24
Aug
Scientific Breakthrough Sheds Glowing Light on Pesticide Research
(Beyond Pesticides, August 23, 2023) Researchers are investigating a cutting-edge method to identify the impact of pesticides on reproductive health—shrinking the wait time from months to weeks. Scientists at the University of California, Davis, are developing a method for identifying harmful chemicals in pesticides with the help of glowing fish. This scientific breakthrough could revolutionize pesticide research and help prevent long-term health problems caused by exposure to these chemicals.Â
Pesticide exposure can cause acute and long-term health problems for the human endocrine system, the hormone system that regulates many biological processes from reproduction to blood sugar, growth, and more. Beyond Pesticides has written about the connections between EPA-registered pesticides and involuntary abortions, reproductive cancers, pregnancy loss, early-onset puberty, and more. Â
The American Academy of Pediatrics (AAP) has expressed concern over the limited or missing data regarding the health effects of pesticides and food additives on infants and children, who are more vulnerable to chemical exposures. AAP has identified several compounds as being of particular concern, including bisphenols, which are commonly used in the lining of metal cans; phthalates, which are used in adhesives and plasticizers; nonpersistent pesticides, which have been addressed in a previous AAP policy statement; perfluoroalkyl chemicals (PFCs), which are used in grease-proof paper and paperboard food packaging; perchlorate, an antistatic agent used for packaging in contact with dry foods with surfaces that do not contain free fat or oil; nitrates and nitrites; and artificial food coloring. In 2012, AAP issued a statement on childhood exposures to pesticides concluding that reducing pesticide exposures in foods may be significant for children. AAP also noted that choosing organic food, which has significantly lower toxic pesticide residues, is also beneficial to larger environmental issues, as well as human health impacts like pollution and global climate change.Â
These risks to reproductive health and multigenerational impacts is where the red- and green-glowing zebrafish come in. Sean Burgess, PhD and Bruce Draper, PhD are developing a new approach with a genetically modified strain of zebrafish called Danio rerio. The modified or “transgenic†strains of fish have been developed through a process of altering the fishes’ DNA by combining it with DNA from other organisms or inserting foreign DNA. Fluorescent genes can be added to aid in tracking proteins, cells, and organs (like gonads and ovaries). The new strain of zebrafish, Danio rerio, displays their sex through color coding, with green fluorescent protein produced by Sertoli cells found only in the male gonad and red fluorescent protein produced by oocytes found only in the female gonad. By exposing a few dozen zebrafish larvae to a chemical and waiting several weeks to see if their sex ratio is skewed toward males, scientists can quickly determine if the chemical is harmful.Â
The new method, developed by Dr. Burgess and Dr. Draper, is much faster than traditional methods, which require waiting until 90 days post-fertilization to distinguish sexually-mature male and female zebrafish visually. The UC Davis researchers claim that the fishes’ color-coded gonads should allow scientists to determine the sex of the genetically modified zebrafish within 10-20 days post-fertilization. Â
Dr. Burgess, a professor in the Department of Molecular and Cellular Biology, studies the reproductive toxicity that can result in infertility, repeated miscarriages, or children with increased risk for Down syndrome and other chromosome disorders. Dr. Burgess said, “[The new method is] way more efficient than anything else out there right now. We have high expectations that this is going to work.”Â
Traditional testing methods for pesticide impact on reproduction are often time-consuming and costly, as they rely on dissecting mice to find the chemical effects on reproductive tissues. To avoid this process, Zebrafish are freshwater fish native to South Asia and they are frequently used to study the early stages of human development. Dr. Draper said, “Seventy percent of the genes in zebrafish have human counterparts, called orthologs.”Â
The researchers hope to begin using their “GloNad” assay for toxicity screening in a pilot experiment to screen nine of the most commonly used pesticides in California for reproductive effects. This initial test could eventually pave the way for broader use of the GloNad assay. Critics of transgenic strains, like the Danio rerio, have voiced moral, environmental, and public health concerns about genetic modification. However, Dr. Burgess and Dr. Draper are not planning to release the fish into the natural environment or sell them for consumption, rather they are being used for pesticide research alone. Â
Ninety pesticides are currently known to the state of California to cause birth defects or reproductive harm and require cancer warnings under Prop65. But these toxicities could potentially be linked to a broader range of pesticides and other chemicals, such as the aforementioned bisphenols, which are used in manufacturing some plastics.Â
The method developed by Dr. Burgess and Dr. Draper could benefit millions of people in California’s Central Valley, who are at elevated risk for exposure to pesticides because they live or work near agricultural production sites. With the help of red- and green-glowing zebrafish, scientists may be able to identify harmful chemicals far more quickly and prevent the long-term health impacts of pesticides. Read more about the connection between reproductive health and pesticides in Beyond Pesticides’ Daily News archives here. Â
All unattributed positions and opinions in this piece are those of Beyond Pesticides.Â
