State the adverse effects of polyhalogenated compounds. How can the adverse effects of chlorofluorocarbons be prevented?

(N/A) $(i)$ Methylene dichloride: Exposure to lower levels of methylene chloride in air causes dizziness,nausea,tingling,and numbness in the fingers and toes. In humans,direct skin contact with methylene chloride causes intense burning and mild redness of the skin. Direct contact with the eyes can burn the cornea.
$(ii)$ Trichloromethane (Chloroform): Inhaling chloroform depresses the central nervous system. Breathing about $900 \ ppm$ of chloroform for a short time can cause dizziness,fatigue,and headache. Chronic chloroform exposure may cause damage to the liver,where it is metabolized to phosgene,and to the kidneys. $2 CHCl_{3} + O_{2} \xrightarrow{\text{Light / Oxidation}} 2 COCl_{2} + 2 HCl$. Chloroform is slowly oxidized by air in the presence of light to form an extremely poisonous gas; therefore,it is stored in closed,dark-colored bottles completely filled to exclude air.
$(iii)$ Tetrachloromethane $(CCl_{4})$: Exposure to carbon tetrachloride causes liver cancer in humans. Common effects include dizziness,lightheadedness,nausea,and vomiting,which can cause permanent damage to nerve cells. In severe cases,it leads to stupor,coma,or death. It can cause irregular heartbeat and eye irritation. When released into the air,it rises to the atmosphere and depletes the ozone layer,increasing human exposure to $UV$ rays,which leads to skin cancer and immune system disruption.
$(iv)$ Freons: In the stratosphere,freons initiate radical chain reactions that upset the natural ozone balance.
Prevention of adverse effects of $CFCs$: $CFCs$ are highly stable and non-reactive. They initiate chemical chain reactions that disturb the ozone layer. It is recommended that $CFCs$ used in refrigerators be replaced by other environmentally friendly compounds.