41-46 Human defense mechanisms could be disrupted by a class oforganic pollutants in fish and other food, according to new research.The study appears to be the first to identify the mechanism bywhich chemicals like flame retardants—present in many householdfurniture items, like sofas and mattresses—and the pesticide DDTblock a key protein from removing toxins from the body. The protein,P-glycoprotein, defends against toxins that entered the body bytransporting them for removal. The new research shows that persistentorganic pollutants, known as POPs, latch onto proteins and preventthem from functioning.“These environmental chemicals form intimate interactions,” saysAmro Hamdoun, a researcher at the University of California, SanDiego. “But instead of being expelled, these proteins interfere with theability of p-glycoprotein from doing its job.”Awareness about the risks of POPs is nothing new. Internationalhealth campaigners have sought to remove POPs from the environmentfor decades. But until now scientists did not understand exactly how thepollutant harmed humans. Researchers had previously thought thatPOPs simply slipped by the protein. But the new study shows that thepollutants actually interact with the protein and make it less effective.The study also shows that POP can exist at risky levels in theenvironment. Some fish caught in the Gulf of Mexico were found tohave levels of the pollutant that could lead to high levels ofp-glycoprotein inhibitors. That finding could prevent humans whoconsume polluted fish from defending themselves against a variety oftoxins, according to the study. And, while the study looked only at fish,Hamdoun says high levels of POPs could be present in meat and dairy.“This is something that scientists and policymakers will thinkabout and make sure that those fish don’t end up in our food supply.”
41 Which one is not existent in our environment?
(A) flame retardants
(B)POPs
(C) pesticide DDT
(D) P-glycoprotein