Flue gas of incinerators and health effects

When an incinerator is badly operated, or if the choice of the type of combustion chamber has been made wrong, the flue gases may affect human health. Correct and strict application of emission regulations are a must to preserve public health.

Incinerators must be equiped with a continuous emission monitoring system which calculates the half hourly average values and the daily average values of all emissions.

Below we comment::

• which chemical reaction occurs at given temperatures,
• what are the most common pollution sources 
• how health can be affected
• advized values for safe emission levels, if any.

Substance	Generation, source and heath effects
Dioxins and furans	Chemical formation Dioxins are formed with 2 chlorinated benzene rings, linked together by one or two O-atoms . Connection with 1 O-atom: PCDF (polychloredibenzofurane) Connection with 2 O-atoms: PCDD (polychloredibenzodioxines) If the temperature is high enough, min. 850 C and the combustion time is long enough (2 sec)  the dioxins are completely destroyed.If the temperature of the combustion system is below 850 Degr.C,dioxin molecules may be "cracked" into smaller molecules and dioxin molecules may be reformed at temperatures of  around 400 Degr.C (for example in heat exchangers).In the latter case,heavy metals - present in the flue gas stream - act as a catalyst. Pollution source Dioxins and furanes are mainly generated by heat systems and open fires. Dioxins are also created by waste incineration, the non-ferro industry and by domestic heat systems (especially wood furnace). The dioxins get into the human body mainly by the food chain. Mostly: fat fish, milk, fat of meat, product with animal fat like sauses, cakes and desserts. Most important health effects Dioxins are causing cancer and may have an effect on the growth and development of the human body. It may disturb the normal functioning of hormones and the immunity system of the human body. Human biomonitoring results (table 1) in different geographical area’s of environmental assessment (in Belgium, Europe) show that humans have always a certain level of dioxins and furanes in their body. There are no significant differences of the levels measured in different area’s of environmental assessment. table 1 : Dioxins and furanes (pg Calux TEQ/g fat) in human bodies Sea port zone City aglomeration Agricultural zone Fruit tree zone Domestic waste incinerator zone 18,5 21,2 21,0 21,6 20,7 Advized values of safe levels There is no advise for safe levels.The lower the concentration of dioxins in the human body , the lower the chance for cancer.
PCB's	Chemical formation Formation PCB’s are formed by the chemical reaction of a free Cl-atom with two benzene rings,linked together with an O-atom. The reaction temperature is situated  between 250 °C and 400 °C. Pollution sources PCB's have 209 chemical derivations. PCB138, PCB153, PCB180 are the most frequent. PCB's where produced and used by the industry, due to their excellent thermal properties. For example in transformators of refrigerators.At present they are banned and may not be produced or be used anymore. But they remain in our environment due to leakages and treatment of PCB containing machines. PCB's accumulate in fat of fish, fat of meat, milk, etc. Most important health effects PCB's may cause a reduced weight of newly born babies, disturb the normal functioning of the thyroid gland and may cause a slower development of intelligence. PCB's may disturb the housekeeping of hormones and the immunity system in the human body.
Cadmium	Pollution sources One of the most important pollution sources of cadmium is cigarette smoke. In the past,mainly non-ferro industry and household waste incinerators were the cause of cadmium emissions. Also some construction materials where containing cadmium. Cadmium can be present in salads, spinach and seldom,but also in meat from animals being breaded in polluted area's. Food and cigarette smoke are the most common potential sources of cadmium exposure for the population. An average person ingests about 30 micrograms (ug) of cadmium from food each day. Smokers absorb an additional 1 to 3 ug per day from cigarettes.( Average cadmium levels in cigarettes range from 1,000 to 3,000 ppb.) Most imporatant health effects During pregnancy,cadmium may disturb the functioning of the placenta. This may cause a loss in weight of the baby.This is why babies of smoking mothers are mostly lighter. Cadmium may also affect the functioning of the kidneys, disturb bone production and cause cancer. Some adviced values for safe levels Cadmium present in human blood may safely reach 5 µg/L,Cadmium in urine, 2 µg/g. Persons who smoke one or more packs of cigarettes per day,reach easily 2 ug/l, tenfold the level of nonsmokers (about 0.2 ug/l).
Lead	Pollution sources In the past mainly, non ferro industry, cars using leaded  fuel, lead tubes for drinking water and lead based paint were the main pollution sources. Today a lot of these sources don't exist anymore. But,due to continuous circulation of dust and water,some lead remains in our environment. Most important health effects Exposure to lead before or after birth of young children,may have a negative effect on inteligence development and/or or concentration capacity. By a prolonged exposure to low amounts of lead may affect the functioning of the kidney's and even fertility may be disturbed. Some adviced values of safe levels The WHO (World health organization) considers that  health is not endangered for levels below 100 µg/L of blood.
Dust (PM10, PM20, PM50)
CO
HCl
NOx