Selling, General and Administrative Expenses:
Selling, general and administrative expenses were approximately $26,335,000 for the nine months ended September 30, 2022, as compared to $25,308,000 for the nine months ended September 30, 2021, an increase of $1,027,000. This increase is related to an increase in salaries, severence, commissions and related costs of approximately $1,326,000, an increase in sales and marketing costs, which include advertising and conference attendance of approximately $1,098,000, an increase in travel and entertainment costs of approximately $513,000, an increase in occupancy costs of approximately $1,110,000 related to the rent expense on our new manufacturing facility and an increase in other general and administrative expenses of approximately $53,000. These increases were offset by a decrease in royalty expenses of approximately $691,000, a decrease in non-cash restricted stock expense of approximately $1,711,000 related to restricted stock units granted to the Company’s executive officers and a decrease in non-cash stock compensation expense of approximately $671,000.
Loss on Foreign Currency Transactions:
For the nine months ended September 30, 2022, the loss on foreign currency transactions was approximately $6,967,000 as compared to a loss of approximately $2,084,000 for the nine months ended September 30, 2021. The 2022 loss was directly related to the decrease in the spot exchange rate of the Euro to the U.S. dollar as of September 30, 2022 as compared to December 31, 2021. The spot exchange rate of the Euro to the U.S. dollar was $0.98 per Euro as of September 30, 2022, as compared to $1.14 per Euro at December 31, 2021. The 2021 loss of approximately $2,084,000 was directly related to the decrease in the spot exchange rate of the Euro as of September 30, 2021 as compared to December 31, 2020. The spot exchange rate of the Euro to the U.S. dollar was $1.16 per Euro at September 30, 2021, as compared to $1.22 per Euro at December 31, 2020.
History of Operating Losses:
We have experienced substantial operating losses since inception. As of September 30, 2022, we had an accumulated deficit of approximately $253,232,000, which included losses of approximately $32,046,000 and $15,252,000 for the nine-month periods ended September 30, 2022 and 2021, respectively. Historically, losses have resulted principally from costs incurred in the research and development of our polymer technology, clinical studies, and general and administrative expenses.
Liquidity and Capital Resources
Since inception, our operations have been primarily financed through the issuance of debt and equity securities. As of September 30, 2022, we had current assets of approximately $32,381,000 including unrestricted cash on hand of approximately $22,552,000 and current liabilities of approximately $10,119,000. As of September 30, 2022, $25 million of our total shelf amount was allocated to our ATM facility, all of which remains available. In addition, we have $15 million of debt availability, providing financial flexibility, if needed. In April of 2022, we received approximately $740,000 in cash from the approved sale of our net operating losses and research and development credits from the State of New Jersey.
As of September 30, 2022, cash and cash equivalents were $22.6 million compared to $30.2 million as of June 30, 2022. The change in cash, or our third quarter 2022 cash burn, was approximately $7.7 million. This cash burn was due to lower-than-expected sales volumes, product gross margins that were lower due to decreased production volumes, and other factors (e.g. a delay in realizing savings from cost cutting due to notice periods and labor laws in Europe). A reduction in product gross margins from 80% in Q1 2022 to 64% (excluding the previously mentioned inventory write-off) in Q3 2022, unfavorably impacted our cash burn by approximately $1.9 million. We expect product gross margins to return to previous levels as we transition production fully to the new facility by the end of this year, end the lease at our Deer Park Drive facility, and begin to capture manufacturing efficiencies driven by expected improvement in market conditions and increased product demand.
We are also managing our resources proactively, continuing to invest in key areas such as our U.S. clinical program. while driving cost-cutting throughout our Company. At the beginning of Q2 2022, we began instituting tighter cost controls and have reduced our headcount (including full and part-time employees and consultants) internationally by 10%, with the goal of reducing our cash burn. In addition, we have shifted our R&D headcount to funded grant programs, where we have an extensive $13.2 million backlog as of September 30, 2022. Some of our costs savings of our headcount reduction are not yet visible in our results due to notice periods and labor laws in Europe, but will be reflected in our 2023 operating budget. We are continuing to identify areas for additional potential cost savings to reduce our future cash burn. Meanwhile, we are working diligently to prioritize activities that we believe have a near-term return on