Dar seafood ppp standard

Hazard identification and characterisation: Methylmercury is readily (>95%) absorbed from the gut following ingestion and is rapidly distributed via blood to the tissues, including the brain where it accumulates and is slowly demethylated to inorganic mercury. The major routes of excretion are through the bile and faeces, with lesser amounts in urine.
The toxic effects of methylmercury, particularly on the nervous system, are well documented and an extensive body of literature is available. Most of what is known about effects in humans has been derived from investigations of large-scale poisoning episodes in Japan and Iraq, although more recently attention has focused on effects following chronic low-dose exposures through fish consumption. The severity of the effects depends largely on the magnitude and duration of the dose, with effects in adults occurring at much higher levels of exposure than those linked to effects in children following in utero exposure. The developing nervous system is thus considered the most sensitive target for toxicity, with the critical exposure period being during in utero development when the foetus is undergoing very rapid neurological development.
In the adult, the first effect observed following exposure to high levels of methylmercury is typically paraesthesia (numbness and tingling in lips, fingers and toes), which frequently appears some months after the exposure first occurred. In severe cases, there is progression to loss of coordination, narrowing of the visual fields, hearing loss and speech impairment, paralysis and death. The lowest observed effect level or threshold dose for neurological effects in adults following short to medium-term exposure to methylmercury is 200 ppb blood mercury (equivalent to 50 ppm hair mercury or an estimated intake of 2.8 µg/kg bw/day) (WHO 1990). The applicability of this level to chronic low-level exposure (for example, from fish consumption) is uncertain.
In the infant, following in utero exposure through maternal fish consumption, the effects observed typically manifest as decreased scores on tests that measure neurocognitive and fine motor function. A level of maternal hair mercury estimated to be without appreciable adverse effects in the offspring of fish eating populations is 14 ppm (equivalent to 56 ppb blood mercury or an intake of 1.5 µg/kg bw/day) (JECFA 2003).
A PTWI for methylmercury of 3.3 µg/kg bw was established by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) in 1988 (WHO 1990). This level was considered protective of the general population, but not the developing foetus. In June 2003, JECFA established a lower level of 1.6 µg/kg bw, to take account of the most sensitive population subgroup (JECFA 2003).