Table 1.

Strengths and limitations of C. elegans as an experimental model organism. [ERA] is a code added to identify those features that prominently apply also to Environmental Risk Assessment.

Strengths	Limitations
• Rapid and productive life cycle (≈3 days generation time and ≈300 progeny per hermaphrodite worm – primary form)1,2 [ERA]	• Become sterile at temperatures above 25 °C1
	• Not all metazoan genes are found in its genome
• Organism transparency allowing a good visualization of internal structures under a microscope1,2 [ERA]
	• No C. elegans cell culture lines are commercially available1
• Small body size (around 1 mm long) and relatively simple physiology and anatomy1,2
	• Experimental manipulation of individual tissues can be difficult due to its small size 1
• Easy and relative inexpensive maintenance in the lab, including to feed experiments1 [ERA]
	• Absence of some molecular pathways of mammals2
• Non-hazardous to lab workers2 [ERA]
	• Absence of several mammalian organs such as eyes, lungs, heart, kidney and liver2
• Exists primarily as a self-fertilizing hermaphrodite1,3
• Simple synchronization of organisms by isolation of newly hatched larvae or by treatment of gravid adults with bleach, with posterior isolation of the eggs1 [ERA]
	• Absence of adaptive immunity2
	• The relatively impermeable cuticle limits toxicants internalization via direct dermal absorption2 [ERA]
• Sexual crosses can be easily performed3
• Complete genome sequence available1 [ERA]
	• Small, unwanted changes in culture conditions, namely in temperature, salt and nutrients concentrations can alter assay results2 [ERA]
• Good conservation of genes (60–80 % homologue genes), signaling common pathways and cellular machinery for DNA replication and repair between C. elegans and humans1,2,4
	• Bad culture practices can result in altered gene expression patterns and accumulation of “dauer” larvae and males2 [ERA]
• Mutant and transgenic C. elegans strains are readily available for many genes2 [ERA]
• Reliable and reproducible DNA mutations are easily inducible3
• A small-scale C. elegans larval growth assay can be conducted in less than a week2 [ERA]
• Possibility of long-term cryopreservation1
• Presents neuronal, motor, digestive, reproductive and endocrine systems2
• Shows endocrine signaling and sensory/behavioral responses to stimuli2 [ERA]
• It is a well understood model organism, namely regarding its genetics, physiology, morphology, neurology and cell signaling pathways1,2 [ERA]

¹Corsi et al., 2015

²Hunt, 2016

³McVey et al., 2012

⁴Leung et al., 2008