The toxicity of the biocides zineb, nabam and their derivatives to the ship‐fouling diatom Amphora coffeaeformis

Abstract

The toxicity of the fungicides zineb and nabam has been studied, using the persistent ship‐fouling diatom Amphora coffeaeformis. Growth and oxygen evolution/consumption studies showed that time was required for zineb to exert a toxic effect, suggesting that toxicity may be due to the degradation products 5,6‐dihydro‐3H‐imidazo (2,1‐c)‐1,2,4‐dithiazole‐3‐thione (DIDT) and ethylene diisothiocyanate (EDI). These were found to be more toxic than zineb and nabam, EDI being the most potent of the compounds tested.

A marked synergism was observed between zineb and copper (from cuprous oxide and copper thio‐cyanate) and nabam and copper. Zineb and tributyltin oxide (TBTO) showed an antagonistic response. The zineb derivative DIDT and copper showed the most pronounced synergistic effect. EDI and cuprous oxide showed an additive or mildly antagonistic effect.

Key words:

• Amphora coffeaeformis
• zineb
• nabam
• DIDT
• EDI
• antifouling paints
• synergism

Notes

Present address: International Paint Ltd, Stoneygate Lane, Felling, Gateshead, Tyne & Wear NE100JY, UK.

To whom reprint requests should be sent.