Science in the box

Environmental risk assessments are iterative, i.e. the assessments are repeated and refined across all environmental compartments and continuously bringing in more realistic assumptions.
An ingredient is judged to be environmentally compatible if the Predicted No Effect Concentration (PNEC) – that is, the concentration that causes no adverse effect to the environmental organisms – is higher than the Predicted Environmental Concentration (PEC) – which is the concentration one estimates to find in the environment.
The assessment has to be repeated for each relevant environmental compartment, such as wastewater treatment plants, rivers and soils.

The PEC/PNEC ratio is used as an indicator of risk and is called the Risk Quotient (RQ):

• RQ < 1 (i.e., PEC < PNEC): PEC is smaller than PNEC. This means that the concentration in the environment will be below levels that can cause adverse reactions. Therefore, no adverse effects are anticipated. The substance can be used safely.
• Environmental Risk Assessment (ERA) is a tiered process that progresses from using screening-level tests and conservative assumptions to increasingly more realistic experiments paired with more realistic assumptions.

The environmental assessment is developed using a step-wise approach. There are five steps in an environmental risk assessment addressing both short-term and long-term exposures in order to understand the biodegradation profile of a laundry cleaning product, detergent or soap and its affect on the environment, wastewater and ecosystems.
The first phase involves the calculation of the predicted environmental concentrations. We have to address short-term exposures, such as an accidental spill, which may result in high concentrations in a river but for a relatively short period of time, as well as long-term exposures that are the result of down-the-drain discharge of used products by the consumer. An important part of the exposure assessment is to understand the biodegradation profile of the ingredient and the extent to which we expect it to be removed during wastewater treatment .

Next, the toxicity of the ingredient to certain environmental "indicator species" is assessed. For the aqueous environment, indicator species are typically a freshwater fish, a freshwater invertebrate and freshwater green algae. For sediments and soils, they are sediment dwelling organisms, earthworms and terrestrial plants. For air, the indicator species would be birds. However, for these types of products, the concentrations of detergent ingredients in air are usually so low that bird toxicity data are not needed for the risk assessment.

In the final phase, the probability of adverse effects or the environmental risk is assessed, given the estimated environmental concentrations and the toxicity to indicator species extrapolated to ecosystems. For high volume ingredients, P&G may decide to monitor the concentrations of these ingredients in the environment after they have been on the market for some time, to confirm the accuracy of the predicted environmental concentrations. A simple environmental risk assessment may be completed in a few weeks or months, but comprehensive environmental programmes for high volume ingredients may take years to complete.

STEP 1: Review of Physical-Chemical Properties

The first step in any ERA is to identify the target environmental compartments (water, soil, air…).
First, the physical-chemical properties of the substance are obtained from the literature or measured in the laboratory. These properties - water solubility, fat solubility , vapour pressure, melting point, boiling point, octanol /water partition coefficient, hydrolysis, surface tension and photolysis will be needed by the toxicologists and the environmental scientists for their work.

This information is used in multimedia environmental models to assess the target environmental compartments. From this exercise, it becomes apparent which compartments (water, soil, air…) will be important to consider in the risk assessment.

STEP 2: Estimation of Environmental Exposure

Exposure models are calculated and assessed for each of the relevant compartments.
For new substances, the expected environmental concentrations are calculated using exposure models and a realistic prediction of the anticipated market volume of the product(s) for which the ingredient is intended. For laundry and household cleaning ingredients, water and soil are the most important compartments.

STEP 3: Environmental Fate and Effects

Where QSARs may not provide enough information, further information about environmental fate is needed.
The toxicity data for environmental indicator species are obtained from the literature, from historical P&G records or from laboratory testing. In some instances, toxicity estimates from Quantitative Structure-Activity Relationships (QSAR) may suffice, such as for a low volume ingredient or an ingredient with very low toxicity or both. However, the uncertainty associated with QSAR estimates is much higher than with measured values, and this uncertainty has to be taken into account in the risk assessment via the use of assessment factors. These factors are used to divide the lowest available effect level (or no observed effect level in case of tiers 3 and 4 tests) to derive a Predicted No Effect Concentration (PNEC) for the ecosystem.
Information about the environmental fate of the ingredient is needed as well and may be obtained from the literature, historical P&G records or laboratory testing. Here, the physical/chemical properties provide valuable information about the likely partitioning behaviour of the ingredient in the environment. For instance, poorly soluble ingredients will likely be removed in sewage treatment. Ingredients that are very sorptive to organic matter will be largely removed as well, specifically via a sorption mechanism.

