Water treatment equipment identifies and processes chemicals

a. For non carcinogens, there is an obvious dose-response relationship. When it is lower than a certain dose level, it will not cause harmful effects. This dose is called "threshold". The water treatment equipment is calculated based on the daily tolerable intake (TDI) when establishing the limit of such chemicals.

b. Daily tolerable intake (TDI). When a chemical substance is ingested from food or drinking water in a lifetime without causing obvious health hazards, the estimated daily intake is the daily tolerance, calculated in mg / kg.

c. No harmful effects were observed at the dose level (NOAEL). In animal experimental studies, the highest dose (or concentration) in which no harmful effects were observed was NOAEL. The lowest dose (or concentration) of harmful effects was LOAEL.

d. Uncertainty coefficient. As mentioned earlier, the limits are largely based on the data obtained from animal experiments. Obviously, there are many uncertain factors when extrapolating from animal experimental data to human beings. In order to ensure that the established limits of chemical substances are sufficient to protect human health, uncertainty factors need to be fully considered when calculating the limits. Therefore, uncertainty factors are often used, which can also be understood as "safety factors", so that the established limits have sufficient limits

In general, the sources and values of uncertainty coefficients are considered as follows:

The uncertainty coefficient caused by interspecific differences (extrapolated from animal data to human) is generally 100 days, and the uncertainty coefficient caused by intraspecific differences (individual differences) is generally 10 days. The uncertainty coefficient due to experimental suitability (availability) is determined according to the specific situation, and the maximum is 10. The uncertainty coefficient due to the nature and severity of the toxic effect is determined according to the specific situation, and the maximum is 10. The uncertainty coefficient of each source is determined according to the source and degree of uncertainty of the above uncertainty factors, but the overall uncertainty coefficient shall not exceed 10000. Otherwise, such a huge uncertainty will make the calculated TDI value inaccurate. Generally speaking, the uncertainty coefficient is 100 ~ 1000.