Higher levels of fluoride in water may be associated with lower intelligent quotient (IQ) in children, revealed a study by National Toxicology Program of USA.

According to the study, including the treated public water, other sources of fluoride such as beverages, toothpaste, and mouthwash can result in exceeded consumption of fluoride.

It concluded that ‘higher levels of fluoride exposure, such as drinking water containing more than 1.5 milligrams of fluoride per litre, are associated with lower IQ in children’.

However, it also stated that the NTP review was designed to evaluate total fluoride exposure from all sources and was not designed to evaluate the health effects of fluoridated drinking water alone. 

On the flipside, the study revealed that there was insufficient data to determine if the low fluoride level of 0.7 mg/L currently recommended for US community water supplies has a negative effect on children’s IQ.

The conclusion regarding lower IQs in children was mainly drawn from epidemiological studies conducted in non-US countries, including Canada, China, India, Iran, Pakistan, and Mexico, where some pregnant women, infants, and children were exposed to fluoride levels exceeding 1.5 mg/L in drinking water.

It is important to note that the World Health Organization (WHO) has set a safe limit for fluoride in drinking water of 1.5 mg/L, according to the study.

The NTP also did not find any evidence of negative effects of fluoride on adult cognition.