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Fate of Triclosan in Irrigated Soil: Degradation in Soil and Translocation into Onion and Tomato
Author(s) -
Mendez Monica O.,
Valdez Erika M.,
Martinez Eileen M.,
Saucedo Melissa,
Wilson Brittan A.
Publication year - 2016
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2015.07.0386
Subject(s) - triclosan , degradation (telecommunications) , chromosomal translocation , soil retrogression and degradation , agronomy , environmental science , soil water , biology , soil science , engineering , medicine , pathology , telecommunications , biochemistry , gene
This study determined the fate of triclosan, a prevalent wastewater contaminant in recycled waters and surface streams, when soil and crop plants were irrigated at environmentally relevant concentrations. Soil triclosan concentrations were monitored in an 8‐wk and in a 16‐wk study without plants to determine triclosan degradation. Onion ( Allium oschaninii O. Fedtsch.) and tomato ( Solanum lycopersicum L.) were assessed for growth and triclosan accumulation at four levels of triclosan exposure (0, 0.015, 0.15, and 1.5 µg L −1 ) in irrigation waters within ranges of those found in recycled waters and associated receiving streams. Onions were grown for 8 wk and tomatoes were grown for 8 wk (short‐term study) and 12 wk (long‐term study) in potting soil. Soil triclosan concentrations increased (5‐fold) with triclosan levels applied to soils alone. With repeated application, the half‐life of triclosan was 18 d, with low‐level accumulation in soil. Bioaccumulation of triclosan was observed in all edible portions of onions (115–435 ng g −1 ), primarily in bulbs, with no discernible impact on biomass. In both short‐ and long‐term tomato studies, triclosan translocated to shoots and fruits (approaching a translocation factor of 1) at the highest level examined. Even at low triclosan concentrations typically found in recycled waters and receiving streams, agricultural irrigation presents an additional exposure route for organic contaminants to humans via commercial crops. Our study indicates that bulb crops, in particular, would likely accumulate high levels of triclosan. However, concentrations detected in both onions and tomato fruits determined here are below current human exposure limits. Core Ideas Irrigation waters are a potential source of triclosan exposure to crops. Environmentally relevant concentrations of triclosan were examined. Triclosan bioaccumulated in edible tissues of onions and tomatoes. Concentrations determined are not considered harmful at current limits of exposure.