Ham and cheese sandwiches are a lunchbox staple; a quick and easy throw together lunch to tick the carb, dairy, protein – and delicious – boxes. So some parents have been left scratching their heads at a new ban on the simple sanga in public schools across WA.

The change comes about under a restructure of the “traffic light” system set out for school canteens to ensure kids are offered healthy choices at the tuck shop. The green-amber-red system classifies food and drink in the state’s public schools, moving ham and other processed red meat from an earlier “amber” label to “red”, limiting its sale in canteens.

While the overhaul has raised eyebrows among some parents, the new rules could be a step in the right direction as consuming too much processed meat, like ham, has been proven to increase the risk of bowel cancer.

The sandwich in question has landed in the hinterland of the light system though, leaving parents and canteen workers – many of whom are volunteers – confused. Ham and cheese toasties served with salad sit in the ‘selected red’ category, meaning that they can be sold in canteens two days a week. A plain ham sandwich is in the red category and is not allowed.

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A fact sheet released in December by the department states the reclassification of some foods from amber to red was designed to align schools Australian Dietary Guidelines, the Australian Curriculum and a federal government health council guide to reduce children’s exposure to unhealthy food and drink. The fact sheet also reclassified previously red and amber foods into the green section, like full fat dairy products moving from amber to green.

Green food and drink items now include all dairy products, canned vegetables and legumes, plain pizza bases, tinned fish, vegetables, falafels and tempeh, cheese and cracker snack packs and plain popcorn.

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Amber foods now reclassified as red include hot potato and sweet potato chips and wedges, ham, sausages and frankfurters, pies and sausage rolls, chips and savoury biscuits, cookies, cakes, desserts, sweet pastries, and fruit juice slushies. Curiously though, the same fruit juice products are in the amber category if they’re not frozen.

Food items that now need to be served with at least half a serving of salad or vegetables include chicken wings and nuggets, burger patties, rissoles, meatballs and fish cakes, pressed chicken, plant-based meat alternatives such as vegetarian sausages and ready-made hot meals.

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