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EC number: 202-936-7 | CAS number: 101-37-1
Workers might be exposed to triallyl cyanurate (liquid or vapour) during manufacture, processing or filling in appropriate containers. During formulation, triallyl cyanurate-coated silica particles containing 50 or 70 % TAC are obtained. Exposure may occur to liquid triallyl cyanurate or the vapour; however, the predominant relevant way of exposure is via triallyl cyanurate-coated silica particles.
Since no usable dose descriptors for the dermal and inhalation exposure route are available, the only usable dose descriptor (oral route) to derive long-term DNELs, the dermal as well as inhalation DNELs, regarding acute and long-term effects on workers were determined using route-to-route extrapolation, according to the ECHA guidance document "Guidance on information requirements and chemical safety assessment. Chapter R.8: Characterisation of dose [concentration]-response for human health", November 2012.
For the derivation of all relevant DNELs a NOAEL of 30 mg/kg bw/day obtained in a 90-day gavage study in rats was used. The establishment of an acute toxicity DNEL set for effects occurring after a single exposure of a few minutes up to 24 hours is unnecessary for TAC, as the long-term DNEL is sufficient to ensure, that these effects do not occur. TAC has a very low vapour pressure at room temperature and as a consequence, the formation of aerosols can be considered negligible. Thus, peak exposure significantly higher than the average daily exposure and the long-term DNEL are very unlikely. In addition since TAC did not show any irritating effects, no DNELs for local effects were derived. The assessment of hazards for acute systemic effects and local effects are sufficiently covered by derivation of the DNEL for long-term systemic exposure.
As starting point for derivation of the DNELs, a NOAEL of 30 mg/kg bw/day (for systemic effects) was used which was found in a subchronic toxicity study performed according to OECD 408 (2012-0288-DGT). In this GLP guideline study TAC was administered via gavage at concentrations of 10, 30 and 120 mg/kg bw/day for 90 days. Additional satellite animals for the control, mid and high dose group for observation of reversibility, persistence or delayed occurrence of toxic effects were included for 56 days post treatment. A NOAEL of 30 mg/kg/day was derived based on the significant histopathological changes in the liver in male rats dosed with 120 mg/kg bw/day at the end of the treatment period (which have mainly subsided after the recovery period) and other evidence of toxicity as clinical signs, reduced body weight, effects on functional observational battery parameters, and increased liver weights observed in both female and male animals dosed with 120 mg/kg bw/day. Thus, the NOAEL value of 30 mg/kg bw/day was selected as relevant dose descriptor.
To convert an oral NOAEL (in mg/kg bw/day) into a dermal NOAEL (in mg/kg bw/day, the differences in absorption between routes as well as differences in dermal absorption between rats and humans have to be accounted for. According to QSAR predictions obtained from the Danish (Q)SAR database (2009), gastrointestinal absorption is presumed to be 100%, whereas dermal uptake is predicted to be low (0.001 mg/cm2/event). Based on this, a dermal uptake of 20% is assumed. No differences in dermal absorption between rats and humans are presumed.
The conversion of the oral NOAEL into the dermal NOAEL is performed using the following equation:
Corrected dermal NOAEL = oral NOAEL x ABS oral / ABS dermal
= 30 mg/kg bw/day x 100 / 20 = 150 mg/kg bw/day
Subsequently, the following assessment factors are taken into account for the final DNEL calculation: interspecies differences (4), remaining interspecies-differences (2.5), intraspecies differences (5) and duration extrapolation: subchronic - chronic (2), resulting in an overall assessment factor of 100.
As a consequence, the resulting DNEL for long-term dermal systemic effects is 1.5 mg/kg bw/day for workers.
For calculation of the DNEL for long-term inhalative systemic effects, the dose descriptor has to be converted into a corrected starting point by route-to-route extrapolation. According to QSAR predictions obtained from the Danish (Q)SAR database (2009), gastrointestinal absorption is presumed to be 100 %. The inhalative absorption is considered to be in the same order of magnitude as the oral absorption. Therefore no additional factor is applied for differences between the oral and inhalative intake.
The conversion of an oral NOAEL into an inhalation NOAEC is performed using the following equation:
For workers (light activity):
Corrected inhalatory NOAEC = oralNOAEL x 1/sRVanimal x ABSoral / ABS inhalation x sRVhuman / wRV
The standard respiratory volume for the 8 h exposure is 0.38 m3/kg bw for rats and 6.7 m3 (per person) in humans. The default 8-h respiratory volume of a worker is 10 m³ taking increased activity into account.
For a short-term scenario of 15 min exposure, different standard parameters are used. The standard respiratory volume for the 15 min exposure is 0.012 m3/kg bw for rats and 0.21 m3 in humans. The default 15 min respiratory volume of a worker is 0.3125 m³.
This results in the following equations:
For 8 h exposure:
Corrected inhalatory NOAEC = oralNOAEL x 1/0.38 m3/kg bw x 6.7 m3 / 10 m3
For 15 min exposure:
Corrected inhalatory NOAEC = oralNOAEL x 1 / 0.012m3/kg x 0.21 m3 / 0.3125 m3
Subsequently assessment factors (AF) are listed, which have to be taken into account for the final DNEL calculation: remaining interspecies-differences (2.5), intraspecies differences (5), duration extrapolation: subchronic - chronic (2), resulting in an overall assessment factor of 25 for long-term exposure and 12.5 for short-term exposure (no duration extrapolation applied). The inhalative DNELs for workers are calculated according to the formula DNEL = (corrected starting point)/(overall AF). Thus, the resulting DNEL for long-term inhalative systemic effects is 2.12 mg/m³ and the resulting DNEL for short-term inhalative systemic effects is 134.4 mg/m³.
Since exposure for the general public is precluded, DNELs for the general population are not relevant and thus not derived.
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