STEP 4: Risk Assessment

Environmental risk assessments combine the first three steps, comparing the anticipated exposure with toxicity information.
Having reviewed all the available information and conducted necessary testing, the risk assessment combines the information from Steps 1, 2 and 3. For each of the relevant compartments (i.e., water, soil, sediment), the anticipated exposure concentrations are compared with the toxicity information. Short-term exposure scenarios are compared with acute (short-term) toxicity data; long-term exposure scenarios are compared with chronic (long-term) toxicity data. Before safety clearance can be granted, the risk assessor must be able to demonstrate that adequate safety margins exist in each of the relevant compartments.

For down-the-drain products, wastewater treatment and septic tanks are always considered in the risk assessment. Since most P&G products are intended for markets around the world these days, the scenario of direct discharge of wastewater treatment plant effluents, still common in developing countries, is also included in the assessment.

See a P&G Environmental Risk Assessment Case Study on the environmental impact of compaction.

STEP 5: Post-Market Environmental Monitoring

It is not uncommon for P&G to send scientists around the world to measure the actual environmental concentrations of a product after it has been marketed for some time. This is called field monitoring. This is done most often for high volume ingredients, many of which are commodity ingredients; in other words, they are used by many companies.

The result, ideally, is a confirmation of the expected concentrations of these ingredients in household wastewater, effluent from wastewater treatment plants and rivers downstream from these plants. We normally find that the actual concentrations are lower than the estimated ones, which is due to the built-in conservatism in our estimation methods.

Once completed, the ecotoxicology, environmental fate and environmental risk assessment as well as monitoring studies are often published in peer-reviewed scientific literature.

P&G employs scientists with diverse expertise related to fate, effects and risk assessments and life cycle assessments to ensure that there are no adverse effects of P&G laundry and cleaning products on the environment.

The Environmental Stewardship Organization (formerly Environmental Safety Organization) at P&G has been in existence since the late 1960s. For twenty years it was located almost exclusively in Cincinnati, Ohio in the United States. Today, the organization employs about 40 scientists worldwide, with approximately 20% of them working in Europe, primarily at the Brussels Innovation Center near Brussels, Belgium.

The Environmental Stewardship Organization at Procter & Gamble employs Ph.D. scientists in such diverse fields as environmental toxicology, microbiology, biodegradation, ecology, environmental engineering, analytical chemistry, microbial ecology, environmental modelling and life cycle assessments.

In addition to laboratory research, much of the expertise lies in computer-based applications such as exposure modelling, structure-activity relationships (SAR), probabilistic risk assessment, and geographical information systems (GIS).

Environmental Risk Assessment (ERA) integrates a tiered approach to effects testing (from predictive models, to short-term testing, to long-term testing, to ecosystem tests) with a tiered approach to fate testing (from predictive models, to respirometry and benchtop sewage treatment simulation, to testing at realistic concentrations using radio-tracer substances, to measurement of actual concentrations in the environment).

In the 1990s, P&G expanded its in-house ecotoxicity testing and research capabilities with algae, invertebrates, fish and tissue cell cultures as well as its treatability and fate testing capabilities. Current testing capabilities include:

• Toxicity to aquatic plants using green algae and a microtiter plate test design
• Flow-through fish and invertebrate testing of substances
• Respirometry for biodegradation screening
Continuous Activated Sludge and "porous pot" testing for removability
• Benchtop septic tank model

Analytical chemistry support toxicity and fate testing (GC/MS, LC/MS, MS/MS, RAD-TLC, RAD-LC, RAD-GC, LSC, combustion analysis).