediately stop using it.Here's why: Older pans are more likely to chip or flake, and chipped/flaked pans may release toxic compounds.