The sodium citrate developer is a very safe developer, consisting only of citric acid and sodium carbonate.
The contrast agent used with the developer is potassium dichromate. It is classified as moderately toxic by skin contact and ingestion and highly toxic by inhalation, and a *suspected* carcinogen. You can buy it in solution from B&S which avoids the inhalateion issue. Dichromates are no more toxic than many substances in common use in photography, including hydroquinone and many other reducers, selenium, the ferric salts we use in vandyke and kallitype printing (ferric oxalate and ferric ammonium citrate). If used with the same care we should give all toxic substances used in the darkroom the risks of dichromate are very small, IMO.
Originally Posted by Wayne