The Grand Tour rider was out training this morning when the incident occurred. According to reports in De Telegraaf the car was travelling at 80kph when it hit ten Dam from behind.
The rider was taken to hospital with injuries sustained to his back and arms. His team were unavailable for comment when contacted by Cyclingnews.
Ten Dam is meant to line up at the Vuelta a España, which starts later this month.
"It's never great of course when you get hit by a car but the timing of this couldn't have been worse since I was really looking forward to the last part of the season and especially the Vuelta. It's still too early to really understand exactly what impact this injury will have on the rest of my season but as always I'll come back fighting."
More to follow...