Child’s Development and Respiratory System Toxicity

Humans grow slower than many other species. A lot of growth and weight gain happen during childhood, and specifically during the first two years of age. Humans reach 70% of their adulthood height at the age of six. Growth accelerates during certain periods of childhood known as growth spurts. These growth spurts happen six times through childhood which are; neonatal, infantile, early childhood, middle childhood, late childhood, and pubertal period [1]. Yet, growth during each of these growth peaks varies remarkably among individuals, mainly due to the integrative and mixed influence of cultural, behavioral, nutritional, genetic, and environmental factors. General body growth (i.e. weight and height) differs from internal organs growth. Human organs grow at different rates because cell divisions in these organs vary in time and pattern. While the liver and kidneys grow fast throughout childhood, the brain has shown minimal weight increase from childhood to adulthood. Growth of adipose tissues and muscles in childhood is not as fast as it is in teenage and adult years. The Lungs grow and gain weight faster than the kidneys, but slower than the liver [2,3].