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

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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

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Water Classification

1.

Untreated water

2.

Effluent

3.

Effluent-impacted environmental

4.

Environmental waters

5.

Post-treatment drinking water

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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

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Triclosan Meta-data

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 46 studies included; raw data from 44 studies

N=242 N=192 N=228 N=1195 N=453 Untreated Effluent Effluent-Impacted Environmental Environmental Finished 83% 93% 62% 11% % = detection frequency 1%

Triclosan Meta-data

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ng/L Untreated Effluent Effluent- Impacted 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

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

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Risk Characterization - Human Health

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EPA Chronic RfD

 EPA chronic RfD = 0.3 mg/kg bw/day = 1.05 x 107 ng/L

(70 kg human and 2 L drinking water per day)

 Max TCS concentration in finished water = 734 ng/L

 TCS in drinking water does not pose a significant human

health risk

Risk Characterization - Ecological

 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

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Orvos et al. Wilson et al.

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)

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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

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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

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