Abstract
Environmental risk assessment of chemicals is based on single species tests at the individual level with single compounds.
However, the protection goal is the sustainability of a population, which faces several natural stressors and mixtures of chemicals in the
environment. Therefore, experiments were undertaken to quantify the combined effects of chemicals with different modes of action on
Daphnia magna populations. Populations continuously exposed to dispersogen A and at abundance equilibrium were treated with a 2-d
pulse of p353-nonylphenol. In previous studies, dispersogen A was shown to act as a natural info-chemical, promoting the reproduction
of daphnids (higher offspring quantity) coupled with reduced offspring fitness, whereas nonylphenol in pulsed-exposure caused sizeselective
mortality. Dispersogen A caused accelerated population growth to maximum abundance, shifted the population structure
towards smaller individuals, and increased the population sensitivity to nonylphenol. The authors showed that a positive effect observed
at the individual level can be transposed to a negative effect when monitored at the population level. So far, positive effects are not
addressed in environmental risk assessment, and even in higher-tier testing, population structure is not quantified. Both factors indicate a
potential mismatch between protection aim and risk assessment practice.
However, the protection goal is the sustainability of a population, which faces several natural stressors and mixtures of chemicals in the
environment. Therefore, experiments were undertaken to quantify the combined effects of chemicals with different modes of action on
Daphnia magna populations. Populations continuously exposed to dispersogen A and at abundance equilibrium were treated with a 2-d
pulse of p353-nonylphenol. In previous studies, dispersogen A was shown to act as a natural info-chemical, promoting the reproduction
of daphnids (higher offspring quantity) coupled with reduced offspring fitness, whereas nonylphenol in pulsed-exposure caused sizeselective
mortality. Dispersogen A caused accelerated population growth to maximum abundance, shifted the population structure
towards smaller individuals, and increased the population sensitivity to nonylphenol. The authors showed that a positive effect observed
at the individual level can be transposed to a negative effect when monitored at the population level. So far, positive effects are not
addressed in environmental risk assessment, and even in higher-tier testing, population structure is not quantified. Both factors indicate a
potential mismatch between protection aim and risk assessment practice.
| Original language | English |
|---|---|
| Pages (from-to) | 1604-1610 |
| Number of pages | 7 |
| Journal | Environmental Toxicology and Chemistry |
| Volume | 31 |
| Issue number | 7 |
| Early online date | 30 Apr 2012 |
| DOIs | |
| Publication status | Published - Jul 2012 |