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Proposals to Amend the New Zealand (Maximum Residue Limits of Agricultural Compounds) Food Standards 2008

11 Proposal to exempt Chlorhexidine

It is proposed that an MRL exemption is set for chlorhexidine when used as a topical antiseptic for all food producing species except fish. It is proposed that Schedule Three of the NZ (MRL) Food Standards 2008 be amended to include the following; this will be the resulting entry for chlorhexidine in Schedule Three of the NZ (MRL) Food Standards 2008:

Amendment Rationale

The proposed MRL exemption represents a reassessment of a currently approved use patterns for chlorhexidine, which has a very low toxicity. Chlorhexidine is commonly used in human medicine, and following the treatment of food producing species with chlorhexidine, any levels of residues likely to exist are insignificant. For these reasons chlorhexidine residues do not require a regulatory limit. Chlorhexidine can therefore be exempted from the requirement of a New Zealand MRL.

Chemical Information

Good Agricultural Practice

Chlorhexidine and chlorhexidine digluconate are used as general disinfectants for cleansing wounds, skin, instruments and equipment. They are also used as teat dips and sprays for an aid in the control of mastitis in dairy cattle.

Residues Information

Chlorhexidine is poorly absorbed after topical application. Following use as an antiseptic treatment of wounds or skin, residues in tissue would be expected to be insignificant. The use of chlorhexidine as a teat dip or spray in dairy animals usually occurs following milking; residues are unlikely to occur in milk from the following milking.

Dietary Risk Assessment

Residues of chlorhexidine are unlikely to occur in consumed milk or animal products. In addition chlorhexidine is poorly absorbed orally through the gastrointestinal tract with the majority of residues passing unchanged into the faeces. Given the low reported toxicity of chlorhexidine it would not be expected to result in any dietary risk.

Toxicological / Public Health Assessment

Chlorhexidine has a long recorded history of safe use in human medicine for topical antiseptic and disinfectant use and within oral preparations such as lozenges and dental gels. Human volunteers have been reported to easily tolerate levels of 2000mg orally administered chlorhexidine per day for 7 days. Given that residues are unlikely to occur following the use of chlorhexidine as a veterinary medicine there is no risk to the public through the proposed MRL exemption.

Other International MRLs

To meet New Zealand’s obligations under the Agreement on the Application of Sanitary and Phytosanitary Measures the proposed MRL exemption will be notified to the World Trade Organization. Any country may choose to comment if they believe the proposed MRL exemption represents a barrier to their trade.