# Presentation: 362496

## Dr. Richard Reiss
Sciences International, Inc.

October 20, 2005

**Sciences International, Inc.**
**October 20, 2005**

**Environmental Safety of Active Pharmaceutical Ingredients**

## Introduction

**Talk will focus on triclosan (TCS) and triclocarban (TCC)**
**For each chemical, I will provide:**
**General environmental fate characteristics**
**Representative environmental concentration data**
**Toxicity levels of most sensitive species**
**Comparison of concentrations and toxicity levels**

## General Environmental Fate Properties

**Both compounds have similar fate properties:**
**Very low vapor pressures**
**Soluble in water**
**Highly adsorbent to organic matter**
**Both compounds will reach the environment through down-the-drain disposal**
**Both show significant degradation in water treatment plants (next slide)**
**TCS shows rapid removal from water column in die-away studies (2-5 hour half-life)**
**Also, biodegrades in soil in 17-35 days**
**TCC shows rapid degradation in biosolids (10 hour half-life)**

## Average Removal Rates in Wastewater Treatment Plants

| Actives | Activated Sludge | Trickling Filter |
| --- | --- | --- |
| TCC | 94% | 77%
 |
| TCS | 95% | 83% |

**Predominant pathway is biodegradation**

## Freshwater Aquatic Environmental Concentrations in U.S. for TCC

| Source | Results |
| --- | --- |
| TCC Consortium, 2002
 | Max=0.23 ppb, 90% less than 0.05 ppb |
| Halden & Paull, 2005 | Max=6.8 ppb in sites with significant raw sewage
 |
| EPA E-FAST model, TCC consortium, 2002 | Model estimates, high-end at outfall = 0.017 ppb, median at outfall = 0.0013 ppb |

## Freshwater Aquatic Environmental Concentrations in U.S. for TCS

| Source | Study |
| --- | --- |
| USGS, 2002 | 75th Percentile = 0.2 ppb, median of measured conc =0.14 ppb.  Sampling locations chosen as “susceptible to contamination.” |
| USGS, 2004
 |  Non-detectable in typical flow conditions, Max=0.14 ppb in low flow conditions |

## Most Sensitive Aquatic Species

| Actives | Chronic Toxicity and No Observed Effect Concentrations (NOECs) |
| --- | --- |
| TCC | Waterflea, Ceriodaphnia dubia, NOEC = 1.5 ppb
Algae, 6 ppb, minimum algistatic concentration |
| TCS | Blue-green algae, NOEC = 0.5 ppb  (algistatic, not algicidal, recovery in 3-6 days)
Waterflea, Ceriodaphnia dubia, NOEC=6 ppb |

## Comparison of Environmental Concentrations to NOECs for TCC

**TCC Consortium**
**Measurements**

## Comparison of Environmental Concentrations to NOECs for TCS

**USGS Measurements**

## Terrestrial Risk

**Both TCS and TCC can be present in sewage sludge in small concentrations**
**Sludge may be used as soil amendments in agriculture**
**Low potential of exposure to ecological species**
**Due to low mammalian toxicity, low sludge concentrations, and low potential for exposure, risks to ecological species are expected to be minimal ****(Federle et al., 2002)**

## Conclusions

**The large majority of the TCC and TCS mass will degrade in treatment plants, but some will be present in effluent and sludge**
**Neither is expected to persist in the environment**
**TCC shows low risk to aquatic species when high-end concentrations are compared to the no effect level for the most sensitive species**

## Conclusions (cont)

**TCS may have transitory algistatic effects on some algal species under worst case conditions and only in aquatic environments close to the effluent pipe**
**Downstream effects are not expected**
**TCS is unlikely to have any significant effects on non-algal species**