Triclosan concentrations in freshwater systems in the United States - PowerPoint PPT Presentation

Triclosan concentrations in freshwater systems in the United States Angela L. Perez, Ph.D. January 11, 2017

Purpose of our study  Characterize TCS in freshwater aquatic systems and untreated and treated source waters supplying municipal drinking systems in the US, 1999-2012  Compare measured values to health and aquatic guidance values 1/11/2017 2

Objectives  Create database of freshwater TCS concentrations  Literature search 1999-2012  “triclosan”, “triclosan AND water”, and “antimicrobial AND water”  Peer-reviewed studies, gray literature, municipality reports  Raw data and summary statistics  500 papers identified  46 fit data quality objectives  45 states and 1 US territory 1/11/2017 3

Water Classification 1. Untreated water Effluent 2. Effluent-impacted environmental 3. 4. Environmental waters Post-treatment drinking water 5. 1/11/2017 4

Statistical Analysis  Regression on order statistics (ROS)  Extrapolate values from samples below LOD or censored data  ANOVA on water categories  Dunn’s all-pairwise for significant differences  Kaplan Meier to calculate upper confidence limit 1/11/2017 5

Triclosan Meta-data  46 studies included; raw data from 44 studies N =242 Untreated N =453 93% N=192 1% Effluent 83% N=228 Effluent-Impacted 62% Environmental Environmental N=1195 11% Finished % = detection frequency 1/11/2017 6

Triclosan Meta-data Effluent- Impacted ng/L Untreated Effluent Environmental Environmental Finished N 237 192 228 1195 453 mean (imputed) 9715 775 130 13 4 maximum* 393000 8000 2300 2830 734 *Based on raw data 1/11/2017 7

Sources of Variability  Lack of information on sampling locations  Challenges classifying water categories (e.g. effluent-impacted classified as environmental)  Spill events  TCS input: Rural vs. urban, heavy vs. light industry  Wastewater treatment processes vary across locations  Biological and chemical transformations  Half life between 2 days and 2000 days  Stream pH affects solubility/adsorption  Stream flow, seasonal effects 1/11/2017 8

Risk Characterization - Human Health  EPA chronic RfD = 0.3 mg/kg bw/day = 1.05 x 10 7 ng/L (70 kg human and 2 L drinking water per day)  Max TCS concentration in finished water = 734 ng/L EPA Chronic RfD  TCS in drinking water does not pose a significant human health risk 1/11/2017 9

Risk Characterization - Ecological Wilson et al. Orvos et al.  Algae most sensitive species  15 ng/L Chronic LOEC (Wilson et al., 2003)  In exceedance:  82% effluent-impacted waters  11% environmental waters  500 ng/L Chronic NOEC (Orvos et al., 2002)  In exceedance:  5.3% effluent-impacted waters  0.25 % environmental waters  376 ng/L Health Canada PNEC 1/11/2017 10

Reflections  Strengths  Sample size  Geographically comprehensive  Careful analysis of each paper  Weaknesses  Categories not well defined (effluent-impacted vs. effluent or environmental)  Sources of variability not accounted for (e.g. stream sizes) 1/11/2017 11

Conclusions  In over 2300 samples, TCS is widely detected  Low human health risk as a result of triclosan exposures via drinking water  Effluent-exposed freshwaters may exceed threshold indicators for ecological health, esp. algae  Contact: angela.perez@cardno.com 1/11/2017 12

Research Questions  Are TCS concentrations or detections in aquatic systems decreasing over time?  Does the recent FDA ban on TCS in hand-soap result in a change in TCS concentrations detected in aquatic systems?  Contact: angela.perez@cardno.com 1/11/2017 13

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