Problem 1: Number of chromosomes. A human cell has 46 total or 23 pairs of chromosomes. Following mitosis, the daughter cells would each have a total of ______ chromosomes. After meiosis I, the two daughter cells would have _____chromosomes, and after meiosis II ______ chromosomes.
The permissible exposure limit (PEL or OSHA PEL) is a legal limit in the United States for exposure of an employee to a chemical substance or physical agent.For chemicals, the chemical regulation is usually expressed in parts per million (ppm), or sometimes in milligrams per cubic meter (mg/m 3). TWA is the average exposure over a specified period of time, usually a nominal eight hours. This means that, for limited periods, a worker may be exposed to concentration excursions higher than the PEL, so long as the TWA is not exceeded and any applicable excursion limit is not exceeded.
The maximum permissible exposure for a person under 18 working with radiation is one-tenth the adult limit or not to exceed 500 millirems per year above the 300+ millirems of natural sources, plus medical radiation.5,000 millirems per year level was the federal occupational limit during World War II and until about 1950 for radiation workers and soldiers exposed to radiation. The occupational limit became 15,000 millirems per year around 1950. In 1957, the occupational limit was lowered to a maximum of 5,000 millirems per year.