Phosphoryl trichloride

Endpoint summary

Description of key information

"Phosphoryl trichloride is hydrolyzed in seconds or minutes in water or moist air. Studies on metabolism and toxicokinetics of the parent compound are not feasible" (OECD SIDS for phosphoryl trichloride, 2004).

 

Regarding the justification for the read-across to the degradation products phosphoric acid and hydrochloric acid please refer to "Justification for a read-across of Phosphoryl trichloride (CAS no. 10025-87-3, EC no. 233-046-7) [Target] and its hydrolysis products phosphoric acid (CAS no. 7664-38-2, EC no. 231-633-2) [Source] and hydrochloric acid (CAS no. 7647-01-0, EC no. 231-595-7) [Source] concerning toxicity and ecotoxicity" (Heilkenbrinker, 2019), which is attached to the concerned (target) endpoint study records and the section 13 (Assessment reports).

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Additional information

“Phosphoryl trichloride is hydrolyzed in seconds or minutes in water or moist air. Studies on metabolism and toxicokinetics of the parent compound are not feasible. Distribution in the body is limited due to hydrolysis. Phosphoryl trichloride is a toxicant acting at the portal-of-entry. It is unlikely to reach organs distant from the portal of entry. Therefore, systemic toxicity not related to the effects of irritation is not expected by any route. The products of hydrolysis, hydrochloric acid and phosphoric acid, also act at the portal of entry” (OECD SIDS for phosphoryl trichloride, 2004).

Phosphate and chloride are normal constituents of the body (OECD SIDS for hydrogen chloride, 2002; EFSA, 2005).

 

Chloride:

"Chloride is a normal constituent of the blood and the excess is expected to be excreted into the urine (Ganong, 2001). The uptake of sodium chloride via food is about 3.5-9 gram per person per day (Battarbee and Meneely, 1978; FASEB, 1979). It means 2.1-5.5 g chloride is taken into the body via food. The daily intake through inhalation during an 8-hour work shift is estimated to be only 108 mg/day under the worst case at the working place. The body pool of this anion (Cl-) is large, and the uptake of chloride via exposure to hydrogen chloride/ hydrochloric acid is much less than the uptake of chloride via food, it is therefore unlikely that occupational aerosol exposures significantly alter the normal body load. The uptake of protons via exposure to hydrogen chloride/ hydrochloric acid is not expected to change the pH in the blood under normal handling and use conditions (non-irritating). The pH of the extracellular fluid is regulated within a narrow range to maintain homeostasis. Via urinary excretion and exhalation of carbon dioxide, the pH is maintained at the normal pH of 7.4 (Ganong, 2001)"(OECD SIDS for hydrogen chloride, 2002).

 

Phosphate:

"Phosphorus (as phosphate) is an essential dietary constituent, involved in numerous physiological processes, such as the cell’s energy cycle (high-energy pyrophosphate bonds in adenosine triphosphate [ATP]), regulation of the whole body acid-base balance, as component of the cell structure (as phospholipids) and of nucleotides and nucleic acids in DNA and RNA, in cell regulation and signaling by phosphorylation of catalytic proteins and as second messenger (cAMP). Another important function is in the mineralization of bones and teeth (as part of the hydroxyapatite). Reviews and safety evaluations for phosphorus are available from the Joint FAO/WHO Expert Committee on Food additives (JECFA, 1982), the Food and Nutrition Board of the Institute of Medicine (FNB, 1997), and the UK Expert Group on Vitamins and Minerals (EGVM, 2003). JECFA has used the nephrocalcinosis, induced by excessive phosphate intake in rats, as the critical effect to set a maximum tolerable daily intake (MTDI) of 70 mg/kg for phosphoric acid and phosphate salts. The FNB set an upper level for phosphorus of 4.0 g/day for adults, based upon a NOAEL which represents the extrapolation of the phosphorus intake to serum phosphorus concentration curve in adults up to the intake of phosphorus which would result in serum phosphorus levels of infants, which are considered to be safe for tissues with respect to metastatic mineralization. The UK Expert Group on Vitamins and Minerals used the gastrointestinal effects due to high supplemental phosphate intake, to establish a NOAEL of 750 mg/day for supplemental phosphorus"(EFSA, 2005).