Every Wednesday, 9NEWS Medical Expert Dr. Comilla Sasson answers your questions about the health news that's fact and what's fiction.

The latest edition deals with aluminum foil, washing plastics, and the air filters in your furnace.

1) Aluminum foil in the oven is safe (FICTION)

A study from 2012 suggests that when aluminum foil is placed in the oven and heated at high temperatures, or if it is used to cook highly acidic foods like tomatoes and lemon juice and certain spices, it can cause the aluminum to leech into the food.

The World Health Organization says for a 150-pound person, they can have up to 2,400 mg of aluminum per day.

But, there is aluminum in a lot of other sources as well, such as water, anti-perspirents, antacids, cheeses, spices and cooking utensils.

There is also a possible link between high levels of aluminum and Alzheimer's disease. So, although it may make the clean up time a bit worse, it may be worth forgoing the aluminum foil ... for now.

2) Washing plastics dishes, bottles, Tupperware in the dishwasher is safe (FICTION)

When plastics are heated to high temperatures (in the dishwasher for example), bisphenol A (BPAs) can be released. There are also other chemicals, even in the BPA-free bottles, that people need to watch out for, specifically phthalates and phenols.

These release an estrogen0type compound that can interfere with the endocrine, thyroid and metabolism.

BPA was banned from kids' products in 2012. But still so many chemicals that do leech out these chemicals. The American Academy of Pediatrics just released their own guidelines on this for children.

3) Air filters for your furnace need to be replaced every 1-3 months (FACT)

It depends a bit on the type of filters and the thickness, but it is important to change these out every one to three months.

Lots of dust and dirt that can get trapped in here and then get spread across the house. Dirty air filters can affect people with lung issues like emphysema and asthma, give you that runny nose/congested feeling, and could even affect your heart over time.

So check to see what the recommendations are for changing out your filters.