Table 2.
What makes water supplementation acceptable as a public policy?
| Aspects in favor of adding lithium in drinking water | Aspects against adding lithium in drinking water | |
|---|---|---|
| 1.- Balance of risks and benefits | ||
| Lithium in drinking water could generate public health benefits | There is an inverse association between trace dose levels of lithium in drinking water and the suicide mortality rate in women and the total population (8–10). | There is susceptibility to ecological fallacy in the meta-analysis of ecological studies. Memon et al. propose conducting randomized clinical trials supplementing water supplies with lithium (10). |
| Efficacy of low-dose lithium at the population level appears to be better than a selective intervention | Individual risk of committing suicide is difficult to know in advance. Many times, health systems and services do not have enough tools for timely and effective help (7). Population-level interventions to prevent suicide are highly cost-effective in most scenarios (61). | Suicide is relatively a rare event, where supplementation of drinking water with lithium would act in a mostly low-risk population. |
| Trace amounts of lithium appear to have little or no serious adverse effects | Adverse effects from lithium are dose dependent (12). Serious renal adverse effects are rare and associated with chronic use for decades (22). | Broberg et al. (50) reported an association between urinary lithium concentration and thyroid function markers. However, no association was found between lithium and thyroxine or thyroid stimulating hormone values outside the normal range. Harari et al. (51) reported an association between lithium levels in maternal blood and urine, and lower fetal measurements. |
| The practice of fortifying food and drinking water is already established and successful. | There are examples such as water fluoridation, food supplementation with vitamins and minerals, at an international level (57, 59, 60) | |
| Lithium's adherence to drinking water is not that different in principle from current fortification practices | ||
| 2.- The potential of alternatives that are of a lower range of intervention to achieve the same goals | ||
| Alternative 1: Table salt (62). | Risk of stigmatization: choosing salt rich in lithium can lead to stigmatization of the population that consumes it. Ignorance can discourage the purchase of fortified foods. The benefits would be less compared to a more massive policy like water supplementation | Table salt would involve lower risk of exposure to potentially vulnerable populations (for example, children) |
| Alternative 2: General medication (62). | General medication leaves unprotected people at risk who do not have access to health services, especially mental health. | In high-risk patients, prophylactic measures such as lithium as general medication are taken in those with suicidal considerations or with high-risk factors. As it is a choice, it is possible to obtain consent. Adverse effects end up being more justified since they are high-risk patients, and it allows monitoring. |
| Alternative 3: Individual prescript (62) | The population impact would be quite low with individual prescription. Evidence regarding the dose associated with reducing suicide risk is still heterogeneous and limited (9, 11). | Similar to general medication, individual prescription could be offered to patients at high risk of suicide, with the possibility of obtaining consent, and with adverse effects being more justified than a general measure. |
| 3.- The role of consent in the event of possible harm | ||
| Confidence level in the measure to be implemented | Distrust can alter the implementation of population-based health measures, especially where there is a lack of credibility in the authority (60, 62), and the substance to be added is psychotropic, such as lithium. | |
| Collateral consequences | Collateral consequences should be considered, such as increased trade in lithium-free water leading to more monetary expenses, environmental waste, or increased consumption of sugary beverages due to avoiding drinking water (62). | |