English Language · English

Comprehension: Read the given passage and answer the question that follows. Microplastics were once thought to be only an ocean problem. But now, scientists have found them in the air, soil, and even drinking water. Studies show that these tiny plastic pieces can travel long distances through wind and water, making it almost impossible to avoid them. Because of this, scientists are now studying how microplastics affect humans, animals, and the environment—not just oceans. Researchers are trying to understand how these particles behave inside living organisms. Early research shows that most microplastics pass out of the body, but some may stay in tissues or carry harmful chemicals. However, scientists still don't fully know the long-term effects because many studies are small. Microplastics are now seen as signs of deeper problems in how we produce, use, and throw away plastic. Scientists warn people not to panic—finding microplastics does not automatically mean they are toxic. But their presence everywhere raises questions about waste, pollution, and the durability of plastic. The issue is no longer a local problem; it has become a global challenge, and experts say we need better materials and more responsible consumption. Question: According to the passage, what is a primary reason why the long-term health effects of microplastics remain uncertain?