POTENTIAL DEVELOPMENTAL NEUROTOXICITY OF PESTICIDES USED IN EUROPE Bjorling MA, Andersen HR and Grandjean P.,

Environmental Health, 7:50 (2008) http://www.ehjournal.net/content/7/1/50/abstract/

This study centered on the use of pesticides in the 27 nations of the European Union (EU), which are primarily the same pesticides that are used in the US. Published studies on the neurotoxicity of pesticides were examined, and special attention given to risks associated with early development, mixed exposure to pesticides and the accompanying neurological deficits.  While some of the pesticides in these studies are now banned, those in current use are thought to have the same toxic characteristics and mechanisms. Widely-used pesticides that are potentially neurotoxic include: organophosphates, carbamates, chlorophenoxy herbicides, pyrethroids, and ethylenebisthiocarbamates. 

“Laboratory experimental studies using model compounds suggest that many pesticides used in Europe …can cause neuro-developmental toxicity,” according to Philippe Grandjean of the Harvard School of Public Health. Likewise, because many pesticides by design are toxic to insect brains, the same could be true for people. Of particular concern is the brain of a developing fetus is far more vulnerable than that of a young child. Grandjean is concerned because the testing of pesticides does not include developmental neurotoxicity studies. Furthermore, because adverse side effects can be severe, long lasting and irreversible on brain development even at low exposure, preventing exposure should be a serious priority.

This study urges greater testing, targeted research and caution when approving pesticides since scientists are unsure as to their effects.  These researchers therefore advise, “While awaiting more definite evidence, existing uncertainties should be considered in light of the need for precautionary action to protect brain development.”

LOW-DOSE AGROCHEMICALS AND LAWN-CARE PESTICIDES INDUCE DEVELOPMENTAL TOXICITY IN MURINE PREIMPLANTATION EMBRYOS. Greenlee, A. et al.,

Environmental Health Perspectives, 112(6): 703-709 (2004) http://ehp03.niehs.nih.gov/article/fetchArticle.action?articleURI=info:doi/10.1289/ehp.6774

This murine embryonic study found that parental exposure to pesticides could profoundly effect the development of embryonic cells. Results conclude that occupational exposure to pesticides may increase infertility, spontaneous abortion, preterm delivery, and congenital anomalies. 

Combinations of pesticides meant to mimic formulations of pre-emergent herbicides (those that prevent the germinating weeds from establishing) and post-emergent herbicides showed cell death similar to that of the individual pesticides dicamba and pendimethalin and dicamba, 2,4-D, and atrazine.

However, combinations mimicking insecticides (chlorpyrifos, terbufos, and permethrin), and lawn-care herbicides (dicamba, 2,4-D, and MCPP) show increased cell death as well as reduced blastocyst development.  Furthermore, effects on mice reveal 58–65% fewer embryos incubated with the mixture of lawn herbicides (dicamba, 2,4-D, and MCPP) progressed to blastocyst.

INTERACTIONS BETWEEN PESTICIDES AND COMPONENTS OF PESTICIDE FORMULATIONS IN AN IN VITRO NEUROTOXICITY TEST Axelrad J.C., Howard C.V. and McLean W.G.

Toxicology. 173(3):259-268 (2002) http://www.ncbi.nlm.nih.gov/pubmed/11960678

This study seeks to determine if combinations of the organophosphate pesticides diazinon and chlorpyrifos, as well as the additives in commercial compounds, cause cell damage directly. The researchers used live cells that are sensitive to neurotoxicity and were able to determine that certain combinations may cause synergy, or greatly enhanced, direct neurotoxicity to live cells. This data suggests that although some chemicals on their own are non-toxic or somewhat toxic, combinations, such as those found in commercial pesticide products, may be much more dangerous, and require more research.

DEVELOPMENTAL TOXICITY OF COMMERCIAL HERBICIDE MIXTURE IN MICE: EFFECTS ON EMBRYO IMPLANTATION AND LITTER SIZE. Cavieres, M. et al.,

Environmental Health Perspectives, 110:1081-1085 (2002) http://www.jstor.org/pss/3455431

This toxicological analysis found that the herbicides dichlorophenoxyacetic acid, mecoprop, dicamba and their inactive ingredients have severely inhibited the ability of fertilized eggs to implant in the uterine wall in mice.  The study is important because it raises the question of toxicity of the inactive ingredients of herbicide mixes that are currently protected by law under the ubiquitous term ‘trade secrets’.