The following is a bit terse, but I would point to several key points of relevancy:
* measuring the sublethal physiological impacts of pesticides -- particularly in the field -- requires a more sophisticated experimental design than measuring acute mortality in a controlled laboratory setting.
* single-chemical risk-assessment method does not support reliable predictions
* we encourage an increased exchange of ideas and research tools among the disciplines of toxicology, ecology, and conservation.
* * *
Changing pesticide-use patterns over time
> In the mid-twentieth century, concerns over pesticide effects on the health of humans and the environment were largely focused on the organochlorine class of insecticides, including DDT (dichlorodiphenyltrichloroethane), aldrin, chlordane, dieldrin, endrin, heptachlor, and toxaphene. The number of chemicals under consideration was relatively low, and the organochlorine pesticides were overtly toxic to aquatic life, with mass fish kills commonly reported following their application (e.g., Cottam and Higgins 1946). The pesticides were and are measurable in sediments and tissues (and, to a lesser extent, water), making it possible to track their movements to the present day. Moreover, they are highly persistent and lipophilic and accumulate in species at upper trophic levels. Most uses of DDT and the other organochlorines were banned in the United States in the 1970s, in part because pesticide biomagnification was linked to eggshell thinning, clutch failure, and the decline of eagles, osprey, pelicans, and other piscivorous birds (e.g., Porter and Wiemeyer 1969).
>
> The banning of organochlorines reduced the inputs of a few high-profile insecticides into aquatic ecosystems, including the San Francisco Estuary. Nevertheless, the number and diversity of pesticides (e.g., insecticides, herbicides, fungicides) in current use have greatly expanded during the past 50 years. These chemicals are by design less persistent than the legacy pesticides listed above, and many are more difficult to measure in aquatic systems such as the San Francisco Estuary (see Kuivila and Hladik 2008). Fish kills, now rare, do not necessarily reflect the comprehensive effects of toxics on ecosystems. The leading edge of toxicological research is focused instead on sublethal health effects, including endocrine disruption, impaired immune function, abnormal development, altered behaviors, reduced growth, and reproductive impairment. Sublethal toxicity can influence both individual fitness and interspecific inter-actions (e.g., predator–prey dynamics, disease transmission). However, measuring the sublethal physiological impacts of pesticides -- particularly in the field -- requires a more sophisticated experimental design than measuring acute mortality in a controlled laboratory setting.
>
> Uncertain linkages between pesticides and accelerated population declines are not restricted to the San Francisco Estuary and watershed. For example, pesticides are suspected as drivers of the recent colony-collapse disorder among honey-bees (Apis mellifera) and other pollinators in North America and Europe. An extensive exposure survey recently showed complex combinations of pesticides and pesticide meta-bolites in bees and hives (wax and pollen), with an average of 6 and a maximum of 39 residue detections per sample (Mullin et al. 2010). Despite this relatively refined exposure information, pollination researchers confront many of the same uncertainties as the aquatic research community. For example, pesticides are one of many categories of chemical and nonchemical stressors whose interactions are poorly understood, the toxicity of pesticide mixtures is poorly understood, the effects of pesticides may be sublethal (e.g., memory loss and other forms of disorientation among foraging bees), and a single-chemical risk-assessment method does not support reliable predictions (Mullin et al. 2010). Pesticides have also been implicated in the worldwide decline of amphibians (e.g., Davidson et al. 2001), and research in recent years has been focused on pesticide mixtures, sublethal effects, and the impacts of interacting chemical and nonchemical stressors. To meet these common scientific and management challenges, we encourage an increased exchange of ideas and research tools among the disciplines of toxicology, ecology, and conservation.
quoted for review purposes only
A Perspective on Modern Pesticides, Pelagic Fish Declines, and Unknown Ecological Resilience in Highly Managed Ecosystems
Author(s): Nathaniel L. Scholz, Erica Fleishman, Larry Brown, Inge Werner, Michael L.Johnson, Marjorie L. Brooks, Carys L. Mitchelmore, Daniel SchlenkReviewed work(s):
Source: BioScience, Vol. 62, No. 4 (April 2012), pp. 428-434
Published by: University of California Press on behalf of the American Institute of Biological Sciences
Stable URL: http://www.jstor.org/stable/10.1525/bio.2012.62.4.13 .
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