BALLABGARH, India — In late November, an urgent email popped up in the inbox of Hindustan Syringes & Medical Devices, one of the world’s largest syringe makers.It was from UNICEF, the United Nations agency for children, and it was desperately seeking syringes. Not just any would do. These syringes must be smaller than usual. They had to break if used a second time, to prevent spreading disease through accidental recycling.Most important, UNICEF needed them in vast quantities. Now.“I thought, ‘No issues,’” said Rajiv Nath, the company’s managing director, who has sunk millions of dollars into preparing his …