Jiro Hamasumi speaks on May 1 at the third Preparatory Committee for the 2020 Review Conference for the Nuclear Nonproliferation Treaty in New York. (Toko Tanaka)

NEW YORK--When the atomic bomb was dropped on Hiroshima on Aug. 6, 1945, Haruko Hamasumi, who was about three months pregnant, was at home about four kilometers from ground zero.

Her son Jiro, born in February 1946, urged representatives attending a U.N. conference here on May 1 to work toward eliminating all nuclear weapons.

"Even though I was in my mother's womb when the atomic bomb was dropped that does not mean I avoided any damage," the 73-year-old said at the third Preparatory Committee for the 2020 Review Conference for the Nuclear Nonproliferation Treaty.

The blast killed Jiro Hamasumi's father, Masao, who was at work at his company office about 500 meters from ground zero when the bomb was dropped.

Jiro believes that he was born in exchange for the death of his father. But it was only when he became a father himself after marrying that he began imagining Masao's anguish at not being able to spend more time with his family because he was suddenly taken away from them by the atomic bomb.

Jiro, who currently resides in Tokyo, was the last of seven siblings. Haruko supported the family by growing produce in the family garden and collecting electricity fees.

It was not until he began working in the hibakusha movement, in his 60s, that Jiro learned that many others who were in their mother's womb when the bomb exploded died at an early age or suffered from illness caused by radiation.

Jiro himself has not experienced any major health problems, but he hasn't stopped worrying about what might happen to himself or his children.

Next year will mark the 75th anniversary of the dropping of the atomic bomb and the 50th anniversary since the NPT went into effect.

But recent trends have gone in the opposite direction from eliminating nuclear weapons.

The United States announced it was withdrawing from the intermediate-range nuclear weapons ban treaty it had signed with Russia.

While the Treaty on the Prohibition of Nuclear Weapons passed in 2017, it has not yet taken effect. Japan, along with all the nuclear powers, has not agreed to the treaty.

Hamasumi feels that the existence of about 14,500 nuclear warheads around the world means "war has not yet come to an end."

He said at the U.N. conference that even 74 years after the dropping of the atomic bomb the effects are still felt physically and psychologically by the hibakusha.