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Water treatment equipment identifies and processes chemicals

Time:

Jul 28,2022

For non-carcinogens, there is a clear dose-response relationship for their toxic effects, which do not cause harmful effects below a certain dose level, which is called the "threshold". Water treatment equipment When setting limits for these chemicals, they are calculated based on the Tolerated Daily Intake (TDI).

Water treatment equipment identifies and processes chemicals
Water treatment equipment identifies and processes chemicals

a. For non-carcinogens, there is a clear dose-response relationship for their toxic effects, which do not cause harmful effects below a certain dose level, which is called the "threshold". Water treatment equipment When setting limits for these chemicals, they are calculated based on the Tolerated Daily Intake (TDI).

 

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

 

c. Dose level at which no adverse effect was observed (NOAEL). In animal studies, the highest dose (or concentration) at which no adverse effects were observed was NOAEL. The lowest dose (or concentration) at which a deleterious effect was observed was the LOAEL.

d. Uncertainty factor. As mentioned earlier, the limits are determined to a large extent on the basis of information obtained from animal experiments. Obviously, there are many uncertainties when extrapolating from animal experimental data to humans. In order to ensure that the developed limits of chemical substances are sufficient to protect human health, uncertainties need to be fully considered when calculating the limits, so the uncertainty factor is often used, which can also be understood as a "safety factor", so that the developed limits have sufficient safety limits.

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

The uncertainty coefficient resulting from inter-species differences (extrapolated from animal data to humans) is generally 100 days, and the uncertainty coefficient resulting from intra-species differences (individual differences) is generally 10. The uncertainty factor due to experimental suitability (availability) is determined on a case-by-case basis and is a maximum of 10. The uncertainty factor due to the nature and severity of the toxic effect is determined on a case-by-case basis and is a maximum of 10. The uncertainty factor of each source is determined according to the source of the above uncertainties and the degree of uncertainty, but the overall uncertainty factor should not exceed 10000, otherwise, such a huge uncertainty will make the calculated TDI value extremely inaccurate.

Indeed. Generally speaking, the uncertainty coefficient is 100~1000.

Key words:

water equipment

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