Table 1.

Summary of toxicity data available for photoinitiators used in stereolithography resins.

Compound	w/w	Available	Toxicological Information
Phosphine oxide compounds 1 (Type II)	0.1–5%	FORMlabs e.g., Dental and E-Shell series	Fertility impairing effect [47], acute and chronic toxic for aquatic organisms [48], toxic effect on mouse NIH 3T3 cells [38]. Not readily biodegradable by OECD criteria [48,49]. LD50 Oral rat > 5000 mg/kg (OECD) [48] LC50 (48 h) Oryzias latipes—6.53 mg/L (JIS K 0102-71) [49,50] EC50 (48 h) Daphnia magna—3.53 mg/L (OECD 202) [48,50] EC50 (72 h) Pseudokirchneriella subcapitata—1.56 mg/L (OECD 201) [49]
Hydroxy- acetophenone (Type II)			Readily biodegradable (OECD 301B) [51] LD50 Oral Rat—2.240 mg/kg [51] LC50 (96 h) Salmo gairdneri—25 mg/L [51] EC50 (48 h) Daphnia magna—50 mg/L [51]
Benzophenone compounds 2 (Type II)	<10%	UV-cured inks	Causes liver hypertrophy and kidney adenoma in rats [52] EC50 (24 h) Daphnia magna—0.28 mg/L [53] LC50 (96 h) Pimephales promelas—14.2 mg/L [53] BP-3 and BP-4: LC50 (48 h) Daphnia magna—1.09 and 47.47 mg/L LC50 (96 h) Brachydanio rerio—3.89 and 633.00 mg/L
Camphorquinone		Dental resins	EC50 mouse fibroblasts—235 $\mathsf{\mu }$M [30]
1-hydroxy cyclo hexyl phenyl ketone		FORMlabs Irgacure 184	LC50 (96 h) Danio rerio—24 mg/L [54] EC50 (48 h) Daphnia magna—59.3 mg/L (OECD 202) [54] EC50 (72 h) Desmodesmus subspicatus—14.4 mg/L (OECD 201) [54]
Triarylsulfonium salt (Cationic)3	1–10%	3D Systems	EC50 (24 h) Daphnia magna—4.4 mg/L [55] EC50 (48 h) Daphnia magna—0.68 mg/L [55]

¹ Including diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) and bis acyl phosphine oxide (BAPO). ² Including benzophenone-3 (BP-3), benzophenone-4 (BP-4) [56]. ³ 50% propylene carbonate and 50% mixed triarylsulfonium salts, i.e., an antimonate mixture.