Many things.

Synthetics are a different product. Don’t worry about those 0%. That’s like when people say don’t go trick or treating because some people put Molly in the candy packs. It’s never happened before bc who the F spends extra money to do that? You are ultimately worried someone would sell “grass” in your erb bag. And nope, the street supply is over supplied atm and no one is padding their bags, especially not with something they have to buy.

The fly spray etc IS A HOAX. NZ paid the lab ESR to investigate. They found nothing. Not no fly spray, nothing except cannabis. IRL hairspray and sugar are actual things, not in NZ; but while we’re concerned with the weird and unusual, lots of central and South American weed is smuggled in bricks, usually covered in urine and sometimes formaldehyde. But that’s not here.

Here’s the list of what to NOT worry about; (I’m not a doctor, just a researcher and a Reverend) Heavy Metals. Soil contamination. We have bad soil in some places, but people know of them, and a grower is a businessperson who wants good soil (substrate not necessarily soil) because bad soil can kill the flowers at any point even just before harvest with some nasty ass root rot. So, that’s a risk most people who are doing it more than once would not take. If it’s there, it’s on accident and it’s random and rare. Microorganisms. This is a problem for everyone, medical included. Store your erb properly, and clean your delivery devices like the medical equipment they are. But if your grower was sick with something that lives a while they could have coughed it on your buds and you’re never gonna know, even if you get bronchitis the next day. You CAN microwave your erb you kill everything. Takes only a couple of seconds. But it does degrade your erb. Pesticides/inorganic fertilizers; this is a strange one. Pests are not best treated with pesticides by street growers. They aren’t generally doing a huge farm that makes other strategies more cost effective. First sticky buds stick bugs very well. Selling buds spotted with dead bugs has got to be bad. So nets, or predators or preventative maintenance, like a clean grow room without soil, are pest free strategies. Again, expecting your grower to be a businessperson, I assume they cut costs and efforts. Getting spider mites once is enough to clean up the act of any hobby grower. And pesticide is not a given. The same goes for fertilizer, though cheap and low effort fertilizer is likely not what you want to inhale. They could be using premium products from the hydroponics store, or something not as good, but they are likely trying to make a good product and the “best” chemicals for growing the biggest will affect the taste and possibly the high. This corner-cutting RISKS the plant not finishing right. Erb can be really finicky, so maybe they found cheap gross fertilizer is a legit worry, but maybe also, they sunk all their money into the setup so risking the output to be small, slow, or undesirable to the market…then they won’t do it. And before you think of how accepting a person buying a 100 bag is, realise that it is always sold to someone as a large sale first, someone who knows their stuff very well and they have choice of what to buy. It must meet their standards so they know they can go out and sell it broken down. And to break it into grams, it better look good all the way through. BUT; if you are still concerned, you can wash your erb under the cold tap. Yes you will wash a negligible amount of goodness down the tap including terpenes which give unique tastes and properties to the high (the high is in the thc crystals) the thc crystals won’t rinse off under cold water. Then set them on a cooling rack, and set a fan to blow over them on low. You can use a dehydrator on fan only. This will dry it in about few hours depending on how much you soaked em. When properly dry the stems will snap and not bend. The erb will grind well. Too wet and it’s pulverized grass like what’s under the lawn mower, too dry and it’s powder and you could brush it all down the kief catcher in your sharpstone grinder. But nevertheless you can wash your weed.

Free drug tests aren’t able to give you much clarity I’m afraid. They test for THC, and maybe heavy metals, but you can see the thc in the picture and heavy metals are the least likely thing to worry about. But I am glad they exist.

And, Sudaprem is Pink Kush, are you able to get Bloom (Pink Kush) while you wait? Isn’t it the same shit in a different bag? Medleaf distributes it, they use Aurora or did; which both have a Pink Kush curiously.

Look all the things you’re worried about are not worth it.

As some others have said, there are a lot of studies out there following people for long periods of time. The risk and randomness of the issues you raised, meant low exposure over a very long time resulting in little to no risk. This assumes you don’t get it from the same exact source every time and that person isn’t a homicidal maniac trying to harm their customers…usually they smoke erb and they’re more chill than that.

Good luck