Phytotoxicity of Phthalate Plasticisers: 1. DIAGNOSIS AND COMMERCIAL IMPLICATIONS

The toxicity caused by a volatile constituent from certain samplesof flexible polyvinyl chloride (PVC) was due to dibutyl or diisobutylphthalate (DBP or DIBP) plasticisers. It has caused seriousfinancial losses in the horticultural industry. The two phthalateesters have low volatilities, so any toxicity lasts for manyyears. Radish (Raphanus sativus L. cv. Cherry Belle) seedlings,exposed to an air stream containing 160–180 ng dm^–3of butyl phthalates developed chlorotic leaves within 3–4d and died within 12 d. Neither dioctyl nor diisodecyl phthalate(DOP nor DIDP) produced damage in the test plants. Measurementsof photosynthetic and respiratory gas exchange in intact shootsof affected radishes showed that photosynthesis was severelyinhibited whilst respiration was virtually unaffected. Electronmicrographs of sections from young leaves showed disruptionof thylakoid formation and granai stacking. In mature leaves,thylakoids and grana were well formed but chloroplasts wereswollen and the thylakoids were pushed towards the vacuolarside of the chloroplast. Sensitivity to toxic phthalates variesbetween species; all members of the Cruciferae tested were susceptible,tomato less so, and lettuce and ryegrass were resistant. Toxicityof DIBP, from PVC glazing strip, caused a reduction in cropvalue of ?20 000 per acre per year in commercially grown, monocroptomatoes. Key words: Phthalates, plasticiscd PVC, radish bioassay, glasshouse, tomato, toxicity