As we used to say here, perfumes are added to detergents mainly with the aim to mask bad smells of not well washed away soil; the impression is that the stronger is the fragrance, the greater is the manufacturer’s concern about the detergents effectiveness…
Very persistent scents specifically intended for laundry detergents are made by specialized laboratories: such fragrances must hold on to the textile fibres even throughout various rinsing phases, must be distinctly perceptible even after ironing or tumble-drying; maybe they should perfume the wardrobe too… Using perfume-less detergents, many washes must be carried out to remove such strong fragrances from clothes.
Perfumes – either of natural or synthetic origin – often carry with them some concerning issues, about health risks. Once their molecules are absorbed by the breath or through the skin, almost all tend to bioaccumulate in fatty tissue and in breast milk; they are little and light-weighted (indeed they are air-dispersed), so they are quite “intrusive” and easily pass through natural barriers, such as blood vessels and placenta. If they were safe and healthy, it would be no problem; unfortunately some of them show long term toxicities, including mutagen action towards DNA and chromosomes, reproductive system toxicity, teratogenicity, endocrine disruption and, often, allergenicity.
A good scent is pleasant and may be accompanied by a sense of well-being, kind of like when we climb a mountain and we take a deep breathe of clean air; it’s just that… it is not only “air” and in excessive doses may lead to health problems, especially kids. Therefore it is recommended to be exposed to low doses of perfumes and, if possible, to avoid not only allergen-based, but very persistent perfumes too.