Researchers have attempted to quantify the environmental effects of the Food and Drug Administration’s (FDA) recommended policy of disposing certain drugs by flushing down a toilet or sink if take-back programs are not readily available.

The active pharmaceutical ingredients (APIs) on the FDA’s ‘flush list‘ include buprenorphine, diazepam, fentanyl, hydrocodone, hydromorphone, meperidine, methadone, methylphenidate, morphine, naloxone, naltrexone, oxycodone, oxymorphone, sodium oxybate, and tapentadol.

The results, published in Science of The Total Environment, showed that even if the entire mass supplied for clinical use was flushed (taking into account illicit sources of API), and “no metabolic loss, environmental degradation, or dilution of wastewater effluents were used in estimating concentrations”, that the release of 10 ‘flush list’ APIs (buprenorphine, diazepam, fentanyl, hydromorphone, meperidine, methadone, methylphenidate, morphine, oxycodone, tapentadol) poses a ‘negligible’ eco-toxicological risk.

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More eco-toxicological data is required for the remaining APIs (hydrocodone, GBH/sodium oxybate, naloxone, naltrexone, oxymorphone). However, the researchers suggest that these would also be negligible, posing a ‘low eco-toxicological risk’.

The FDA maintains the flush approach as they believe that the risks of harm or death from keeping these products far outweigh any potential risk to human health or the environment that may come from disposal by flushing. 

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