Environmental Project, 944 – Evaluation of Health Hazards by exposure to Triazines and Degradation Products – 7 Risk characterisation via drinking water exposure

Evaluation of Health Hazards by exposure to Triazines and Degradation Products

7 Risk characterisation via drinking water exposure

A NOAEL of 0.20 mg/kg bw/day is selected for the human risk characterisation of the triazines and their degradation products in drinking water.

The general population is predominantly exposed to triazines and their degradation products from intake of contaminated drinking water.

Table 2 shows data for selected intakes of triazines and their degradation products via drinking water. The intakes are calculated based on the assumption that an adult weighing 70 kg in average drinks 2 litre of water every day and a child weighing 10 kg in average drinks 0.8 litre of water every day. If, e.g., the water contains 0.1 μg/l, which is the administrative threshold limit in drinking water for individual pesticides, the intake will be 0.003 μg/kg bw/day and 0.008 μg/kg bw/day for adults and children, respectively.

Table 2. Selected intakes of triazines and their degradation products via drinking water

Water concentration	Intake for adults	Intake for children
0.1 μg/l	0.003 μg/kg bw/day	0.008 μg/kg bw/day
1.0 μg/l	0.03 μg/kg bw/day	0.08 μg/kg bw/day
10.0 μg/l	0.3 μg/kg bw/day	0.8 μg/kg bw/day
100.0 μg/l	3 μg/kg bw/day	8 μg/kg bw/day

Table 3 shows calculated margins of safety for triazines and their degradation products.

The margin of safety (MOS) is calculated as:

MOS = NOAEL / intake of triazines and their degradation products

Table 3. Margin of safety (MOS)

Water concentration	MOS for adults	MOS for children
0.1 μg/l	66667	25000
1.0 μg/l	6667	2500
10.0 μg/l	667	250
100.0 μg/l	67	25

When evaluating specific contaminations for the purpose of setting a MOS the following should be kept in mind. First the abovementioned theoretical MOS are based on a NOAEL which in fact may turn out to be a LOAEL, however the relevant study is not yet fully reported. Furthermore, any situation where setting of MOS for these substances is required should be seen in context with the possible effects of other contaminants. Finally the setting of MOS should always be related to the level of concern for the actual situation, e.g. impact of the contamination over time.