What we found

Our selection of dyes included major brands Clairol, Garnier, L'Oreal, Schwarzkopf, and Wella. We also included a product called Just for Men, one "herbal" hair colour purchased from a health store, and Shinuo hair dye from The $2 Shop in Wellington.

No ingredients disclosed

Of all the products we bought, Shinuo hair dye gave the most cause for concern. The list of ingredients was incomplete. And there was no information on how to contact the New Zealand importer or the manufacturer if someone wanted to ask questions. What's more, about half the writing on the packaging was in Chinese.

When we contacted The $2 Shop's head office, managing director Brian Salmon told us the product had not been approved for sale in the store. Salmon said the Wellington shop was in breach of its franchise for selling the dye and would receive written notice of this.

The hair-dye could contain chemicals declared unsafe to use - we just don't know. We don't think it should be on sale and we strongly advise against buying it.

Banned in the EU

Our shopping expedition also turned up one product, Schwarzkopf's Live Salon Permanent (dark brown), which indicated it may contain an ingredient called 2-aminomethyl-p-aminophenol. A potential allergen, this substance was banned in the EU in 2006. It can still be sold here because our regulations haven't been updated.

Schwarzkopf told us it stopped using the ingredient in 2007. But, as we found, old stock that may contain the substance can still be bought in stores here.

Risks from skin sensitisers

We couldn't tell exactly what was in the dye we bought at Wellington's $2 Shop - but all the other products we purchased contained ingredients classified by the European Commission's Scientific Committee on Consumer Products (SCCP) as "extreme" or "strong" skin sensitisers. These are ingredients that have the potential to cause serious allergic reactions. In our sample, all except the "herbal" hair colour Herbatint listed at least two different skin sensitisers. (See Products compared for the sensitisers we found in each product.)

Herbatint - which markets itself as a more gentle dye - nevertheless contains an ingredient called p-phenylenediamine (PPD). PPD is classified as an "extreme" sensitiser and is identified as a key cause of allergic reactions. It's estimated PPD is used in over two-thirds of permanent hair dyes that you can buy off the shelf and is also common in salon dyes. We found it in five of the products in our sample.

PPD used to be banned from hair dyes in some European countries. But EU regulations now allow it to comprise up to six percent of a product - the same rule that we have here. Manufacturers aren't required to state exactly how much PPD is present and, depending on the colour, the level can vary. There tends to be more PPD in darker dyes, which is bad news for wannabe brunettes. Semi-permanent dyes, which use different ingredients, don't usually contain PPD.

Several of the other skin sensitisers we found in our sample are listed among the 42 ingredients provisionally approved for use in Europe while they're being evaluated to assess their safety and work out acceptable levels. This provisional approval expires on 31 December 2009.

"Natural" hair dyes

As we discovered with Herbatint, products that claim to be more "natural" can contain some of the same kinds of ingredients as mainstream brands. The UK consumer magazine Which? recently tested five "natural" hair dyes. Three of the five products were found to contain synthetic chemicals, including extreme or strong skin sensitisers such as PPD.